When to recharge NiMH and LSD NiMH batteries?

[aab]

When is it best to recharge NiMH and LSD NiMH batteries? Is it better to drain them almost fully before recharging or to charge them when they have maybe half the capacity left?

Also with non digital devices like flashlights, peppermills, etc. which don't cut off when the voltage drops, is it better to recharge before there's even a sign of the battery going weak or is it best to wait until the light/motor is getting weak before recharging?

Is it different for LSD and non LSD batteries?

Thanks

 

[Flying Turtle]

With NiMH batteries of either kind it's best to charge them before they drop off too far. If you're measuring that would be around 1.0 volts. In flashlights I usually just wait until I see a noticeable drop in output. If you're not sure, just charge them cause it can't hurt. It can damage the battery if it goes down too far.

Geoff

 

[BatteryCharger]

Just think about it like this: Running = 1.2v Dead = 0.9v to 1.0v

If you only have a one or two cell device, you're only talking about a .4v difference between full and dead. This would be much harder to notice and allow overdischarge easier. With more cells, like an 18v cordless drill, you've got a voltage difference of 3 volts, which is much easier to notice!

Generally, I charge my batteries whenever it is convenient, whether they need it or not. I don't wait until they're used up entirely...unless I'm lazy or in the woods.

 

[45/70]

Generally, I charge my batteries whenever it is convenient, whether they need it or not. I don't wait until they're used up entirely...unless I'm lazy or in the woods.

While it's important to not over discharge NiMH cells (more so than with NiCd cells), and it doesn't hurt to recharge them often, or when convenient, they should be mostly discharged every month or two, to keep them healthy.

Not discharging NiMH cells completely (beyond 0.9-1.0 Volt under load, as BatteryCharger suggested) every use, will extend their cycle life, however an occasional "deep" cycle keeps the chemicals within the cell more evenly distributed for better performance.

Also, a slow discharge (0.2C, or less) followed by a 14-16hr 0.1C "forming charge" done every 3 months to a year, depending on usage, provides a more complete redistribution of the chemicals within the cell. If your cells are frequently discharged to a lower level, particularly at low current rates, they are less likely to need this, as the cell's chemicals have been kept more or less, evenly distributed. The cells will still likely benefit from this to some degree however, and it is a recommended practice.

Dave

 

[BatteryCharger]

Yeah - that's why it's a good idea to have a charger with some sort of refresh or discharge/recharge option. Just run 'em through a cycle every now and then.