EV Digest 5229
Topics covered in this issue include:
1) Re: How simply can battery voltage monitors be made?
by "Mark Fisher" <[EMAIL PROTECTED]>
2) Totally OT but... So you thought you had problems
by Neon John <[EMAIL PROTECTED]>
3) Re: Totally OT but... So you thought you had problems
by "Andre' Blanchard" <[EMAIL PROTECTED]>
4) Alltrax for E-volks Geo Metro
by "jmygann" <[EMAIL PROTECTED]>
5) RE: How simply can battery voltage monitors be made?
by "Christopher Tromley" <[EMAIL PROTECTED]>
6) 1) Dragtimes voting, 2) Summer plans
by James Massey <[EMAIL PROTECTED]>
7) Re: GFCI again (Was: Re: Charging outlet - what is common?)
by James Massey <[EMAIL PROTECTED]>
8) Re: GFCI again (Was: Re: Charging outlet - what is common?)
by Neon John <[EMAIL PROTECTED]>
9) Re: GFCI again (Was: Re: Charging outlet - what is common?)
by Neon John <[EMAIL PROTECTED]>
10) Re: GFCI again (Was: Re: Charging outlet - what is common?)
by "Roland Wiench" <[EMAIL PROTECTED]>
11) RE: Transformer cores
by Cor van de Water <[EMAIL PROTECTED]>
12) RE: GFCI again (Was: Re: Charging outlet - what is common?)
by Cor van de Water <[EMAIL PROTECTED]>
13) RE: How simply can battery voltage monitors be made?
by Cor van de Water <[EMAIL PROTECTED]>
14) Re: GFCI again (Was: Re: Charging outlet - what is common?)
by Neon John <[EMAIL PROTECTED]>
--- Begin Message ---
Lee:
YOu wrote:
...Thanks! I sometimes think I spend too much time writing stuff like this;
most people probably wish I just gave a brief answer and shut up. It's
good to know that the additional detail isn't a waste of time!
.......
Don't forget all us lurkers that are busy copying down the circuit too.
Thanks for your time, and clarity.
.....If you are running wires directly from your batteries to your dash,
treat all these wires and everything connected to them as if it were
connected to your full pack voltage.........
I still remember seeing the smoke come out from under my Triumph TR-3's dash
(dear Lucas). However, wouldn't your idea to use 1/4 watt resistors on every
attachment point to a battery render this system fairly safe? Or in-line
fuse holders on each line AT the battery. I'm thinking in terms of a 48v
scooter system.
Mark
--- End Message ---
--- Begin Message ---
with squirrels in your bird feeder....
http://www.geekbase.org/squirrelproblem
Amazing. Nothing to do with EVs but this is just too sweet not to
share.
John
---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN
A foolish consistency is the hobgoblin of little minds.-Ralph Waldo Emerson
--- End Message ---
--- Begin Message ---
At 03:01 PM 3/3/2006, you wrote:
with squirrels in your bird feeder....
http://www.geekbase.org/squirrelproblem
Amazing. Nothing to do with EVs but this is just too sweet not to
share.
John
---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN
A foolish consistency is the hobgoblin of little minds.-Ralph Waldo Emerson
To cool.
A friend was in a tree stand bow hunting deer. A young bear like this one
was walking by and spotted him, and then climbed up the tree. My friend
had to give the bear a little poke with an arrow to get it to climb back
down. Bear then went over to another tree about 4 feet away and climbed up
it, they stared at each other for about 3 hours before the bear decided to
climb down and wander off.
__________
Andre' B. Clear Lake, Wi.
--- End Message ---
--- Begin Message ---
I have added a file to the files showing a proposed diagram adding a
Alltrax 7245 for a E-volks Geo Metro 48 volts
I would appreciate any opinions or advice ...
--- End Message ---
--- Begin Message ---
Lee Hart wrote:
> Thanks! I sometimes think I spend too much time writing stuff like
this;
> most people probably wish I just gave a brief answer and shut up. It's
> good to know that the additional detail isn't a waste of time!
Oh, I can't let this one pass without a comment.
I'm sure I'm not the only one who frequently prints and saves the more
useful posts from this list. It didn't take me long to realize that
more than half of them are Lee's. Pretty impressive, especially when
you consider I ignore much of what's discussed here because it's way
over my head.
There's a deceptive simplicity in Lee's posts. He'll frequently talk
about seemingly old-fashioned stuff like using a light bulb as a
resistor, or the finer points of contactor or drum controllers, or
lament that no one uses compensating windings any more. That's not
because he's a hopeless romantic or his mind has rusted shut. Trust me,
I've seen him parry and thrust on the EVTech list with the young
whippersnappers with all their new-fangled high tech notions. He easily
holds his own. He's very current, he just has the perspective to know
that current isn't always best.
I also know he has a passion for robustness of design. Those simple,
elegant, even quaint circuits he tosses off every so often are *very*
well thought out. For one example (of many), his Battery Balancer might
seem hopelessly crude with its arrays of clicking relays. But if you
look closely you see that relays are the best choice. And then you
notice all the other things he thought of (that you probably wouldn't
have) that make it such a bullet-proof design.
So Lee, don't you worry about boring us with your posts. I still have
plenty to learn, and lots of shelf space to fill up!
