[ausev] Cold weather on lead acid batteries?

[Marc Kohler]

Three things may be working against you.
1. Colder temps make the batteries have higher resistance and therefore
voltage drops faster under acceleration.
2. Colder batteries need a higher charging voltage to get completely charged
(so the charger may not be doing as much as it used to), therefore
decreasing usable capacity.
3. Lead acid batteries offer less energy as the temperature drops.

You can really only control the effects of #2 (change the profile of the
charger).  Adding the temp sensor to the link 10 may make it more accurate
but won't help the situation much other than making you more aware.
#1 and #3 can be resolved by adding battery heaters or insulating the box
(if there is room).  Not common here in Texas.

700W load just sitting around?  Seems like a lot.  What is pulling that
much?
Marc Kohler

-----Original Message-----
From: ausev-bounces at austinev.org [mailto:ausev-bounces at austinev.org] On
Behalf Of Brian Lasseter
Sent: Tuesday, November 18, 2008 12:26 PM
To: AustinEV News Announcements and General Discussion
Subject: [ausev] Cold weather on lead acid batteries?

So now that it is getting cold... what exactly would I be looking for
as an indication that my batteries are losing their effectiveness in
cold weather?

My Xantrex Link 10 battery gauge was pretty good during the summer,
though even when I got home with 3% of the batter left one day, I
could still drive reasonably at 40mph or so.

Yesterday however... I was having a hard time with hills as my car got
down to 19% as I was coming home from my son's daycare.  The voltages
seemed nominal enough at 19% state of charge.   I was still seeing
140volts at a stop (There is a 5 amp drain still on the battery pack
when the car is at a dead stop due to the DC/DC converter, and the
various 12volt loads.)   When stepping on the gas however, the voltage
quickly dropped off to 105 volts as I gave 100amps to the motor going
up the hills going south on Metric Blvd from Parmer Lane.

For reference I run 18x 8volt batteries, in a 144 volt flooded lead acid
pack.

Maybe this will get me off of my bum to install the battery temp
sensor into the Xantrex, instead of letting it collect dust in my
garage.   Or maybe I should just change programmed battery temp.  I
think I set it to 90 degrees F when I set up the battery meter.


-- 
TTFN,
Brian "Lasso" Lasseter

"No Sane man will dance."   -Cicero (106-43 B.C.)
_______________________________________________
AusEV mailing list
AusEV at austinev.org
http://www.austinev.org/mailman/listinfo/ausev
No virus found in this incoming message.
Checked by AVG - http://www.avg.com 
Version: 8.0.175 / Virus Database: 270.9.2/1785 - Release Date: 11/18/2008
11:23 AM