Can heating up battery give longer distance?

scootergrisen

scootergrisen

100 W
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Feb 26, 2018
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154
It seems the lower the temperature is in a lithium battery the lower the capacity will be. The shorter distance the scooter can go.
So if this is the case i was wondering can you use some of the battery charge to heat up the battery so its capacity increases and get more distance?

Suppose you charge the battery inside in 20°C and then before you ride put a heating element around the battery which runs on the battery and keeps the battery at 20°C during your ride.

Or would that always use more battery charge on the heating then you could get in return in capacity/distance?
 
Short answer is yes.

The battery DCIR drops the warmer it is, but also bear in mind anything over about 35'C is doing irreversible damage to the cells. You will get more range on warm days, but the overall calendar life of the cells will drop.
 
So if its better for the battery and the capacity/distance and everything about it is good then why are we not doing this?
Have anyone seen it used on scooters?

Lets say you have a battery case with two layers, that must give good insulation and heating element inside the battery, perhaps between the layer.
And then some control that is able to heat the battery in a good way and turn off when good tempeature is reached and turn on again when drop below some temperature so the battery is kept at optimal temperature.
I guess it could be combined with a fan/vent for getting out heat when used in hot weather. Maybe the fan could also be used when cold to circulate the hot/cold air around the cells so the battery heats up evenly and not hot spots.

Irreversible damage over 35'C. That dont sound right.
I just tried 35°C water on my hand and that don't feel warm.

Battery says:
Charge environment: 0°C~45°C
Discharge environment: -20°C~60°C

Hmm it says "environment".
It dont actually say the battery/cells have to be that temperature.
 
scootergrisen said:
So if its better for the battery and the capacity/distance and everything about it is good then why are we not doing this?
Click to expand...

Cause some of us live in a furnace...

slomocoalfurnace.jpeg



35'C is just where damage can start - of course it's not that bad at 35'C, but detectable after say, a couple of years. At 45'C its twice as bad, and at 55'C it's three times as bad.
 
jonescg said:
Short answer is yes.

The battery DCIR drops the warmer it is, but also bear in mind anything over about 35'C is doing irreversible damage to the cells. You will get more range on warm days, but the overall calendar life of the cells will drop.
Click to expand...

Theres not a Tesla on earth that goes into Ludicrous+ mode until the battery reaches 50C.
 
I'm surprised it's that high!
Then again, Tesla has spent a lot of time and money developing chemistry which is OK with heat, but that doesn't change the Arrhenius law.
 
I have an external 52V battery I carry in the bag on my seatpost bike rack that connects to my controller through an external harness I rigged up. Last week, when the temp was -15C, I placed a liquid fuel handwarmer in the bag beside the battery when I went for a ride. I did not notice any sudden power sags when the controller was shut off at those cold temps, and then powered on again after 20 minutes. I think I will continue to use this system for cold days.

In a similar vein, none of my vehicles have block heaters anymore. Instead they all have battery maintainers that stay plugged in when the temps are below -5. Even at -30C I have not had any issues starting the vehicles in the morning using this system, and the power bill is much friendlier to the pocket.
 
jonescg said:
I'm surprised it's that high!
Then again, Tesla has spent a lot of time and money developing chemistry which is OK with heat, but that doesn't change the Arrhenius law.
Click to expand...

Yes and do you think they would do this if it caused early demise of battery packs and massive loss in revenue, due to warranty claim?

I contest there is nothing particularly special about 18650 high drain battery chemistry provided to Tesla, by Panasonic. Nearly all changes to the original cell have been due with cost, weight and Lithium content reduction. Many cells are so similar in fact, that modules can be filled with similar spec Sony, Samsung or LG cell with zero perceivable difference to the end user and without any negative effects on the longevity of the pack, as a whole.

Nearly all 500,000 Tesla battery packs( currently in road going vehicles), spend most of their life in a perpetual cycle of heating. If it's below 58F the pack is heating (even while the car is not in use). If you set the navigation to go to any supercharger location the pack is heating. If you engage a performance driving mode (Insane+/ Ludicrous+) the pack is heating to 50C .

