Replacement for an old LED flashlight's NiMh battery

owleye

Newly Enlightened
Joined
Aug 5, 2017
Messages
2
Hello CPF gurus.

I call upon your collective knowledge to try and help a family member. This person has what I think must be an old generation LED flashlight, bought from a sports equipment store. It uses a pack of 3 small NiMh cells (don't know what size). The markings on the wrapping state "BPW NIMH 1/3A750mAh 3.6V". It came with a charger for the pack. The dock for charging the pack connects to a transformer with the following specs: Input - 230V AC 50Hz Output - 12V DC 500mA

Here are some pictures:

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Flashlight + battery pack + a regular AA sized rechargeable for comparison

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Battery pack

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Disassembled flashlight

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Disassembled flashlight

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Emitter's back

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Emitter's front

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Tail cap with spring

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Charging dock + transformer


So, the problem is, the pack is dead. I unwrapped the pack (more like I destroyed it) and there was some leakage from one of the cells. This person asked me to try and find a replacement for the battery, since he was satisfied with the flashlight. It was adequate enough for his needs. I don't really know much about batteries and flashlights and I was unable to find a similar pack for sale (we live on western EU).

Are this type of packs still available? Can anyone point me in the right direction? Should I suggest a Li-ion replacement? Would the flashlight accept and be OK with it? If so, what kind? Protected? What capacity? What size? Would a flat top work? Would the original NiMh charger be able to safely charge the Li-ion?

Thanks for any help you can provide.
 

terjee

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Joined
Jul 24, 2016
Messages
729
Location
Bergen, Norway
Can I be honest? I'd look for a replacement light, using either AAs or 18650 batteries.

You could maybe use a stack of three half-length AAs, but I'm not aware of a source for those in NiMH anymore. You could use a LiIon 14500 cell with spacer(s) to use the light, but you couldn't charge it with the charger, and trying to do so could be dangerous. Even if you find NiMHs suitable for making a new pack (you probably could, if you spend enough time on it), this will still be a light that's hard to get batteries for, and NiMHs are basically a consumable item.

Best solution would probably be to figure out why he likes it, and try to find a light that matches or exceeds his expectations, but with a standard battery. I get that the rechargability can be a major point, but you have dockable lights now (olight and nightcore comes to mind), and an even wider selection of micro-USB rechargeables. Even some USB-C ones now.

Doesn't have to be that expensive either. Something could probably be bad for the price of replacing the current pack 1-2 times.

As for finding packs, if you do want to go that route, could you approximate the diameter and length that the pack was?
 

keithy

Enlightened
Joined
May 8, 2015
Messages
212
I'm no guru, but the markings on the battery pack indicates that it is made up of 1/3 A sized cells. The "A" sized cell is from memory 17mm x 50mm. The pack sounds like it is in series to bring the nominal 1.2V to 3.6V.

It is not that common a battery, and no wonder it is difficult to find a replacement.

It might be a better option to replace the flashlight with a newer Lithium ion flashlight, or even a newer LED flashlight that uses standard AAs.
 

terjee

Enlightened
Joined
Jul 24, 2016
Messages
729
Location
Bergen, Norway
I'm no guru, but the markings on the battery pack indicates that it is made up of 1/3 A sized cells. The "A" sized cell is from memory 17mm x 50mm. The pack sounds like it is in series to bring the nominal 1.2V to 3.6V.

It is not that common a battery, and no wonder it is difficult to find a replacement.

It might be a better option to replace the flashlight with a newer Lithium ion flashlight, or even a newer LED flashlight that uses standard AAs.

I definitively agree about the markings, but from the picture, I can't help but feel the cells look too long for 1/3A. It also seems significantly longer than the AA, which should be about the same length as A (though thinner). Going by the picture alone - and my tired eyes could be deceiving me - this looks so much more like 1/2 or 2/3A. Also, at 1/3, the cells should be about as tall as they are wide 17mm wide, 50/3 ~= 17mm tall, and they seem longer than that. Would be interesting to get some actual numbers on the dimensions of the cells.

