EV Digest 6923
Topics covered in this issue include:
1) Lead Acid Batteries
by "Rob Hogenmiller" <[EMAIL PROTECTED]>
2) RE: Motor speed
by Mike Willmon <[EMAIL PROTECTED]>
3) Re: Does twisting matter?
by "Loni" <[EMAIL PROTECTED]>
4) Re: Dc to Dc
by Dan Frederiksen <[EMAIL PROTECTED]>
5) Re: Does twisting matter?
by Rod Hower <[EMAIL PROTECTED]>
6) Re: Motor speed
by "Rob Hogenmiller" <[EMAIL PROTECTED]>
7) Re: Motor speed
by "Rob Hogenmiller" <[EMAIL PROTECTED]>
8) Re: Internal Resistance? Peukert's Exponent? Voltage Sag?!?!
by "Joe Smalley" <[EMAIL PROTECTED]>
9) Re: Does twisting matter?
by "Tehben Dean" <[EMAIL PROTECTED]>
10) Motor Speed
by Storm Connors <[EMAIL PROTECTED]>
11) RE: Lead Acid Batteries
by Cor van de Water <[EMAIL PROTECTED]>
12) RE: Internal Resistance? Peukert's Exponent? Voltage Sag?!?!
by Joseph Tahbaz <[EMAIL PROTECTED]>
13) Re: Internal Resistance? Peukert's Exponent? Voltage Sag?!?!
by "Joe Smalley" <[EMAIL PROTECTED]>
14) Re: Lead Acid Batteries
by "Rob Hogenmiller" <[EMAIL PROTECTED]>
15) RE: Internal Resistance? Peukert's Exponent? Voltage Sag?!?!
by Joseph Tahbaz <[EMAIL PROTECTED]>
16) Re: Chargers?
by "Joe Smalley" <[EMAIL PROTECTED]>
17) Re: Internal Resistance? Peukert's Exponent? Voltage Sag?!?!
by "Joe Smalley" <[EMAIL PROTECTED]>
18) Re: Lead Acid Batteries
by Danny Miller <[EMAIL PROTECTED]>
19) Re: 55mph
by "Peter Gabrielsson" <[EMAIL PROTECTED]>
20) Improving hillclimbing without mudering the pack?
by Markus Lorch <[EMAIL PROTECTED]>
21) RE: contacting Electro Automotive (electroauto.com)
by Mike Willmon <[EMAIL PROTECTED]>
22) Re: 55mph
by Victor Tikhonov <[EMAIL PROTECTED]>
23) RE: Motor speed
by Mike Willmon <[EMAIL PROTECTED]>
--- Begin Message ---
I was wondering what kind of distance I could get out of a two (12V) 31
group batteries.
If I have a 24 volt system, with a two 100amp continous & max output motors,
how long would the battery last?
They have 1200 Amps, and a reserve capacity of 195 minutes.
If my math is correct it would be:
195minutes x 2 batteries / 8 (draw of amps by two motors)= 48.75 minutes.
Are we allowed to put link addresses on here of projects we are working on?
God bless
--- End Message ---
--- Begin Message ---
Storm,
My WarP9 finds its sweet spot around 3500 RPM, which in 2nd gear happens to be
35 mph. at 37mph I can feel acceleration start to
taper and seems the perfect shift point to 3rd gear.
Mike
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of Jim Husted
> Sent: Wednesday, June 20, 2007 6:01 PM
> To: ev@listproc.sjsu.edu
> Subject: Re: Motor speed
>
>
> Hey Storm
>
> Actually you don't want to lug the motor and you have
> plenty of room and would say it'd be happier at the
> 3000 to 4000 rpms, you got lots more rpm to play with
> 8^)
>
> Hope this helps
> Jim Husted
> Hi-Torque Electric
>
>
> --- Storm Connors <[EMAIL PROTECTED]> wrote:
>
> > I got the tachometer installed, now the big
> > question.
> > What is the best speed to aim for with my ADC 9"
> > motor
> > pushing almost 3500 pounds? I have been keeping it
> > between 2000 and 2500 RPM generally. My thinking is
> > that if the revs are too low under load, there is
> > the potential of overheating. I have red lined it at
> > 5000 so as not to break the motor.
> >
> > What do you think? I have been treating it like an
> > ICE
> > but don't know if that is right.