If you sniff the CAN bus on a Tesla, you will see that nearly all performance related "throttle backs" caused by hot lapping, are almost always to do with stator temps, instead of battery module temps, preferring a warm battery for lower I/R and a cool stator is the goal.

Performance Ebike builders are implicitly aware of these via the use Hubsinks, stator-aids and reduced power limits based on motor temps, while not even giving the battery the benefit of fresh air cooling, let alone liquid cooling.
 
st35326 said:
jonescg said:
I'm surprised it's that high!
Then again, Tesla has spent a lot of time and money developing chemistry which is OK with heat, but that doesn't change the Arrhenius law.
Click to expand...

Yes and do you think they would do this if it caused early demise of battery packs and massive loss in revenue, due to warranty claim?

I contest there is nothing particularly special about 18650 high drain battery chemistry provided to Tesla, by Panasonic. Nearly all changes to the original cell have been to do with overall cost and Lithium content reduction. Many cells are so similar in fact, that modules can be filled with similar spec Sony, Samsung or LG cell with zero perceivable difference to the end user and without any negative effects on the longevity of the pack, as a whole.

Nearly all 500,000 Tesla battery packs( currently in road going vehicles), spend most of their life in a perpetual cycle of heating. If it's below 58F the pack is heating (even while the car is not in use). If you set the navigation to go to any supercharger location the pack is heating. If you engage a performance driving mode (Insane+/ Ludicrous+) the pack is heating to 50C .

If you sniff the CAN bus on a Tesla, you will see that nearly all performance related "throttle backs" caused by hot lapping, are almost always to do with stator temps, instead of battery module temps, preferring a warm battery for lower I/R and a cool stator is the goal.

Performance Ebike builders are implicitly aware of these via the use Hubsinks, stator-aids and reduced power limits based on motor temps, while not even giving the battery the benefit of fresh air cooling, let alone liquid cooling or even monitoring.
Click to expand...
 
st35326 said:
jonescg said:
I'm surprised it's that high!
Then again, Tesla has spent a lot of time and money developing chemistry which is OK with heat, but that doesn't change the Arrhenius law.
Click to expand...
Yes and do you think they would do this if it caused early demise of battery packs and massive loss in revenue, due to warranty claim?
Click to expand...

I make no comment on Tesla's business decisions concerning warranty, but I will restate Arrhenius' law - that for every 10'C increase in temperature the reaction rate will double. Now that rate may not be all that fast because of the chemistry selected and cell properties chosen, but it's a well known reality that chemistry happens faster at higher temps.

https://www.nature.com/articles/srep12967
https://ieeexplore.ieee.org/document/5736181
And many others.
 
Holding an 18650 cell at 50*C significantly reduces it's calander life - check the datasheets. Tesla warns that frequent supercharger use will prematutely wear the battery. The compromise is that only occasional use at high temp. and/or c-rates doesn't horrendously shorten battery life.

In terms of one-time maximum performance with no regard for battery damage then the hotter the better - probably just under the temperature of significant electrolye decomposition.
 
I have another idea.
How about using the battery to charge it self.
So that the cells get heated.
So maybe the cells both gets heated during discharge and recharge.
And if the battery cells generate heat there might be no need for extra heating element since the cells acts as heating elements.
Then maybe you could have the battery in a state of "optimal temperature" all the time during use and maybe you can push a switch sometime before you ride so the battery have time to heat up in case its outside in the cold.
 
Punx0r said:
Holding an 18650 cell at 50*C significantly reduces it's calander life - check the datasheets. Tesla warns that frequent supercharger use will prematutely wear the battery. The compromise is that only occasional use at high temp. and/or c-rates doesn't horrendously shorten battery life.

In terms of one-time maximum performance with no regard for battery damage then the hotter the better - probably just under the temperature of significant electrolye decomposition.
Click to expand...

