Is There A Way To Check Battery's Health?

[Witterings]

Is there a way to check a battery's health, I've certainly at leat one that if I charge it still takes a good percentage of it's original mah but if I put a torch on high / turbo it almost immediately switches to a lower setting ... I'm guessing this is because the battery is old / in poor health and can't cope with the current draw.

Be good if there was some way I could measure and see which batteries are getting "tired" and maybe best retired ... be especially useful as I do quite a lot of cycling and go out in the winters evenings, you're suddenly grabbing a torch / battery that hasn't been touched for 6 months and don't fancy getting to the furthest point and finding both batteries (carry a spare) have failed.

A secondary question but for the same reason ... a 14500 / 18650 that has sat unused for a while and seems a depleted, are they like NiMH that if they get used again / cycled they can recover to a degree or does the different chemistry just mean they're dead?

 

[alpg88]

Internal resistance, measure it when the battery is fully charged, you need a charger that has this function.
Depends how low they self discharged, if to 0 then trash it, if 2.5 and up most likely still good

 

[Witterings]

Internal resistance, measure it when the battery is fully charged, you need a charger that has this function.
Depends how low they self discharged, if to 0 then trash it, if 2.5 and up most likely still good

OK - I've just googled and found my Miboxer C4-12 does this but one review said it's inconsistent / not accurate.

I do have a high quality charger in a cupboard somewhere from when I used to fly RC things many moons ago .... I'd have to get a battery holder and knock up some wires with 4mm banana plugs for the charger but is certainly doable.

Any idea what sort of readings would be seen as good / acceptable and what are bad?

 

[alpg88]

10 Things To Know About Lithiuim Ion Battery Internal Resistance - XTAR

Milli-Ohm

www.xtar.cc

 

[vicv]

Yeah, I would not rely on the chargers internal resistance measurement. They are not accurate. Basically I do a discharge of the battery. If it's below 70% of its original capacity, it's tired and ready to be tossed.

 

[alpg88]

They maybe not 100% accurate, but it would give you an idea which cell out of 2 or more is in better health. if t is off by 50 mohm, or even 100, it would apply equally to all cells it measures.

 

[aznsx]

They are not accurate

That's an over-generalization. Some are. Shop wisely.