How to Protect LiPo Batteries from Crashes / Physical Damage

by Oscar

Given the amount of crashes we have with flying FPV drones, we ought to do more to protect our LiPo batteries from physical damage. In this tutorial I will show you a few ways how to add extra protection to LiPo and make them tougher.

Further Reading: How to choose LiPo Battery for Racing Drones?

Protecting LiPo Batteries from Physical Damage

LiPo battery is probably one of the most vulnerable part of an FPV drone, and yet it’s usually placed at the most unprotected place on our mini quad. It usually just sits on the top or bottom plate of the frame which makes them completely exposed to impact in crashes or get punctured by spinning propellers.

The general recommendation is to throw away dented or bent LiPo batteries for safety reasons. Damaged LiPo batteries can be dangerous and potentially cause fire. Do not risk your house over a $20 battery!

Pro Tip: How to dispose LiPo battery safely?

LiPo batteries are rated for over 300 charging cycles, if you had to dispose them early, you are not getting the most out of them :)

With flying mini quads, crashes are inevitable. This makes LiPo protection very important, but it’s often overlooked.

Heat Shrink for LiPo Batteries

Heatshrink provides basic protection to your LiPo batteries, it’s light-weight, cheap and easy to apply. Most LiPo already comes with a thin heatshrink but it doesn’t hurt to add an extra layer.

There are two types of heatshrink for LiPo:

  • PVC Shrink Film
  • Rubberized Heatshrink Tube

PVC Heatshrink Film

PVC Heatshrink film is extremely light weight (less than 2 grams per pack), thin and stiff, it’s commonly used in battery packaging, your batteries are most likely already wrapped with this.

In my opinion PVC heatshrink can be useful to taking a few scratches, but they add little to none protection to your batteries against heavy impacts. You can buy spare to replace your old one or add extra layers for protection.

Rubberized Heatshrink

Compared to PVC heatshrinks, rubberized heatshrink is a much better option for protection. It’s much thicker (~0.5mm), more flexible, more durable, and it actually sticks to your anti-slip battery pad much better too. However it is quite a bit heavier, about 6 grams per pack for 4S 1500mAh for example.

Picking Heatshrink Size

For a typical 4S 1300-1800mAh battery, 70mm to 80mm flat sized tubes should do nicely (equivalent to diameters of 45mm, 50mm and 55mm).

There are two sizes shops normally use:

  • diameter, the diameter of the tube
  • flat size, the width of its flat form (half of the circumference)

You can convert between diameter and flat size using this formula:

Flat Size = 3.14 x Diameter / 2

You should choose a flat size that is larger than the combined width and height of your battery (only take two sides out of the four). Most of these heatshrink has a 2:1 shrink ratio, so the maximum flat size must NOT be larger than twice of that number.

How to Apply Heatshrink?

You can either remove the original packaging, or keep it as an “extra layer of protection”. By removing it you can save a couple of grams. And make sure you keep the label sticker for identification.

For safety, avoid using a lighter or any form of fire, it’s a bad idea to “barbecue” your battery.

It’s best to use a hot air gun. If you don’t have one you can try a hairdryer (it might take longer because they are not hot enough). Keep rotating the battery, avoid applying too much heat at the same spot for long as typical hot air guns are capable of melting through the plastics used in a LiPo battery.

Now put the sticker back on so you know the capacity and cell count of that battery.

Heatshrinks are also a great way to customize the colors of your battery :D

PVC Corners

This has to be the ultimate protection for your LiPo.

I get these 90-degree PVC corners and just stick them to my batteries. This stuff is available in hardware stores for close to no money. You can also find them online at: https://amzn.to/2J1FXfs (affiliate link).

From my experience, most battery damages happen at the corners. Simply wrap these PVC corners tightly to the battery with fiberglass tape will provide effective and strong protection to physical damage.

However these PVC corners are not the lightest, you could be adding 10g to 15g of weight to each battery (4S 1500mah). I’ve tried two different sizes, 10mm and 15mm. 10mm is lighter, but 15mm covers a larger area.

  • Added weight per pack (10mm): ~9g
  • Added weight per pack (15mm): ~14g

You will also need some fibre tape (Buy: BanggoodAmazon) to secure the corners, I love these tapes because they are extremely strong and sticky. Or you can just use heatshrink if you want.

Extra bonus: If you have bottom mounted battery, the corners will help your quad stand perfectly level on uneven surfaces :)

Bicycle Inner Tube

Be safe, put a rubber on.

I have numerous people commented that they use the inner tubes from bikes instead of rubber heatshrink and getting great results.

Bike Inner Tube for LiPo battery protection

Image Credit: ‎Idan Elefant

It’s not easy to slide the battery into the tube, but these tubes are even thicker and more rubbery than heatshrink. The rubbery surface is ideal for providing strong grip to the frame / battery pad too.

It’s recommended to use 20″ tubes for 3S, and 26″ tubes for 4S. Probably a good idea to go down to your local bike shop and ask if they have any unwanted tubes so you can get them for free :)

Some simple instructions on how to fit the tube over the battery:

  • Cut the tube into sections longer than the pack, and slide over the lipo
  • Slip the tube over with a set of pliers, open them to stretch the tube, then start inserting the battery
  • Maybe even use 2 sets of pliers from both sides. It’s easier if you can get someone to help you

Added weight per pack: ~10g.

