Is this battery usable?

-------UNIMPORTANT CONTEXT------- Couple of months ago I ordered 50 cells to build a 10s5p battery pack. Since I didn’t have a spot welder (still don’t) I had to find someone local to do it. I could only find one dude here in Northern Europe who offered the service of welding battery packs. I took the cells to him and described I wanted a two-layer pack showing some pictures. He then takes around three hours, doesn’t connect bms balance wires, cables or anything. Just welds. So now I have this battery pack that is seemingly alright (gives off 35.8 volts), but god damn it looks sketchy. Since I can’t trust myself with evaluating battery packs, I figured you guys might have some thoughts.

Anyway, what do you think of this battery pack? Is it usable after connecting a bms and heatshrinking? If not, what should I do in order to make it usable? If it’s completely garbage, then perhaps can anyone point me towards a batterybuilder in the Baltics/Nordic area.

I tried to get pictures from different angles. Have a look:

20190225_153851 20190225_153909 20190225_153840 20190225_153846

This whole thing looks jank as f*ck. In my opinion, the pack is dangerous and a fire hazard… :slight_smile: The strips are way too long and could short out pretty easily. Maybe also post some pictures of the actual welds… :slight_smile:

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It seems the pack has been glued with what seems to be some form of insulation between the two halves am I right? The excess nickel strips should have been cut off and rounded to prevent accidental shorting. Can you tell how many layers of nickel are on the series and parallel connections.

Be careful take off all jewelry from hands and wear gloves when handling this pack Capture%20_2019-01-25-11-54-31


The guy is an ass for gluing the cells as any hope of rebuilding will require you taking the cells apart but that will rip the cell insulation/shrink wrap.

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There are minimum of 5 nickel strips for serial connections, but I can’t remember the parallel connection nickel strips. I think one long strip of nickel for parallel…

I can take pictures of the welds in an hour or so. Currently away from home.

As you can see from the pictures and replies above, I wouldn’t recommend this battery builder :sweat_smile::sweat_smile:

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Welds are seen on this picture. Also parallel connection seems to have 2 long strips. 20190225_204221

Also, the cells are glued together with hot glue. Is this good or bad in my situation? :smiley:

Hot glue is actually a good thing. A little acetone I believe will break down the adhesion and allow you to take apart. I think the job as it stands is not super safe to use. But I also think this could be salvageable as long as the welds are good.


What steps would you recommend to salvage it?

What kind of cells are these and are they protected?

Here’s a thread from a while ago when I asked for advice on the cells:

I ended up going for them.

What do you mean by protected, though?

Methyl Hydrate breaks the surface tension of the hot glue and it pops right off. For spry adhesives, like 3M 777, use WD40, it turns the glue into a rubber ball.



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Alcohol will easily release hot glue and leave the wrap intact.

It’s hard to tell how safe the pack is from those photos. A bit sloppy looking but beside the too long nickel on the ends, nothing obviously terrifying?

The guys who are nervous, can you be more specific?


I’m not sure why they would leave that extra nickel wrapped around the edge atleast they used fly paper

Yeah that is what I was getting too. The welds look pretty okay, he doubled his nickel strips, and at least wrapped it a bit.

Only thing I would be worried about is the strips sticking way past the edges, but you could just trim those, no?

I literally ruined 10 30Q cells a few days ago, wish i red this earlier…

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If it’s the wrap that’s torn, you can rewap. 18650 srzed heat shrink is cheap and common thanks to vapers.

Yes and some cells have dents so I will use them for lights etc I found some hot glue that holds incredibly well, a little too well i suppose