Thread: Replacing headlight batteries

Hi all. Hoping to get some advice about rechargeable batteries. I have a couple of rechargeable headlights here with buggered batteries. One is a led lender h7r signature and the other is a Fenix hm65r. Looking at replacement options online, the led lenser 21700 batteries are twice the price of a lot of the other options. Is there any reason why I need to stick to the same brand battery as the head torches or will all 21700 batteries function the same?
Thanks

www.batterymasta.co.nz

There are probably a hundred websites that will compare cell (battery) manufacturers. 21700 is simply the size: 21mm diameter, 70mm long. Any 21700 battery will fit, and the computer chips controlling charging shouldn't have an issue.

I doubt lensers are anything special. Any brand off aliexpress will probably be fine, or if you can find some cells from an old laptop battery or powertool...

Ive got a single cell (18650) LED lenser power bank and it will charge my cellphone with the lenser batt but not with an Ali Express special . However in the headlamp MH10 single cell (18650) the Ali batt works fine snd costs about 1/4 as much. I think its just the power-bank application is very demanding as one Li Ion batt doesnt really have the 5V voltage and must need to be magically stepped up ( contradicting the principles of DC electroteknik.)

Check the mAmp.hr ratings.

If the headlamps themselves are old I personally would buy two cheap ones so I know ive always got one fully charged batt on me.

There're a few chaps on trademe, that sell re purposed (from power tools etc) 18650 cells and test them first, so you can get ones that are 80% ~ 90% good, for cheap.

I've been known to solder a bunch together to get a light weight 12v battery for my Kayak fishfinder.

Still working well for fishfinder use after 3 years. And just enough grunt, to start the car, when the car battery was not quite turning over the motor after leaving the lights on one day.

although 18650 rates as 18mmx65mm, there is also mAh to be considered but also weher the battery is designed for a long slow output such as a backup light, medium output over medium time such as a headlight or big output short time like a taser gun

Originally Posted by gonetropo

although 18650 rates as 18mmx65mm, there is also mAh to be considered but also weher the battery is designed for a long slow output such as a backup light, medium output over medium time such as a headlight or big output short time like a taser gun

That would probably be the C-rate or C/20 rate. Lithium battery tech fares pretty well in terms of discharge-current, and for a headlamp I don't think it would matter. A fast-rate battery will still only output as much as the device needs. And usually cost more to boot.

As many have posted in the past, have a look at what Jacob at Piercing The Darkness (forum member) has to offer.

Just replaced some 18650s with his Sanyo branded (IIRC) cells. Very happy with his service.

Without repeating what has appeared on many forums, google etc, there are some dodgy cheap cells out there. Labels mean nothing unless dealing with a reputable seller who will stand by his product. Labels are easily counterfeited.

Originally Posted by zimmer

As many have posted in the past, have a look at what Jacob at Piercing The Darkness (forum member) has to offer.

Just replaced some 18650s with his Sanyo branded (IIRC) cells. Very happy with his service.

Without repeating what has appeared on many forums, google etc, there are some dodgy cheap cells out there. Labels mean nothing unless dealing with a reputable seller who will stand by his product. Labels are easily counterfeited.

a few years ago a customer wanted to give all his staff powerbanks as a xmas gift, he gave me a sample with a ridiculous rating of 4x 8000mAh cells (18650's)

well i never got anything like that out the units, closer to 5000mAh total.
so i cracked one open. inside were the 4 unbranded cells which i desoldered from the board to find 2 were suspiciously lighter than the others and had no charge at all.
reason was they were a tube filled with sand!

Sand = Chinese electrolyt?
I guess the other one is the recyled, stuffed laptop cells.