Winter battery method

[Atavar]

This is my first winter with an e-bike. Magicycle 52v. I have two spare batteries.
What I have been doing in <32° weather is I brought my two extra batteries and my charger in to a metal cabinet in the house. I keep the two house batteries charged 50% to 80% and top one off to 100% just before a ride. When I go to ride I swap out the battery in the bike for the freshly charged one, and after the ride bring the least charged battery in to the house to warm then charge. If the battery in the bike is low charge I bring both in for a storage charge. If the battery in the bike is 50% or more I leave it in the bike.
Is this the best plan or what should I do differently?

 

[Annieolnie]

You are in Minnesota. Is your bike in a semi-heated area?

 

[Atavar]

It is in an unheated garage that stays at least a dozen degrees or so above ambient.

 

[Annieolnie]

Maybe my perception is off, but you are in Minnesota. I just started looking at this issue and the general concensus is lithium batteries are not happy below 32 degrees. The electrolytes can start to separate, which can do long lasting damage, so it is best not to let them freeze. I'm beginning to think I may throw one of those little chemical hand warmers into my neoprene battery cover for going out in hideous weather. I found this interesting lithium site, see what you think:

 

[hugh]

Sounds to me like you are doing everything right. Here in Winnipeg which is roughly 80 miles north of Grand Forks N.D. we have similar weather to you. Maybe a bit colder at times. My personal cut off is minus 20 celcius and I made a cover for the rack mounted battery and do slip a chemical hand warmer under it in the colder temps. Never had a problem and my fat bike gets transported upright in the back of my truck for what is usually a 20 minute ride to reach the trails.

 

[Atavar]

I love Winnipeg! Such a wonderfully diverse city with a rich music culture. So many great foodie choices.
Is the Windsor Hotel still hosting world class Blues?

 

[Smaug]

Ideally, bring in the battery on the bike, too. When you start a ride, it'll be more powerful as its voltage won't have dropped from being out in the cold. Then, as you use power, the current draw will keep the battery from getting quite as cold as if you had started with a cold battery.

Just rotate them out, so they're all getting used. I don't have a spare battery for any of my eBikes, as the main one I ride has quite a good range and I haven't yet needed that full range on one charge. I like to cycle the charge from 80 to 20% and back. They don't like sitting without activity for months at a time; it sounds like you've got a handle on that.

On the other hand, in the cold, your charges will not last you as long as in the warmer months, so you may actually find yourself using the full charge more frequently.

Sounds like you went a bit overboard on batteries, hehehe. Have you ever yet taken a ride where you needed all three?

 

[Atavar]

No, it was just that when I bought the bike with its 20ah battery they had 15ah batteries on clearance for $200 (vs $600 for 20ah).
I know the smaller batteries are not ideal but actually even the 15ah has been enough for my usual rides. On my occasional long ride the 20ah plus a 15ah has been plenty, and leaves me with a fresh 15ah ready when I get home.
My next purchase will be studded winter tires. I hate falling on ice.

 

[Atavar]

I found out my batteries fit in the drawer of a metal filing cabinet. It’s not the best battery storage but it’s better than stacked on a shelf in the furnace room.

 

[HumanPerson]

I found out my batteries fit in the drawer of a metal filing cabinet. It’s not the best battery storage but it’s better than stacked on a shelf in the furnace room. View attachment 16946

Ceramic matting: https://www.amazon.com/s?k=furnace+...6b53&tag=txtstdbgdt-20&ref=pd_sl_2krjqqy85m_p

 

[Atavar]

Ceramic matting: https://www.amazon.com/s?k=furnace+...6b53&tag=txtstdbgdt-20&ref=pd_sl_2krjqqy85m_p

Thanks!

 

[m@Robertson]

Everything I have heard about li-nmc batteries is you can USE them below freezing, and they will give you less range. But you must charge them after they have warmed up.; Charging at or below freezing causes permanent damage immediately. So I would add some fudge to that and only charge in a room you'd be comfortable sitting in. Or one that is heated to that level.

 

[Atavar]

Everything I have heard about li-nmc batteries is you can USE them below freezing, and they will give you less range. But you must charge them after they have warmed up.; Charging at or below freezing causes permanent damage immediately. So I would add some fudge to that and only charge in a room you'd be comfortable sitting in. Or one that is heated to that level.

That is my understanding also. My cabinet is in
my media room so I can monitor it, however I understand extinguishers are not effective so I don’t know what the point is.
I’m not going to pick up a flaming battery in thermal runaway and carry it outside. Lol

 

[m@Robertson]

I’m not going to pick up a flaming battery in thermal runaway and carry it outside. Lol

for sure. I try and throw in as many fail safes as possible. My bike is charging right now... at 0.5a. And its on a mechanical cutoff timer that will stop at 6 hours. I doubt I'll reach 80% before the power is cut. But the charger is set to 80% voltage so there's another layer to the onion.

