Re: (ET) Battery dilemma

["David Roden" <etpost drmm net>]

On 3 Jun 2019 at 0:02, David Tiefenbrunn wrote:

> A few years back, I got a fancy 36V modern charger, but found that it
> was horribly power hungry in idle / float mode, and the float set point
> was too high, boiling water away too fast, and NO adjustment!

Zivan chargers were infamous for that problem.  From what I could tell, the
US Zivan distributor (who programmed the chargers) was convinced that
undercharging was worse than overcharging.

I just don't agree with that.  I'm not an electrochemist, but from my own
observation and experience, more batteries die early from overcharging than
from undercharging.

Both are bad, though.

Overcharging causes positive grid corrosion, which decreases capacity and
increases internal resistance.

Positive grid corrosion is accelerated if you don't water your batteries
often enough.  In extreme cases, a failure to water will expose a fair part
of the grids to air, and then it's pretty well game over.

Chronic undercharging causes irreversible pathological sulfation, which
results in a permanent loss of capacity.


>
>   The last set of batteries I bought new Duracells from Sam's or BJ's.  
> They
> are showing low capacity already, only been a year or so.   I've been 
> using
> 3 smart energy efficient 12V chargers to keep them at proper float
> voltage. 

Last I heard, Duracell was a licensed name that East Penn (Deka) slapped on
their golf car batteries.  I've never used East Penn flooded golf car
batteries, so I can't say how well they stand up, but their gel batteries
are prime goods.  I have a fair number of group 24 Deka Dominators that are
just in the last couple of years finally starting to drop one by one.  I've
been using them in my ETs for 22 years, and they were already used 
batteries
when I got them.

As for what might have happened to your batteries, it's kind of duh-worthy,
but when batteries fail prematurely, it's because of some combination of
defective or low-quality batteries, improper use, or improper charging.  We
don't really know any of the details of any of these, not even your 
charging
(no offense meant, but "3 smart energy efficient 12V chargers" is kind of
vague).  So anything I/we say has to be speculation.

Constant float charging will overcharge your batteries.  That's why UPS
batteries die in 3-5 years whether they ever run your computer or not. If
your chargers were floating your batteries on every charge, that wouldn't 
be
good for the batteries, but it seems to me that your chargers would have to
hit them well above normal float voltage to knock them down in just a year.

Come to that, though, how hot does your storage get?  "Normal float 
voltage"
at 20 deg C and 40 deg C are not the same!  Heat lowers the battery's float
voltage as it accelerates grid corrosion chemically, so it's a double
whammy.

Basics of lead battery charging:

http://www.evdl.org/pages/hartcharge.html


David Roden - Akron, Ohio, USA

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