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I have some 2650MAh NiMH batteries that i bought last winter for using in my Tesco 3w torch. Last year all was good and they held their charge well but this year they seem not to hold it too well. Last time i used them was about 2 weeks ago so charged them up straight afterwards until the light on the charger went green as usual. plopped them in the torch last night and they didnt last 5 minutes so i'm starting to worry that in the past 2 weeks they have been sat discharging.
When I charge my batteries I dont always spot that the light has changed so they sometimes sit charging (overcharging?) for a good few hours more or sometimes a whole day. Is this bad for the batteries? or have i just got a set of dodgy batteries? or could it be something to do with the torch itself?
I do have another pair of the same batteries which I could charge up and see if that makes any difference but dont want to damage them in the same way with my slap-dash approach to charging batteries.
Also, last time I used the torch it was used as an actual handheld torch rather than a headtorch so was being turn on and switched off several times over in a short period of time - can this have an effect on battery life or should that make negligable effect?
Don't know about your batteries Swoosh - best to fully discharge them before charging though for max capacity, but...
...I have dabbled with Tesco torchs and had similar symptoms to yourself - in my case it was the "cheapness" of the on/off switch that was the weak point. You will need to test the batteries independantly to verify this though.
I managed to get the switch back to life by fiddling around a bit loosening/tightening, on/off with varying degrees of anger, etc and eventually it started working again. I don't think these switches like the cold and/or wet.
Green light on charger = trickle charge with a very low current so quite safe for the batteries. My charger frequently switches to the trickle mode well before the batteries are fully charged when charging only 2 cells at a time... So sometimes it takes several repeat charges to get them topped up. I use a timer plug now which gives me lots of 3 hour bursts of charging over a 24-hour period.
Yeah, it sounds that your charger is switching to a trickle mode. Perhaps your charger is detecting the batteries are fully charged before they actually are and so you aren't getting a full charge into them or out of them.
I bought some high capacity rechargables for my old digital camera & found that they discharged loads quicker than the lower capacity rechargables I already had. They also seemed to deteriorate a lot quicker too and are now pretty useless, whereas the lower cap ones are still OK..
Two interesting points there guys.
I will try switching the charger off and seeing what happens when i put it back on (see if it stays green (full) or if it goes back to red (charging)) and will try hitting the switch a bit harder than I have been doing.
Any other thoughts on the battery life or the torch?
If battery charging is the issue see
http://www.batterylogic.co.uk/technoline/technoline-BL700.asp
for the mother of all battery chargers - tells you everything that's going on with charging and has a refresh facility to bring batteries back to full capacity.
Only works with AA & AAA and is a wee bit pricey, but will save you in the long run I reckon.
If you have more than a one cell battery (or power source) never fully discard it. One of the cells we go negative and this will knacker it.
well i tried charging the batteries again and they went red (again) so left them like that for a while and they seemed to last pretty well last night. Was out for about 1 hour 45 mins and had the torch on for about half of that and it didnt go dim at all. much better than the previous time i tried the torch.
Thanks a lot guys for all your tips.
Pleased that you had a result!
Try and use them regularly & give them a few discharge/recharge cycles - you might get even more life back in them. If it's just the tesco torches, you can just leave them to discharge in the back garden or something - they don't really generate any heat I've noticed.
If you find that you aren't using the batteries that often, perhaps look at something like the Eneloops or similar that hold their charge much better than normal rechargables.