PV System Worksheet --Charge acceptance factor [RE-wrenches]

[Windy Dankoff, Dankoff Solar]

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>Windy:
>
>For the type of charging algorithms we have in PV systems the charge
>acceptance of the battery will be defined by the Amp hour law.
>According to the Amp hour law the maximum instantaneous charge current
>will be proportional to the number of Amp hours out of the battery.
>Essentially this says the closer you get to full charge the slower you
>have to charge the battery.
>Hard to model when you don't kow how many Ahrs have been discharged.

Harder to model when the charger is may or may not be capable of 
reaching the max that the battery can absorb.

>
>In classes I try to explain that it is kind of like pouring a cold one
>and trying to fill the glass right to the top.
>At first you can go glug, glug, glug and you won't spill a drop.
>Once the glass starts to fill up you have to slow down or you end up
>with foam spilling out (gassing in battery speak).
>At the end you have to put in one drop at a time or it will spill.
>After you get the glass full you have to keep adding a drip now and
>then to compensate for evaporation (self discharge in battery speak)

I normally compare it to pouring water onto a sponge. The drier it 
is, the faster you can pour water on without spilling it over.

I like both our analogies. I'll compromise and compare it to pouring 
beer onto a sponge.

Isn't this list great? You get to see which of your colleagues have 
nothing better to do on a Friday night.

Windy

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