[ausev] A Battery Question...

[Erik]

I believe you'll always want to shoot to keep your batteries above 1.5 volts
per cell, or about 110 in your cause, at all times. When the batteries are
low, it's a lot easier to sag them to 1.5 VPC than when they are full. You
have to take it easier as they get lower.

The danger is reversing a cell. If you know that all of the batteries are
perfectly in balance the danger is basically non-existent, and the batteries
will last in accordance with how deeply you discharge them. The reality is
that all cells will be a little different, and it is much easier to reverse
a cell on a heavy discharge when you're running low. Without being able to
see the voltage of each battery in real time, it's difficult to know if
you're damaging them, unless you're keeping it above 1.5 VPC. You can still
reverse a cell while above 1.5 VPC, but you're batteries would have to have
fairly different capacities.

Erik


On Tue, May 27, 2008 at 11:26 AM, Brian Lasseter <
blasseter.cmpe01 at gtalumni.org> wrote:

> I have 18x 8 volt US8VGC batteries in my car.  That's 144volts nominal
> pack voltage.  The batteries float charge at 185 volts, I set my low
> battery indicator (In the Zilla Motor controller) at 110 volts, and my
> battery cutoff is at 80 volts.
>
> My question, is when should I measure 110 volts as being "low"?  Is
> that 110 volts under load, under a small load, or not under any load?
>
> i.e.  If I'm at a stop light reading 140 volts (after driving 25 miles
> already that day), I can stomp on the gas, push 350 amps through the
> Zilla to the engine, and the battery pack will sag to 107 volts or so
> briefly flashing the "low" battery indicator until I take my foot off
> of the gas.  Is that really "low", or am I waiting until a more normal
> 200 amp acceleration pushes the pack to below 110 volts, or am I
> waiting for when the pack reads 110 volts while sitting at a stop
> light?
>
>
>
> --
> TTFN,
> Brian "Lasso" Lasseter
>
>  · (512)736-1677 · AIM:digininja · ICQ:2238123 · MSN:azoreg ·
> "No Sane man will dance." -Cicero (106-43 B.C.)
>
> _______________________________________________
> AusEV mailing list
> AusEV at austinev.org
> http://www.austinev.org/mailman/listinfo/ausev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.austinev.org/pipermail/ausev/attachments/20080527/76ceb477/attachment.html