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Light & Motion(6 posts)

Light & Motionpjvbiker
Jan 5, 2004 12:01 PM
Question regarding the Commuter model w/NiMH battery and trickle charger:
Directions say to NOT fully dicharge battery prior to recharging. However, with NiMH, I've read where it's good to FULLY discharge battery, then recharge to avoid "memory effect" and reduced battery performance. Any experience with either theory and this model? So far, I'm following the manufacturer's instructions. Thanks in advance!
re: Light & MotionIan
Jan 5, 2004 4:07 PM
With NiMH, you do not have to worry about memory. That was with NiCad batteries. So if you run the battery half way down, feel free to re-charge it.

But the battery can be over discharged. When running the light, once it starts to dim (after about 2 hours), it should be turned off and the battery discharged. If you leave it plugged in the drain on the battery can damage it.

Ian
re: Light & Motional0
Jan 6, 2004 10:52 AM
Sorry, but you are wrong, HiMH batteries (unlike LiOn)
b do
have memory effects. This effect are not so pronounced as with NiCd, butit stiil exists, so NiMH batteries need service cycle (full discharge) once in a while (I dare to say once full discharege fir each 20-30 charge/discharge cycles). Some NiMH battery manufacturers claim that their batteries do not have memory effects, but this is marketing hype (really they have while much less then avg. NiMH battery). BTW, almost all advanced models of battery recharges (and even built-in rechargers in some mobile phones, e.g. Simens M50) have "service mode" for NiMH batteries. This mode consists of full discharge/charge cycle.
re: Light & MotionIan
Jan 6, 2004 11:20 AM
Comparing NiMH and NiCad, for most people's use, it is enough to know that NiMH does not have memory. For example, with NiCad, if you use half the battery and then recharge, it will only charge halfway, thereby cutting the battery life in half.

If you run down a NiMH battery halfway and recharge, you will still have full life. Would you lose a percent or two? Maybe, but nothing compared to NiCad.

Is it good to discharge a battery fully every once in a while? Sure. You suggest every 20-30 cycles. For most people that will be a years worth of use. And I would hope that sometime in that time they have occasion to have run it down pretty far.

The question is, how much time should be spent worrying about the battery? For NiMh, I don't worry about it.

Ian
re: Light & Motionpjvbiker
Jan 7, 2004 10:03 AM
Thanks for the input. I'll try the occasional full discharge and see what kind of run time I get. I bought it at Performance, so if it doesn't work out they have a liberal return policy.

Paul
Memory is basically a myth for normal users.jw25
Jan 7, 2004 10:33 AM
The whole "memory" phenomenon came about from satellites using solar panels to recharge internal ni-cd batteries. Since the satellite's orbit is fixed, for all intents and purposes, the batteries were seeing the exact same charge/discharge cycle every orbit, and over time, like thousands of cycles, the engineers noticed severely limited battery capacity.
For more random charge/discharge cycles, there's very little to no memory effect. NiMH chemistry is more resistant to memory, and the Li-Ion is even better, I think.
See here: http://www.buchmann.ca/Article10-Page1.asp for more info.
NiMH batteries, and most rechargable batteries, for that matter, don't like to be fully drained. In multi-cell packs, which is all lighting packs, cells can reverse voltage when fully drained, and cause major damage to the pack during recharging. Try to stop using the light when the beam starts to dim or turn yellow(er) to avoid taking cells down that far.