Chris
--- End Message ---
--- Begin Message ---
G'day All
1) Well, the "florida style" voting at Dragtimes may have been nipped off,
but it looks like the cheaters are ahead for the moment.
John or someone with the ear of the Dragtimes operators, I find that some
of their confirmation numbers are exceptionally hard to read (dim), could
someone point this out to them?
2) We're starting to think of Autumn here, so I'm guessing many of the
Northern Hemisphites (if that's a word) are thinking of spring. So what's
the EV plans for this year? Racing or otherwise, who is planning what?
Anyone planning long EV trips? getting Li-Po battery? Getting a vehicle
(back) on the road? Going for a timeslip to post to Dragtimes?
In anticipation
James
--- End Message ---
--- Begin Message ---
At 02:42 PM 3/03/06 -0500, David Roden wrote:
On 3 Mar 2006 at 10:09, Rich Rudman wrote:
> it
> has the higher but still safe ground current cut off.
What level is that? I hope it's not 20ma. From what I've read, anything
above 5ma risks heart seizure.
G'day David - and All
Well, I don't know why, but here in Australia, where single-phase outlets
come in "10A" (16A breaker) and "15A" with a 20A or 25A breaker delivering
240VAC 50Hz, and 3-phase comes in two [effective] sizes of two flavours
(20A and 32A, with or without neutral), 415V phase-to-phase. The higher
voltage may lead you to assume to be more hazardous than the normal US
voltages, yet we have 20mA "earth leakage" breakers.
20mA? yes, everywhere.
5mA? unheard of.
Number of people electrocuted each year who die from a 20mA protected
circuit? Never hear of any.
Maybe it is because here it is hard to get a shock off the standard
connectors we use, and possibly the higher voltages cause fast current
rise-times and fast breaker cutoff relative to the "safer" lower voltages
common in the US?
[Just gloating a little over our seemingly better electrical distribution
system :^) ]
Regards
James
--- End Message ---
--- Begin Message ---
On Fri, 3 Mar 2006 10:09:22 -0800, "Rich Rudman" <[EMAIL PROTECTED]>
wrote:
>Joe we should make it clear that the best GFCI is a 50 amp Hot tub unit. it
>has the higher but still safe ground current cut off.
>
>Also doing the split 120 to get 240 is going to violate the ground current
>requirements limits of any GFCI.
>This is a neat trick but as a manufacturer... I clearly don't recomend it
>for saftey issues.
I don't follow that. Are you saying that it is wrong to put a 120
volt load between one hot lead and neutral on a 240 volt GFI protected
circuit? If so, then that is not correct. In fact, that is a common
practice.
If you're saying that it's wrong to use a 240 volt GFI on a 120 volt
circuit, then I also have to disagree, as long as the 120 volts are
applied between one hot leg and neutral and not between the hots.
A 240 volt GFI MUST function any time there is power available and
that includes the dead leg condition where one side of the 240 volt
line is dead for whatever reason. IMO, it is MORE important for it to
function properly under those conditions because one dead leg can
easily fool an inexperienced person into thinking the line is dead and
therefore human contact with something hot is more likely.
In practice, every GFI that I've tested has functioned properly under
dead leg conditions. My list isn't exhaustive but I've had my hands
on pretty much everything available from the big box stores and from
the local wholesaler. I try to stay abreast of developments on the
GFI front so I buy (or borrow) anything new and examine it. Sometimes
destructively.
>
>In Fact I won't do it even in tight circumstances. I just won't settle for
>that level of hacking safley.
That really isn't hacking since a dead leg is a designed-for
circumstance for the GFI.
>I'll just go get the right cables and find the right branch circuit.
That's nice except when you can't. I face exactly the same problem
with my concession trailer. I use a hot tub GFI in the panel. The
trailer is wired to accept either 120 or 240 (flip a switch) at 50
amps. I could write a book on obtaining power at public events. This
includes climbing a pole and clipping onto the drop leads, popping the
cover off service panels and clipping to the service entrance, etc.
Yet, with employees and customers about, it must be safe. I've
certainly tested my setup under every condition I can conceive of
including dead-legging (aka, operating on 120v.)
>
>Take it from Madman... If I don't do it... it's hairier than it looks.
I can understand your thought process as a manufacturer, considering
how lawyers can twist around whatever you do. You could be assaulted
for installing an "off circular" GFI and for NOT installing one.
Either way you lose if it comes down to throwing lawyers at each
other.
Two terms of art that I've seen arise over and over in cases where
I've been an expert hired by one side or the other are "Best
Practices" and "Best Effort". Best Practices is whatever the industry
consensus is at the time, which really comes back to bite when the
consensus changes rapidly. Published standards are the best
indication of current best practices.
Best Effort is taking the best practical steps to protect against an
anticipated safety problem. Best Effort is generally regarded as
taking at least two independent steps to mitigate the hazard. For
example, covering a live terminal with a protective barrier AND
fastening the cover with tamper-resistant fasteners. The legal
reasoning is that for a person to harm himself, he would have to
defeat two separate engineered safeguards. There is a limit even
today to how far a court will hold a manufacturer liable, especially a
small one.
If I were in your shoes, I'd do the GFI. That is a proactive step
toward mitigating the known hazard of a non-isolated charger. Warning
labels, warnings in the manual, physical barriers and such will likely
serve as the second one. Of course, I'd want a legal opinion from a
product liability lawyer.
