Does anyone here make custom battery packs?

So here is my dilemma.

I have a couple of Fenix TK70's that i really like.

I have no interest in D sized NIMH's.

What I would love is for someone to manufacture few packs (i would need about 4)

Ideally they could be the length of 3D or 4D batteries so they can fit into the light using
the already existing body tubes I have.

High capacity 21700 or 26650 cells are a priority.

I dont need high amperage cells.

I would need them to have an included USB-C charging port to make them easier to work
with away from home.

Where could i go to get this done?

Rommul said:

High capacity 21700 or 26650 cells are a priority.

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I'm not sure what you're thinking, so maybe you could be more specific.

But a flashlight with a driver that runs on 4xD NiMH only takes 4.8V, so how many 3.7V Li-ion does it take to match 4.8V? Unless mistaken, I think it would only take 2 @ 7.4V-8.4V to blow the lights for good, if that is what your intention is. I can't think of a combination of any Li-ion chemistries that adds up to the voltage of 4xD 1.2V cells, unless it is only one cell.

I checked specs for TK70 at Battery Junction, and it does allow primary Lithium, that would be LiFeS2, like Energizer Lithium AA (they don't make a D cell), which means it may take up to 7.4V, max., and one might assume it could take 2x Li-ion. Li-ion cells are fully charged at 4.2V, so two at 8.4V fully charged would probably blow the driver.

You can find IFR26650 cells in LiFePO4 chemistry, 3.2V nominal, 3.7V fully charged, 3.4V rested, and use only 2 for 6.4V total, but you will get much better performance from 4xNiMH, a brighter light with far longer runtime.

Unless someone figures out how I am wrong here, you should reconsider NiMH. It is a great chemistry, safe at high amps with a lot of energy.

The light in question has tubes that allow the use of 3 or 4 D sized cells.

This means it is a 3.6 volt or 4.8 volt light.

What I am looking for is someone who could manufacture a battery pack with 3 3.6 volt cells in parallel
welded so the battery pack has integrity.

The charging mechanism would be through the use of a common USB-C charging plug found on many cell
phones.

Well, that makes far more sense. Just to make it clear to others, you want the charger built in, so that you just connect it via USB cable to power?

chillinn said:

Well, that makes far more sense. Just to make it clear to others, you want the charger built in, so that you just connect it via USB cable to power?

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Exactly.

Keep bumping your thread every few days, and someone will be along with information for you. Sorry I couldn't help more.

Im still looking for this.

my brain cell likes that idea... i have a tk70 and a tk60 currently loaded with eneloops and adapters. workable so far, but i think the adapters are a weak link with a lot of use.

So you want a pack that fits and connects like a stack of either 3 or 4 D cells, but contains 3 LiIon cells in parallel, and a charger circuit with USB-C connector.

This is a lot more than a custom battery pack. This is a project unto itself. Welding the battery tabs is trivial compared to the rest of what needs to be done, mostly in the mechanics of how everything must go together.

The cells need to be in a tube, with the proper ID and OD to fit the cells and the light. Does the light require a button-top battery type connection at the top of the pack?

I see there are available LiIon charger boards that look like they might fit crosswise in a D-size tube. One of these would need to be fitted either between two cells or at the top or bottom of the pack.

Then you have to provide for the proper spacing from the bottom of the pack, which might be the negative of a cell (with a tab welded onto it), to the top, which might need to be a button top simulator. So there's a lot more mechanical stuff to work out than in a typical battery pack. I think it's very unlikely you will find someone who is doing something like this professionally, for retail sales.

That said, this is the kind of thing I do both for a living and for fun. I think if I really wanted to do this, I could. But for me to do it for you, you'd have to give me a big incentive. What kind of price would you think you'd have to (and be willing to) pay for such a pack? I expect the price I would quote you professionally would send you running for the hills. However, I've done several projects to benefit the CPF community that don't reward me financially. Convince me that this is a worthy project and I might take it on.

To be clear, I'm NOT offering to do this for you. I'm just a guy with enough knowledge to be dangerous, having a conversation about it.

I have made some single 26650 to 3D cell adapters, no onboard charging but they work real well.

looks nice. before the virus stuff started i started some classes at the local library to learn how to use their 3d printer, can't wait to get back there,

YAK-28 said:

looks nice. before the virus stuff started i started some classes at the local library to learn how to use their 3d printer, can't wait to get back there,

Click to expand...

Thanks, 3D printing is a lot of fun and can be practical too.

If you can put 2 of the extenders together to make a 2 cell configuration, a 26650 to 2D adapter like this should work:



If anyone is interested in these or other battery adapters, please feel free to shoot me a PM, I make a bunch of different types.