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Self build LiPo packs

Old 02-06-2006, 02:21 PM
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steveclv
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Default Self build LiPo packs

I have been building electronics for some years and seeing as I can find good 4000mAH or larger LiPo cells at fairly low prices (and as I need at least 8 packs for a days boating) I'd like to build them myself but as expected (as it's discouraged from a safety point of view) finding info is hard!

I can build my own heavy duty circuit boards but does someone have an appropriate design for a layout of a board for a 4s1P pack - needs to have the cell monitor/balance connections?

One of the other reasons to build myself is that most pre-built packs don't cater for us boaters and seem to lack very much in the way of waterproofing.

Many thanks

Steve
Old 02-06-2006, 04:26 PM
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JNorton
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Default RE: Self build LiPo packs

So why don't you get 4 identical LiPo and solder Deans connectors on them. Then use the FMA connector list below. At each point where a positive and a negative join wire a connector of your choice for balancing. Get the balancer first because they all use different connectors.

http://www.fmadirect.com/detail.htm?...974&section=35

John
Old 02-06-2006, 07:40 PM
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steveclv
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Default RE: Self build LiPo packs

Because I can't buy individual LiPo packs for the price of the individual cells

For example, 15C 4000mAH cells cost me $17.50 each and 8000mAH cells are $38 each.

I can produce 4 circuit boards for about $10 and say another $40 for the silicon cable, heat shrink and plugs for 4 packs means that I can make a 4S1P 4AH for about $83 each and 4S1P 8AH for about $165

That's 'cheap' boating.
Old 02-06-2006, 07:54 PM
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Default RE: Self build LiPo packs

Did you look at the URL. I think we are having a disconnect. I'm just talking about putting Deans connectors on individual cells and using the FMS circuit board to wire them in series into a pack. Just what I thought you wanted to do. I'm sorry if I've missed understood your question.
John
Old 02-06-2006, 08:02 PM
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steveclv
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Default RE: Self build LiPo packs

Ah, ha - yes my fault - misunderstood what was meant

I'll take a look at those connectors and see if they will work - I'm fairly certain that you can't solder wires to the tabs on the cells - they need to be soldered (carefully) to a circuit board land which is why I am contemplating designing (or copying) a circuit board design that allows that. The tabs are quite fragile.

Thanks
Old 02-06-2006, 08:20 PM
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Default RE: Self build LiPo packs

Ah and now I understand. I thought the cells had wires attached.
john
Old 02-06-2006, 09:21 PM
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Default RE: Self build LiPo packs

Some of the LiPo cells have aluminum tabs. You can use 60/40 solder with this flux.
http://www.tanicpacks.com/catalog/pr...roducts_id=378
John
Old 02-06-2006, 09:30 PM
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Default RE: Self build LiPo packs

The positive tabs of a LiPoly cell are aluminum. Because aluminum conducts heat extremely well you can damage the seals by too much heat. You really need to practise soldering so you can use as little heat as possible. Do not forget that the flux is corrosive and will needs to be washed off. Only a very little is needed. Clean the aluminum with some fine scotch brite not steel wool and some alcohol. Practise soldering on some aluminum foil.
John
Old 02-06-2006, 10:18 PM
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steveclv
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Default RE: Self build LiPo packs

Yep, that's why I want to solder them to the copper clad board - the board takes a lot of the heat away from the cell. I just need to design the PCB myself I guess as I can't find anything pre-designed on the web - either that or dismantle one of my existing 4S1P packs.

Thanks

Steve
Old 05-16-2007, 11:20 PM
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Default RE: Self build LiPo packs

Found this old post while searching for LiPo pack assembly tips. So, has anyone successfully soldered three LiPo packs in series and what is the best technique? I understand to use a small amount of heat with low temp solder. Do I need to use the silver solder and will only special aluminim flux work? Solder tab to tab and 14awg wire to inout and output tabs? I bought three 4000mah LiPo cells with tabs but have not assembled them yet. Waiting to understand the correct process.

Thanks,
Frank

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