Looking after LiPos between race days

Packs are usually killed by how they are stored, not by how they are raced. Two habits will roughly double the useful life of every LiPo you own.

Habit one: store at storage voltage

A LiPo degrades fastest when it sits either full or empty. Left at 4.2 V per cell for a fortnight, a pack measurably loses capacity. Left flat, it may drop below the point where a charger will safely recover it.

Storage voltage is 3.80–3.85 V per cell. Every charger worth owning has a storage mode that will either charge up or discharge down to reach it.

The habit: if you are not running a pack within about two days, put it into storage mode. It is one button press.

Habit two: do not run them flat

Set your ESC's low-voltage cutoff and leave it on. 3.0 V per cell under load is the usual limit, which settles to around 3.6–3.7 V once the pack rests. Below that you are taking permanent capacity out of the pack every time.

If a run ends with the pack at 3.2 V per cell resting, you went too far. Gear down or shorten your runs.

Reading a pack's condition

• Puffing — the pouch swelling. Gas generated inside by cell breakdown. A slightly puffed pack may still work, but it has begun to fail, and it will not improve. Retire it before it gets worse.
• Cell drift — one cell consistently lower than the others after a balance charge. The pack is only as good as its worst cell.
• Falling capacity — note how much your charger puts back in after a run. A pack that used to take 4400 mAh and now takes 3600 is worn out, whatever the label says.
• Getting hot — packs warm in use, but hot to the touch after a normal run means the internal resistance has climbed.

Physical care

Keep them somewhere cool, dry and fireproof — a metal box in a cupboard, not a hot car boot. Watch the leads: repeated flexing where the wire meets the pack eventually shorts, which is spectacular. Transport packs so nothing metal can bridge the terminals.

Disposing of a dead pack

Do not put a LiPo in household waste, and never in a bin lorry. Discharge it fully, then take it to a battery recycling point — most hobby shops, tip sites and larger supermarkets accept them.

The old advice was to discharge in salt water for days before disposal. It works but it corrodes the terminals into a mess and produces unpleasant runoff. If your charger has a discharge function, use that instead, then recycle the pack as it is.