A must see when in Detroit

[Joseph T.]

So this means that you don't want to charge the battery over ~80% DOD
for shallower discharges and that you want to fully charge the battery
when you have discharged it more deeply (around 50%) Right?

On Fri, Jul 4, 2008 at 12:50 PM, Lee Hart <leeahart@...> wrote:

> Rick Beebe wrote:
>> Is it better for the pack to wait until 50% discharged before recharging as opposed to topping it off every night?
>>
> Yes, as a rule.
>
> Batteries don't generally wear out; they are murdered from abuse. They
> are harmed by overcharging, and harmed by being discharged too deeply,
> and harmed from being left sitting around for weeks in a significantly
> discharged state. The effects are cumulative; every charge cycle, every
> deep discharge, and every week it sits around partially discharged does
> a little more harm, until enough damage has accumulated to render the
> battery useless.
>
> To maximize life, you need to avoid these conditions. Best life
> generally results from recharging when you get down to about a 50% depth
> of discharge. This reduces the number of charge cycles over life. It
> also avoids deep discharges. When it takes a few days to reach a 50%
> discharge, there is some damage from sitting partially discharged, but
> it is more than compensated for by avoiding overcharging and deep
> discharging damage.
>
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[Lee Hart]

Joseph T. wrote:
> So this means that you don't want to charge the battery over ~80% DOD
> for shallower discharges and that you want to fully charge the battery
> when you have discharged it more deeply (around 50%) Right?
>
>  
Ideally, you would charge to 100% (and no more) for shallow discharges,
and then fully charge only as needed, when the batteries need
equalization. But no normal charger can do this; they don't know how
many amphours you took out, and don't know the individual battery's
relative states of charge.

But you could do this with an E-meter and battery balancing system.
You'd program the E-meter to turn off the charger when the amphours went
back positive. You'd program the Balancer to measure each battery's
voltage (or better yet, each's state of charge) and balance each one
accordingly.

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[Robert MacDowell]

Lee Hart wrote:

> Rick Beebe wrote:
>> Is it better for the pack to wait until 50% discharged before recharging as opposed to topping it off every night?
>>  
> Yes, as a rule.
>
> Batteries don't generally wear out; they are murdered from abuse. They
> are harmed by overcharging, and harmed by being discharged too deeply,
> and harmed from being left sitting around for weeks in a significantly
> discharged state. The effects are cumulative; every charge cycle, every
> deep discharge, and every week it sits around partially discharged does
> a little more harm, until enough damage has accumulated to render the
> battery useless.

But isn't that ALSO true if you baby the batteries tenderly?  Ulimately,
within 5-10 years, the batteries will be junk.  Lead acid batteries just
don't last.

If I'm wrong about that, and there's a way to get 30 useful years out of
a lead-acid battery with proper management -- I would be KEENLY interested.

Obviously, I'm holding lead-acid batteries to a standard other than
itself.  But to other battery technologies which have existed for 100
years.

Robert

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