Lipo pics

[Doozie870]

Decided to open up a good 2s pack The wiring diagrams were helpfull but needed to see first hand how things where done. A couple things surprised me. Only two layers of stranded masking tape (one on each tab) keep the two tabs from shorting on each other (have a lot more respect for this end of the pack now lol) The two cells are linked in series by some sort of tab stamp method. Nothing is between the two cells metal on metal. Still toying with the idea of converting 2 2s packs into one 4s.

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[Doozie870]

[ATTACH]5496[/ATTACH]

[chisoxguy13]

What batteries are those?

[Doozie870]

18C polyrc, dont get me wrong, the packs have proven to be very robust. wet three times and over discharged pretty low one time with no problems. got a screaming deal on 8 2s packs and need 4s2p for a upcoming project. So does anyone have any tips on soldering the tabs? I have heard there is a seal or gasket where the tab enters the cell that could be damaged, would heat absorbant paste work? thanks

[GregS]

Is this the first time taking off the outer shrink wrap? If so, it doesn't look like the tabs corroded at all from when they got wet.

Greg

[Doozie870]

This one has not been wet. (sister packs)

[D. Newland]

Dooz-I messed with Poly RC packs (swapped out a dead cell). You need to use aluminum flux.

I was not successful as corrosion happened anyway and the pack failed a few months after I worked on it. Maybe I did it wrong, but I learned a lesson: I'm not going to mess with assembling my own LiPo's anymore.

Is there a way you can accomplish your goals with some type of Y or parallel harness?

[GregS]

Why not just connect the 2 2S packs in series for 4S or do you want it to be a single more compact unit?

Also, did you remove the shrink from the packs you did get wet? Reason I ask is I dunked my Polyrc packs a couple of months ago and went through a process of drying with a hair dryer and leaving out in the sun but did not remove the shrink. So far the packs are still fine but I'm wondering if problems are likely down the road.

Greg

[Flyguy55]

Hi James
What kind of connectors are you using? I use 6 mm bullets. I have some 2S packs I use in series in my monos. I made a short jumper between the - of one pack and the + of the other pack . You can make a series Y connecter if you use deans connectors. Keep them short as possible .

Dick

[Eyekandyboats]

to solder packs you need aluminum solder. and a lipo chiller ... basically a VERY VERY cold icepack for it.
prep everything before you go ahead and solder it. you want as minimum contact as possible.
infact the crimp method that is shown in the picture above is very good conductor..

[flyboy320]

to solder packs you need aluminum solder. and a lipo chiller ... basically a VERY VERY cold icepack for it.
prep everything before you go ahead and solder it. you want as minimum contact as possible.
infact the crimp method that is shown in the picture above is very good conductor..

What is the ice pack for? Is it cool the tabs before soldering them?

Also, does aluminum solder melt at a different temp. than normal solder?

[ghostofpf1]

If the tabs are already soldered once and there's an area already tinned I don't believe you need special aluminum flux just to reattach things.You only need that flux when soldering on new tabs that are aluminum.
I've never used a cold pack while soldering but it sounds like a good idea since these cells typically don't like a lot of heat but if you're already pretinned you should be able to make the joint quickly enough that heating the cell is not a problem
Good Luck
Ghost

[flyboy320]

Anyone know if you can solder an aluminum tab to a copper tab, I'm not sure if you can mix the different metals?

[Doozie870]

Thanks for all the info, mainly trying to keep things simple without a lot of adapters and extra jumper harnesses. I will stay away from soldering tabs for now, instead will jump pos to neg with the exisiting leads they may stick out of the shrink a little on the output side. 80% sure on wiring to a single tap!

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[Doozie870]

Good news!! soldered - to + on the output leads (plan on shortening the length later) started with red on the tap (cut off the second red) and inserted each black progressively. Charger read the pack as 4s and began charging

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