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Dividing up a multi cell pack :

Old 08-30-2013, 11:46 AM
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solentlife
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Default Dividing up a multi cell pack :

Has anyone ever split a 4S pack into 2 x 2S packs to power a twin model ? The pack still stays as 1 x 4S ... but extra power out leads added to supply 2 x 2S to the twin 2S capable motors. Note this is not same as splitting the power out lead ... I'm talking actually soldering leads to the cells to create 2S power out ..

I have a batch of 2S motors ... anothers info incorrectly said they could handle 3S without problem - total BS ... it burnt out in sec's !

So these 2S motors are excellent little workhorses but I don't have 2S packs ...

Idea is to access the terminals in the 4S pack ... solder extra 2 leads to provide 2 x 2S power out from a single 4S pack .. still able to charge as a 4S ... Means single pack installation in model etc. etc.

Nigel
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Old 08-30-2013, 12:19 PM
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CHELLIE
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Hi Nigel most of the Lipo cells that I have tried to split Have fuse welded aluminum Tabs, and you cant solder a wire onto the individual cells, I have had a few lipo cells that i could solder wires on to, but i dont find those lipos out there any more, Take care, Chellie
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Old 08-30-2013, 01:18 PM
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solentlife
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I know that soldering to some of my packs is near impossible as Chellie says - they are Hard soldered jobs not soft. I have one that cells are perfect - but one lead came of and it's now unuseable.

Another - the balance lead came away and I soldered that back easily.

It was only a thought anyway ..

Nigel
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Old 08-30-2013, 05:35 PM
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Without dismembering the pack if you try it you will be DEAD SHORTING 2 cells...
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Old 08-30-2013, 07:51 PM
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solentlife
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Originally Posted by fhhuber View Post
Without dismembering the pack if you try it you will be DEAD SHORTING 2 cells...
Please explain ... as I reckon you are wrong.

If I take the 4S pack and connect 2 further power leads in addition to the existing 4S power lead ... making each lead take power from 2 cells ... feed that to separate ESC's as if they were connected to separate 2S packs .... HOW can that be shorting any cells ?


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Old 08-31-2013, 02:21 PM
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Walt Thyng
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A trick I use for soldering to Lipos is to harvest the tabs from dead cells. When I run into one I can't solder I make a "sandwich" with a harvested tab, put the heat to it and voila! a solid solder joint. I also use the biggest iron I can because the aluminum sucks the heat away so quickly.
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Old 09-01-2013, 10:38 AM
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solentlife
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Originally Posted by Walt Thyng View Post
A trick I use for soldering to Lipos is to harvest the tabs from dead cells. When I run into one I can't solder I make a "sandwich" with a harvested tab, put the heat to it and voila! a solid solder joint. I also use the biggest iron I can because the aluminum sucks the heat away so quickly.
Walt
I have a LiPo that one of the ally tabs has broken away - but the cell is fine .. seems shame that LiPo is basically unuseable because of that ...

I wonder if your idea can resurrect it ... I have old LiPo's that I use as bench test etc. as they just don't punch out anymore.

Nigel
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Old 09-01-2013, 04:02 PM
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Walt Thyng
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Nigel, if there's no solder on what's left of the tab punch several holes thru it and then put a used tab with solder on both sides. I saved a very expensive TP pack using this technique.
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Old 09-19-2013, 07:06 PM
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All you need to solder to AL tabs is the right solder and flux, needs to be zinc bearing I believe.
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Old 09-19-2013, 10:03 PM
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The LiPo has no tab left to connect to ! It's basically back to the cell covering.

Nigel
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Old 09-19-2013, 10:58 PM
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Yeah, I was steering that towards folks who actually had something left to solder to!
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