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Today my 48v 15Ah LiFePO4 ebike battery fell off from my bicycle and got a little bit of road rash on the corner:

48v 15Ah LiFePO4 ebike battery

It still works. Does not seem to be heating or discharging on its own.

However, between battery minus and a tiny bit of the exposed area (not all exposed area in the picture is metal though) there seem to be +2V, which is making me somewhat nervous.

What would happen if I would simply apply liquid electrical tape on that area and call it a day?

Thoughts going on in my head:

  1. Could internal short happen and battery catch on uncontrolled fire?
  2. Does LiFePO4 chemistry play any role in this as well and add to the safety?
  3. I don't know what form factor cells are inside the battery pack and if that plays any role as well. Obviously dont seem to be anything durable like 18650.
  4. Should I simply throw away this battery and get a new one?

P.S. since its Halloween I am up to hear all horror stories on what may happen...

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LiFePO4 is a fairly safe chemistry and can take more abuse than most. The electrode material is far more stable than that used in LiPo/Li-ion cells, and most if not all incidents are electrical (i.e. short circuits leading to fire) rather than chemical in nature.

Nonetheless exposed metal surfaces should be insulated using a generous layer of silicone caulking or similar material (certainly not "liquid wire", since such a liquid is actually conductive). For additional protection the entire battery pack should then be placed in a silicone or rubber sleeve in order to provide further protection.

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  • \$\begingroup\$ I had a typo. Instead of "electrical wire" I meant "liquid electrical tape". Perhaps a silly question - how do I know that electrolyte is ok for that cell? The puncture somewhat smells, but I did not see any liquid. \$\endgroup\$ – Hans Solo Nov 1 '17 at 6:08
  • \$\begingroup\$ The electrolyte would be contained inside the metal casing. Since the casing itself doesn't appear to have been punctured, merely the outer insulating layers have been scraped away, there is little chance of the electrolyte escaping. \$\endgroup\$ – Ignacio Vazquez-Abrams Nov 1 '17 at 6:10
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A battery of that voltage and capacity has got some serious juice in it cause a big fire if things do go wrong. When compared to a Li-ion cell a LiFePO4 is much more safer. But still poses some hazard.

Well internal shorts occur when the + and - electrodes get shorted inside. I'm more worried about the fact fact that you mentioned that there is a potential difference between - terminal and the exposed area. So a short between these two points need to be avoided. If there is no leak of electrolyte from the punctured area then it could be 18650 cells (can't say for sure). One way to go for a fix if the battery seems okay is seal the punctured area with some industrial grade tough glue like epoxy etc.

Finally, since you have mentioned that "Should I simply throw away this battery and get a new one?" I'm assuming you have the budget to get a new one. If that's the case that would be the best and safest thing. But these batteries cost around $420 if my guess is correct for a good quality one.

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