AA battery holder questions & more

I'm workin' on a project for fun. It's a dual XM-L light with a peak draw of almost 2A between two XM-L's (about 1400mA on one, and 350mA on the other) regulated by 7135's. The power source is 4 AA Eneloops in a series holder. The voltage is higher to account for resistive losses in wires, regulation losses, etc. This theoretically means I'll get about 1 hour run time. First off - how does this sound?

Moving on...
I'm having the hardest time sourcing a 4AA series holder that doesn't suck. There are a million plastic holders with 26AWG wires and multiple steel spring contacts. These don't look good, they aren't easy to use, and just suck overall. Great for devices, not great for durability and being waterproof. Does anyone know of a nice quality one?

If I'm forced to make my own, anyone know of a good source for conical spring contacts? Preferably copper, or gold plated something.

kuksul08 said:

I'm workin' on a project for fun. It's a dual XM-L light with a peak draw of almost 2A between two XM-L's (about 1400mA on one, and 350mA on the other) regulated by 7135's. The power source is 4 AA Eneloops in a series holder. The voltage is higher to account for resistive losses in wires, regulation losses, etc. This theoretically means I'll get about 1 hour run time. First off - how does this sound?

Moving on...
I'm having the hardest time sourcing a 4AA series holder that doesn't suck. There are a million plastic holders with 26AWG wires and multiple steel spring contacts. These don't look good, they aren't easy to use, and just suck overall. Great for devices, not great for durability and being waterproof. Does anyone know of a nice quality one?

If I'm forced to make my own, anyone know of a good source for conical spring contacts? Preferably copper, or gold plated something.

Click to expand...

Odd Mods ( mdocod ) used to make absolutely fantastic custom battery carriers, but has not been on the board now for quite a while ...

http://www.candlepowerforums.com/vb...ns-Dummy-cells-Customs!&p=3717111#post3717111

Not exactly what you are looking for, but MartinDWhite makes battery charging carriers and might be worth contacting for suggestions ?

http://www.cpfmarketplace.com/mp/sh...-ion-into-an-18650-charger-(Pila-IBC-or-other

I bought these:

http://www.batteryjunction.com/titanium-3aa1d-ser-adapter.html

They are very good, apparently the US army uses them...

archimedes said:

Odd Mods ( mdocod ) used to make absolutely fantastic custom battery carriers, but has not been on the board now for quite a while ...

http://www.candlepowerforums.com/vb...ns-Dummy-cells-Customs!&p=3717111#post3717111

Not exactly what you are looking for, but MartinDWhite makes battery charging carriers and might be worth contacting for suggestions ?

http://www.cpfmarketplace.com/mp/showthread.php?244152-charging-adapters-to-fit-ANY-SIZE-li-ion-into-an-18650-charger-%28Pila-IBC-or-other

Click to expand...

That's sure some quality stuff. Still nothing I see that quite fits the bill, but I got a few ideas.

Looks to me like odd mod's holders aren't using springs anywhere to maintain compression on the cells? Seems like a major limitation for most holders - how to hold tension and keep low resistance. Unfortunately I can't find any brass or bronze springs.

Like you, I have been unable to source brass or bronze coil springs at reasonable cost.

Try MPD (memoryprotectiondevices.com) and Keystone (keyelco.com). Both are stocked at Digikey.

They both make crap, but they also make some good ones. I've used the aluminum ones from Keystone, and they have very good retention and very low resistance, but they tend to tear the plastic sleeves on the batteries.

Keystone makes leaf springs, some of which are phosphor bronze. I've used some of the bronze ones in lights with good success.

I'm planning on using a holder from MPD in a product at work, I'm expecting that despite the fact the springs are nickel plated 304 Stainless, the fact that they are leaf springs instead of coils should keep the resistance low. Because of the large width and short length, a leaf spring has far lower resistance than a coil spring of the same material.

Most coil springs are either spring steel (usually nickel or gold plated) or 304 stainless with a spring temper. The resistivity of spring steel is many times that of copper, brass, or bronze, and 304 stainless is about 3 times that of spring steel. Any plating, even gold, is too thin to make a difference in the resistance, and also too porous to protect from rusting. It's only there to make good contacts and/or to make it pretty.

I've also used the Keystone holders, and they left a lot to be desired as far as ergonomics. Yes, the resistance was quite low, but they are sharp and difficult to insert or remove cells.

I noticed that even my Zebralight uses a steel spring in the tailcap. Gold plated, so they can solder it to a contact board. This is the closest thing I have found, and possibly is what they are using: http://www.cnqualitygoods.com/goods.php?id=1127 I think it's just a gold plated spring steel though (.9mm diam). Alternatively, this http://www.digikey.com/product-detail/en/BCAA-HD/BCAA-HD-ND/3042462 is nickel plated spring steel (.8mm diam).

My understanding is that a big source of resistance aside from the current traveling through the spring is due to contact resistance. Hopefully gold or nickel helps with this. Also, you'd expect a steel spring to be stronger, which means more force and less contact resistance. But yeah, still searching.