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1/2 D size LiPo?

skjult

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The gearshift handle that is my avatar is being made into a host. There's a hidden compartment which will perfectly hold 2/3 of a D cell. There exists a 1/2 D cell - awesome! But only in NiMH, so I have found.

1/2D Size Rechargeable Battery 2400mAh NiCd High Top | eBay

A few thoughts on this:

1. You can fit 3 of these in a 2 D flashlight host and produce a very high current 3.6v and have much more room for goodies, like a larger driver, etc.

2. Is there a boost driver that can take 1.2v all the way up to the ~4v the 445nm needs?

This almost-host is all-aluminum. It begs to be mod'ed! :)
 

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Wolfman29

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You would need a really high switch current, and as far as I know, there are none out there that are capable without paralleling them. However, what size limitations do you have on driver size? With adequate size it should be easily doable if you just shove a large MOSFET onto the board.

(Just so you know, 445s require 4.5-5V).
 

Jacob32123

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You could get a 1/2 D sized holder made that holds 3 14250s in parallel. Your capacity would be 900 mah, which is low, but it would work.

You could even go with a slightly longer cell if it will hold 2/3 of a D and have increased capacity.

EDIT: if you used an 18350 you only need a sleeve to make it fit, and you might need to stick a magnet on the end to make it longer. That would give you 1000 mah, and would be a lot cheaper.
 
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skjult

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Though something of a pain to recharge, it may work best to get a bunch of these sorts of cells, putting them into 2 sets of parallel arrangements, put into series together for 7.4v. Create 2 custom cells, in effect. Could probably wrap each to fit half the compartment.

I wonder if charging say 3 or 4 cells in parallel would work. Well, it will work - I just wonder if it's safe.

Mini 1 x 210mAh 3.7v 1S 15C MAX 20C LiPo Battery AKKU For RC Fly Mode Helicopter | eBay
 

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Jacob32123

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Though something of a pain to recharge, it may work best to get a bunch of these sorts of cells, putting them into 2 sets of parallel arrangements, put into series together for 7.4v. Create 2 custom cells, in effect. Could probably wrap each to fit half the compartment.

I wonder if charging say 3 or 4 cells in parallel would work. Well, it will work - I just wonder if it's safe.

Mini 1 x 210mAh 3.7v 1S 15C MAX 20C LiPo Battery AKKU For RC Fly Mode Helicopter | eBay

Those can be charged in parallel (or at least people do). I think the 18350 is easier to charge (and cheaper to implement.) One of the forum machinists could probably build a sleeve pretty cheaply.
 

skjult

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Two 16340s fit side by side. Easy way to stick to cheap standard size and get 7.4v. Now, have to figure out how to get them in a holder that doesn't add to the width. They are snug. I don't see any with tabs.

Another possibility is a bunch of 10440s without protection circuit. Might still have to shave the cap down.

Probably the best solution is the two 16340s in series with a buck driver.

There are some likely bogus 16340 current ratings. Looks like the standard is about 880ma. There are some claiming 2000mA! Assuming 880mA, what would be the highest load a driver could deliver to a 445nm? Let's say 1500mA is desired. Can those 880mA batteries driver that, close to the 30 min one might expect?
 

LarryDFW

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skjult;

Li-Po's will deliver the high current you will need.

Getting them in that form factor is another question.

I have some 2200mah LiPos that are 5mm thick x 39mm wide x 93mm long.

They can be manipulated, but i am not sure about folding them in half.
(39mm x 46mm)

LarryDFW
 
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