[RE-wrenches] OB Battery Charging

[R Ray Walters]

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




On Nov 7, 2009, at 1:10 PM, Allan Sindelar wrote:

> Ray,
> We usually include the Mate if we expect a backup generator to be  
> the periodic source of a higher C/rate than the PV array for  
> equalizing batteries. The Mate is necessary to initiate an EQ charge  
> algorithm. How do you accomplish periodic EQ with an Outback  
> inverter and no Mate?
> Thanks,
> Allan Sindelar
> Allan at positiveenergysolar.com
> NABCEP Certified Photovoltaic Installer
> EE98J Journeyman Electrician
> Positive Energy, Inc.
> 3201 Calle Marie
> Santa Fe, New Mexico 87507
> 505 424-1112
> www.PositiveEnergySolar.com
>
> From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches- 
> bounces at lists.re-wrenches.org] On Behalf Of R Ray Walters
>
> As far as customer interaction with the MATE, we generally don't  
> provide one. They're way too expensive and hard to understand, and  
> the chances of them screwing up the programming are too great.
> We install just the cable, and coil it up so that when we come out,  
> we can access the programming without having to remove all the cover  
> plates.
> Only customers that are comfortable with changing settings, etc.  
> actually get a MATE. (1 out of 10)
>
> R. Walters
> ray at solarray.com
> Solar Engineer
>
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