E-Bike Battery Care: Charging, Winter Storage and Cold Weather

Looking after an e-bike battery is mostly about what happens off the bike: how you charge it, where it lives between rides, and what it goes through in a cold, damp winter. Bosch and DJI, who make the Avinox system, publish advice that lines up closely. Here it is side by side, with what I'd add from riding an e-MTB through Forest of Dean winters since 2018.

The short version: charge it indoors at room temperature, store it off the bike at part charge somewhere dry and not freezing, bring it in when it's cold, and stop using it the moment it's swollen, damaged or showing an error.

How should you charge an e-bike battery?

Both makers give the same temperature window. Bosch says the air should be between 0 °C and 40 °C when you charge, ideally at room temperature, and Tern's Bosch battery guide puts room temperature at roughly 20 °C, with the battery on a flat surface in a dry, clutter-free spot. DJI gives 0 °C to 40 °C for Avinox batteries too. In practice that means charging in the house, not in a freezing shed or a cold van.

How long it takes depends on the battery and the charger. DJI's figures for its 508 W charger are 1 hour 42 minutes from empty to 80% on the FS600 battery and 1 hour 45 minutes on the FS800, and a full charge takes about 2 hours 23 to 2 hours 28 minutes.

That matters on a downhill day. At the Cycle Centre, my idea of a perfect day is about a dozen runs, then back to the start, have lunch, charge up and do it all again. My downhill and uplift guide has the detail.

Avinox has one more setting worth knowing. In the Avinox Ride app you can set a charge limit of 100%, 95%, 80% or 70%. None of the advice quoted here puts a number on what a lower limit does for battery life. What both makers do say is that a stored battery should sit at part charge rather than full, and DJI's manual gives about 30% to prevent ageing. So if the bike's going to stand for a few days and you don't need the whole battery, a lower limit at least stops it sitting at 100%. My Avinox settings guide goes through the modes and the rest.

How should you store an e-bike battery?

Between rides, keep it dry, out of the sun and away from frost. For anything longer, like a winter lay-up or a few weeks off the bike, both makers want the battery out of the bike and at part charge.

	Bosch	DJI Avinox
Charge to store at	About 30 to 60% (2 to 3 bars on the indicator)	About 30%
Where	Dry, at room temperature; ideally 10 °C to 20 °C over winter	Cool and dry, out of direct sunlight and out of reach of children
Temperature limits	Not below 0 °C or above 40 °C	0 °C to 40 °C
Long-term	Take the battery and display off the bike	Take the battery out of the frame

Two details stand out. First, Bosch's own advice narrows the temperature to between 0 °C and 20 °C when the air is dry, and 10 °C to 20 °C when it's humid enough for dew to form. That second one sounds a lot like a Forest of Dean shed in November, so the house is the better bet. Second, both makers say part charge: not full, and not flat. The Avinox user manual says about 30% guards against both ageing and over-discharge.

E-bike batteries in cold weather

Bosch puts it plainly: cold weather reduces battery performance. That's one reason the same loop takes more battery in January. Bosch also lists what range depends on (support level, how you ride, air resistance, rider weight, tyre pressure and terrain), and on its smart system that spreads from under 50 km to about 170 km on a charge. A winter ride in a high mode on heavy ground sits at the thirsty end.

Below 0 °C, Bosch's advice is to bring the battery into a heated room and let it warm to room temperature before you ride. If the bike has to live outside or in a shed, take the battery indoors to charge through the winter. DJI gives the Avinox system a normal operating range of -10 °C to 40 °C, with the same 0 °C to 40 °C for charging, so a battery that's just come in from a frosty ride wants to warm up before it goes on the charger.

How to lay an e-bike up for winter

If the bike's going away for a few months:

1. Clean it first, with the battery off and the covers closed. My guide to cleaning an e-bike covers the safe way.
2. Take the battery out. On a Bosch bike, take the display off too.
3. Get it to part charge: 30 to 60% (2 to 3 bars) for Bosch, about 30% for Avinox.
4. Store it indoors: dry, out of direct sunlight and out of reach of children. Bosch's ideal is 10 °C to 20 °C.
5. Keep the connectors clean and dry. DJI says never put grease or adhesive on them.
6. Before the first ride back, charge it at room temperature and check for a firmware update. On Avinox, updates come through the Avinox Ride app.

How long does an e-bike battery last?

DJI gives one figure: an Avinox battery keeps up to 80% of its original capacity after 500 charge cycles, measured in the lab at 25 °C (Avinox FAQ). Real riding in a cold, wet winter isn't a lab, so treat it as a best case. Bosch doesn't give a lifespan in the advice quoted here. The useful measure is battery health: how much of its original capacity is left.

The Plus1 Garage uses these as its starting points:

• Check battery health every 12 months. Ask your dealer about it at the yearly drive system service.
• 80% or less: getting tired.
• 70% or less: worn out.
• Replacement: 96 months (eight years) as a starting estimate, or sooner at 70% health, or when the range has clearly dropped.

They're best guesses for a tracker, not a promise from any maker, and you can change them. The everyday signal is range. If the loop you always ride starts needing a higher mode or a bigger bite of battery, and it isn't just the cold, get the health checked.

E-bike battery safety: when to stop

• Swollen, damaged or showing an error: stop. Don't ride with it and don't charge it. Ask your dealer what to do next.
• Never open a battery, and never modify the drive system. DJI says any modification voids the warranty and may break the law, and only official Avinox parts work with it.
• No third-party range extenders. DJI says they aren't compatible, that using one voids the warranty, and that it could be a fire hazard.
• Keep water out. Tern's Bosch guide says never submerge a battery or clean it with a direct jet of water or a high-pressure hose. Wipe it with a damp cloth or sponge, and keep water and cleaning products out of the port. Avinox batteries are rated IP56, and DJI still says no high-pressure water.
• Charge somewhere sensible: indoors, on a flat, dry surface, with nothing piled round it.

Remembering the bits you'll forget

Most battery care is habit: charge indoors, store at part charge, bring it in when it's cold. The bits people forget are the yearly health check and the firmware. The free Plus1 Garage reminds you on the day the battery health check (every 12 months) or a firmware check (every six months) is due, and keeps battery contacts on its routine checklist. Add your bike, type in the miles off the display now and then, and it keeps an eye on the chain, pads, tyres and fork too.

For the Avinox side in more depth, see how to maintain DJI Avinox, and for the whole bike on one page, the e-MTB maintenance schedule. Next: how to clean an e-bike.