To prove that you acted as a "reasonable man", another legal term of
art, I'd read and then document my interpretation of the applicable
standards. Hopefully you keep a legally acceptable engineering
journal (bound and numbered pages in a book that makes tampering
evident.) The UL standard, for instance. I might even solicit the
sealed opinion of a licensed professional engineer. I might also seek
a letter from the GFI mfr regarding its performance under dead leg
conditions. No mfr is going to bless your application but one should
certify that the GFI itself meets the standard for dead leg
protection. Your liability insurance carrier is another good source
of advice in this area.
I think that you have a large exposure without the GFI, given how many
exposed high voltage points there are in the typical EV AND how many
leakage paths there are to the car body. True, you might get nicked
for an "off circular" application of the GFI but I don't think the
exposure is nearly as bad as not having one.
If you choose not to use one then I suggest you write the installation
instructions to require the use of a disconnect plug so that the pack
must be disconnected from the car for charging. An Anderson plug on
the charger and between the pack and controller will work. Most
people are going to ignore this requirement but you've done your best
effort to render the rest of the car cold.
One other comment while I'm thinking of it. There are rather
inexpensive ground current detectors available that detect excessive
current to ground. Normally this type of unit goes in the main ground
lead for a cabinet or machine and is a simple AC milliamp trip device.
Including one of these in your charger's ground lead would catch all
instances of leakage to ground potentially making the car body hot. It
would not protect the user from direct contact with a pack lead but it
would eliminate the possibility of shock from the car body. The
ground current detector will also catch incipient faults before they
turn to arcs. Leakage tracks, for instance.
John
---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN
A foolish consistency is the hobgoblin of little minds.-Ralph Waldo Emerson
--- End Message ---
--- Begin Message ---
On Fri, 03 Mar 2006 11:51:01 -0700, Rush <[EMAIL PROTECTED]> wrote:
>My plan was to run a 240 v 50 amp line, 10 ft from main panel, #8 wire, to a
>sub panel which will have a 240v 50 amp GFCI and a 120v 20 amp GFCI breakers
>in it. I can then plug either 120 or 240 vac into my plugs and be protected.
>Correct?
See my other post in this thread. Use the 50 amp hot tub type GFI to
avoid nuisance trips. Connect your 120 volt outlet through the 50 amp
GFI and whatever size breaker you desire. That'll save you the cost
of a second expensive panel GFI AND nuisance trips.
John
>
>Rush
>Tucson AZ
>www.ironandwood.org
>
>
>----- Original Message -----
>From: "Rich Rudman" <[EMAIL PROTECTED]>
>To: <[email protected]>
>Sent: Friday, March 03, 2006 11:09 AM
>Subject: Re: GFCI again (Was: Re: Charging outlet - what is common?)
>
>
>> Joe we should make it clear that the best GFCI is a 50 amp Hot tub unit. it
>> has the higher but still safe ground current cut off.
>>
>> Also doing the split 120 to get 240 is going to violate the ground current
>> requirements limits of any GFCI.
>> This is a neat trick but as a manufacturer... I clearly don't recomend it
>> for saftey issues.
>>
>> In Fact I won't do it even in tight circumstances. I just won't settle for
>> that level of hacking safley.
>> I'll just go get the right cables and find the right branch circuit.
>>
>> Take it from Madman... If I don't do it... it's hairier than it looks.
>>
>>
>> ----- Original Message -----
>> From: "Joe Smalley" <[EMAIL PROTECTED]>
>> To: <[email protected]>
>> Sent: Friday, March 03, 2006 4:06 AM
>> Subject: Re: GFCI again (Was: Re: Charging outlet - what is common?)
>>
>>
>>> There is no GFCI inside the PFC chargers because we could not find a dual
>>> voltage GFCI during design.
>>>
>>> If you wanted proper protection it was appropriate to purchase TWO inline
>>> GFCI adapters.
>>> One for 120 VAC and one for 240 VAC and use the one appropriate for the
>>> power source.
>>>
>>> On a search tonight, I located a 20 Amp dual voltage inline GFCI at
>>> http://www.trci.net/products/shock_shield/pdf/25000.pdf
>>> Cost is listed as $55.67 at
>>> http://www.trcelectrical.com/search.php?byItemNumber=25000
>>>
>>> There is a 40 amp version described at
>>> http://www.trci.net/products/hd_pro/pdf/24130.pdf that would be
>> appropriate
>>> for a PFC-30 or PFC-40. Cost is listed as $214.53 at
>>> http://www.trcelectrical.com/search.php?byItemNumber=24130
>>>
>>> A 60 amp version is described at
>>> http://www.trci.net/products/hd_pro/pdf/24520.pdf that would be
>> appropriate
>>> for a PFC-50. There is no dual voltage listed therefore two devices would
>> be
>>> needed for protection at both 120 VAC and 240 VAC. Cost is listed as
>> $424.55
>>> at http://www.trcelectrical.com/search.php?byItemNumber=24520
>>>
>>> I did not find distributor information for these devices.
