Re: NiMH battery care and feeding
--- In force_ev@y..., "Tom Hudson" <tomhudson@e...> wrote:
...We now live in Wisconsin and own a '97 lead-acid Force that's
getting upgraded to NiCD...
I'm contemplating a NiCd pack option for a new NEV . Could you single
out a few particular considerations with respect to NiCd vs PbA
(Trojans) in EVs for me?
Like charging, maintenance, monitoring, etc.
Bil Gladstone, \
"e-scooter commuter" O=--O
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- bil@... writes:
> Date: Sun, 22 Jul 2001 21:38:31 -0000Tom has a very interesting page on this:
> From: bil@...
> I'm contemplating a NiCd pack option for a new NEV . Could you
> single out a few particular considerations with respect to NiCd vs
> PbA (Trojans) in EVs for me? Like charging, maintenance,
> monitoring, etc.
> I'm contemplating a NiCd pack option for a new NEV . Could you singleDavid Roden can probably fill in any gaps or correct me on any of the
> out a few particular considerations with respect to NiCd vs PbA
> (Trojans) in EVs for me?
> Like charging, maintenance, monitoring, etc.
The NiCDs are interesting to me because you have about double the range of a
comparably-sized lead-acid pack. The NiCDs are way more forgiving than
lead-acids, you can leave them discharged and they don't have problems like
lead-acid sulfation. They have incredible cycle life.
Downsides: They are more expensive to buy, though their longer life more
than compensates for this. They need watering, unlike my current sealed
lead-acid pack. The charging profile requires that the charger be tied into
an amp-hour counter/e-meter so that the proper amount of overcharge can be
done. Mine are water-cooled, necessitating water pumps and radiators,
though they also come in an air-cooled version. I had to go with
water-cooled due to space restrictions -- No room around the batteries for
I've spoken to people who had older, used NiCD packs they bought and after
they did the commissioning charge, the pack was right up to spec. Amazing.
http://portdistrict5.org -- 5th District Aldermanic Website
http://portev.org/solectria/ho -- Our Electric Vehicles
http://portev.org/solectria/ho/pvs.htm -- Solar Power
http://portev.org/solectria -- Solectria Owners Website
http://portgardenclub.org -- Port Washington Garden Club
http://portlightstation.org -- Light Station Restoration
- Tom summarized the advantages and disadvantages of nicads very well. I
have only a few items to add.
Nicads are the advanced batteries that some people can actually afford.
They are not as sophisticated as NiMH, but those have some distance yet
to go before they are at a price point that the average hobbyist EV owner
can really consider them.
Nicads have much better specific energy than lead (that is, 55+ watt-
hours per kilogram compared to typical 28-36 wh/kg for lead -- the East
Penn gel batteries are about 22 wh/kg at 75 amps). So Tom is right that
a pack of equivalent weight nicads will nearly double your range.
They also have better energy density (watt-hours per liter) but it is not
as large a difference.
Lead batteries lose capacity when called on to deliver high currents.
Nicads lose appreciably less at high currents.
Nicads are almost entirely unaffected by cold weather. You lose much
less range in winter than with lead batteries. (If you have a thermal
management system this may not matter to you.)
On the other hand nicads don't much like very high temperatures. They
shouldn't be charged when their temperature exceeds about 40 deg C (105
degrees fahrenheit). The chargers usually are programmed to turn on the
fans or cooling system and wait until the temperature falls to around 30
deg C, probably at night. If you have nighttime temperatures in the 85-
degree-plus range, you may not get a charge that night!
They calculate out to be cheaper per mile of actual use than East Penns,
Optimas, and Hawkers. They are theoretically cheaper than Trojans but in
practice are probably about the same (but you don't have to change them
every few years as you do the Trojans).
Here is a cost per mile comparison:
Battery cost DOD Life Range@DOD Total Mi Cost/Mi
Trojan 27TMH $960 80% 300 40 12,300 $0.078
East Penn 8g27 $1560 100% 200 40 8,000 $0.20
East Penn 8G27 $1560 50% 400 20 8,000 $0.20
East Penn 8G27 $1560 30% 1300 12 15,600 $0.10
Saft 5-100MR $7680 80% 3000 64 192,000 $0.04
Cycle life specs are from manufacturers' datasheets. Your mileage may
In practice the Safts should last the life of the vehicle. If we take
that as 100,000 miles, the real cost is probably about $0.077 per mile.
David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1979 General Engines ElectroPed 24vdc
1974 Honda Civic EV 96vdc
1970 GE Elec-trak E15 36vdc
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I'll get on your list ASAP. I'm getting info ready now for the EV Album / Mike
I bought my car from Stephan Miracle at EVermont, a non-profit in Vermont.
I'm delighted with the car, however I am not familiar with the NiMH batteries
and their care. So far, it's just charge and drive!
This is what the public needs to have available, however at a more affordable
price when new.
My wife wants to drive it to commute to work. She really likes the attention! I
guess I'll have to settle for my TEVan.
What range did you get with Lead-acid? What do you expect with NiCD?
----- Original Message -----
From: "Tom Hudson" <tomhudson@...>
Sent: Wednesday, July 18, 2001 3:51 PM
Subject: RE: [force_ev] NiMH battery care and feeding
> Hi Don! Man, another EV in Kansas City! My wife and I used to live there;
> We now live in Wisconsin and own a '97 lead-acid Force that's getting
> upgraded to NiCD. I can't help you on the battery care issue, but I'd like
> to invite you (and any other Force owners who are lurking) to get listed on
> our Solectria Owner's website (see link below). No cost or obligation, I
> just want to get as many of us listed as possible.
> Out of curiosity, how did you get that car?
> Thomas Hudson
> http://portdistrict5.org -- 5th District Aldermanic Website
> http://portev.org/solectria/ho -- Our Electric Vehicles
> http://portev.org/solectria/ho/pvs.htm -- Solar Power
> http://portev.org/solectria -- Solectria Owners Website
> http://portgardenclub.org -- Port Washington Garden Club
> http://portlightstation.org -- Light Station Restoration
> > -----Original Message-----
> > From: Don Buckshot [mailto:scanner@...]
> > Sent: Wednesday, July 18, 2001 12:49 PM
> > To: firstname.lastname@example.org
> > Subject: [force_ev] NiMH battery care and feeding
> > I took delivery of a '96 Force on July 4th and am very pleased with it.
> > This is what the public ought to see more of in oreder appreciate what is
> > already available to us.
> > Can someone direct me to a resource for the care and feeding of these NiMH
> > batteries?
> > I know they are very expensive and don't want to screw them up.
> > I have read the Email by Dave Roden (June 10th) about battery
> > life on the lead
> > acid units and would like to research the NiMH.
> > Help? anyone.
> > Don Buckshot
> > Kansas City,MO
> > 1993 TEVan
> > 1996 Solectria Force
> > 816-556-6356 IBM
> > 816-531-2206 home,
> > 816-582-6891 PCS anytime
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