> >
> >
>
>
>
>
> ____________________________________________________________________________________
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--- End Message ---
--- Begin Message ---
Very convincing. Are hundreds of EVers going to go re-wire everything now?
Yikes!
http://www.ppminc.com/Does_Twisting_Matter2.pdf
--- End Message ---
--- Begin Message ---
To avoid running down one battery or having an extra battery
Phelps wrote:
What the propose of that?? You all ready have D C and if you got 8 batteries
you can use and combo to get ant voltage you want..
I don't get the reason for it.
Or I could throw in one more battery and a dc to ac converter and run any
thing I wanted T V heater radio..
Mitchell
--- End Message ---
--- Begin Message ---
No, probably not. I previously worked at GE-EVS on
golf carts, utility vehicles and electric greens
mowers. The greens mower would not even work without
having the wires from the accelerator pedal twisted.
This is probably worst case, but it provides
incentives for those building an EV conversion to pay
attention to details like this!
Twisting the wire may make the AM radio sound better,
or in other situations make the EV actually work.
Rod
Twisting wires with my electric drill!
--- Loni <[EMAIL PROTECTED]> wrote:
> Very convincing. Are hundreds of EVers going to go
> re-wire everything now?
> Yikes!
>
> >> http://www.ppminc.com/Does_Twisting_Matter2.pdf
>
>
--- End Message ---
--- Begin Message ---
So when you shift into 3rd gear what does that allow you to increase your
speed to?
God bless
----- Original Message -----
From: "Mike Willmon" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Wednesday, June 20, 2007 10:21 PM
Subject: RE: Motor speed
Storm,
My WarP9 finds its sweet spot around 3500 RPM, which in 2nd gear happens
to be 35 mph. at 37mph I can feel acceleration start to
taper and seems the perfect shift point to 3rd gear.
Mike
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Jim Husted
Sent: Wednesday, June 20, 2007 6:01 PM
To: ev@listproc.sjsu.edu
Subject: Re: Motor speed
Hey Storm
Actually you don't want to lug the motor and you have
plenty of room and would say it'd be happier at the
3000 to 4000 rpms, you got lots more rpm to play with
8^)
Hope this helps
Jim Husted
Hi-Torque Electric
--- Storm Connors <[EMAIL PROTECTED]> wrote:
> I got the tachometer installed, now the big
> question.
> What is the best speed to aim for with my ADC 9"
> motor
> pushing almost 3500 pounds? I have been keeping it
> between 2000 and 2500 RPM generally. My thinking is
> that if the revs are too low under load, there is
> the potential of overheating. I have red lined it at
> 5000 so as not to break the motor.
>
> What do you think? I have been treating it like an
> ICE
> but don't know if that is right.
>
>
____________________________________________________________________________________
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--- End Message ---
--- Begin Message ---
When you type 3500rpm for an electric motor, where is that determined at?
By/at the shaft circumference point, inside the motor, or some other
location?
God bless
----- Original Message -----
From: "Mike Willmon" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Wednesday, June 20, 2007 10:21 PM
Subject: RE: Motor speed
Storm,
My WarP9 finds its sweet spot around 3500 RPM, which in 2nd gear happens
to be 35 mph. at 37mph I can feel acceleration start to
taper and seems the perfect shift point to 3rd gear.
Mike
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Jim Husted
Sent: Wednesday, June 20, 2007 6:01 PM
To: ev@listproc.sjsu.edu
Subject: Re: Motor speed
Hey Storm
Actually you don't want to lug the motor and you have
plenty of room and would say it'd be happier at the
3000 to 4000 rpms, you got lots more rpm to play with
8^)
Hope this helps
Jim Husted
Hi-Torque Electric
--- Storm Connors <[EMAIL PROTECTED]> wrote:
> I got the tachometer installed, now the big
> question.
> What is the best speed to aim for with my ADC 9"
> motor
> pushing almost 3500 pounds? I have been keeping it
> between 2000 and 2500 RPM generally. My thinking is
> that if the revs are too low under load, there is
> the potential of overheating. I have red lined it at
> 5000 so as not to break the motor.
>
> What do you think? I have been treating it like an
> ICE
> but don't know if that is right.
>
>
____________________________________________________________________________________
Never miss an email again!
