Have rechargeable batteries got better?

[Davidc]

It used to be a regular whinge on here (including by me) that NiMH batteries failed too regularly.

I had one fail today, and it's the first time this year. I took a new one from the box of spares, and there are still 6 more left. I last bought some (8) in early 2011. I always use like with like pairs, and use chargers with separate channels for each cell, but no more care than that, and the newest ones are ReCyco brand Low Self Discharge ones.

Have I just been lucky or are other people finding these things more reliable than they once were?

 

[HLaB]

I've never had a NiMH battery fail on me but when I started at this job there was a whole load in a drawer and they had dead cells.

 

[andytheflyer]

Forget NiMH. Go for Eneloops. I fly model aeroplanes and the batteries (radio and servos) take a hammering - NiMH are generally fine if you look after them The Eneloops have negligible self discharge rates.

 

[Davidc]

Forget NiMH. Go for Eneloops. I fly model aeroplanes and the batteries (radio and servos) take a hammering - NiMH are generally fine if you look after them The Eneloops have negligible self discharge rates.

Eneloops ARE NiMH batteries. They are one of the Low Self Discharge brands, as are ReCyco, Hybrio, Instant and more.

Whether self discharge rates are of importance depends entirely on how long you store the batteries after charging them.

As above, I'm just intrigued by how much longer all of the NiMH batteries seem to be lasting than they did a few years ago.

 

[cosmicbike]

Not completely convinced they have improved, though capacity and discharge rates are up considerably from many years back. Realistically they, even Eneloops (etc etc) are old tech and lithium in either ion (like the 18650 cells) or polymer are the better option, provided they are charged, stored and so forth correctly. In 10 years of using packs up to 10S 5000mAh at discharge rates of 2kW I never had any lithium polymer issues.
Like any cells, NiMh like to be used. Leaving them flat or part charged for extended periods, such as Summer time when we tend to use less lights on our bikes, does them no favours..

 

[cosmicbike]

Forget NiMH. Go for Eneloops. I fly model aeroplanes and the batteries (radio and servos) take a hammering - NiMH are generally fine if you look after them The Eneloops have negligible self discharge rates.

Miles off topic, but why not run 2S lipo and regulators?

 

[Davidc]

Miles off topic, but why not run 2S lipo and regulators?

Sure Andy will answer for the RC kit, but for me it's because the NiMH batteries (conventional or LSD) work perfectly well and it's simpler to just put them into bike lights designed for them. They're also smaller and lighter than LiPo plus regulators.

Where something's been designed to work with Li batteries then I agree it makes sense to use them, with their greater energy storage per unit mass, and flatter discharge curve.

I use NiMH batteries in most battery operated things we own, and again the fact that a NiMH battery is a direct fit with a voltage in the operating range is a clincher, though more things are now being supplied with LiPo or Lion batteries built into them or as an option.