>>>
>>> Joe Smalley
>>> Rural Kitsap County WA
>>> Fiesta 48 volts
>>> NEDRA 48 volt street conversion record holder
>>> [EMAIL PROTECTED]
>>>
>>>
>>> ----- Original Message -----
>>> From: "Doug Weathers" <[EMAIL PROTECTED]>
>>> To: <[email protected]>
>>> Sent: Thursday, March 02, 2006 2:53 PM
>>> Subject: GFCI again (Was: Re: Charging outlet - what is common?)
>>>
>>>
>>> >
>>> > On Mar 2, 2006, at 9:29 AM, Rush wrote:
>>> >
>>> > > Also somebody, Nick Viera I think, put up a web site that had all the
>>> > > NEMA plugs and specs. I thought I had it book marked, but haven't been
>>> > > able to find it. He has also made a nice schematic of his modular
>>> > > plugs
>>> > > http://go.driveev.com/jeepev/convpgs/charger.php, which I plan to
>>> > > copy...
>>> >
>>> > Looks nice. I'm pondering the same thing at the moment.
>>> >
>>> > I have a PFC-20 and want to be able to use it safely on either 120v or
>>> > 240v. I know that there was a lot of discussion recently about GFCI
>>> > for the Manzanita Micro PFC chargers, but sadly, I don't think there
>>> > was ever a consensus on the best solution. So I'm reopening the
>>> > discussion again - sorry about that.
>>> >
>>> > I haven't been able to find a dual-voltage GFCI (does anyone know of
>>> > one?), so I need two of them. One solution is to put two GFCI male
>>> > plugins inside the vehicle and wire them both to the charger. This
>>> > makes it necessary to prevent power being present on the unused pins,
>>> > so there would need to be safety interlocks and/or relays that
>>> > disconnect the unused outlet.
>>> >
>>> > Another solution that just occurred to me would be two inline
>>> > waterproof GFCIs. Add them to Nick's adapters. Plus another one for
>>> > L6-30 outlets (the long extension cord doesn't have a GFCI in it).
>>> >
>>> > So is this a stupid idea, or a waste of time? Should I just build the
>>> > dual outlets and interlocks? Or not worry about GFCI?
>>> >
>>> > >
>>> > > Rush
>>> > >
>>> > > Tucson AZ
>>> > > www.ironandwood.org
>>> > >
>>> > >
>>> > --
>>> > Doug Weathers
>>> > Bend, OR, USA
>>> > <http://learn-something.blogsite.org/>
>>> >
>>>
>>
>>
>>
>
---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN
A foolish consistency is the hobgoblin of little minds.-Ralph Waldo Emerson
--- End Message ---
--- Begin Message ---
I thought that Rich was replying to someone installing two 120 volt GFCI
receptacles on a 240 vac line, where each receptacle would be on the two
different lines.
If this was done this way, then there would be no current flow on the
neutral back to the circuit breaker panel, because the load and ampere is
the same on each line.
If you connected two 120 volt GFCI together, would you just connect the load
neutrals together only and or leave them disconnected as where you would
have no neutral wire anyway to the load side of the receptacles of a 240 vac
circuit? Would you still run a neutral on the line side back to the panel
which may be needed to power the 120 volt GFCI circuit?
Would a 120 vac GFCI work this way with no current flowing on the neutral
and only current on the Line 1 and Line 2 wires?
I have tested out a 120 vac GFCI receptacle with no ground wires or
grounding circuits,(the green wire), and it still works. The only thing
without a ground wire, is that you cannot test out the GFCI by pushing the
test button.
We are allow to replace two wire receptacles in a older house than does not
have any ground wires, with a GFCI receptacle on the first receptacle from
the fuse panel and protecting the rest of the receptacles down the line.
This is allow under NEC Article 210-7(d),(b).
Roland
----- Original Message -----
From: "Neon John" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Friday, March 03, 2006 4:40 PM
Subject: Re: GFCI again (Was: Re: Charging outlet - what is common?)
> On Fri, 3 Mar 2006 10:09:22 -0800, "Rich Rudman" <[EMAIL PROTECTED]>
> wrote:
>
> >Joe we should make it clear that the best GFCI is a 50 amp Hot tub unit.
> >it
> >has the higher but still safe ground current cut off.
> >
> >Also doing the split 120 to get 240 is going to violate the ground
> >current
> >requirements limits of any GFCI.
> >This is a neat trick but as a manufacturer... I clearly don't recomend it
> >for saftey issues.
>
> I don't follow that. Are you saying that it is wrong to put a 120
> volt load between one hot lead and neutral on a 240 volt GFI protected
> circuit? If so, then that is not correct. In fact, that is a common
> practice.
>
> If you're saying that it's wrong to use a 240 volt GFI on a 120 volt
> circuit, then I also have to disagree, as long as the 120 volts are
> applied between one hot leg and neutral and not between the hots.
>
> A 240 volt GFI MUST function any time there is power available and
> that includes the dead leg condition where one side of the 240 volt
> line is dead for whatever reason. IMO, it is MORE important for it to
> function properly under those conditions because one dead leg can
> easily fool an inexperienced person into thinking the line is dead and
> therefore human contact with something hot is more likely.
>
> In practice, every GFI that I've tested has functioned properly under
> dead leg conditions. My list isn't exhaustive but I've had my hands
> on pretty much everything available from the big box stores and from
> the local wholesaler. I try to stay abreast of developments on the
> GFI front so I buy (or borrow) anything new and examine it. Sometimes
> destructively.
