How to charge your Maxon BIKEDRIVE — full procedure + fast-charge strategy

How to charge your Maxon BIKEDRIVE

The complete charging guide for your Paratu CP. Verified against the Maxon BIKEDRIVE AIR Operating Manual (Sep 2023), with the lunch-break strategy that opens up 4,000 m climb days.

30-second quick reference

  • Main battery (BX400I, 400 Wh): plug the charger into the charging socket on the bike. Charging starts automatically, auto-stops at 100%.
  • Range Extender (BX250E, 250 Wh): unplug it from the bike first. Then plug the charger directly into the RE.
  • You cannot charge both at once from one charger. Sequential only.
  • Always charge BOTH to 100% before a big ride. If you rode with the RE attached, both batteries need a refill, not just the main.
  • If you finish a ride empty: immediately put it on charge to at least 60% capacity — Maxon's manual rule for cell health.

How the Range Extender feeds the main battery during a ride

This is the key behaviour that confuses most first-time owners — and why our calculator's predictions are so accurate.

When you attach the Range Extender at the start of a ride:

  1. The RE drains FIRST. It continuously feeds power back into the main battery.
  2. The main battery's displayed % stays at 100% for as long as the RE has charge left.
  3. Only AFTER the RE is fully empty does the main battery's displayed % start dropping below 100%.

So if you finish a ride with main showing 65% and the RE attached: the RE was fully drained (250 Wh used) AND the main lost 35% (140 Wh). Total energy consumed = 390 Wh, even though the main display only dropped by 35 points.

Maxon's recommendation: "Switch on the Range Extender at the beginning of your tour to achieve the maximum range."

Two chargers — standard 2A vs fast 6A

Every Paratu CP frame kit ships with the Standard 2A charger (199 g). For big-day riders we offer the optional Fast 6A charger (699 g).

Task Standard 2A Fast 6A
Main 400 Wh empty → 80% 2 h 30 min ~50 min
Main 400 Wh empty → 100% 3 h 30 min ~1 h 10 min
RE 250 Wh empty → 80% 2 h 30 min ~30 min
RE 250 Wh empty → 100% 3 h 30 min ~50 min
After-ride: BOTH to 100% (sequential) ~7 hours ~2 hours

→ The Fast Charger isn't just lunch-break convenience — it determines whether you can recover for the next day after a big ride.

Buy: Standard 2A charger · Fast 6A charger

Lunch-break charging — the 4,000 m unlocker

This is the sales argument for the Fast Charger.

A 4,000 m climb day on natural Maxon settings needs roughly 830 Wh. A fully-charged 400 Wh main + 250 Wh RE gives you 650 Wh — that's 180 Wh short. No amount of pedalling smarter closes that gap.

With the Fast Charger and a 60-minute lunch stop:

  • Plug the 6A into the bike's charging socket during lunch
  • By the end of lunch the main battery has refilled by ~320 Wh
  • Total available energy on the ride: ~970 Wh
  • 4,000 m day verdict: finishes with ~14% reserve

On the standard 2A, that same 60-minute lunch only adds ~128 Wh — not enough to close the gap. This is why the Fast Charger exists.

Try the math on your own ride profile: Range Calculator.

Charging the main battery (step by step)

Source: Maxon BIKEDRIVE AIR Operating Manual, §4.2 (page 24).

  1. Select a cool location. Permissible charging temperature: 0 – 40 °C. Below 0 °C, charging is blocked for cell safety — bring the bike indoors first.
  2. Connect the charger to a 220–240 V power socket (110 V variant available for US/CA markets).
  3. Connect the charger to the charging socket on the bike and secure it with the bayonet lock.
  4. The charging process starts automatically. POWERTAB LEDs show progress: red = charging, green = full.
  5. Once 100% is reached, the charger and bike automatically switch off.
  6. Open the bayonet lock and unplug the charger from the bike.
  7. Disconnect the charger from the power outlet.
  8. Close the charging socket cover to keep dirt and water out.

Charging the Range Extender (step by step)

Source: Maxon BIKEDRIVE AIR Operating Manual, §4.8 (page 35).

  1. Switch off the bike (long press on the POWERTAB).
  2. Open the bayonet locks on both ends of the RE connection cable.
  3. Unplug the connection cable between the Range Extender and the bike.
  4. Close the socket on the bike to keep dirt out.
  5. (Optional) Remove the RE from its bottle-cage bracket for desktop charging.
  6. Plug the charger directly into the RE's charging socket and lock the bayonet.
  7. The RE's amber LED indicates charging in progress.
  8. When the amber LED turns off and the white charge-level bars show 5/5, the RE is at 100%.
  9. Disconnect the charger and reattach the RE to the bike for the next ride.

The multi-RE strategy (for 4,000 m+ days)

Maxon's manual (§4.7.2) supports it explicitly: "It is also possible to carry several Range Extenders and exchange an empty Range Extender with a full one. This extends the range many times over."

For ultra-long days, the alternatives to lunch-break charging:

  • Carry a second fully-charged RE in your pack. Swap it on when the first empties. No charging stop needed. Adds ~1.6 kg in the pack but adds another 250 Wh.
  • Pre-position a second charger at your lunch stop. Charge main and RE in parallel — fastest recovery.
  • Combine: Fast 6A charger + carry a spare RE. Roughly 1,150 Wh of effective capacity for a 1-day ride.

Safety + common mistakes (from Maxon)

  • Only use the original Maxon charger. Third-party chargers can cause cell damage, fire, or void warranty.
  • Don't charge a wet or damaged charger. Inspect the cable and plugs before each use.
  • Cold weather: if the battery is below 0 °C, charging is blocked. Bring the bike inside and wait ~1 hour before plugging in.
  • Don't leave the battery on charge for extended periods unused. Once full, disconnect.
  • Storage: if storing the RE for more than 1 month, charge it to >50% SOC and recharge every 6 months. Keep at ~20 °C in a dry place.
  • Don't disassemble or modify the charger. If it's damaged, take it to an authorized Maxon / DIRTLAB service partner.

FAQ

Can I charge the main and RE at the same time from one charger?

No. The charger plugs into one port at a time — either the bike's charging socket (charges main) or directly into the RE (after detaching it from the bike). To charge in parallel you need two chargers.

Does the RE charge the main while plugged in but not riding?

Yes — as soon as the RE is connected to the bike and the system is switched on, the RE feeds the main battery at a predefined current. This is true whether you're riding or stationary.

Why does my main battery still show 100% after a long ride with RE attached?

Because the RE was still feeding the main. The HMI shows the main battery's state of charge — once the RE empties, the main will start dropping. Look at the RE's own LED bars to see the RE charge level.

How much faster is the 6A Fast Charger really?

Roughly 3× the speed of the Standard 2A. Where the standard takes 7 hours to refill both batteries to 100% (sequential), the fast charger does it in ~2 hours. Lunch-break charging adds ~320 Wh on the 6A vs ~128 Wh on the 2A in the same 60 minutes.

Is the Fast Charger compatible with both AIR (Paratu HL) and AIR S (Paratu CP)?

Yes. Same charging socket family across both Maxon systems.

What happens if I forget to charge the RE and only the main is at 100%?

The RE will charge from empty during the start of your ride (because the bike's charging port supports both directions). But that's slow and you'll only get the energy that the main battery feeds back to it — about 25% of the RE's capacity in the first hour of riding. Better to charge the RE fully before leaving.