Which type of rechargeable battery?

D

Deleted2797112

I've got a small tree in the front garden that I'd like to put Christmas lights on but have no accessible power supply so I've got some battery operated LED outdoor lights. They have an automatic timer, run for 6 hours a day. The control/battery unit has an O ring seal but I thought I might bubble wrap it and put it in small plastic box for extra weather protection? What kind of rechargeables will last longest between charges with this kind of use in very cold conditions (size is AA)? Many thanks!

ETA - while scouring battery websites for the answer, I did find a statement that battery life is prolonged if the lights are set to flash/twinkle rather than static but no explanation why - is it correct?
 
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12.5w at 12v is around 1 amp
work out the consumption off your lights then find a battery that will run them for 6/12/or 18hrs
 
You want NiMH, and look for Low Self Discharge ones. The 2000mAh Eneloop are as good as any if not better. Panasonic and others are good. Buy from 7dayshop or ebay. Don't buy a fast charger, they damage batteries.

Non LSD batteries lose up to 1% of the charge each day. LSD ones can store charge for years. And don't think high capacity ones are better, they aren't.

Cold reduces the power of batteries.
 
big-all said:
12.5w at 12v is around 1 amp
work out the consumption off your lights then find a battery that will run them for 6/12/or 18hrs
Click to expand...

Thanks big-all. I have no idea how to go about doing that! The only technical data on the box reads Spec: 4.5Vd.c.

WalksWithTurkeys said:
You want NiMH, and look for Low Self Discharge ones. The 2000mAh Eneloop are as good as any if not better. Panasonic and others are good. Buy from 7dayshop or ebay. Don't buy a fast charger, they damage batteries.

Non LSD batteries lose up to 1% of the charge each day. LSD ones can store charge for years. And don't think high capacity ones are better, they aren't.

Cold reduces the power of batteries.
Click to expand...

Thanks WWT. I'll look for those and try to insulate the battery unit. I've been testing them on some ancient clapped-out rechargeables and they're lasting pretty well indoors so hopefully better batteries will do the job outdoors.
 
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how many batteries does it hold??
if you get 2 sets off lithium ion[li-ion] or nmh rechargable batteries then you can use one set whilst the other is on charge
 
It takes 3 x AA cells. I was really just trying to understand which battery type Ni-mh, Ni-cd, L-ion etc would be likely to do best outside at this time of the year. I don't mind re-charging them but as I need to buy new batts, I might as well get whichever will survive the cold best.
 
NiCads are almost impossible to find now. The EU has banned them. The new NiMh seem OK but the first ones were rubbish.
 
just be aware lithium batteries in power tools at least don't like the cold.

This may have just been early generation ones but worth a mention in case it's relevant.
 
ceres said:
ETA - while scouring battery websites for the answer, I did find a statement that battery life is prolonged if the lights are set to flash/twinkle rather than static but no explanation why - is it correct?
Click to expand...

Flashing is switching power on and off in succession. If they are off, they are not consuming power so yes, it's correct.

Agree on the low self discharge NiMh. Often marketed as 'pre-charged' or 'always ready'. Eneloop are good. Uniross do one that is good and I have a few other brands that are also good. Avoid the cheap ones from the likes of Lidl / Aldi. You should be able to get a pack of four decent ones for not much more than a fiver if you shop around.
 
Thanks everyone. Low self discharge Ni-mh it is then with plenty of insulation. Found some good deals around. The marketing blurb on the eneloops says they go down to -20 but no information on the drop-off in performance. I've found surprisingly little info on how batteries perform in cold conditions given all the gadgets we use outdoors now - cameras, bikelights, GPS, torches etc.
 
get 8 batteries as you can only charge in pairs unless the the charger can charge odd numbers

number the batteries charge both sets off 4
use the first set then place one in the too charge pile and charge the other two
when the other 3 are flat charge with the odd battery

keep all the flat batteries separate from the charged batteries
if you try and charge a fully charged battery it may overcharge or undercharge the other batteries
 
ceres said:
Thanks everyone. Low self discharge Ni-mh it is then with plenty of insulation. Found some good deals around. The marketing blurb on the eneloops says they go down to -20 but no information on the drop-off in performance. I've found surprisingly little info on how batteries perform in cold conditions given all the gadgets we use outdoors now - cameras, bikelights, GPS, torches etc.
Click to expand...

I carry a torch when running at night through woods and across fields. I burn through a set of 4 AA Eneloop in one hour and I see no degradation at about 0C. However the fast discharge does warm the cells, but even with a slow discharge they should be okay. Of course you will get some loss, but LSD cells seem to do well.
 
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