>
> >
> >In Fact I won't do it even in tight circumstances. I just won't settle
> >for
> >that level of hacking safley.
>
> That really isn't hacking since a dead leg is a designed-for
> circumstance for the GFI.
>
> >I'll just go get the right cables and find the right branch circuit.
>
> That's nice except when you can't. I face exactly the same problem
> with my concession trailer. I use a hot tub GFI in the panel. The
> trailer is wired to accept either 120 or 240 (flip a switch) at 50
> amps. I could write a book on obtaining power at public events. This
> includes climbing a pole and clipping onto the drop leads, popping the
> cover off service panels and clipping to the service entrance, etc.
> Yet, with employees and customers about, it must be safe. I've
> certainly tested my setup under every condition I can conceive of
> including dead-legging (aka, operating on 120v.)
> >
> >Take it from Madman... If I don't do it... it's hairier than it looks.
>
> I can understand your thought process as a manufacturer, considering
> how lawyers can twist around whatever you do. You could be assaulted
> for installing an "off circular" GFI and for NOT installing one.
> Either way you lose if it comes down to throwing lawyers at each
> other.
>
> Two terms of art that I've seen arise over and over in cases where
> I've been an expert hired by one side or the other are "Best
> Practices" and "Best Effort". Best Practices is whatever the industry
> consensus is at the time, which really comes back to bite when the
> consensus changes rapidly. Published standards are the best
> indication of current best practices.
>
> Best Effort is taking the best practical steps to protect against an
> anticipated safety problem. Best Effort is generally regarded as
> taking at least two independent steps to mitigate the hazard. For
> example, covering a live terminal with a protective barrier AND
> fastening the cover with tamper-resistant fasteners. The legal
> reasoning is that for a person to harm himself, he would have to
> defeat two separate engineered safeguards. There is a limit even
> today to how far a court will hold a manufacturer liable, especially a
> small one.
>
> If I were in your shoes, I'd do the GFI. That is a proactive step
> toward mitigating the known hazard of a non-isolated charger. Warning
> labels, warnings in the manual, physical barriers and such will likely
> serve as the second one. Of course, I'd want a legal opinion from a
> product liability lawyer.
>
> To prove that you acted as a "reasonable man", another legal term of
> art, I'd read and then document my interpretation of the applicable
> standards. Hopefully you keep a legally acceptable engineering
> journal (bound and numbered pages in a book that makes tampering
> evident.) The UL standard, for instance. I might even solicit the
> sealed opinion of a licensed professional engineer. I might also seek
> a letter from the GFI mfr regarding its performance under dead leg
> conditions. No mfr is going to bless your application but one should
> certify that the GFI itself meets the standard for dead leg
> protection. Your liability insurance carrier is another good source
> of advice in this area.
>
> I think that you have a large exposure without the GFI, given how many
> exposed high voltage points there are in the typical EV AND how many
> leakage paths there are to the car body. True, you might get nicked
> for an "off circular" application of the GFI but I don't think the
> exposure is nearly as bad as not having one.
>
> If you choose not to use one then I suggest you write the installation
> instructions to require the use of a disconnect plug so that the pack
> must be disconnected from the car for charging. An Anderson plug on
> the charger and between the pack and controller will work. Most
> people are going to ignore this requirement but you've done your best
> effort to render the rest of the car cold.
>
> One other comment while I'm thinking of it. There are rather
> inexpensive ground current detectors available that detect excessive
> current to ground. Normally this type of unit goes in the main ground
> lead for a cabinet or machine and is a simple AC milliamp trip device.
> Including one of these in your charger's ground lead would catch all
> instances of leakage to ground potentially making the car body hot. It
> would not protect the user from direct contact with a pack lead but it
> would eliminate the possibility of shock from the car body. The
> ground current detector will also catch incipient faults before they
> turn to arcs. Leakage tracks, for instance.
>
> John
> ---
> John De Armond
> See my website for my current email address
> http://www.johngsbbq.com
> Cleveland, Occupied TN
> A foolish consistency is the hobgoblin of little minds.-Ralph Waldo
> Emerson
>
>
--- End Message ---
--- Begin Message ---
Well,
To take this off on a tangent:
You actually do not need to build all this high-power switching
stuff if you can find a battery charger that has a switching
power supply and your battery voltage is somewhere in the range
of 96V - 156V (Assuming that the switching charger has 110V AC
specification, if it goes to 240V AC then your battery can be
as high as 312V without destructing the capacitor in the
charger.
(a 110V switching power supply usually has a 250V Electrolytic
capacitor, a 240V power supply has a 450V one)
Do not connect anything AC that you have not checked with a
DVM to have 2 diodes and a capacitor in its path - if you
connect a transformer to your battery pack you may be in for
a nasty surprise.
(yes, the fuse next to the transformer will blow)
(yes, the current may be capable of jumping the fuse and
continuing flowing through the plasma channel)
Regards,
Cor van de Water
Systems Architect
Email: [EMAIL PROTECTED] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [EMAIL PROTECTED]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Proxim Wireless Networks eFAX: +1-610-423-5743
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Evan Tuer
Sent: Friday, March 03, 2006 2:07 AM
To: [email protected]
Subject: Re: Transformer cores
On 3/2/06, Lee Hart <[EMAIL PROTECTED]> wrote:
>
> You could with a 12v 15amp battery charger; it already has the
> transformer, rectifier, ammeter, and sometimes charge control circuitry.
