[RE-wrenches] PV excellent battery charger

[drake.chamberlin at redwoodalliance.org]

My understanding is that the voltage, in excess of battery voltage, from
the array, represents energy that is dissipated as heat in the batteries. 
This extra voltage, multiplied by the amperage is wattage. This extra
power can produce more amps at a reduced voltage.  It is amperage that
charges the battery.

Thanks,

Drake

> MPPT doesn't really do that much for the battery, it just makes the PV
> modules more effective.
> The real magic is:
> A) the 3 stage charging (compared to traditional single stage AC chargers)
> B) Temperature compensation
> C) PWM that helps pulse off sulfation
> D) Slower charge rates let batteries charge more fully without damage from
> overheating.
>
> R. Walters
> ray at solarray.com
> Solar Engineer
>
>
>
>
> On Mar 24, 2010, at 7:04 PM, drake.chamberlin at redwoodalliance.org wrote:
>
>> Can anyone tell me why PV is considered an excellent battery charger? I
>> think it is, only after the addition of a MPPT charge control.
>> Otherwise,
>> the battery drags the PV voltage below Vmp.
>>
>> One of the NABCEP objectives for the entry level class is to explain why
>> PV modules make excellent battery chargers and show this through the IV
>> curve.
>>
>> Thank you,
>>
>> Drake
>>
>> _______________________________________________
>> List sponsored by Home Power magazine
>>
>> List Address: RE-wrenches at lists.re-wrenches.org
>>
>> Options & settings:
>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>>
>> List-Archive:
>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>>
>> List rules & etiquette:
>> www.re-wrenches.org/etiquette.htm
>>
>> Check out participant bios:
>> www.members.re-wrenches.org
>>
>>
>
> _______________________________________________
> List sponsored by Home Power magazine
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Options & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> List-Archive:
> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
>
> Check out participant bios:
> www.members.re-wrenches.org
>
>