Yahoo! Toolbar alerts you the instant new Mail arrives.
http://tools.search.yahoo.com/toolbar/features/mail/
--- End Message ---
--- Begin Message ---
The battery short circuit current (Isc) can be calculated from (Voc / Rint)
where
Voc is the open circuit voltage of the battery pack
Rint is the sum of internal resistance and the wiring resistance
Maximum power (Pm) for the battery is (Voc / 2 * Isc / 2) where
Voc is the open circuit voltage of the battery
Isc is the short circuit current of the battery.
If the controller battery current limit (Ic) is less than Isc / 2, then
the controller is the current limit rather than the battery.
In this case, the controller power input limit is Voc * (1 - Ic * Rint) *
Ic.
You then multiply by the controller and motor efficiencies to get the
mechanical power available.
Joe Smalley
Rural Kitsap County WA
Former owner of 48 Volt Fiesta
NEDRA 48 volt street conversion record holder
[EMAIL PROTECTED]
----- Original Message -----
From: "Joseph Tahbaz" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Wednesday, June 20, 2007 7:46 PM
Subject: Internal Resistance? Peukert's Exponent? Voltage Sag?!?!
I'd like to know what the maximum power of my future EV would be.
I first calculated what the max. power of my EV would be using the good old
volts x amps equation. (144 x ~650) I took the 93.6 Kw and multiplied it by
the efficiency of the controller and motor. (93.6 x 0.95 x 0.90 = 80 Kw or ~
105 hp) I thought, "105 hp isn't half bad!"
Then I learned about how internal resistance and Peukert's Exponent cause
voltage sag.
How do you account for these two factors in an equation?
_________________________________________________________________
Make every IM count. Download Windows Live Messenger and join the i’m
Initiative now. It’s free.
http://im.live.com/messenger/im/home/?source=TAGWL_June07
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--- Begin Message ---
Thanks guys. I will aim for 3000-3500RPM as a norm.
--- End Message ---
--- Begin Message ---
Rob,
It looks like you are confusing a few things, let me try to understand:
You quote the two motors as 100A continuous as well as a total 8 for
two motors, so I am guessing that they are 100W motors (24V 4A each)
The reserve capacity of 195 minutes stays 195 and is not multiplied
by 2 when using two batteries in series, because the 25A load current
for this specification stay the same in series configuration, as
it is the voltage that is doubled.
So, in theory you would have 195 min x 25A / 8A = 10 hours.
Now, in practice it is real easy to have an incorrect gearing and
bog down the motors too much (lugging = running at too low speed)
which will not only overheat them, but also allow much more than
rated current to flow. Careful calculations and some experimentation
is required to find the optimal gearing.
Hope this helps,
Blessings to you as well.
Cor van de Water
Systems Architect
Proxim Wireless Corporation http://www.proxim.com
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
Second Life: www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Rob Hogenmiller
Sent: Wednesday, June 20, 2007 8:28 PM
To: EV Discussion
Subject: Lead Acid Batteries
I was wondering what kind of distance I could get out of a two (12V) 31
group batteries.
If I have a 24 volt system, with a two 100amp continous & max output motors,
how long would the battery last?
They have 1200 Amps, and a reserve capacity of 195 minutes.
If my math is correct it would be:
195minutes x 2 batteries / 8 (draw of amps by two motors)= 48.75 minutes.
Are we allowed to put link addresses on here of projects we are working on?
God bless
--- End Message ---
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--- Begin Message ---
Copper wire is rated in ohms per 1000 feet or milliohms per foot.
You get these values from the manufacturer of the wire.
Joe Smalley
Rural Kitsap County WA
Former owner of 48 Volt Fiesta
NEDRA 48 volt street conversion record holder
[EMAIL PROTECTED]
----- Original Message -----
From: "Joseph Tahbaz" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Wednesday, June 20, 2007 9:24 PM
Subject: RE: Internal Resistance? Peukert's Exponent? Voltage Sag?!?!
Thank you for the equation and your explanation but as you can imagine, I
know little of electronics so I have a question. What is the resistance of
2/0 capper wire? There are different numbers for different lengths.
