charging times

mlrobbo said:

hi, i have just acquired a vistalite nightstick ns2-hyp 15 lighting system from my father.

he has lost the instruction manual & cannot remember how long to charge the batteries for.

the batteries are nightstick 2200mAH Ni-MH and the charger is the 600mA model.

Does anybody know how long these should be charged for? i really don't want to over charge them.

thanks, mike from NZ

(this advice is NOT specific to your stated light)
It's usually about 4-5 min charging for every 1 min of usage, assuming "typical" matching of battery, load and charger.
I recharge to this formula most of the time, but I eventually get concerned that I lose track of exactly far from full charge the battery is. To counteract this, every so often I let it charge on my desk at work and disconnect it immediately upon the battery becoming warmer than ambient temperature, which I consider, as a non-engineer, a proxy for exceeding full charging time. This may be harmful - who can advise?

I am not familiar with this charger. Does the manufacturers website have instruction manuals? Or could you phone them to ask? Meanwhile...

I also reckon 4hrs max with that charger. (If the battery is rated at 2200MilliampHours, putting 600Milliamps into for four hours should be plenty.)

Handy hint: I use a plug in mains timer to cut the power after the right amount of time.

For sure, if it's hot when you've charged it, it's been on too long, you should certainly reduce the charge time next time.

All this is assuming the charger is simply a transformer rather than an intelligent charger that reduces its output when it senses the battery is full. Manufacturer will advise further.

NiMH batteries do not like being left on the shelf for months on end.
If yours has been, runtime may improve after a few cycles (charging, discharging, charging, discharging).
However, don't let the battery pack run down to completely nothing (i.e. pale light, brown light, no light) as this risks reverse charging the weaker cells. Charge it up again before it's completely flat.

Plenty of places to read up on batteries on the web for the details of why. This isn't a bad place to start:
http://www.buchmann.ca/

All the best.