Re: [pvusers] Battery Time

[Bill Schudlich <bill_s@outsidemag.com>]

On 11/12/2002 7:47 AM, Scott Willing <willing@mb.sympatico.ca> wrote:
>I wonder if Bill's charging system is temperature compensated. Makes 
>a big difference - if the batteries are cold they need to be charged 
>to a higher voltage. Our batts are in a box in the pantry, which 
>is  on the cool side especially in winter, but still inside and far from 
> "cold" -- perhaps 60 degrees F on average. Temp-compensated C-40 
>charger takes the batts to around 15 or 15.1V in the winter vs 14.6 
>or so (the basic set-point) in summer.
>
>If charging isn't temp-compensated, it could be the reason for 
>undercharging and/or premature retirement.

That's an interesting point.  The batteries are charged through our Trace 2012SW inverter.  I can get voltage level readings from the control panel that are temperature compensated, but never thought if the charging regime takes that into account. I'll have to look that up.

>I'd also want to break that battery bank apart and ensure that there 
>wasn't a bad cell or battery somewhere that's pulling down the net 
>performance of the bank.

That is my next chore.  This weekend, I'll check the specific gravity of the cells.

>And a kerosene heater in a box full of charging batteries? Hmm...

No, I ain't not that stooopid...the heater is in the 10x10 shed.  The batteries are in a closed box inside the shed vented to the outside.  And if I run the heater it is at night - not much charging going on at that time. 

The battery box temp typically hovers in the 20's f during the winter, which leads to another question - which may be a stupid one. Since a battery at 20f maxes out at about 50% of capacity, am I then damaging (cycling too deep) the battery if I continue to draw power from it?  Or is this figure just a reflection of available power from the battery? 


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Bill Schudlich
Santa Fe, NM  
bschudlich@outsidemag.com

Outside Magazine - Celebrating 25 Years Outside
http://www.outsidemag.com/
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