If it's 2/3A, then there's this: http://www.batteryspace.com/custom-flashlight-battery-3-6v-1600mah-nimh-stick.aspx

If it's 1/2A, then I didn't find a pack for it, but it should be possible to get the cells at least.

It's late night here, could anyone doublecheck my thinking?

Really though, best would be to get a new light.
 

SilverFox

Flashaholic
Joined
Jan 19, 2003
Messages
12,449
Location
Bellingham WA
Hello Owleye,

Welcome to CPF.

Unfortunately the 1/3 A size cell is very difficult to find and it may be obsolete. I think it would be best to retire that light and replace it with another one that uses NiMh cells.

Another option is to look to Li-Ion cells but unless your family member understands the dangers involved with that chemistry it would be better to avoid it.

A little time spent searching the various reviews of lights should give you a direction to follow.

Tom
 

owleye

Newly Enlightened
Joined
Aug 5, 2017
Messages
2
Hello Owleye,


Welcome to CPF.
Thank you.


Can I be honest?
You sure can. Honesty is always welcomed ;D


I'm no guru...
Still, you probably know a lot more about this subject than I do. I'm just starting to dip my toe in these waters, and oh boy! are they deep... so any help is welcomed.


You could maybe use a stack of three half-length AAs, but I'm not aware of a source for those in NiMH anymore.
It is not that common a battery, and no wonder it is difficult to find a replacement.
Unfortunately the 1/3 A size cell is very difficult to find and it may be obsolete.
Yes, I'm giving up on that.


Another option is to look to Li-Ion cells but unless your family member understands the dangers involved with that chemistry it would be better to avoid it.
I'm not sure I understand them all that well either (I'm still reading on this topic), and when I mentioned it to him I noticed some apprehension. Still, I'm investigating this option.


As for finding packs, if you do want to go that route, could you approximate the diameter and length that the pack was?
...but the markings on the battery pack indicates that it is made up of 1/3 A sized cells. The "A" sized cell is from memory 17mm x 50mm. The pack sounds like it is in series to bring the nominal 1.2V to 3.6V.
I definitively agree about the markings, but from the picture, I can't help but feel the cells look too long for 1/3A. It also seems significantly longer than the AA, which should be about the same length as A (though thinner). Going by the picture alone - and my tired eyes could be deceiving me - this looks so much more like 1/2 or 2/3A. Also, at 1/3, the cells should be about as tall as they are wide 17mm wide, 50/3 ~= 17mm tall, and they seem longer than that. Would be interesting to get some actual numbers on the dimensions of the cells.
I took a better look at the pack and found out that the top cell is longer than the other ones, due to the button top. I took some measurements and found that the longer cell is around 17mm in diameter and 24mm in lenght.
The other two I didn't measure, but must be between 1-2mm shorter. So around 22-23mm in lenght.
I tried one of these AAA holders that I had lying around, but it wouldn't fit. It's a bit large at 21mm.
What type of Li-ion rechargeable cells would fit? 17670? 2xRCR123A? 18650 might be a tight fit, and I don't have any to try it out.
I don't know what I did wrong with the previous posting of the images, so I leave here a link to all the pics i took this time.


You could use a LiIon 14500 cell with spacer(s) to use the light...
What kind of spacer? Could you link an example?
On a parallel topic, do spacers for turning flat top cells (18650) to button top ones have to be magnetic? Or is that just a convenience? Would any bit of metal be OK for that application?


I'd look for a replacement light, using either AAs or 18650 batteries.
I think it would be best to retire that light and replace it with another one that uses NiMh cells.
It might be a better option to replace the flashlight with a newer Lithium ion flashlight, or even a newer LED flashlight that uses standard AAs.
I'm currently exploring those options. Do you have any suggestions? Something small but that would fit well someone with big hands. Easy to operate. Durable. Rechargeable or that can use rechargeable NiMh AAs. Affordable - <30€ or <50€ (if it comes with battery and charger). Preferably with a more natural light colour and mainly for close range usage, but still adequate for medium range.
 
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