LiPo batteries are fantastic. They give more power, higher speed and deliver constant performance throughout the whole run – which is exactly why they have become the standard in RC gear. But they have one big Achilles' heel that far too many people overlook: they must not be over-discharged.
What is over-discharge – and why is it a problem?
Over-discharge happens when the voltage in the battery falls below the recommended minimum per cell. For a LiPo battery, each cell must be kept above 3.2 volts – and never below 3.0 volts. If it happens anyway, the cells become unstable. As a result, the battery may:
- No longer charge
- Bulge or swell up – a clear sign that it must be disposed of
- In the worst case become a fire risk
The classic mistake: "hibernation"
One of the most common causes of over-discharged LiPo batteries is that they are put on the shelf after the season – with a low charge – and not touched again until spring. A LiPo battery slowly discharges by itself, and after months of rest it can be so deeply discharged that it never recovers.
How to avoid it
Storage charging is the solution. Before the battery is put into storage, it should be charged to approx. 3.8 volts per cell – equivalent to approx. 75–80% charge. Most LiPo chargers have a built-in "Storage Mode" function that does this automatically. If your charger does not have this function, you can simply charge the battery halfway (approx. half the normal charging time).
Also remember to:
- Disconnect the battery from the car, boat or drone after use – even if there is an on/off switch
- Turn on LiPo Cutoff on your speed controller (ESC), so the model stops by itself before the battery drops too low
- Use a LiPo alarm / buzzer that beeps when the battery approaches the limit
In short
LiPo batteries need a little extra attention compared with the old NiMH batteries – but if you treat them right, they last a long time and perform at their best. If you treat them badly, they are wasted money.
Has your battery already swollen up? Then take it out of use immediately and hand it in at your local recycling centre. Never continue to use or charge a swollen LiPo battery.
We always recommend storing and charging LiPo batteries in a LiPo safety bag – and using a LiPo alarm/buzzer for extra peace of mind while driving.
