Protect LiPo Battery from Mini Quad Crashes

Given the amount of crashes we have with mini quad and racing drones, we ought to do more to protect LiPo battery from physical damage. In this tutorial I will show you the different ways of adding extra protection to your LiPo batteries.

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

Protecting LiPo Batteries from Physical Damage

The LiPo battery is one of the most unprotected part on our mini quad. It usually just sits on the top or bottom of the frame which makes them completely exposed to impact in crashes, or puncture 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 cause fire.

Pro Tip: How to dispose LiPo battery safely?

Flying mini quads, crashes are inevitable, especially if you fly indoors, race and fly close proximity. This makes LiPo protection necessary, but it’s often overlooked.

Some LiPo battery manufacturers already started adding thin fibreglass sheets to their batteries. In case yours don’t have these sheets, or you simply want to play safer, I will show you some DIY ways of LiPo battery protection.

Heat Shrink for LiPo Batteries

The cheapest and easiest protection for LiPo batteries would be heatshrink. When I was researching, I found two types of heatshrink for LiPo:

  • PVC Shrink Film
  • Rubberized Heatshrink Tube

PVC Heatshrink Film

PVC Heatshrink film is commonly used in battery packaging, you probably have it already on your batteries.

This stuff is extremely light weight, thin and stiff. In my opinion they can be useful taking scratches, but they add little to none protection to your batteries against impacts. You can buy spare to replace your old one or add extra layers for protection.

Added weight per pack: ~2g

Rubberized Heatshrink

On the other hand, rubberized heatshrink is a much better option. It’s thicker (~0.5mm), more flexible, more durable, and it sticks to your anti-slip battery pad much better. However it will add some weight to your battery.

Added weight per pack: ~6g

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 use: diameter, the diameter of the tube; And 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 total of width and height of your battery (only two sides out of four). Most of these heatshrink has a 2:1 shrink ratio, so the maximum flat size mustn’t 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.

Avoid using lighters 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, although they might not be hot enough. Keep rotating the battery and avoid applying too much heat at one spot as typical hot air guns are capable of melting through the plastics used in a LiPo battery.

I also prefer to peel off the label and stick it back on the new shrink-wrap so I know the capacity and cell count.

PVC films are not the best for physical protection, but they are useful for changing the colour of your batteries :D Great way to customize your battery collection.

PVC Corners

In case heatshrink isn’t enough, you can consider 90 degree PVC corners. This stuff is available in hardware stores for close to no money. You can also find them online at:

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 light, you will add 10g to 15g of weight to your battery. I normally use two different sizes, 10mm and 15mm. 10mm is lighter, but 15mm protects 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, this type of tape is extremely strong and sticky:) You can also just use heatshrink film if you want.

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

I got this idea from a friend on Facebook, Vincent Offenbeck. Many thanks to him!

Bicycle Inner Tube

Be safe, put a rubber on.

So many people commented that they use inner tube from bikes for protecting their LiPo batteries, and have good 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 much thicker than heatshrink and should provide better protection. The rubbery surface should also give good enough grip to the frame to replace your velcro.

I have not personally tried it, but I have been 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 :)

This is how you can fit the tube over the battery:

Cut it 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 battery. You can print it yourself if you have a 3D printer and TPU filament, or you can buy it.

Added weight per pack: ~16g.

Conclusion

I hope the added battery protection in this tutorial can help you 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 these tricks have given me much better battery longevity, fewer dents and punctures, most importantly the peace of mind when landing and crashing. :)

Please consider supporting me on Patreon for more tutorials like this in the future.

Happy flying.

10 thoughts on “Protect LiPo Battery from Mini Quad Crashes

  1. DaveE128

    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
    1. Oscar Post author

      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
  2. Tier

    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
    1. Oscar Post author

      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.

      Reply
  3. TOmas

    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
  4. Mike

    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
  5. Dafunk

    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
    1. Oscar Post author

      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
  6. Paul Riding

    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

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