Re: [EVDL] Have LOTS of Saft aircraft nicads

Tue, 09 Apr 2013 02:13:36 -0700 

I should probably clarify another goal.
The van is a conversion with insulation in the walls and the windows are tinted. It also has a small air conditioner installed in the back window that uses about 500W. I have a big inverter which starts and runs that AC ok. 


I have a couple of dogs, but I'm in Texas, and it limits what I can do 
with them in the car.  Actually it doesn't heat up THAT fast if the 
reflector is put in the windshield, in most conditions.  But in general, 
no, you really shouldn't plan to stop anywhere in the daytime, even for 
groceries.



So that'd be about a 50A discharge rate.  The deep-cycle batt that's 
there is a Wal-Mart Maxx29, "supposed to be" 125AH, but Peukert and age 
reduce that significantly.  With a solid 80AH (or tripled to 120AH) 
nicad with no Peukert-like effects and a predictable 1.6 hr AC runtime, 
that would be PRETTY handy!  If the batt's charged, I could stop for 
groceries, or even to eat.


Danny

On 4/9/2013 3:51 AM, Danny Miller wrote:

Hmm, some are larger 40AH and 43AH batts.  Some "Sonotone" brand.


Can these effectively be paralleled?  I recall hearing there was a 
problem with that... but people say lots of things, like battery memory.



I've been through a lot of lead acid batts on my camper van's 
secondary deep cycle batt.  I wouldn't mind something more reliable 
and able to support high discharge and charge rates and more cycle life.



Well, see it's like this when camping- if I run the batt down, sure I 
can still start it, but that batt's not just going to "be charged" in 
a few minutes, and that van costs a lot to idle for hours to get a 
lead-acid batt back up.


Saft's manual does specify a 1-hr charge rate, which sounds dandy.


I'm a decent microcontroller guy with board-level and power design 
experience.  There's a huge alternator on it.  That's not hard to 
build a charge monitor for.  I also see Saft specified a 1.57v/cell 
for 1hr rate.  If I turned the 24v 40AH batt into 80AH 12v, it'd need 
a boost to 15.7V @ 80A, and isolated from the other batt, which is not 
trivial but completely do-able.  And some sort of charge monitoring of 
course, which is kinda tricky, I understand.



I could also put in a control for "normal" or "fast", because most of 
the time it wouldn't need to be fast like that.


Danny

On 4/2/2013 10:00 AM, Roland Wiench wrote:

The aircraft NiCad cells were place in a very tight fitting aluminum 
battery
box.  These boxes had liquid neoprene rubber that coat the entire 
surfaces
inside in out.  Look like the whole box was submersed into this 
compound.



Then there was a layer of about 1/8 inch neoprene rubber sheets that 
adhered
to the liquid coating.  The bottom of the top cover press against the 
cell
caps to keep them in place. Then we coated this neoprene rubber with 
a GE
Dielectric grease which is like the compound use on spark plug boots 
except

we got it in large tubes that cost us about $10.00 back in 1955.


Before inserting the cells into the battery box, we coat the cells 
with a
lot of this dielectric compound which ease the insertion into the 
battery

box.  After installing the links and buss connections to the exterior 28
volt receptacle that was mounted on the outside surface of this box, we
completely cover all the links and connections with this dielectric
compound.

Today I used a acid resistance rubber compound on all my battery

connections. After making up these links with the heat shrink not 
install
yet, I insert a small cork in the battery clamp contact area and dip 
it into

this compound. Leave 24 hours to dry and than install the heat shrinks.


Install one of those red and black battery felt pads over the battery 
post
and install the battery clamps with a stainless steel bolt. Applied 
another

coating with this acid resistance compound with one of those small flux
compound brushes.


Let set for another 24 hours and than applied the dielectric compound 
over

the entire link, top of post and the buss link if you have one. Did this

method on Sept 4 2009 and the batteries still look like the day I 
install

them.

Roland


----- Original Message -----
From: "Cor van de Water" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Tuesday, April 02, 2013 2:01 AM
Subject: Re: [EVDL] Have LOTS of Saft aircraft nicads



Chris (and others) have also used these cells in their US Electricar
truck.
The take away: do *not* use flooded NiCD cells in an aluminum battery
box.
The KOH will eat the alu - even when coated several times in advance.
The NiCD work very well in cold weather if that is where you live...

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.info
Skype: cor_van_de_water Tel: +1 408 383 7626


-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of EVDL Administrator
Sent: Tuesday, April 02, 2013 12:56 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Have LOTS of Saft aircraft nicads

On 1 Apr 2013 at 15:25, Danny Miller wrote:


I know that CO2 from the air reacts with the potassium hydroxide and
forms carbonate.  If this happens, does this poison the plates for

good, or

simply weaken the electrolyte?

I'm not an expert on these matters, but from what I've read (in Home
Power),
I don't think it does any permanent damage.

According to the HP guide I have, you're supposed to check the
concentration
of K2CO3 every year or so.  You replace the electrolyte if it goes over
15%,
or every 5 years just to be sure.  I have the HP instructions for
titrating
the electrolyte to determine K2CO3 concentration if you're interested,
or
you can do it the easy way just change it now and every 5 years.

To change the electrolyte, you will probably want to have something on
hand
to neutralize the KOH in the old stuff.  I'm not sure, but you may need
to
make arrangements with some kind of hazardous waste disposal facility,
since
your waste electrolyte will contain lithium.

Have the new electrolyte ready before you start; you're not supposed to
let
the cell sit empty more than 5 minutes.  It's KOH and distilled water.
It
should have an SG of 1.190 and should be doped with about 12g of LiOH
per
liter.

Remove the caps (if your cell or monoblock has them) and invert the
cell/block over a plastic tub.  The instructions I have don't mention
using
Roland's distilled water rinse.  Refill with fresh electrolyte.

Stationary cells normally get a 1/8" to 1/4" layer of mineral oil
(Chevron

#22 Utility Oil only) atop the electrolyte to protect is from CO2 in 
the

air
and thus carbonation, but I don't think that would work so well for
mobile
cells.  AFAIK none of the Saft EV cells or modules has ever used oil.

What you really need here is sage counsel from folks who used these
specific
cells.  I thought there used to be a Yahoo group of BB600 users, but I
can't
find it now.

There's also at least one person on the Elec-trak mailing list
(Christopher

Zach) using BB600 NiCds in his ET, though he seems pretty cavalier 
about


caring for them.  I don't know whether he's a member of this list.

 From what he says, mostly he just hammers them with the Elec-trak's
blunderbuss charger, and waters them every now and again.  I think he's
been

running them a good 8-10 years and doesn't seem to have any 
problems, so



they must be pretty durable.  However, you should probably ask him 
about

the
particulars. You can subscribe to the ET mailing list here:

http://cosmos.phy.tufts.edu/mailman/listinfo.cgi/elec-trak

Hope this helps.

David Roden - Akron, Ohio, USA
EVDL Administrator

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