# Mechanical robustness/shock resistance LiPo batteries

How mechanically robust are LiPo batteries? How much force or acceleration can they maximally withstand before failure? What is their (mechanical) shock resistance?

For some electrical components used in robots, such as IMU's, it can be found in datasheets that they can suffer mechanical failure if accelerated or loaded beyond given values. For IMU's, this is typically somewhere between $2000g$ and $10000g$ (where $1g = 9.81 m/s^2$).

I'm wondering if similar values are known for LiPo batteries, since they are known to be vulnerable components. But, is there any quantification known for their claimed vulnerability?

• Check the data sheet for your particular battery, some are more resistant than others. – Brian Lynch Dec 4 '15 at 18:42
• @Brian I have yet to find a manufacturer that actually specifies mechanical robustness. Please point me to one! – JJM Driessen Dec 12 '15 at 19:03
• I also didn't see much when I tried hunting down some examples. You might be able to look at those specs for UAVs with similar batteries and assume those shock loads are acceptable. – Brian Lynch Dec 12 '15 at 19:27

Typically, with LiPo batteries, they don't have a hard case. The hazard comes when the battery internals get dented, which causes the battery to short out internally. LiPo batteries can dump enough current when shorted to cause a fire and/or explode when shorted.

The deformation that causes a dent in the battery is generally caused by a high local pressure, the same way you might crack the screen of your phone if your car keys press against it in your pocket. Actually, I would bet this is the reason that a lot of cell phones catch fire in people's pants.

So anyways, pressure is force over some area ($P = F/A$). The force may be cause by acceleration or shock, as $F=ma$. In this instance, then, catastrophic damage would depend on how the battery hit more so than the actual shock rating.

That is, if the battery hit on the corner, then the contact area is small, so the pressure is high, so the battery may deform. If the battery hits on its face/back/etc., then the area is large, so the pressure is low, so the battery may not deform. Again, this is how you could drop your phone on its back on the floor and the screen is fine, or you drop it on its corner and the screen cracks.

All of this is to say that I would imagine battery manufacturers would probably not shock rate a LiPo battery because the outside of a typical LiPo cell is so soft that the impact orientation would play a very large role in whether or not the battery fails.

If you're concerned about battery damage then I would consider packing the battery in a hard shell.

• One could argue that most LiPo batteries have hard cases. The shrink-wrapped pouch cells that hobby guys use are probably a minority when you compare the numbers to cell phone, power tool, and laptop battery packs. – hauptmech Dec 5 '15 at 1:07
• @hauptmech - I disagree; the batteries you mention are not commercial, off-the-shelf batteries for purchase by an end user for a generic application. They are designed by the product manufacturer for use with one specific device. I sincerely doubt there is a significant number of people using laptop batteries or power tool batteries in generic applications, probably because the power connectors are product-specific. When you search for LiPo batteries online, all the results show the "soft-shell" batteries I mentioned. – Chuck Dec 5 '15 at 22:02
• Yeah, you are right. Somehow I read it as Li-ion even as I responded with LiPo. Of course LiPo is a loaded term. Anyway, I'll tweak my answer so it reflects that. – hauptmech Dec 6 '15 at 1:21
• You are saying that the battery combusts because of a short caused by the puncture. Other sources claim that this happens due to the cell (lithium) being exposed to oxygen. Can you provide a source for your claims? – JJM Driessen Dec 12 '15 at 17:55

as @Chuck points out, LiPo cell are sensitive to thermal runaway triggered by mechanical rupture or deformation.

An example of a manufactures shock spec can be found here. (They test for a drop onto concrete).

Mechanical failure from impact depends on so many factors that I don't think you will find specifications more specific than the one above.

For pure acceleration (vibration in a rocket launch or a sensor in a centrifuge for instance) they should perform pretty well. The electrolyte is a paste...