> From: [EMAIL PROTECTED]> To: ev@listproc.sjsu.edu> Subject: Re: Internal
Resistance? Peukert's Exponent? Voltage Sag?!?!> Date: Wed, 20 Jun 2007
20:52:10 -0700> > The battery short circuit current (Isc) can be calculated
from (Voc / Rint)> where> Voc is the open circuit voltage of the battery
pack> Rint is the sum of internal resistance and the wiring resistance> >
Maximum power (Pm) for the battery is (Voc / 2 * Isc / 2) where> Voc is the
open circuit voltage of the battery> Isc is the short circuit current of the
battery.> > If the controller battery current limit (Ic) is less than Isc /
2, then> the controller is the current limit rather than the battery.> In
this case, the controller power input limit is Voc * (1 - Ic * Rint) *> Ic.>
> You then multiply by the controller and motor efficiencies to get the>
mechanical power available.> > Joe Smalley> Rural Kitsap County WA> Former
owner of 48 Volt Fiesta> NEDRA 48 volt street conversion record holder>
[EMAIL PROTECTED]> > > > ----- Original Message ----- > From: "Joseph
Tahbaz" <[EMAIL PROTECTED]>> To: <ev@listproc.sjsu.edu>> Sent: Wednesday,
June 20, 2007 7:46 PM> Subject: Internal Resistance? Peukert's Exponent?
Voltage Sag?!?!> > > > I'd like to know what the maximum power of my future
EV would be.> > I first calculated what the max. power of my EV would be
using the good old> volts x amps equation. (144 x ~650) I took the 93.6 Kw
and multiplied it by> the efficiency of the controller and motor. (93.6 x
0.95 x 0.90 = 80 Kw or ~> 105 hp) I thought, "105 hp isn't half bad!"> >
Then I learned about how internal resistance and Peukert's Exponent cause>
voltage sag.> > How do you account for these two factors in an equation?>
_________________________________________________________________> Make
every IM count. Download Windows Live Messenger and join the i’m> Initiative
now. It’s free.> http://im.live.com/messenger/im/home/?source=TAGWL_June07>
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New MSN Mobile!
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--- End Message ---
--- Begin Message ---
Here is the data.
2 Motors 100Amp Continuous.
2 (12 Volt Batteries Put Together To Make 24 Volt System Each Battery Has
1200 Amps And Each Battery Has 195min Reserve Capacity)
No they are 3750 Watts motors. Not 100Watt Motors.
195 x 25a/200a= 24.375 Minutes
I'm still learning terminology and math (in relation to electric motors)
thank you for your patience.
God bless
----- Original Message -----
From: "Cor van de Water" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Wednesday, June 20, 2007 10:58 PM
Subject: RE: Lead Acid Batteries
Rob,
It looks like you are confusing a few things, let me try to understand:
You quote the two motors as 100A continuous as well as a total 8 for
two motors, so I am guessing that they are 100W motors (24V 4A each)
The reserve capacity of 195 minutes stays 195 and is not multiplied
by 2 when using two batteries in series, because the 25A load current
for this specification stay the same in series configuration, as
it is the voltage that is doubled.
So, in theory you would have 195 min x 25A / 8A = 10 hours.
Now, in practice it is real easy to have an incorrect gearing and
bog down the motors too much (lugging = running at too low speed)
which will not only overheat them, but also allow much more than
rated current to flow. Careful calculations and some experimentation
is required to find the optimal gearing.
Hope this helps,
Blessings to you as well.
Cor van de Water
Systems Architect
Proxim Wireless Corporation http://www.proxim.com
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
Second Life: www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Rob Hogenmiller
Sent: Wednesday, June 20, 2007 8:28 PM
To: EV Discussion
Subject: Lead Acid Batteries
I was wondering what kind of distance I could get out of a two (12V) 31
group batteries.
If I have a 24 volt system, with a two 100amp continous & max output
motors,
how long would the battery last?
They have 1200 Amps, and a reserve capacity of 195 minutes.
If my math is correct it would be:
195minutes x 2 batteries / 8 (draw of amps by two motors)= 48.75 minutes.
Are we allowed to put link addresses on here of projects we are working
on?
God bless
--- End Message ---
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* is not set to send PLAIN TEXT ONLY and needs adjusting *
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--- Begin Message ---
If the charger is set up to charge 12 volt (10 cell) NiCd or NiMH batteries,
then the charger will safely fill the 12 volt SLA or VRLA battery to about
80%.
If you have a voltage sensor that turns off the charger when the battery
voltage reaches about 14.5 volts, then it will shut off at about 80% full.
You can do this for several dozen cycles until the battery starts degrading
from being chronically undercharged.
