Help with multi-cell headlamp

Marquis07

Newly Enlightened
Joined
Aug 27, 2022
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Location
B.C. Canada
Hey, I have 2 TH30 headlamps that I am wiring together with an external battery pack. The design is really simple, and I can easily convert the lights back to their original state.

I have the lights running off one cell right now, but I plan on running them on three 18650s in parallel.


I've got a few questions about the batteries mainly. Sorry for my ignorance.

Question 1. The headlamps take 15A 18650s. Since both headlamps are drawing from the same batteries in series parallel, do my 3 cells need to be good for 30A each?

Question 2. When I connect the cells together in parallel, how even does the voltage have to be between them. If they are within 0.2 V difference, is that fine?

Question 3. This is probably a no brainer, but do the cells all have to be the same type, or is it fine if they are mismatched, providing they are at the same voltage?

Question 4. The headlamps have built in charging. Is it possible to charge the battery pack straight from one of the lights, or would I still have to charge the cells individually? I don't have a bay charger yet, so I just charge my cells in a spare flashlight. I'm planning to get one soon.

Thanks,
Mark



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Edited to change series to parallel.
 
Last edited:

alpg88

Flashlight Enthusiast
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Apr 19, 2005
Messages
5,208
1 you will be fine with 15A each
2, it is fine, they will equalize.
3 yes it is fine as long as they are same 3.7V nominal voltage, they can even be different brands/capacity, in parallel wiring it does not matter, done it many times.
4 you should be able to charge using build in charger, but it will take longer.
 

Dave_H

Flashlight Enthusiast
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Nov 3, 2009
Messages
1,308
Location
Ottawa Ont. Canada
I recommend not mixing cell capacity, brand, type, and cell condition/age when paralleling. Get three new identical cells. Certainly it's not that difficult or costly, to avoid possible problems.

Dave
 

Marquis07

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Joined
Aug 27, 2022
Messages
79
Location
B.C. Canada
@alpg88
I just realized that I said in series when referring to the cell amperage. Those are actually parallel, duh! Sorry about that.

@Dave_H
Yup, more cells are on the list! Just waiting for this money thing to work out. :broke:

Thanks for the help guys,
Mark
 
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