> The simplest circuit is probably a half-bridge, with 2 SCRs and 2
> capacitors, like this:
>
Hello Lee,
Thanks for this, I've been experimenting with something similar for
a different application and hadn't tried this simple SCR arrangement
yet (largely because modern design references and text books don't
cover it!).
Best regards
Evan
--- End Message ---
--- Begin Message ---
My understanding of Rich's comment of split 120V is where
someone wires 2 120V power cords in SERIES and plugs each
cord into a different leg to get 240V and (2x) GFCI
*****BUT**** he will have 120 on the pins of the cord that
is _unplugged_ when the other cord is plugged in - its
GFCI will not prevent that and shocking yourself with 120V
at 15 or 20A without tripping something, from the pins of
a power cord plug is what I think Rich is talking about,
but I may be mistaken.
Cor van de Water
Systems Architect
Email: [EMAIL PROTECTED] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [EMAIL PROTECTED]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Proxim Wireless Networks eFAX: +1-610-423-5743
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Roland Wiench
Sent: Friday, March 03, 2006 5:36 PM
To: [email protected]
Subject: Re: GFCI again (Was: Re: Charging outlet - what is common?)
I thought that Rich was replying to someone installing two 120 volt GFCI
receptacles on a 240 vac line, where each receptacle would be on the two
different lines.
If this was done this way, then there would be no current flow on the
neutral back to the circuit breaker panel, because the load and ampere is
the same on each line.
If you connected two 120 volt GFCI together, would you just connect the load
neutrals together only and or leave them disconnected as where you would
have no neutral wire anyway to the load side of the receptacles of a 240 vac
circuit? Would you still run a neutral on the line side back to the panel
which may be needed to power the 120 volt GFCI circuit?
Would a 120 vac GFCI work this way with no current flowing on the neutral
and only current on the Line 1 and Line 2 wires?
I have tested out a 120 vac GFCI receptacle with no ground wires or
grounding circuits,(the green wire), and it still works. The only thing
without a ground wire, is that you cannot test out the GFCI by pushing the
test button.
We are allow to replace two wire receptacles in a older house than does not
have any ground wires, with a GFCI receptacle on the first receptacle from
the fuse panel and protecting the rest of the receptacles down the line.
This is allow under NEC Article 210-7(d),(b).
Roland
----- Original Message -----
From: "Neon John" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Friday, March 03, 2006 4:40 PM
Subject: Re: GFCI again (Was: Re: Charging outlet - what is common?)
> On Fri, 3 Mar 2006 10:09:22 -0800, "Rich Rudman" <[EMAIL PROTECTED]>
> wrote:
>
> >Joe we should make it clear that the best GFCI is a 50 amp Hot tub unit.
> >it
> >has the higher but still safe ground current cut off.
> >
> >Also doing the split 120 to get 240 is going to violate the ground
> >current
> >requirements limits of any GFCI.
> >This is a neat trick but as a manufacturer... I clearly don't recomend it
> >for saftey issues.
>
> I don't follow that. Are you saying that it is wrong to put a 120
> volt load between one hot lead and neutral on a 240 volt GFI protected
> circuit? If so, then that is not correct. In fact, that is a common
> practice.
>
> If you're saying that it's wrong to use a 240 volt GFI on a 120 volt
> circuit, then I also have to disagree, as long as the 120 volts are
> applied between one hot leg and neutral and not between the hots.
>
> A 240 volt GFI MUST function any time there is power available and
> that includes the dead leg condition where one side of the 240 volt
> line is dead for whatever reason. IMO, it is MORE important for it to
> function properly under those conditions because one dead leg can
> easily fool an inexperienced person into thinking the line is dead and
> therefore human contact with something hot is more likely.
>
> In practice, every GFI that I've tested has functioned properly under
> dead leg conditions. My list isn't exhaustive but I've had my hands
> on pretty much everything available from the big box stores and from
> the local wholesaler. I try to stay abreast of developments on the
> GFI front so I buy (or borrow) anything new and examine it. Sometimes
> destructively.
>
> >
> >In Fact I won't do it even in tight circumstances. I just won't settle
> >for
> >that level of hacking safley.
>
> That really isn't hacking since a dead leg is a designed-for
> circumstance for the GFI.
>
> >I'll just go get the right cables and find the right branch circuit.
>
> That's nice except when you can't. I face exactly the same problem
> with my concession trailer. I use a hot tub GFI in the panel. The
> trailer is wired to accept either 120 or 240 (flip a switch) at 50
> amps. I could write a book on obtaining power at public events. This
> includes climbing a pole and clipping onto the drop leads, popping the
> cover off service panels and clipping to the service entrance, etc.
> Yet, with employees and customers about, it must be safe. I've
> certainly tested my setup under every condition I can conceive of
> including dead-legging (aka, operating on 120v.)
> >
> >Take it from Madman... If I don't do it... it's hairier than it looks.
>
> I can understand your thought process as a manufacturer, considering
> how lawyers can twist around whatever you do. You could be assaulted
> for installing an "off circular" GFI and for NOT installing one.
> Either way you lose if it comes down to throwing lawyers at each
> other.
