Battery Charger
🟢 Start — zero knowledge, plain words. 🟡 Hands-on — building or buying, specifics and tradeoffs. 🔴 Advanced — the physics and math behind it.
🟢 Start. A LiPo charger is not a phone charger: it must balance — hold every cell in the pack at the same voltage — because the pack is only as safe as its worst cell. That is what the small white multi-pin plug on every pack is for. The rules from the battery page apply at the charger, doubly: charge supervised, on a non-flammable surface or in a LiPo bag, and put packs into storage mode (~3.8 V/cell) after every session instead of leaving them full.
At a glance
| Type | Power | Best for |
|---|---|---|
| AC single-channel (all-in-one) | ~50–100 W | The starter choice — nothing else needed |
| DC dual-channel + separate PSU | 2 × 150 W+ | The hobby standard once you have a pack fleet |
| Parallel charging board | shares one channel | Experienced users only — see the mistakes below |
🟡 Hands-on. The habits that make packs last:
- Charge at 1C — pack capacity in amps: 1.3 A for a 1300 mAh pack. Faster is possible on good packs; it trades pack lifetime for bench time.
- Storage mode is a feature, not a luxury. Packs stored full puff and fade (battery); the charger automates getting them to 3.8 V/cell.
- Read the internal resistance. Decent chargers report per-cell IR — the honest health number that C-ratings pretend to be. Log it when packs are new; retire a pack when IR has roughly doubled (Module 6 shows why that pack now sags and heats).
- Pick the right chemistry profile. LiPo and Li-Ion charge to different curves and cutoffs, and LiHV goes to 4.35 V/cell — charging a standard LiPo on an LiHV profile overcharges it every time.
One 6S 1300 at 1C needs about 33 W (25.2 V × 1.3 A). Four packs between flights on a 50 W charger means charging in series — an hour-plus of waiting. This is why dual-channel 150 W+ chargers are the standard second purchase: the charger's wattage is really your packs-per-hour number.
🔴 Advanced. Lithium charging is CC/CV: constant current until the cell reaches 4.20 V, then constant voltage while the current tapers toward zero. Two consequences worth owning:
- The pack spends the last ~20 % of the charge in the slow CV taper — "90 % in 40 minutes, 100 % in 70" is normal physics, not a broken charger.
- Balancing happens by bleeding the highest cells through small resistors during CV. A pack that takes ever longer to balance is drifting — its cells no longer age together, and the IR log will usually confirm it.
Charging is also where the energy bookkeeping from Module 6 becomes tangible: a 6S 1300 holds ~28.9 Wh, so refilling four flown packs moves ~100 Wh through the charger — factor in ~85–90 % efficiency and a field-charging battery box needs real capacity, not a cigarette-lighter socket.
⚠️ Common mistakes
- Charging unattended. There is no safe version of this (battery says it; the charger is where it happens).
- Charging a pack still warm from flying, or one that has been crashed hard.
- Parallel-charging packs at different voltages or cell counts — the boards assume you checked; the packs equalize through each other violently if you didn't.
- Leaving packs full for weeks because storage mode felt like a hassle.
- Buying a no-name "USB LiPo charger" without balancing. It's not a charger; it's a countdown.
- Ignoring the IR readout for years while flying progressively saggier packs.
Where this connects
- Battery — voltages, C-ratings, sag, and the discharge-side discipline
- Module 6 — Power system — internal resistance, energy math, why abuse ages cells
- First flights — the field routine these habits slot into
Image ideas
🖼️ Photos: your own charger showing a per-cell IR readout, annotated; a balance plug macro; your storage-charged pack shelf with voltage labels; a field-charging box wired up.