3D Printed TPU LiPo Protector & Landing Gear

This one is pretty cool because it requires no modification to your batteries.

Added weight per pack: ~16g.

Conclusion

Please consider supporting me on Patreon for more tutorials like this. I hope it helps you to save a few battered and bruised LiPo batteries.

I really like the idea of applying a layer of rubberized heatshrink, then some PVC corners. A bit heavier perhaps, but my batteries are certainly lasting longer! Most importantly it gives me the peace of mind when landing and crashing hard :)

Happy flying.

A reader of mine made a video demo, how cool is this?!

Edit History

  • Apr 2018 – article created
  • Jun 2019 – added a demo video, updated product links
  • Mar 2021 – revisited post, updated product links

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16 comments

mrhuggy 30th October 2021 - 2:07 pm

Hi Oscar, yes this is a old post but I was looking for ideas to protect lipo’s. I would recommend not to use bike inner tubes for batteries, the inner tubes are made from butanol, yep it’s a Butane compound which is highly flammable, put it this way i use old inner tubes as a fire lighter as they burn very hot and nice and slowly.

Reply
XenOff 9th July 2019 - 3:34 pm

There is a little bit more complicated, but much more durable way to protect batteries.
Plastic PET bottle from yogurt or else shrieked to the size of battery. You will need to make wooden template to make that battery armor, do not even try to shrink on a battery.
We call it “battery armor”, as it is very stiff and durable, and also very light – about 7g. Also it does not give batteries to puff, and they seem to last a little longer.

Here is a video from my teammate, it explains how to make it:
youtube.com/watch?v=i_hhbrPRoU4

Reply
Leurne 16th June 2019 - 9:03 am

Hi god of FPV Oscar Liang,
i’ve made a video for my french fpv friends to show your tips for LIPO protection:
https://youtu.be/GbB5pvuweh4

:D short video but just to illustrate it :D

Reply
Oscar 17th June 2019 - 6:06 pm

That’s awesome dude! I will share it

Reply
Leurne 19th June 2019 - 12:53 am

i didnt expect so much :P just to inform that i used your idea to be fair :)
But thanks a lot dude :)

Reply
dangar27 9th April 2019 - 8:59 am

Dear Oscar
I have been flying with this carbon fiber protector (banggood.com/Realacc-Carbon-Fiber-Battery-Protection-Board-with-Tie-Down-Strap-for-X-Frame-kit-p-1111041.html) and could not be happier. Of course, I am not an expert so the 8.55gr additional is not an issue for me and all my batteries are in quite good shape. I cannot recommend it enough

Reply
DaveE128 30th April 2018 - 9:34 pm

More important than the inner tube wheel diameter (eg 20″, 26″, 29″, 700c) is the tyre width they are designed for (eg 23c, 28c, 1.25″, 1.95″, 2.3″). What sizes are people using on 4s batteries?

Thanks,

Reply
Oscar 9th May 2018 - 11:59 am

to be honest i am not sure. Maybe go to a bike repair shop and ask if they have any useless tyre you can get :)

Reply
Tier 26th April 2018 - 3:27 pm

Hey Oscar,

thanks for these tips. One concern: I wonder what would happen in case of a LIPO-fire having that tape around? Maybe it could even lead to more serious consequences.

Martin

Reply
Oscar 30th April 2018 - 4:32 pm

Fire will just melt through the tape, shouldn’t make fire any more or less dangerous. But the corners provide better protection to reduce the chance of damage to battery.

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TOmas 23rd April 2018 - 7:46 pm

Hi, here is a video with my battery, showing disassembly cell after prop hit one cell…. show attention on welded sheets

youtube.com/watch?v=4lDd02aVCU0&t=10s

Reply
Mike 19th April 2018 - 8:18 pm

there are also these Battery feet from Banggood too Great, your battery strap goes over them and they hold to the battery good, i use them and think they work well
banggood.com/FPV-Racing-Landing-Gear-Battery-Protector-Board-3D-Printed-TPU-Yellow-Green-Red-p-1140905.html

Reply
JB 19th April 2018 - 4:47 pm

Or you can buy hardcase lipos like the Tattu ones.

Reply
Dafunk 19th April 2018 - 1:36 pm

I like your idea of securing balance leads.

Overall it feels like the battery is an “added part” to the racing quad

Some kind of cage protecting batteries would be more than welcome for beginners frame.
Batteries dimensions being standard It shouldn’t be hard to design a universal 4S aluminium cage that may also serve as a landing gear

Just throwin’ ideas :)

Reply
Oscar 23rd April 2018 - 4:22 pm

There were frame designs back in 2015 that allowed you to put the battery inside the frame so it gets protected entirely. But it didn’t become popular because the extra weight with the design.

Reply
Paul Riding 19th April 2018 - 5:41 am

Hi Oscar. Another one to try is 26″ mountain bike inner tube, fits 4s packs perfectly. you can also cut a small band of it to secure balance plugs. Its very cheap and batteries even grip the strap/frame better. Adds 10 to 15 grams.

Reply