Steve Powers wrote:
Thinking through my various options to avoid overcharging the 108V pack of
flooded US-125's. I am considering taking out the Zivan NG3 which I can't
adjust without opening and putting in my Zivan K2 which theoretically can
be adjusted. The K2 is supposed to be setup for 120V and at 120 it is also
too aggressive which is why I quit using it in my old EV...
Hi Steve,
My thought is that the NG3 is a better charger than the K2. The K2 may
not be adjustable down from a 120v to a 102v pack, and even if it did,
you may find you get less charging current out of it. So I would be more
inclined to "fix" the NG3.
It's not all that hard to charge golf cart batteries. They are one of
the most forgiving types of lead-acid batteries with regards to under-
and over-charging.
US Battery favors pretty hard charging. They recommend taking them to
something like 2.57v/cell on every charge cycle (139v for a 108v pack),
and you aren't really hitting them quite that hard.
But I don't like to charge that high on every charge cycle, and
especially not with older batteries that have a lower end-of-charge
voltage anyway. Trying to charge this high is only going to extend
charging time, gas away water, and speed up the demise of the pack.
When I was driving my EV every day, I'd charge to 2.4-2.45v/cell, and
then turn off the charger. This gets them to 80-100% state of charge,
but does not equalize them. Then I'd do a full equalization charge on
the weekend, or whenever the resting voltage difference between
batteries became noticeable (like more than 0.025v for 6v batteries).
It would be pretty easy to set up a voltage monitor to shut off the
charger when the pack reached the desired voltage.
Looks like I will probably go with the 96V delta-q and a second 12V charger
for the last 2 batteries
That can work, but it will be difficult to have both chargers reach
"full" at the same time. You'll also want to have some method to monitor
each partial pack to be sure its charger really did work. Otherwise, you
may wind up leaving home with (for example) the batteries on the 12v
charger only half-charged.
--
Any intelligent fool can make things bigger, more complex, and more
violent. It takes a touch of genius, and a lot of courage, to move
in the opposite direction. -- Albert Einstein
--
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
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