 

[Annieolnie]

That is my understanding also. My cabinet is in
my media room so I can monitor it, however I understand extinguishers are not effective so I don’t know what the point is.
I’m not going to pick up a flaming battery in thermal runaway and carry it outside. Lol

You could pick up one of those flame retardant battery bags. I have one but I don't know how well it works. My hope is that if anything happens it goes through a whole lot of smoldering, so that I have time to react.

 

[HumanPerson]

Layer that stuff i posted up there 3 or 4 times and that should be enough but who really knows with these things.

I've seen that stuff wrapped inside and outside of some crazy metal melting furnaces though.

 

[Atavar]

You could pick up one of those flame retardant battery bags. I have one but I don't know how well it works. My hope is that if anything happens it goes through a whole lot of smoldering, so that I have time to react.

I’ve seen YouTube reviews on the bags that show them to be basically worthless. Just consider that most of them are Velcro closure. That’s not even going to slow anything down.
The main benefit of the bags is they are a padded carrier for transporting.

 

[Smaug]

Everything I have heard about li-nmc batteries is you can USE them below freezing, and they will give you less range. But you must charge them after they have warmed up.; Charging at or below freezing causes permanent damage immediately. So I would add some fudge to that and only charge in a room you'd be comfortable sitting in. Or one that is heated to that level.

That's a LOT of fudge, especially considering that charging creates heat, and heat is the main thing that cuts battery life short. Battery manufacturers specify charging above freezing, that's it. No need to be 30+ degrees above freezing. Room temp is fine, but I just mention this because on a 30° winter day, if our garage is 45°, that's perfectly fine for charging or storage. No fudge needed in this case. What MIGHT be needed is for him to bring it in after a ride on a cold day before charging!

We can overthink it here. This is a realistic approach. There is the ideal range, then there is the operating range:

Source: https://www.fortresspower.com/ideal-operating-temperatures-for-lithium-batteries/

Note that storage below freezing is perfectly fine, and so is discharging below freezing. Depending on where one stores one's bike, it might make more sense to bring the batteries inside on a HOT day than a cold one!

For example, m@ on the CA coast may want to bring them inside on a summer heat wave, but would be perfectly fine leaving them in his garage all winter.

Our OP here in MN will likely not have to worry at all in the summer, but in a cold winter, he will likely want to bring them in.

 

[m@Robertson]

That's a LOT of fudge, especially considering that charging creates heat, and heat is the main thing that cuts battery life short. Battery manufacturers specify charging above freezing, that's it. No need to be 30+ degrees above freezing. Room temp is fine, but I just mention this because on a 30° winter day, if our garage is 45°, that's perfectly fine for charging or storage. No fudge needed in this case. What MIGHT be needed is for him to bring it in after a ride on a cold day before charging!

Well, I am talking to someone who is wintering in Minnesota where there is likely not going to be a whole lot of middle ground, and even if not, room temperature is not going to cause any problems. Plus it is regulated temp. I would not want to forget I left a charger running and it keeps running late after the temp goes down.

Note that storage below freezing is perfectly fine, and so is discharging below freezing.

Yes the only thing that happens is reduced range. Same thing happens with electric cars.

Depending on where one stores one's bike, it might make more sense to bring the batteries inside on a HOT day than a cold one!

I lived in the CA Central Valley for many years, where temps regularly climb over 100 degrees, sometimes for weeks at a time, For the entire summer, the bikes live indoors for parking and charging. Right inside the front door, in the entryway for the house. Same as I recommended above actually . Kept a ramp out of sight to use walk assist to roll up the steps, too.

In my office garage, which was not air conditioned (it was just storage space I set up with charger etc.), I set up two jobsite fans that blew on the bike on low power all day. Kept temps reasonable and had the secondary benefit of drying the sweat off me while I was changing out of my riding gear. For winter in both home and office garage I also kept heaters to deal with the below-freezing weather that happened there, since I had to charge during the day.

For example, m@ on the CA coast may want to bring them inside on a summer heat wave, but would be perfectly fine leaving them in his garage all winter.

My garage right now gets to 85, and over the summer gets to 90+. Metal garage doors + sunlight so even if its 65 according to NOAA, I open up the door for the bikes I keep in the garage. And over the winter it can drop below freezing, although it has been a few years since that happened. I've got a forced-air heater to get me up over the freezing line.

Something else about riding in the heat: Parking on cement or just in the summer sun is something to take into account. A surface thermometer (I duct tape an aquarium thermometer onto the pack) can give a lot of insight.

 

[Annieolnie]

I’ve seen YouTube reviews on the bags that show them to be basically worthless. Just consider that most of them are Velcro closure. That’s not even going to slow anything down.
The main benefit of the bags is they are a padded carrier for transporting.

You could also try carbon fiber felt that they use for welding blankets. It works well for covering sensitive things on the car when you need to use a torch to melt a bolt. I've thought about wrapping the battery in that, although Grin Technologies tests basically found that if you are using name brand cells it is pretty safe. They couldn't force them to catch fire. It's the Chinese generic ones that went poof.