which rechargeable batteries are better?

[gino_76ph]

ive been scouting for wireless headphones. i noticed something. which is ideally better...NiMH or Li-Ion batteries?

[Funkstar]

li-ion are better, but more expensive. These are used in all new mobile phones, MP3 players etc. They are smaller and lighter for the same power output as their NiMh counterparts. They also don't suffer from the same 'memory effect' as NiMh can (although this isn't as much of a problem these days as it used to be, especially with NiCad's).

[gino_76ph]

what do you mean by "memory effect"? (would these apply to NiMH in mobile phones and wireless headphones?)

[snedger]

NiMh batteries can lose nearly all their charge over time, even if just left in a box.
Lithium Ion batteries hold on to the their charge for ages.
Good example is that I have a Bosch cordless screwdriver using Li-ion and was able to use it for occasional jobs on the same charge for over a year - NiMh would have lasted less than 2 months.
You can get hybrid batteries e.g. Uniross Hybrio, which, regarding holding charge, behave like alkaline batteries. I haven't tried them yet I'm still getting over the realisation that I wasted a load of dosh buying a load of batteries that I cannot charge, store and expect to have any charge left when I come to use them.

[Funkstar]

Originally Posted by gino_76ph

what do you mean by "memory effect"? (would these apply to NiMH in mobile phones and wireless headphones?)

I'll quote wikipedia, much easier than putting it into my own words

Originally Posted by http://en.wikipedia.org/wiki/Memory_effect

Memory effect, also known as lazy battery effect, is an effect observed in some rechargeable batteries that causes them to hold less charge. In its original meaning it describes one very specific situation in which certain NiCd batteries gradually lose their maximum energy capacity if they are repeatedly recharged after being only partially discharged. Today, the term is commonly applied to almost any case in which a battery appears to hold less charge than was expected.

With NiCad and NiMh if you repeatedly use them partially and then top the charge up, they start to loose their charge. Also as snedger said, leaving them sitting idle for long periods of time will also drain them. LiIon aren't effected as badly as the other two, although they still do suffer from thsi effect to a certain degree.