[chbot] Deeply discharged

[Volker Kuhlmann]

On Fri 13 Oct 2017 17:36:07 NZDT +1300, Jasper Mackenzie wrote:

>  They are 12V, so yes I am very worried, never seen 12V batteries that low
> and recovered. Trying to fix/reverse engineer my own broken desulfator
> (sigh) and charge at 500mA with my fingers well crossed. I just hoped that
> someone would have a super smart charger that may be more effective.

Something like constant current charge at 0.01C or less might be as good
as you can do. Reconditioning cycles don't really make sense until the
battery is charged again.

I've been using a 2x12V SLA lawnmower battery pack to power camp lights,
and once found them discharged far more than they should have been. It's
not really wise to run any kind of load on a battery without a battery
protection circuit. A quick search hasn't found something ready-made,
but I'd be interested to hear if anyone sees anything.

Some maker used a diode or 3, a resistor, and a AO3415 p-MOSFET (very
low U_GS) to OD-protect 1-2x NiMH, but I reckon it's no good because
with a larger load it'll blow up the FET at half the cutoff point -
there's no sharp schmitt-trigger cutoff.

I'm thinking of fiddling something with a TL431 or a zener, a Nexperia
HEF40106 and a MOSFET. A 1mA draw of the protection circuit should be OK
for a day with that size SLA. No temperature input should be fine too.
Or maybe a 1-cell lithium protector can be misappropriated...

Volker

-- 
Volker Kuhlmann
http://volker.top.geek.nz/	Please do not CC list postings to me.