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
- 50mm Red from Hobbyking – One of the best
- 50mm Black from Amazon – I haven’t tested this
- 40mm Transparent from Amazon – Good for smaller packs (e.g. 1300mah)
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.
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
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.
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.
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. :)
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