Storing battery outside in winter - what insulation?

[WheezyRider]

Agreed, ideally never charge below freezing point, but the point I am making is that one doesn't need to fret about this too much, especially in our climate, as your comment on the Shetlands shows.

Most of us the UK rarely get any chance to charge below zero degrees, since even our sheds and garages rarely get enough below to destroy cells, especially since the charging itself generates some heat within the battery casing.

Here's our two members living and pedelecing far north of the arctic circle in Norway:

View attachment 54208

Depends on the location in the UK, plus the weather's enormous variability. Generally not that cold, but not always mild enough that you can ignore it. Plenty of people die of the cold in the UK in winter despite its "mild" climate.

I spent a winter with the e-bike in the frozen north. Having power to get through 8 inches of snow in the morning made cycling through the winter possible. At -10 to -15, you really feel the loss of capacity though. So it's best to keep the pack indoors until you need it. Then recharge in a heated garage. The problem comes if the bike has to stand all day outside and in use, it's so cold from wind chill, the pack doesn't warm up much on the way home. Often it was a case of bringing the battery indoors once home to defrost for a while before charging.

Charging a pack with a 2 A charger generates very little heat. The charging efficiency is very high, only 1% or so is wasted as heat. So for a 36 V pack, you looking at less than 2 W of heat. For a 4 or 5 kg pack, that is quite a thermal mass to have to heat with such a small input.

 

[flecc]

Depends on the location in the UK, plus the weather's enormous variability. Generally not that cold, but not always mild enough that you can ignore it. Plenty of people die of the cold in the UK in winter despite its "mild" climate.

I spent a winter with the e-bike in the frozen north. Having power to get through 8 inches of snow in the morning made cycling through the winter possible. At -10 to -15, you really feel the loss of capacity though. So it's best to keep the pack indoors until you need it. Then recharge in a heated garage. The problem comes if the bike has to stand all day outside and in use, it's so cold from wind chill, the pack doesn't warm up much on the way home. Often it was a case of bringing the battery indoors once home to defrost for a while before charging.

Charging a pack with a 2 A charger generates very little heat. The charging efficiency is very high, only 1% or so is wasted as heat. So for a 36 V pack, you looking at less than 2 W of heat. For a 4 or 5 kg pack, that is quite a thermal mass to have to heat with such a small input.

You just can't help yourself can you, any lengths to win an argument!

First in my mention of the Shetlands in the furthest north UK sharing a parallel with Norway, you try to convince me how mild it is up there.

Now you try to convince me that in a more southerly northern location that there's commonly -10 to -15 degrees and 8 inches of snow, then talk about loss of capacity. Yes of course there's loss of capacity in the cold, this discussion isn't about that. It's about cells being destroyed by cold charging below zero.

In the 17 year life of this forum there's never been a single report of that happening, yet we have members over much of the world including, as I informed, living and pedelecing far north of the arctic circle. And it doesn't happen when charging e-cars there at up to -10 or even -17 degrees either. I'd love to show you the photos member Boreios posted of him with his Wisper 905 in conditions that would make a husky team bolshi, but annoyingly in the last change of the pedelecs hosting company, up to around a third of the earlier posts from around 2010 on disappeared, including those.

So forget the theories and look at what actually happens in practice.
.

 

[WheezyRider]

You just can't help yourself can you, any lengths to win an argument!

First in my mention of the Shetlands in the furthest north UK sharing a parallel with Norway, you try to convince me how mild it is up there.

Now you try to convince me that in a more southerly northern location that there's commonly -10 to -15 degrees and 8 inches of snow, then talk about loss of capacity. Yes of course there's loss of capacity in the cold, this discussion isn't about that. It's about cells being destroyed by cold charging below zero.

In the 17 year life of this forum there's never been a single report of that happening, yet we have members over much of the world including, as I informed, living and pedelecing far north of the arctic circle. And it doesn't happen when charging e-cars there at up to -10 or even -17 degrees either. I'd love to show you the photos member Boreios posted of him with his Wisper 905 in conditions that would make a husky team bolshi, but annoyingly in the last change of the pedelecs hosting company, up to around a third of the earlier posts from around 2010 on disappeared, including those.

So forget the theories and look at what actually happens in practice.
.

??? Sorry, I seem to be confusing you and that has irritated you. I should have made it clearer, when I said I spent a winter in the frozen north with the e-bike, I didn't mean in the UK. I completely agree, extreme cold does not stop you using e-bikes, as I was reminiscing, you just have to adjust to the conditions.

My point about the UK was that it is generally mild, and as you say, cold spells in most parts often don't stay cold long enough for outdoor garages to go below freezing...but you can't completely take it for granted. However, I would have chosen eastern Scotland, rather than Sheltand as an example. It can get a bit brass monkeys there in winter:

https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/weather/learn-about/uk-past-events/regional-climates/eastern-scotland_-climate---met-office.pdf

Not interested in winning an argument, I just don't want people potentially damaging their packs or ending up with a battery fire.

The general consensus for e-bike packs is not to risk charging below 0 C. If Samsung or one of the other big manufacturers say otherwise, or there is some good scientific literature published, I'm happy to change my views