Michael K Johnson wrote:
Fascinating to learn why UPS batteries die so quickly! The specs for the
Soleil 48V charger I have —
http://www.batterystuff.com/battery-chargers/48-volt/multi-volt-input/SON4812SR.html—
fit the published recommendations for the Deka AGMs, as long as the
pack stays balanced: 14.4*4=57.6 max voltage (58.32 max spec), 13.7*4=54.8 float
voltage (55.2 max spec).
The specs have the usual marketing BS, but it basically sounds like a
reasonable charger. Comments:
- 6a is a low charging current. AGMs tend to do better with more.
This isn't a serious limitation.
- 14.4v is a good ending voltage for daily charging. However,
it is too low to do a proper equalization. Ideally, the charger
would *briefly* take the batteries up to 14.8-15.0v per 12v
battery for 30 minutes or so once in a while to equalize them.
- 13.7v is a reasonable "float" voltage for a NEW 12v battery, at
normal room temperature. But it is too high for a used or hot
battery. During mowing season, you don't need to float the
batteries. It would be better if it just fully charged them,
and then turned off completely.
- Ideally, the charge and float voltages should be temperature
compensated, and be reduced slightly as the battery ages.
It has that odd Chinglish flavor, which makes me suspect it is made in
China. I wouldn't put it on the tractor, where it would be subjected to
vibration, dirt, and possibly rain.
I'm not doing any pickoffs at all precisely to stay balanced
They will drift apart anyway, over time. That's what "equalization" is
for (a slight deliberate overcharging, to get all cells back up to the
same state of charge).
I'll start mowing my front and back yards separately; that's about 1/6 acre
each. Then I can measure SOC and see how much room I have.
Do you have a plan for determining SOC? Maybe I missed it. The easiest
way is to let it sit several hours without charging, and measure each
battery's voltage. Then recharge.
--
We live in a society exquisitely dependent on science and technology,
in which hardly anyone knows anything about science and technology.
-- Carl Sagan
--
Lee Hart -- See my Xmas projects at www.sunrise-ev.com/projects.htm
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