[ale] [OT] any experience with low self discharge NIMH batteries

[Ron Frazier (ALE)]

Alex Carver <agcarver+ale at acarver.net> wrote:

>On 3/8/2013 19:25, Ron Frazier (ALE) wrote:
>>
>>
>> Alex Carver <agcarver+ale at acarver.net> wrote:
>>
>>> On 3/4/2013 21:04, Ron Frazier (ALE) wrote:
>>>> Hi all,
>>>>
>>>> A few months back, we had a thread here about new advanced LED
>>>> flashlights.  I bought one that has the giant 1/4 in LED inside,
>and
>>> is
>>>> bright enough to be competitive with an incandescent krypton bulb.
>>> Love
>>>> the flashlight.  Works great.  However, it's powered by only 2 AA
>>>> batteries and they're dying 6 months later.  I'm considering using
>>> NIMH
>>>> rechargeables there.  The problem with that is that, left on the
>>> shelf,
>>>> standard NIMH batteries lose 10 % - 30 % of their charge per month.
>>> So,
>>>> you could pick up the flashlight and not have it working when you
>>> need it.
>>>>
>>>> Enter Low Self Discharge NIMH batteries.  These are relatively new.
>>> They
>>>> claim to lose only about 15 % of their charge after a year.  So,
>you
>>>> could get away with charging the flashlight batteries only every 6
>>>> months or so.
>>>>
>>>> Two main brands of LSD NIMH seem to dominate.  Eneloop by Sanyo and
>>>> Imedion by Powerex (Maha Energy).  I've used some standard Powerex
>>> NIMH
>>>> 2700 mah batteries and I like them, but I have to charge them if
>>> they've
>>>> been sitting a while.
>>>>
>>>> Does anyone have any experience with the LSD NIMH batteries.  Is it
>a
>>>> good idea to use them in a flashlight, or stick with Duracells at $
>3
>>> /
>>>> pair, or other alkalines?  I know Fry's and Home Depot / Lowes
>>> sometimes
>>>> sell batteries in packages at lower unit cost.  I haven't done a
>>> price
>>>> analysis on those.
>>>
>>> For something like a flashlight that can handle deep discharge try
>one
>>> of the lithium iron (that's Fe not a typo of 'ion') formulations. 
>You
>>> can pick up AA versions at the hardware store next to the solar
>powered
>>>
>>> garden lights.
>>
>> Hi Alex,
>>
>> Thanks for that info.  I did some research on these and they sound
>interesting.  The attributes of that battery chemistry sound cool and
>it's probably worth keeping an eye on.  I don't think it will work in
>my case since these batteries are 3.2 V and my flashlight expects to
>see 3X 1.5 V cells.  I may end up going with some of the LSD NIMH ones.
>>
>> Sincerely,
>
>Ah, but you're missing half the fun of tinkering with the flashlight to
>
>use them. :)  A tiny, three terminal 4.5V regulator wedged inside and 
>you'd be set.
>

Hi Alex,

I'm not sure I need another project to tinker with.  The flashlight I mentioned is one of the new high power led pocket units.  There's barely room for the 3 AAA batteries in it.  I don't think I want to mess with that.  Also, if it's a linear regulator, it would be wasting all the power dropping from 6.4 V to 4.5 V.  The only way you could avoid that would be a switching regulator.

However, I have a couple of bigger flashlights that have the krypton bulbs and the big 6V square lantern batteries.  The batteries are around $ 10 each.  More than the flashlight costs.  I had planned to decommission the units after the batteries die.  A Lithium Iron rechargeable battery pack for those might be worth considering.  I wonder if such a thing is already available in that form factor?

Sincerely,

Ron


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Ron Frazier
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