If you do not have a voltage level shutoff, it will overcharge the battery
and eventually destroying it from overcharging.
If the upper voltage limit is 12 volts, then it will not fill a 12 PbA
battery.
Joe Smalley
Rural Kitsap County WA
Former owner of 48 Volt Fiesta
NEDRA 48 volt street conversion record holder
[EMAIL PROTECTED]
----- Original Message -----
From: "Zeke Yewdall" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Wednesday, June 20, 2007 7:29 AM
Subject: Re: Chargers?
> The fully charged voltage for a 12 volt 5AH NiMH or NiCad battery will
> be around 14.5 to 15 volts. I assume your lead acid battery is a
> sealed gell cell. Generally, it won't like more than about 14.5 volts
> maximum. Other than that, the NiMH generally require more care in
> charging than lead acid, I believe, so it should be able to charge it.
> Unless is has some feature that tests the pack to determine what it
> is, and it can't figure out what the SLA is.
>
> Z
>
> On 6/20/07, Rob Hogenmiller <[EMAIL PROTECTED]> wrote:
> > I have two nice units to charge RC car battery charges.
> >
> > It has NimH and NicD under choices of battery types to charge.
> >
> > They will do up to 12 volts and up to 5000mAh
> >
> > I am wanting to charge a 12 volt 4.5A Lead Acid Battery.
> >
> > Is there any reason I shouldn't use these charges to charge this type of
> > battery?
> >
> > God bless
> >
> >
> >
>
--- End Message ---
--- Begin Message ---
You also need to include the resistance of the lugs, contactors, fuses, and
circuit breakers.
Joe Smalley
Rural Kitsap County WA
Former owner of 48 Volt Fiesta
NEDRA 48 volt street conversion record holder
[EMAIL PROTECTED]
----- Original Message -----
From: "Joseph Tahbaz" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Wednesday, June 20, 2007 9:39 PM
Subject: RE: Internal Resistance? Peukert's Exponent? Voltage Sag?!?!
So do you get the ohm/1000ft rating and find the ohm/1ft and then multiply
it by how many feet of copper wire you will have in your EV?
Also, all copper wire 2/0 ohm ratings are relativelt the same, right?> From:
[EMAIL PROTECTED]> To: ev@listproc.sjsu.edu> Subject: Re: Internal
Resistance? Peukert's Exponent? Voltage Sag?!?!> Date: Wed, 20 Jun 2007
21:27:12 -0700> > Copper wire is rated in ohms per 1000 feet or milliohms
per foot.> You get these values from the manufacturer of the wire.> > Joe
Smalley> Rural Kitsap County WA> Former owner of 48 Volt Fiesta> NEDRA 48
volt street conversion record holder> [EMAIL PROTECTED]> > > -----
Original Message ----- > From: "Joseph Tahbaz" <[EMAIL PROTECTED]>> To:
<ev@listproc.sjsu.edu>> Sent: Wednesday, June 20, 2007 9:24 PM> Subject: RE:
Internal Resistance? Peukert's Exponent? Voltage Sag?!?!> > > > Thank you
for the equation and your explanation but as you can imagine, I> know little
of electronics so I have a question. What is the resistance of> 2/0 capper
wire? There are different numbers for different lengths.> > From:
[EMAIL PROTECTED]> To: ev@listproc.sjsu.edu> Subject: Re: Internal>
Resistance? Peukert's Exponent? Voltage Sag?!?!> Date: Wed, 20 Jun 2007>
20:52:10 -0700> > The battery short circuit current (Isc) can be calculated>
from (Voc / Rint)> where> Voc is the open circuit voltage of the battery>
pack> Rint is the sum of internal resistance and the wiring resistance> >>
Maximum power (Pm) for the battery is (Voc / 2 * Isc / 2) where> Voc is the>
open circuit voltage of the battery> Isc is the short circuit current of
the> battery.> > If the controller battery current limit (Ic) is less than
Isc /> 2, then> the controller is the current limit rather than the
battery.> In> this case, the controller power input limit is Voc * (1 - Ic *
Rint) *> Ic.>> > You then multiply by the controller and motor efficiencies
to get the>> mechanical power available.> > Joe Smalley> Rural Kitsap County
WA> Former> owner of 48 Volt Fiesta> NEDRA 48 volt street conversion record
holder>> [EMAIL PROTECTED]> > > > ----- Original Message ----- > From:
"Joseph> Tahbaz" <[EMAIL PROTECTED]>> To: <ev@listproc.sjsu.edu>> Sent:
Wednesday,> June 20, 2007 7:46 PM> Subject: Internal Resistance? Peukert's
Exponent?> Voltage Sag?!?!> > > > I'd like to know what the maximum power of
my future> EV would be.> > I first calculated what the max. power of my EV
would be> using the good old> volts x amps equation. (144 x ~650) I took the
93.6 Kw> and multiplied it by> the efficiency of the controller and motor.
(93.6 x> 0.95 x 0.90 = 80 Kw or ~> 105 hp) I thought, "105 hp isn't half
bad!"> >> Then I learned about how internal resistance and Peukert's
Exponent cause>> voltage sag.> > How do you account for these two factors in
an equation?>>
_________________________________________________________________> Make>
every IM count. Download Windows Live Messenger and join the i’m>
Initiative> now. It’s free.>
http://im.live.com/messenger/im/home/?source=TAGWL_June07>>
_________________________________________________________________> Hotmail
to go? Get your Hotmail, news, sports and much more! Check out the> New MSN
Mobile!> http://mobile.msn.com>
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--- End Message ---
--- Begin Message ---
It seems very unlikely you're going to have 1200 useful amps out of a
battery with only 195 reserve minutes. Well, there's no fixed
relationship between capacity and peak delivery, but that's not it
unless you have some funky new technology. Maybe if you short circuited
it. However, it's a good idea to not load a 12v batt so it's dragged
below 10.5v or so. Usually that means a limit of a few (couple or so)
hundred amps on a fully charged batt.
The prob is that a lead acid battery which has 195 reserve minutes-
81.25 amp-hrs at 25a- cannot deliver 81.25 amp-hrs @ 100amps. The
half-discharged batt's output voltage will drop way down when you try to
pull high currents even though there are more amp-hrs on paper.
Peukert's Equation will tell you how many amp-hrs you can draw at these
elevated current levels. That equation all hinges on knowing the
Peukert Exponent for that particular batt which is easy enough to
measure, then you can predict capacity for ANY discharge level on that
batt. It is not unusual for a lead-acid EV to not be able to use a
very significant portion of its total batt capacity due to Peukert
discharge limits.
Danny
Rob Hogenmiller wrote:
Here is the data.
2 Motors 100Amp Continuous.
2 (12 Volt Batteries Put Together To Make 24 Volt System Each Battery
Has 1200 Amps And Each Battery Has 195min Reserve Capacity)
No they are 3750 Watts motors. Not 100Watt Motors.
195 x 25a/200a= 24.375 Minutes
I'm still learning terminology and math (in relation to electric
motors) thank you for your patience.
God bless
----- Original Message ----- From: "Cor van de Water" <[EMAIL PROTECTED]>
To: <ev@listproc.sjsu.edu>
Sent: Wednesday, June 20, 2007 10:58 PM
Subject: RE: Lead Acid Batteries
Rob,
It looks like you are confusing a few things, let me try to understand:
You quote the two motors as 100A continuous as well as a total 8 for
two motors, so I am guessing that they are 100W motors (24V 4A each)
The reserve capacity of 195 minutes stays 195 and is not multiplied
by 2 when using two batteries in series, because the 25A load current
for this specification stay the same in series configuration, as
it is the voltage that is doubled.
So, in theory you would have 195 min x 25A / 8A = 10 hours.
Now, in practice it is real easy to have an incorrect gearing and
bog down the motors too much (lugging = running at too low speed)
which will not only overheat them, but also allow much more than
rated current to flow. Careful calculations and some experimentation
is required to find the optimal gearing.
Hope this helps,
Blessings to you as well.
Cor van de Water
Systems Architect
Proxim Wireless Corporation http://www.proxim.com
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
Second Life: www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Rob Hogenmiller
Sent: Wednesday, June 20, 2007 8:28 PM
To: EV Discussion
Subject: Lead Acid Batteries
I was wondering what kind of distance I could get out of a two (12V) 31
group batteries.
If I have a 24 volt system, with a two 100amp continous & max output
motors,
how long would the battery last?
They have 1200 Amps, and a reserve capacity of 195 minutes.
