## Power and lack thereof

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• Dear Solectrians, I was driving home from work the other day when on starting up a hill I found myself without enough power to sustain 30 mph (I was down about
Message 1 of 5 , Oct 27, 2001
Dear Solectrians,

I was driving home from work the other day when on starting up a hill I
found myself without enough power to sustain 30 mph (I was down about 10
amp-hours from full charge at this point, according to the meter).

So the next day, after the car had charged overnight, I measured the
specific gravity in all the cells in all twelve batteries, and they all
measured about 1.265, which is what the manufacturer says they should
measure fully charged.

I wonder if I've got some sort of controller problem?

Rob Landry
umarc@...
• ... It could be a controller problem, or perhaps it was cutting back because the motor was overheating. Did you check the motor temperature? The most likely
Message 2 of 5 , Oct 27, 2001
On 27 Oct 2001, at 11:59, umarc@... wrote:

> I was driving home from work the other day when on starting up a hill I
> found myself without enough power to sustain 30 mph (I was down about 10
> amp-hours from full charge at this point, according to the meter).

It could be a controller problem, or perhaps it was cutting back because
the motor was overheating. Did you check the motor temperature?

The most likely cause of this would be a failing battery. One cell with
unusually high internal resistance will cause a large voltage drop. The
more current that's used, the greater the voltage drop. One cell can
actually cause far more than its own 2 volts of reduction because it acts
like a resistor.

Under normal circumstances, the controller tries to be kind to the
batteries by limiting current to keep voltage above 1.75 volts per cell
(126 volts for a 144v pack, or 136.5 volts for a 156v pack). Thus a low
charge will cause a drop in top speed and acceleration rate. The same
thing will happen in case of a failing battery which drags down the pack

Ideally you should test the pack under operating load by putting a 50 amp
(or more) dummy load across the pack and measuring each battery. This
would quickly tell you which one is acting up. I use a dummy load I made
from heating elements from derelict heat pumps, adding a fan and a spare
contactor. This eats 100-110 amps at 144 volts (and as a cool weather
bonus also warms up my garage nicely while I'm testing).

If you don't have such a load, you may be able to determine the
troublesome one by turning on the heater and all the accessories in your
garage, and measuring the voltage of each battery in turn. Look for a
battery that's about 2 volts lower than the others.

Too bad Solectria didn't fit all cars with voltmeters. This was an
option which should have been standard, as it alerts you to these kinds
of problems.

David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1979 General Engines ElectroPed 24vdc
1970 GE Elec-trak E15 36vdc
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• ... I ve designed and built an instrument for the Force that monitors the voltage on each battery. The display fits into the blank spot in the dash. An
Message 3 of 5 , Oct 30, 2001
At 15:15 10/27/2001 -0400, you wrote:
>Too bad Solectria didn't fit all cars with voltmeters. This was an
>option which should have been standard, as it alerts you to these kinds
>of problems.

I've designed and built an instrument for the Force that monitors the
voltage on each battery. The display fits into the blank spot in the dash.
An article about it is scheduled for publication in the next issue of
Current EVents. The instrument clearly shows what happens if you
regenerate hard on a fully charged pack -- uneven overvoltage -- not good!

I'd be glad to provide advice or help to anybody who wants to do the same
thing. Watch for the article!

Gordon Stallings
1999 Solectria Force
• I can t wait for the article, Gordon! I want one! -Tom (watching the mailbox for Current EVents)
Message 4 of 5 , Oct 30, 2001
I can't wait for the article, Gordon! I want one!

-Tom (watching the mailbox for Current EVents)

> -----Original Message-----
> From: Gordon Stallings [mailto:grs@...]
> Sent: Tuesday, October 30, 2001 9:31 AM
> To: force_ev@yahoogroups.com
> Subject: Re: [force_ev] Power and lack thereof
>
>
> At 15:15 10/27/2001 -0400, you wrote:
> >Too bad Solectria didn't fit all cars with voltmeters. This was an
> >option which should have been standard, as it alerts you to these kinds
> >of problems.
>
> I've designed and built an instrument for the Force that monitors the
> voltage on each battery. The display fits into the blank spot in
> the dash.
> An article about it is scheduled for publication in the next issue of
> Current EVents. The instrument clearly shows what happens if you
> regenerate hard on a fully charged pack -- uneven overvoltage -- not good!
>
> I'd be glad to provide advice or help to anybody who wants to do the same
> thing. Watch for the article!
>
>
> Gordon Stallings
> 1999 Solectria Force
>
>
> To unsubscribe from this group, send an email to:
> force_ev-unsubscribe@egroups.com
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
• I want one to! Don Buckshot Kansas City 1996 Solectria Force NiMH
Message 5 of 5 , Oct 30, 2001
I want one to!

Don Buckshot
Kansas City
1996 Solectria Force NiMH

Tom Hudson wrote:
>
> I can't wait for the article, Gordon! I want one!
>
> -Tom (watching the mailbox for Current EVents)
>
> > -----Original Message-----
> > From: Gordon Stallings [mailto:grs@...]
> > Sent: Tuesday, October 30, 2001 9:31 AM
> > To: force_ev@yahoogroups.com
> > Subject: Re: [force_ev] Power and lack thereof
> >
> >
> > At 15:15 10/27/2001 -0400, you wrote:
> > >Too bad Solectria didn't fit all cars with voltmeters. This was an
> > >option which should have been standard, as it alerts you to these kinds
> > >of problems.
> >
> > I've designed and built an instrument for the Force that monitors the
> > voltage on each battery. The display fits into the blank spot in
> > the dash.
> > An article about it is scheduled for publication in the next issue of
> > Current EVents. The instrument clearly shows what happens if you
> > regenerate hard on a fully charged pack -- uneven overvoltage -- not good!
> >
> > I'd be glad to provide advice or help to anybody who wants to do the same
> > thing. Watch for the article!
> >
> >
> > Gordon Stallings
> > 1999 Solectria Force
> >
> >
> > To unsubscribe from this group, send an email to:
> > force_ev-unsubscribe@egroups.com
> >
> >
> >
> > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
> >
> >
> >
>
>
> To unsubscribe from this group, send an email to:
> force_ev-unsubscribe@egroups.com
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
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