Cold weather LiPo Performance

[o00scorpion00o]

Hi Everyone,

Now that the weather has got much colder the last few days I've noticed a big drop in performance like last winter, no major problem as I really only get to ride at the weekends.

I've my LVC set to around 54-55 volts, so that might be a little low for 16S LiPo but its dying anyway so I don't care. But where I was able to get 5.8kw on acceleration now it's down to just about 3kw so that's a huge drop and really noticable.

As for sag due to cold, well that's hard to say because it's sagging badly anyway and it hit's lvc @ 54 volts from about 66.6 charged or even after using it a bit where it might really be 59 volts, but the overall amount of power has dropped due to cold.

Next year I'll have to replace it so I'm wondering what battery is capable of surviving the cold ? is the nanotech better able for winter use ?

Seemingly Renault's battery for the Zoe is not effected by the colt at all, performance wise, anyone know what they use ?

Is LiFeP04 effected much by cold ?

I'm looking at Zippy Compacts for my next battery, (I still want my fun when I can get out in winter), or maybe a cell-man triangle A123 battery ? But that probably won't do because I need more than 48 volts and LiFeP04 is bigger and heavier, Jesus I thought we would have had something much better than LiPo or LiFe when I bought my LiPo, the technology is sure slow to develop and even slower for us to get our hands on it.

Though LiPo is good power wise it hardly seems economical in the long term and am rethinking how I spend my next pile of hard earned, I'm also thinking if I will abandon Hub motors altogether and maybe the next set up will be far less demanding power wise.

 

[amberwolf]

Seemingly Renault's battery for the Zoe is not effected by the colt at all, performance wise, anyone know what they use ?

Probably has good insulation around it and/or a heater.

Is LiFeP04 effected much by cold ?

Yes, in general all batteries tend to be, but each specific manufacturing process makes each maker's cell a little different from the next, so you can't always draw a generalization that applies to all of them equally. You'd have to look at the datasheet or someone else's direct testing of the specific ones you're after.

 

[o00scorpion00o]

Seemingly Renault's battery for the Zoe is not effected by the colt at all, performance wise, anyone know what they use ?

Probably has good insulation around it and/or a heater.

Is LiFeP04 effected much by cold ?

Yes, in general all batteries tend to be, but each specific manufacturing process makes each maker's cell a little different from the next, so you can't always draw a generalization that applies to all of them equally. You'd have to look at the datasheet or someone else's direct testing of the specific ones you're after.

Afaik Renault don't use a batter heater.

Now that I think of it I remember I used to keep my old ping in the house, so that's probably why I didn't notice the difference. I wouldn't keep the LIPo in the house.

I long for the day we have much better batteries.

 

[Alastor]

Lol why not keep lipos inside your home ? take a nice ammunition box and save yourself the trouble replacing the bricks every year.

Now that i say it i should get one to

 

[o00scorpion00o]

Lol why not keep lipos inside your home ? take a nice ammunition box and save yourself the trouble replacing the bricks every year.

Now that i say it i should get one to

na, I wouldn't take the risk, I don't really have the room to make LiPo shelter , the good old ping I just kept in the press under the stairs.

 

[dogman dan]

Seriously, in a metal box, you should be able to store lipo's that are not known to be risky inside. It's new untested lipo, and ones you know were abused, or have puffed that you need to keep outside.

One option would be to gently heat the lipo before you ride. Use a hot pad, snake warmer, or even a hot water bottle. Then, if you are drawing enough amps the batteries may heat themselves just enough to do better in an insulated box.

One thing I don't see mentioned much, but has to be happening. The wiring on the bike is going to let less power through when it's super cold. Ever notice headlights are dim when it's super cold, and wipers run slow?

I think once it's below freezing, you start getting some effect from that on the ebike too.

 

[Alastor]

Lol why not keep lipos inside your home ? take a nice ammunition box and save yourself the trouble replacing the bricks every year.

Now that i say it i should get one to

na, I wouldn't take the risk, I don't really have the room to make LiPo shelter , the good old ping I just kept in the press under the stairs.