>
> Two terms of art that I've seen arise over and over in cases where
> I've been an expert hired by one side or the other are "Best
> Practices" and "Best Effort". Best Practices is whatever the industry
> consensus is at the time, which really comes back to bite when the
> consensus changes rapidly. Published standards are the best
> indication of current best practices.
>
> Best Effort is taking the best practical steps to protect against an
> anticipated safety problem. Best Effort is generally regarded as
> taking at least two independent steps to mitigate the hazard. For
> example, covering a live terminal with a protective barrier AND
> fastening the cover with tamper-resistant fasteners. The legal
> reasoning is that for a person to harm himself, he would have to
> defeat two separate engineered safeguards. There is a limit even
> today to how far a court will hold a manufacturer liable, especially a
> small one.
>
> If I were in your shoes, I'd do the GFI. That is a proactive step
> toward mitigating the known hazard of a non-isolated charger. Warning
> labels, warnings in the manual, physical barriers and such will likely
> serve as the second one. Of course, I'd want a legal opinion from a
> product liability lawyer.
>
> To prove that you acted as a "reasonable man", another legal term of
> art, I'd read and then document my interpretation of the applicable
> standards. Hopefully you keep a legally acceptable engineering
> journal (bound and numbered pages in a book that makes tampering
> evident.) The UL standard, for instance. I might even solicit the
> sealed opinion of a licensed professional engineer. I might also seek
> a letter from the GFI mfr regarding its performance under dead leg
> conditions. No mfr is going to bless your application but one should
> certify that the GFI itself meets the standard for dead leg
> protection. Your liability insurance carrier is another good source
> of advice in this area.
>
> I think that you have a large exposure without the GFI, given how many
> exposed high voltage points there are in the typical EV AND how many
> leakage paths there are to the car body. True, you might get nicked
> for an "off circular" application of the GFI but I don't think the
> exposure is nearly as bad as not having one.
>
> If you choose not to use one then I suggest you write the installation
> instructions to require the use of a disconnect plug so that the pack
> must be disconnected from the car for charging. An Anderson plug on
> the charger and between the pack and controller will work. Most
> people are going to ignore this requirement but you've done your best
> effort to render the rest of the car cold.
>
> One other comment while I'm thinking of it. There are rather
> inexpensive ground current detectors available that detect excessive
> current to ground. Normally this type of unit goes in the main ground
> lead for a cabinet or machine and is a simple AC milliamp trip device.
> Including one of these in your charger's ground lead would catch all
> instances of leakage to ground potentially making the car body hot. It
> would not protect the user from direct contact with a pack lead but it
> would eliminate the possibility of shock from the car body. The
> ground current detector will also catch incipient faults before they
> turn to arcs. Leakage tracks, for instance.
>
> John
> ---
> John De Armond
> See my website for my current email address
> http://www.johngsbbq.com
> Cleveland, Occupied TN
> A foolish consistency is the hobgoblin of little minds.-Ralph Waldo
> Emerson
>
>
--- End Message ---
--- Begin Message ---
Lee wrote:
>It's good to know that the additional detail isn't a waste of time!
It certainly is not, keep up the good work, I enjoy it.
Blessings,
Cor van de Water
Systems Architect
Email: [EMAIL PROTECTED] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [EMAIL PROTECTED]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Proxim Wireless Networks eFAX: +1-610-423-5743
Take your network further http://www.proxim.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Lee Hart
Sent: Friday, March 03, 2006 11:26 AM
To: [email protected]
Subject: Re: How simply can battery voltage monitors be made?
kluge wrote:
> Thanks for the confirmation of the correct calculation, Lee. At the
> risk of gushing, let me say that the fact that even I could detect a
> flaw in the formula originally posted is a tribute to the clarity with
> which you described the function of the circuit. I really appreciate
> being walked through this stuff
Thanks! I sometimes think I spend too much time writing stuff like this;
most people probably wish I just gave a brief answer and shut up. It's
good to know that the additional detail isn't a waste of time!
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in -- Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
--- End Message ---
--- Begin Message ---
On Fri, 03 Mar 2006 14:42:33 -0500, "David Roden" <[EMAIL PROTECTED]>
wrote:
>On 3 Mar 2006 at 10:09, Rich Rudman wrote:
>
>> it
>> has the higher but still safe ground current cut off.
>
>What level is that? I hope it's not 20ma. From what I've read, anything
>above 5ma risks heart seizure.
It's closer to 50 ma for a normal human. There's a reason why we
neonists use mainly 30 ma high voltage transformers. Even at 50 ma
there has to be a direct path to the heart, something that is
difficult to achieve without an invasive electrode being involved.
This is an example of why I despise UL so. The logic went something
like this: "So some consensus says that 50 ma is LDxx. Just because
we can, let's divide that by 10 and set the limit at 5ma. It's not
going to be us who bear the cost." This isn't the only example where
a UL committee has pulled this sort of logic. The UL and NEC (the two
are incestuously related) "standards" for neon are beyond stupid. But
I digress.
20 ma isn't pleasant but it won't kill anyone other than perhaps a
very elderly person or someone who has heart problems. Any driver
that falls into either of these categories probably should not be
playing with electricity anyway.
I have tested a 5ma GFI with myself, after carefully working up to it
AND after carefully verifying that the GFI in question actually
performed as advertised, of course.
