[RE-wrenches] OB Battery Charging

jay peltz jay at asis.com
Sat Nov 7 12:49:51 PST 2009


HI Ray,

What charge parameters are you using if you are not doing an EQ.
volts absorb and volts float  and absorb time?

thanks,

jay

peltz power
On Nov 7, 2009, at 12:45 PM, R Ray Walters wrote:

> I think that periodic Equalization is "old school", a concept left  
> over from the days of C30 controllers that didn't fully charge the  
> batteries on a regular basis.
> I now only recommend Eq charging if:
> a) the batteries have sat for over a month in a deeply discharged  
> state, or
> b) checking individual cell voltages indicates more than a 2%  
> difference between batteries. (over a tenth on a 6 v battery)
> Eqing every 30 days just isn't necessary with today's PWM temp  
> compensated controllers IMHO.
> Equalization charging can overheat batteries, which according to my  
> research is the number one factor in reduced life.
> Also, even when Eqing, I recommend the generator only be used to  
> bring the batteries up to close to full charge, and then let the PV  
> array perform the Equalization, thus the MATE isn't necessary.
> I still do install MATEs on projects with owners that know what  
> they're doing, and know when to equalize, etc.
> Finally, its very inefficient to use a generator for the hours  
> necessary for Equalization while running at fairly low power.
> Hit the genie early in the morning, shut down most loads, and Eq  
> with the array from 11:00am through the afternoon. If the array  
> can't do this, then its undersized, or you have designed a highbred  
> system that does require a MATE. (and an owner that understands what  
> he's doing)
>
> R. Walters
> ray at solarray.com
> Solar Engineer
>
>
>

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