Cutting open commercial batteries! (Lift, Onean, Flite, etc.)

I took the gamble on purchasing a dead Lift battery which I am hoping to partially salvage for my efoil build. It is reading 0 volts and would not charge for the prior owner. I am hoping to find some usable cells and just a dead BMS and/or a string or two of bad cells. Worst case scenario, if it is full of salt water inside I have a solid paper weight and might be able to reuse some parts for a new battery build. I have my battery welder at the ready if that’s the case.

I have extensive experience with batteries of all types (including much higher voltages and ah) so I will be as safe as possible in this endeavor and try not to let the magic smoke out. My plan is to take it outside carefully use a dremel diamond cutoff wheel around the seam where it was glued together.

There isn’t much info I can find online and it is a little scary going in totally blind.


  1. Anyone opened one of these before?
  2. Does anyone know of any pictures or schematics of the inside so I can see where I need to be extra careful?


No idea which area you need to take care of when cutting in, but here is an early prototype picture they shared. My bet is they still placed the BMS on this exact same place, right in front of the pack.

Maybe rename the thread to « cutting open commercial batteries » so I can also contribute when I cut open my Onean battery pack, what do you think ?
That being said, it would be interesting to know the brand of the bms and also the maximum operating current it is rated for. I’ll share all these data too when I get the time to open my pack I promise.

Really interesting guys !
Please let us know what you find and how the waterproofness part is made with Lift and Onean.

I’ve seen an open one, but can’t remember where. I’ll have a look around and see if I can find the pics. Don’t cut with Dremel yet. Contact lithos and ask the best way to open it.

Jezza, that would be super helpful if you could find the pics. According to the prior owner, Lithos says the battery is unserviceable.

A bit bigger but not LIFT’s: connector is oblique here and horizontal with LIFT’s

Lithos picture1_1

Lithos did have a YT vid showing how they assemble the LIFT battery.

@Vince, had a similar problem 2 months ago.

Lithos picture1_2

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Gosh, this community of people is amazing. That video was really helpful, @SoEFoil.

I found the answer to a lot of my questions. First of all, I probably would not have been super careful around the top of the handle, but it turns out that is exactly where they ran the main power wires (although they have zero potential right now.) You can see quite a bit about the internals from the B-roll footage from the video you mentioned. I have quite a bit more confidence going into this now and still feel cutting right at the seal is the best play.

Here are all the shots I was able to snag:

Nice pics , probably mounted with a plate included fuses on each cells

I can’t do better than that… It actually might be where I saw them…

Have you been in contact with Lift? They may assist you rather than taking matters into your own hands.

Could it be the data cable on the charger or the connector on the battery side? The two do a handshake before charging begins… The pins are very fine gauge wire and any corrosion or bent or broken pins could be a part of the problem.

I suggest a close look in good light at male/female sides of the data cable connections.

The issue could just as easily be with the charger or the connection between the two.

The idea of cutting open a sealed battery based on the evidence that you have shared above seems premature to me.

There is a video that suggests using electrical contact cleaner and ReelX or CorrosionX to protect the date connector from corrosion

What are you waiting for?! Cut the thing open already.

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@yojamey There was not an issue with the charger. I mentioned above, there is no pathway to fixing it with Lift or Lithos.

This big black box is getting opened up.

@noahark Haha, I am eager to, but still getting tooled up. Need to print one more piece for an adapter I am putting together to help me cut it as precisely as possible. Hopefully I will have the time to get her cracked open tonight.


:pray:t4: :crossed_fingers:t4::pray:t4:

I spent some time this evening cutting into the case. The seam where the two halves were fused together has to be by far the thickest part, but I still think it is the safest place to cut it open. Just for kicks, I tried to hit it with a few different types of blades first. Don’t even bother. This thing is pretty dang stout.

My dremel adapter is working really well to precisely hit exactly where I want, but I am getting some melting when I get too aggressive. As I get deeper it is hard to stay in the sweet spot, without stalling the motor or melting the plastic. Regardless, I think I may get a clean enough cut that there is a chance I could re-use the case.

I can’t find a dremel cutting wheel that works well, but I at least found one type that is effective without gumming up too badly. The problem is that they wear down pretty quickly and I have already shrunk 6 of them down to nothing. I might end up going through 20 before this is over.

A coping saw works pretty well on some of the corners. The inside of the handle is going to be the hardest part by far. I can safely say getting to these cells is going to take longer and much more effort than welding together a whole new pack of 18650 cans of the same quantity.

Vasco Velez here in Australia helped a friend cut a Lift battery open and Vasco told me that epoxy is poured in between each battery so you can’t get them out. I have two dead Lift batteries that were replaced under warranty.

Do you have a Fein tool?

As far as I know, Lift is using Polyamide 66 reinforced with glass fiber as battery case material which has a melting point >230°C. Best in class material for this kind of application where the cells and BMS can catch fire.

I would first try to heat the glued parts (sides) with a heat gun up to 150°C to melt the glue. It should be doable this way because I highly doubt they would use a high temperature epoxy as bonding glue (usually more $$ than conventional ~100°C resistant epoxies). The cells should still be fine as they are also protected by a second structure and not touching the sides directly.

Make sure to wear gloves as everything will be pretty hot and goggles too, safety first !

Might be indeed, that’s at least what we see in the video. The purpose of the operation here is however something else (at least for me). We are trying to openly share the specs of the components inside to help the diy community with the choice of BMS / cells or other components for this application.

I feel like my Onean pack is also full of epoxy but we’ll discover this pretty soon too ! Again, what might be interesting is the BMS they use (Onean is 12S16P, to technically up to 160A continuous) and what’s inside too, there are very few informations on this topic out here…

Exactly. Even if there is nothing salvageable, I am interested to see what is inside this 3,500 pack and why it stopped working.

I am resisting the urge to bring out the heavier saws like my large oscillating tool, @noahark. It may come to that today and I might be able to get a fairly clean cut once I get the groove deep enough to guide it.

I don’t think it is epoxied or glued together anymore. They may be using some sort of plastic welding process that fuses the two pieces together by heat. The seam is very tight and material is consistent. A MUCH better job than the multiple flyproducts gas tanks that split at the seams on my paramotor! :open_mouth:

After sleeping on it, I realize that I need to just cut across the top of the case shy of the handle. I do not want to spend the time it will take to carefully cut around the inside of it and would probably butcher it if I tried.

The dremel adapter I printed to precisely control the y and z planes for the cut:

The plastic is hard and waxy at low speed and won’t cut, then quickly hits a flash point where it melts/smokes and gums up the tools.

Progress… with a pretty clean cut