Re: [pvusers] Battery Time

["Scott Willing" <willing@mb.sympatico.ca>]

On 12 Nov 2002 at 12:52, Raned@aol.com wrote:

> Hello,
> 
> This is my first post.  I hope I'm sending to the right address.

Hello back. So far so good!
 
> I wanted to make sure I understood the State of Charge and Freezing
> Temperature Chart correctly:
> 
> Do I have this right?
> 
> * When the temperature is -76 (Fahrenheit) a battery that is 100 %
> charged will freeze.  
> 
> * And at -6 (F) a battery that is 40 % charged will freeze.

That's correct.
 
> At say 0 degrees fahrenheit ( the lowest in my area) at what state of
> charge would a battery freeze?

Around 30%.

And by the time you're at 0%, the electrolyte is essentially water, 
and freezing will occur at 32 degrees F.

The reason I didn't continue the chart down that far is because you 
should never discharge a lead-acid battery below 50% anyway. If you 
want them to last, you don't routinely discharge them anywhere near 
that much.

And of course please note that these numbers are approximate. There 
are lots of minor chemistry variations etc., so if your fully-charged 
battery freezes at -75 degrees, I don't want to hear about it. ;-)

Cheers,
-=s

> 
> In a message dated 11/12/02 10:47:40 AM US Eastern Standard Time,
> willing@mb.sympatico.ca writes:
> 
> > Rough numbers:
> > State of charge (%) /     Freezing Temp (degrees F)
> > 
> > 100 / -76
> > 90 / -69
> > 80 / -62
> > 70 / -27
> > 60 / -17
> > 50 / -11
> > 40 / -6
> > etc. (do we care?)
> 
> 



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