Tip: I only charge my batteries to 70% during colder weather!

[Expidia]

Now that I don't get many days here in the North East U.S. above 40 degrees anymore I've discovered it's a lot easier to only leave my batteries at 70% in order to enter long term storage.

It's 40 degrees out there today and I'll be riding for an hour or two. But I'm start out with only a 70% charge. Probably drop it back to 35% with today's ride and then recharge at 30 min intervals until back to the 70% area.

It's a lot easier to recharge to 70% than it is to have to bring a fully 100% charged battery back down to 70%. Once the weather drops below freezing I don't deal with ice or getting salt and sand on my bikes (my outdoor hoses are already put away for the winter) . . . so my bikes are in quasi drydock for the rest of the winter. But occasionally, we will have a few warm days and I will go on rides, but then only recharge back to 70% again.

When i forgot about lithium battery management the last winter season, I had to ride around looking for steep hills all the while keeping it in turbo and freezing my ass off trying to drop the bike's battery back to 70% for longer term storage. Now that I have two bikes, this would be twice the grief trying to ride a 100% battery back down to 70%

Battery manufacturers should offer an accessory that I could plug into the battery and drain it back down to 70% (anyone know of such a device). If I had a throttle, I could put a bike on my stand and let the bike run down on it's own along with running the lights, but LED's seem to forever. And who needs the added wear and tear on the motor and other moving parts as it wil run for many hours without any load!

 

[Plummet]

My standard process is to charge to 70/80% then leave it. If im going to do a full battery drain ride then i charge full. Otherwise its 80% all the time.

 

[Amber Valley Guy]

But if you charge to only 70% your BMSwon't be doing a automatic cell balance after fully charging (recommended every few charges). And checking every half hour is a bit ermm overkill. Do you treat your car battery the same? Better off, if concerned, to charge to 80% (or 4 bars of 5) if storing for a more than a few days, then a couple of hours before you ride charge again. And remember charging a battery the first 70 or 80% doesn't take long, the last 20% always takes longer regardless of the temperature.

 

[Grendel]

Get a timer plug and experiment with how long it takes you to get roughly to where you want the battery to be and have it cut off. It wouldn’t be exact but I’ll bet you could get pretty accurate with it And it would be very inexpensive. You could even get one of those Alexa-controlled plugs and verbally set how long it charges the bike. Happy riding!

 

[Amber Valley Guy]

Get a timer plug and experiment with how long it takes you to get roughly to where you want the battery to be and have it cut off. It wouldn’t be exact but I’ll bet you could get pretty accurate with it And it would be very inexpensive. You could even get one of those Alexa-controlled plugs and verbally set how long it charges the bike. Happy riding!

That's what I use, a plug in clockwork jobby...dirt cheap, set it for approx 1.5 hours per bar of 5 used (i.e. per 20%).

 

[Expidia]

I do use a wind up Intermatic timer that I installed so the AC is off after charging. When I said checking every 1/2 hour increments, I meant until I bring it back up to 70% after riding. If I left it on the timer for an hour or so after a ride, it would probably go right up to 90%.

I tried the Alexa thing first, but my batteries are in my basement and you really don't know if it actually turned them off.

I also I treat my boat's lithium trolling motor battery the same. I store it at 70% over the winter. My boat's starter motor battery is a standard lead acid one that I leave at 100% on a trickle charger over the winter. These new Lithium batteries for say a boat are amazing. When they first hit the market they were $500. 2 years later they are $100. It weighs 20 lbs compared to the standard 55 lb batteries I used to use. bringing it in and out of basement to charge and store is a joy now.

Same for my Ego Lithium leaf blower battery, I'll store it at 3/4 after we go into a deep freeze. But I hope to use this blower for light snow this winter too. I can regulate the charge with the timer. But it charges from zero to 100% in like an hour anyway.

I'll also keep the two lithium batteries in the electric gloves I just got at 3/4 charge for longer term storage during the warmer months.

 

[Expidia]

But if you charge to only 70% your BMSwon't be doing a automatic cell balance after fully charging (recommended every few charges). And checking every half hour is a bit ermm overkill. Do you treat your car battery the same? Better off, if concerned, to charge to 80% (or 4 bars of 5) if storing for a more than a few days, then a couple of hours before you ride charge again. And remember charging a battery the first 70 or 80% doesn't take long, the last 20% always takes longer regardless of the temperature.

My car batteries are not lithium and the car is never in long term storage anyway. Lead acid are supposed to be kept at 100% and always charged back up by the alternator. Lithium's are a different animal.

Ya, I'm amazed at how fast the Trek Powertubes drain when the temps drop below 40 degrees F and it's also windy out. I know I left a few rides ago at 100% and within an hour I was already down to 70%

 

[Amber Valley Guy]

This is from Shimano for their emtb batteries.

If the battery has been charged in a low temperature environment (5 °C or below), the maximum riding distance per full charge becomes shorter. This is only a temporary effect and if the battery is charged at room temperature, the maximum riding distance becomes normal again. Riding in the cold is fine and will do no lasting harm to the battery’s health but, in the unlikely case you even wanted to, you should not ride at temperatures below -10°C.

.....and if you do (ride in -10C or colder), ensure to let the battery warm up in an environment of 10-20°C before charging.

As for long term storage Shimano also says store at 70% charge and re-charge every 6 months. When ready to ride, charge fully to 100%

All info from Shimano, Bosch and other makes of batteries will probably give the same advice. HTH.

 

[Expidia]

Good cold weather battery info, thanks Alfreton.

 

[Dax]

Firmly file this under ‘life’s too short’.

 

[Expidia]

Firmly file this under ‘life’s too short’.

 

[Stihldog]

Firmly file this under ‘life’s too short’.

Dax Dax Dax. Your skepticism is understandable. My mission is to treat my lithium bike batteries with the best care possible.

I lay my bike battery in a bed of non-allergic-Canada-Goose-down-feathers along with a gentle breeze that helps control the temperature. This method has worked for years and I will continue, regardless.

 

[E Bob]

so you go out with only 70% ? Pisses me off when leaving with 98%...

 

[Expidia]

so you go out with only 70% ? Pisses me off when leaving with 98%...

My rides are shorter in winter anyway. I take the bike with the 625 watt battery most of the time, so 70% is plenty for me to start out with.

 

[yomoe]

How are you guys actually balancing the individual battery cells?

 

[Stihldog]

How are you guys actually balancing the individual battery cells?

70% charge is fine for me also during the winter. I thought the charger or internal battery computer balanced the individual cells.

I realized how important cell balancing was when I picked up my brother one morning after a fun night out.

 

[randycpu]

It is MUCH more important to keep cell groups balanced than avoiding keeping cells at full voltage.
So it is OK to charge to 60-80%, especially for storage. But every few charges need to be to 100% for the BMS to balance the parallel cell groups.

 

[Damin]

How are you guys actually balancing the individual battery cells?

With a scale, silly!

 

[Kevjob51]

after my rides I wait an hour then charge to 60% as my charger has button that stops it at 60%. If I am doing a ride next day I charge to around 100% only takes 1.5 hrs to get from 60-100 on giant reign e+2 625 wh battery