Hahahaha lol lipo shelter well the ammunition box is quite safe to store em in your home think of it as a lipo shelter even if they catch fire they will burn the oxygen inside the box and the fire will die shortly.

Heat shrinking tubes can also be a nice insulation for your battery and wiring hobbyking sells large tubes for the hole battery pack.I picked up some meters and they are quite excellent insulation material.

 

[Trackman417]

The ammo cans are air tight? That's a nice feature 8)
I need to get one of those. How much damage could be done to cells that have been stored outside during the winter? I see a max of -10 degrees F at the coldest. Dont people put their cells in the freezer for storage?

 

[amberwolf]

One thing I don't see mentioned much, but has to be happening. The wiring on the bike is going to let less power through when it's super cold. Ever notice headlights are dim when it's super cold, and wipers run slow?

Actually, the wiring should be *more* conductive the colder it is, although it is possible that connectors make poorer connections for mechanical reasons. Most likely the dimness is caused by the FLA in the car having it's chemistry severely affected by the cold, possibly putting more of a load on the alternator. (the latter part I'm not certain of, but the chemistry is definitely adversely affected by teh cold)

 

[iamsofunny]

I rode my ping pack all last winter and it had no noticeable drop in power or range

 

[DAND214]

I rode my ping pack all last winter and it had no noticeable drop in power or range

I rode LiPo's too, I didn't notice much differance in power or range. but than again I think I was too cold and numb to tell the losses. And the snow and ice was a little more to worry about than doing 40mph into a 20mph headwind and wondering why it's slow. cells were fine this summer and hope to be good enough for this winter again.

i lost track of milage since my CA said 250,000 miles It's very impressive to show to someone that doesn't know what an ebike really is. Guess I'll have to rest th od and start over on new Years.

i try to average 15 to 25 miles a day during the week and less on the week ends. Weekends are for rest after a hard week of riding, and the wife takes up most of my time on the weekends.

I' thinking putting a heating pad around the pack, Will have to see what watts it pulls at 62v. Have to see very soon, only a month or so away.

Dan

 

[sirlenka]

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[dogman dan]

Maybe the effect I was thinking was the wire itself was connectors shrinking , or just the battery sucking up all the alternator could make.

On my ski bug, in a bad enough blizzard, the wipers would come to a complete stop. But I would of course, be running the heater fan full blast as well.

Re lipo storage. You do want to have some vent in a storage box. I drilled some holes in my ammo cans. An airtight seal would not be desirable in an event. Once inside, the vents in the box are pointed toward a more fire resistant surface, like a tiled wall, sheet of thin steel, anything but your drapes.

The theory is that expanding gasses can cool to below ingition temps before they exit the box.

 

[Alastor]

Maybe the effect I was thinking was the wire itself was connectors shrinking , or just the battery sucking up all the alternator could make.

On my ski bug, in a bad enough blizzard, the wipers would come to a complete stop. But I would of course, be running the heater fan full blast as well.

Re lipo storage. You do want to have some vent in a storage box. I drilled some holes in my ammo cans. An airtight seal would not be desirable in an event. Once inside, the vents in the box are pointed toward a more fire resistant surface, like a tiled wall, sheet of thin steel, anything but your drapes.

The theory is that expanding gasses can cool to below ingition temps before they exit the box.

When i suggested the ammo box i only did it so you can store your pack in house and not leave it on out on the cold.
Everything else is better described by dogman with more details.

 

[Ypedal]

My lipo's are boxed in ABS, i take the bike in the house when i get home , charge in the evening, when i set off in the morning the pack is 20 celcius, sits outside all day ( +3 celcius and rain right now ) .. when i leave work for home the voltage drops a bit but a few kms in they get hot and the ABS keeps the heat in nicely so my ride home works fine.

carefull charging lipos in the cold, i recall liveforphysics say something along the line that voltage will rise when cell temps go up, so charging in sub zero fo 4.2v per cell can be dangerous if the pack warms up without being discharged first.