Five ma for half a cycle, the interval that a GFI must perform in, is
felt but not much. More like having someone flip your arm with his
finger.
I've been bitten a few times by 30 ma neon transformer power. It
REALLY hurt but it wasn't strong enough to make me piss myself,
something that a common everyday stun gun does to most people. (One
of my employees demonstrated that fact when, after I'd given him a
stun gun, he decided to see what it felt like. He had his legs
crossed and he did a little shot to his calf. Instant pissed pants!
And all the muscles in his leg spasmed that didn't release for about a
half hour.) No damage done other than a pinpoint burn mark where the
arc formed on my skin. Mostly it makes me hate myself for being dumb
enough to work around an energized circuit.
>
>I remain very concerned about the number of PFC chargers out there. They
>are unisolated and AFAIK all were built without built in GFI protection.
>What percentage are protected by a user-installed 5ma GFI? 80%? 50%? 20%?
> 5%?
As far as the public is concerned, there is essentially no risk as
long as the EV owner has properly grounded his vehicle with the
charging cord's green wire. With the hood and hatches down there are
no exposed live parts. The ONLY way there could be a risk is if there
is a leakage path to the car AND the ground isn't properly made up.
The only real risk is to the owner when he forgets that the charger is
connected and pokes around in the pack wiring and touches something he
shouldn't. That's his business and not mine.
>
>I know nobody likes to think about this, and I've been accused of being an
>alarmist.
You are, in this instance, at least.
>But what is going to happen to the EV movement when some 5 year
>old child is electrocuted by a charging EV?
"EV movement"? If there's any movement, one needs a time lapse camera
to see it. In 5 years it'll be just like it is now - a few of us
nutty people playing with our toys.
>I guarantee it will make
>newspapers and TV newscasts across the nation. They love that sort of "see
>what happens when you rock the boat" story. Before you know it we'll have
>legislation limiting or banning homebuilt EVs.
Really? How many people do you suppose have been killed because
something failed on a hotrod? A race car? Even a common ordinary
shop jack? No legislation there.
One can do the arm waving, sky-is-falling bit until nothing is safe. A
rational approach is to do a probabilistic risk analysis (formally or
off the cuff.) What is the risk of the venerable 5 year old being
shocked by a non-isolated charger vs the risk of him, say, turning the
car on and mashing the accelerator? After all, the kid doesn't have
to know how to start an EV. Or releasing the emergency brake and
letting the car roll away? (I did that as a kid. Thankfully there was
a hedge a few feet behind the car.) Or sticking something in the
charging outlet? Or hammering the cord with something until the
insulation is broken? Or chewing on the cord? Or...... Since there
has not yet been any kid harmed by an EV, at least to my knowledge, it
doesn't appear to be much of a problem.
>
>A GFI is the minimum protection. If you aren't using one, you're on
>borrowed time. Joe has kindly and sensibly shown us where one is available
>at a very reasonable cost, at least for the 20 amp level. Please, if you
>use a PFC, make sure you have a working GFI on it at all times.
On borrowed time? Surely you jest. This sort of hyperbole is highly
counterproductive, especially for those who aren't particularly
trained in electricity. Just what some marginally electrophobic
person needs to hear. NOT!
If I were in Rich's shoes and had my experience with the court system,
a GFI would be inside every charger. Not because there is a pressing
risk to address but simply as lawyer repellant. Legal CYA.
If I had a PFC, I'm not sure what I'd do. If I was a normal person,
I'd not think twice about using the thing without a GFI. I'm a
tinkerer though, more apt than not to have the hatches open while
charging and I'm also experienced enough with working on energized
equipment that I sometimes get a bit too lax. Knowing that, I'd give
a GFI strong consideration.
Since I have several laying on the shelf, I'd probably install one and
see how the false trips stack up. About the first time I woke up to a
dead battery and a nuisance tripped GFI, I'd yank it out. I don't know
whether I'd spend a hundred bux to go out and get one if I didn't have
one on hand.
What we really need is a GFI with an automatic reclosing ability like
utility breakers. If it trips, wait 15 seconds and close back in. If
it was a nuisance trip then it should stay in. If a person caused the
trip then he should be gone by the time the reclose happens. If not,
trip again and lock out. The GFI could close at zero crossing and
monitor the circuit as the voltage rises on the half-cycle. If the
imbalance is trending toward the danger point, trip early.
I will have to admit that I do have a mighty bad boy charger and I
DON'T have a GFI on it and I've never had even a close encounter. I
will admit to being VERY careful around the thing, though.
This non-isolated non-issue gets beaten to death about every 3 months
it seems. Despite all the arm-waving, I have to wonder if anyone has
even been tingled by a non-isolated charger? I've certainly never
seen anyone post about it. I'm not talking about being shocked by the
pack's DC voltage. I'm talking about an AC shock from touching a
single point on the pack wiring (and ground, of course) when a PFC is
connected (or a bad boy or any other non-isolated charger.)
Has anyone been jolted? If so, let's hear about it. With 1000+
members on this list, many of us hackers and tinkerers, if there IS a
real danger, surely at least one person has encountered it.
John
---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN
A foolish consistency is the hobgoblin of little minds.-Ralph Waldo Emerson
--- End Message ---
