Rechargeable batteries

[michi]

I've been using rechargeable NiMH batteries for my portable recorder for quite a few years (AA with 2700mAh capacity). One thing that's really been annoying me is that ordinary NiMH batteries lose their charge quite quickly: 5-10% disappear on the first day and, thereafter, they lose 0.5% - 1% per day. So, charge a set of batteries, put them into your recorder case and then don't use the recorder for a month. When you finally decide to use the recorder, almost half the charge is gone

I did a bit of research and found the Sanyo Eneloop batteries. They are NiMH batteries with a difference: they retain their charge for a long time. Sanyo claim that, after six months of storage, the cells retain 90% of their charge, and still have 85% left after one year. (People have confirmed those claims in independent tests.)

I bought four of these a few months ago. They don't cost any more than ordinary NiMH rechargeables and they are readily available from various mail order and retail outlets. The same type of battery is available from other manufacturers under various names, such as Infinium, Hybrio, and others.

They can be recharged with an ordinary NiMH charger. I would recommend to buy a smart charger with both a delta-V and delta-T cut-off, which prolongs battery life. Also look for a charger with a separate channel for each battery, so you can charge batteries that are at different discharge levels simultaneously without damaging some of them. One option is the Enecharger NC8700-EN4+4, which costs about $80. There are many other smart chargers around that work the same way. (Avoid quick chargers that charge a cell in an hour--they shorten battery life quite dramatically because the batteries get too hot.)

The AA Eneloop batteries have a capacity of 2000mAh, which is less than the highest-capacity ordinary NiMH batteries with 2700mAh, but I think the better charge retention of the Eneloops more than compensates for that.

Cheers,

Michi.

[Djembe-nerd]

Good advice. Thanks