If my math is correct it would be:
195minutes x 2 batteries / 8 (draw of amps by two motors)= 48.75
minutes.
Are we allowed to put link addresses on here of projects we are
working on?
God bless
--- End Message ---
--- Begin Message ---
The forces you need to overcome are aerodynamic drag plus the rolling
resistance. (This presumes level ground and no wind)
The power required to overcome aerodynamic drag = 0.5rho*Cd*A*V*V*V
where rho = density of air = 1.2 kg/m3, Cd = drag coefficient, A =
frontal area of the car in m^2, V = velocity (55mph = 25m/s)
For my fiat the numbers would be something like: P = 0.5 * 1.2 * 0.4 *
0.6 * 25 * 25 * 25 => 2250W or about 3Hp
The power required to overcome rolling resistance = V * Crr * g * m
where V = velocity, Crr = coefficient of rolling resistance (0.006 -
0.01 for lrr tires), g = gravitational constant (9.81m/s^2), m= mass
of car in kg.
So for a 1200kg (2500lbs) car with marginally low rolling resistance
tires the power needed is 25*0.01*9.81*1200 => 3000W or about 4Hp
Total power needed is thus 3+4 = 7Hp at the wheels. In real life you
probably want twice as much at the motor. (due to wind, slopes &
transmission losses)
Someone check for mistakes, it's late ;)
On 6/20/07, Rob Hogenmiller <[EMAIL PROTECTED]> wrote:
What is the mathematical formula to determine how much HP I will need to
maintain 55mph.
For i.e.
5,000lbs vehicle x rolling resistance / 10HP= 50mph would eventually produce
given a long enough run.
(I know that isn't anywhere close to the true formula ust trying to get an
idea)
God bless
--
www.electric-lemon.com
--- End Message ---
--- Begin Message ---
Hi there,
after first experiences with my Tavria EV I wonder how I could
improve hillclimbing ability without mudering the pack by drawing
lots of amps.
Here the specs of my car:
- 90V via 15 6V batteries, Varta 160Ah gel
- series wound, 12kw S2 (60min) motor, about 8", 3500rpm at 90V
- vehicle weight 2500 lb (so a bit over 1/3rd is battery weight)
- curtis 1221R 375A peak controller
- top speed about 50 mph
I have lots of smaller hills with inclines of typically up to 7%. I was
told to keep battery amps below 120A to insure long battery life. I am
right now trying to keep them at least below 160A as a compromise but
EVen at this rate the hillclimbing is more a hillcreeping. Most hills
that I worry about are about 2 miles long. In city driving is not an
issue with up to 160A, but on regular streets where EVery body wants to
go 65 I am not comfortable with going 25 when there is a hill. Even at
160A my motor heats up pretty good once I was going a couple of miles.
My first temp sensor is set to 140deg C and turns on the forced air fan.
I hear the fan almost after every hill. I think I could improve by
running the fan from the start. After a careful trip of 20mi I can
touch my motor for about 3-4 secs. I guess case temp is around 60 deg C.
I know I could put in a larger controller, but wouldn't that just
aggravate the problem as I would draw even more battery amps to get
higher power? So I am looking at alternatives to just drawing a lot of
amps.
Here are my thoughts:
- increasing voltage for hills via two contactors and three 12V 100Ah
batteries that will be switched in instead of the controller and then
drive in 2nd. The first contactor would disconnect the curtis
controller, the other hook the motor directly to the combined battery
with 126V once the curtis is disconnected. Main contactor would act as
safety.
- adding capacitors (fed from higher voltage batteries) to smooth
battery current and provide for peak loads e.g. during accelleration
- lighten the pack and go with 12V SLA 100Ah (according to an old post
from Lee Hart this could make things worse, as I will be drawing similar
currents from much smaller batteries)
- go higher voltage, e.g. 120V and buy a new controller.
- look for NiCad batteries from SAFT to replace lead batteries, but I
read these don't like more than 250A. OTOH, BB600s are higher amperage
but not easy to get and heavier.
- currently not an option: use LiPoly or A123 high current cells due to
price
Thanks
Markus
- 90V Tavria EV
- 36V Elec-Trac E20
--- End Message ---
--- Begin Message ---
They're there, keep trying, and phoning, and e-mailing this list. They'll see
it...EVentually. They are a small shop and seem to
stay pretty busy. They do not discriminate however, they are slow for
EVerybody equally. A little patience and you'll get
through. I have been there, and in retrospect it was worth the wait.
