i bought myself a 50 mw green and a duracell mini charger with some nimh rechargeables. they last a good amount of time but i still have to change them pretty often with the amount of use this thing has been getting. i change the batteries as soon as i notice any loss in the laser's intensity, will it reduce the life of the batteries to be recharging them when they still have a decent amount of energy left? i've heard conflicting things, and these batteries are expensive.
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rechargeable battery question
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mfo
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The phenomenon you are referring to is "Memory Effect". Long story short, it's bs. You can recharge your NiMH batteries when ever you feel like.
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Yeah, it only really happens in NiCd batteries as far as I'm aware (see http://en.wikipedia.org/wiki/Memory_effect); NiMH batteries you can charge back to full no matter how full they are.
The main thing you have to avoid with NiMH batteries is overcharging, and most battery chargers in my experience stop providing current once the battery has reached its capacity, but I would make sure yours does just in case.
mfo
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The thread starter said he had a duracell charger, so no need to worry about that.
Also, I'm pretty sure the memory effect was BS in NiCd also.
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Oh, I didn't catch that haha thanks for the correction.
And yeah I agree, I've always thought the perceived memory effect to be just poor battery design and improper use...but it doesn't really matter since NiCds are a lot less common than NiMH and Lithiums.
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yobresal
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You are ripping yourself off by using those batteries in the first place. You laser is only getting 2.4 Volts from those batteries. If you use 1.5 Volt Alkaline batteries you will see more power.
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While it's true that alkaline and lithiums have more consistent and higher starting voltage, NiMH rechargeables take a WHILE to drop down to 1.2V. Most of my AAAs and AAs come out of the charger at 1.45V and I'll generally charge them back up when they start to near the 1.2V mark.
yobresal
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1.45V?????????!!!!!!!!!??????!!! What brand are those?
i was using standard 1.5 v AAAs for the first couple reloads. the beam seemed just as bright, if not brighter with the rechargeables.
i am a college student, i can't afford to be buying packs of good batteries every day. i have drug habits to maintain.
you are wrong!
the NiMH must be from times to times almost fully discharged (towards 0.9-1V) or it's capacity will decrease.
WARNING they must NEVER be discharged below 0.9V or they will die !
also they must not be overcharged or their lifetime will be shortened.
cheap chargers will overcharge your batteries. the best chargers will stop the charge just at the top charge, and they can fully discharge the NiMH before charging.
i use the lacrosse charger for this.
more info should be on wikipedia
http://en.wikipedia.org/wiki/Nickel_metal_hydride_battery
the NiMH must be from times to times almost fully discharged (towards 0.9-1V) or it's capacity will decrease.
WARNING they must NEVER be discharged below 0.9V or they will die !
also they must not be overcharged or their lifetime will be shortened.
cheap chargers will overcharge your batteries. the best chargers will stop the charge just at the top charge, and they can fully discharge the NiMH before charging.
i use the lacrosse charger for this.
more info should be on wikipedia
http://en.wikipedia.org/wiki/Nickel_metal_hydride_battery
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Most of the ones I own, the 1000mAh OEM LaCrosse-branded ones that came with my charger stay above 1.4V for a good 30 minutes of use in my O-like green ~86mW of power output on the fully charged batteries. The standard 850mAh energizers and 750mAh LSD yuasa enitimes I own aren't quite as good, but they also come don't drop to the 1.2V mark. Most NiMHs in my experience come off a charger at 1.4V+
Yes, you're right that the occasional discharge of a battery is better in the long term for any rechargeable battery (especially with batteries that haven't been used in a while) but there isn't much advantage to doing this EVERY TIME. For the most part, if you charge your batteries when they're not completely discharged, no ill effects will come of it.
You are right in saying, as I warned about before, that overcharging is what REALLY kills NiMHs, but as yobresal pointed out, his duracell charger should protect against that.
Also, in general, the higher current you charge your batteries at, the quicker you will kill them in the long run. I find about 200mAh is a safe bet for most AAAs/AAs. Although unless you have a fancy charger you can't usually select the current. (This is also why I advise against "speed chargers" since all they're doing is running a higher current through the battery, sure you will get a full charge quicker, but you'll fry your batteries in the process.)
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mfo
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Wrong. You can re-charge NiMh batteries whenever you please.
Rapid charging barely makes a difference in the amount of recharges you can get from the batteries.
