Does anyone know if rechargeable batteries are affected by the cold? ie, my CI batteries used to last 11.5 hours before needing recharging, this week its less than that, around 10hours.

Is it a fault or the cold? I'm not out in the cold very much either and have been wearing a hat so seems unlikely

Any battery will be affected by the cold, its just chemistry. For every 10°C temp drop a chemical reaction will go half as fast. If the battery is reaching the end of its life, the cold will accentuate any problems it has.

They're new, as in 5 months old. Supposed to last 4 years.

Rechargables do degrade over time, especially the NiCad ones which are said to have a memory effect that reduces the effective charge over time. Hard to say really...the cold wont help, but it doesnt sound like you are exposing them to the cold much.

Maybe the "lasts 4 years" thing means that in 4 years you will get only 8 hours from them and that is considered too short?

They are Li ion rechargeable and supposed to give at least 10 hours of charge. All I could find on the net was that excess heat doesn't help their life span, nothing about cold.

I'll ask at the hospital and see if anyone else has reported problems.

10 hours is about right, you don't want you battery to die when you are at work- you only get a few seconds notice of this - so battery in at 6.30 and finish work 9 hours later.

Two batteries per day with another one on charge.

You know how reliable forums are for accurate answers, but I found this...

http://forums13.itrc.hp.com/service/...hreadId=186130

I also believe, if they've been in the cold, you should let the batteries get back to room temperature before charging them. I'm not sure if this is meant to maximize the overall life of the battery of the time they last before needing recharging (or maybe both?).

Heat will permanently degrade a rechargeable battery, cold will only temporarily affect it...

We have had rechargeables in our outside thermometer for two years now and we have had no problem with them losing power any quicker than those used inside and these batteries have been outside in 37 below temperatures.

Another thing that degrades the life of a rechargable is leaving it on charge for long periods without regularly letting fully discharge and recharge.

This is dependant on the metal type though - ni-cad being the worst for this.

we have big fat D size batteries in the trail cam in the yard. They are rechargeable and get changed every 5 days.

Last week in the minus 40's they lasted fine, swapped them out for another set, bought em in to charge and will swap those ones out on Monday.

I don't think you need to worry

Mine are special batteries -

Well if it isn't the weather then I am concerned as they are not lasting as long as they used to. It ain't like the NHS I have to pay for a new set once these die off and I have been quoted $400, hopefully thats for 3 and not just one.

I won't even open that. I bet it's about block heaters.

Cheaper to use non rechargeable ones innit?

$400!!! - are they made of solid gold and run on magic?