Mike,
Anchorage, Ak.
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of Florian Schmidt
> Sent: Wednesday, June 20, 2007 4:22 AM
> To: ev@listproc.sjsu.edu
> Subject: contacting Electro Automotive (electroauto.com)
>
>
> does anybody know if the Guys of Electro Automotive have another E-Mailadress
> ? I always get Error Messages when i send
> an E-Mail to [EMAIL PROTECTED]
> --
> Ist Ihr Browser Vista-kompatibel? Jetzt die neuesten
> Browser-Versionen downloaden: http://www.gmx.net/de/go/browser
>
>
--- End Message ---
--- Begin Message ---
Peter,
Everything seem right if you only can fit into a Fiat with
frontal area of 0.6m^2 :-) In reality normal car has about 2m^2,
slick ones like my CRX are 1.7m^2.
Thus, power requirements to ride at 55mph are rather about 8-10kW.
A 0.6 m^2 is frontal area of a slim motorcycle. What kind of Fiat
is this ??
--
Victor
'91 ACRX - something different.
Peter Gabrielsson wrote:
The forces you need to overcome are aerodynamic drag plus the rolling
resistance. (This presumes level ground and no wind)
...
Someone check for mistakes, it's late ;)
--- End Message ---
--- Begin Message ---
Ok, so in a different thread titled "ADC 9" Amps" I didn't lie when I said I
never went above 4500 rpm. It was true for the
0-60mph testing I was doing for that example.
With that cleared up, I have gone 0-85 mph in 3rd gear alone and topped out at
5500 rpm.
Although 55mph at 3500 RPM seems to be the next natural shift point for the
motor. It really likes 35mph at 3500 rpm in 2nd, or
55mph at 3500 rpm in 3rd. Much above that rpm and I can tell that the next
gear gives a little better acceleration. Although
that difference is less and less noticible as the gears increase.
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of Rob Hogenmiller
> Sent: Wednesday, June 20, 2007 7:54 PM
> To: ev@listproc.sjsu.edu
> Subject: Re: Motor speed
>
>
> So when you shift into 3rd gear what does that allow you to increase your
> speed to?
>
> God bless
>
>
> ----- Original Message -----
> From: "Mike Willmon" <[EMAIL PROTECTED]>
> To: <ev@listproc.sjsu.edu>
> Sent: Wednesday, June 20, 2007 10:21 PM
> Subject: RE: Motor speed
>
>
> > Storm,
> > My WarP9 finds its sweet spot around 3500 RPM, which in 2nd gear happens
> > to be 35 mph. at 37mph I can feel acceleration start to
> > taper and seems the perfect shift point to 3rd gear.
> >
> > Mike
> >
> >> -----Original Message-----
> >> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> >> Behalf Of Jim Husted
> >> Sent: Wednesday, June 20, 2007 6:01 PM
> >> To: ev@listproc.sjsu.edu
> >> Subject: Re: Motor speed
> >>
> >>
> >> Hey Storm
> >>
> >> Actually you don't want to lug the motor and you have
> >> plenty of room and would say it'd be happier at the
> >> 3000 to 4000 rpms, you got lots more rpm to play with
> >> 8^)
> >>
> >> Hope this helps
> >> Jim Husted
> >> Hi-Torque Electric
> >>
> >>
> >> --- Storm Connors <[EMAIL PROTECTED]> wrote:
> >>
> >> > I got the tachometer installed, now the big
> >> > question.
> >> > What is the best speed to aim for with my ADC 9"
> >> > motor
> >> > pushing almost 3500 pounds? I have been keeping it
> >> > between 2000 and 2500 RPM generally. My thinking is
> >> > that if the revs are too low under load, there is
> >> > the potential of overheating. I have red lined it at
> >> > 5000 so as not to break the motor.
> >> >
> >> > What do you think? I have been treating it like an
> >> > ICE
> >> > but don't know if that is right.
> >> >
> >> >
> >>
> >>
> >>
> >>
> >> ____________________________________________________________________________________
> >> Never miss an email again!
> >> Yahoo! Toolbar alerts you the instant new Mail arrives.
> >> http://tools.search.yahoo.com/toolbar/features/mail/
> >>
> >>
> >
> >
>
>
--- End Message ---