Oh the data sheet where battery manufacture lie the most, and yet they all seem to do it. Back to reality.

Here I present Tesloop:
https://qz.com/1737145/the-economics-of-driving-seven-teslas-for-2-5-million-miles/

Home of the largest collection and highest mileage Tesla fleet in the world. They operate about a dozen Tesla's that get Supercharged 2-4 times PER DAY to 100% SOC and travel exclusively in some of the warmest climates inside the United States.

So... either a guy with a law named after him is right and warms cells and supercharging are the devil, or its really not as bad as you fellas are leading on. Anybody ever heard of Aether? Was once a well accepted implement inside the physics community in regards to light, until it was disproved.

I am certain that with enough heat everything's lifespan will shorten, I just think the people commenting in this thread have their thermostats set a little too low. Lastly, the fact that me mentioning 50c cell temps surprised or astonished some people in this thread says something, especially when there are presumably thousands of these cars thing hitting 50c temperatures daily.
 
Why would a reputable company like Sony, Panasonic etc when testing their cells according to recognised standards a) lie b) do so in a manner that makes their product appear to perform worse?

Did you previously advise Nissan on their Leaf packs? :D
 
I doubt you can compare tesla batteries with e-bike batteries. While e-bike batteries have a prognosed battery life of 600 - 1000 full charge cycles, Electric vehicules batteries should sustain 4000+ full charge cycles. Replacing your car battery after 3-5 years of use would be very costly.
Tesla (and some other) Electric vehicules have a system that can transfer heat from the motor to the batteries (if they are 2 cold) They also can cool the battery using the same principe as your air conditionner, so they can go below environmental temperature when it's needed. They likely did some research about the aging of their batteries due to temperature and might even optimise their algoritms with firmware updates in the field. They also use the motor heat to warm the car cabinet as it's otherwise lost energy.
 
Re the original question, using the batteries energy to heat it is why your capacity/range is less when its very cold. No free energy in this world, etc. As that battery gets near freezing, it gets terrible saggy, using all its energy up in extra internal resistance. And its costly in watt hours for sure.

But YES, if its cold and your battery box has some insulation, then at least you get to keep the warmth you paid for, and or, your battery ever gets warm as you use it, resulting in lower internal resistance on the second half of your ride. If you live in a furnace though, you gotta let that battery cool better in summer. Especially, don't insulate a cheap bms and cook it off. Then the broken bms burns your house down.

So if your battery is touching metal that is at 0 c, its going to stay cold as you use it, and a lot of your energy will be lost. I used to commute in mildly cold weather, like below freezing, and it helped a ton to stuff some foam in my battery box to keep it warmer. It helped even more if I started out with a room temp battery. Then its starting warm heat, plus the insulation, would get me back to decent performance, similar to a cool day. But every spring when it got hot, boy would I ever notice the battery perk up.
 
As I type this, it is -17C outside, which is the norm. I do not use the integrated battery when it is much below -5C. I've addressed this challenge by making up a small 10Ah external battery pack that goes into the padded saddlebag that is on my seatpost rack. (As I have a Frey M600 with the integrated battery, I made up a 'battery eliminator' interface out of an empty battery case. It connects to my seatpost battery with a 10AWG extension cable and anderson power poles). The battery pack, which is stored inside and not left on the bike at any time, has a thin wall of insulation under the heatshrink. There is still room in the saddle bag so I put a couple of liquid fuel handwarmers into the saddlebag on each side of the battery pack. (I also put a couple of liquid fuel handwarmers into the handlebar mitts as well). My usual daily ride is 25km, it is the stop for errands where the battery sits and is not under load that I primarily want the handwarmers for. Getting ready for the ride: EG, filling 4 handwarmers with Naphtha and activating them, getting dressed, etc., seems to almost take as long as the actual ride itself.

So far this has been working, the battery reports 75% capacity at the end of the ride and seems like it is still around room temp when I remove it from the bag. Makes me think I'd have enough power to heat some heated handlebar grips if there were such a thing. However, I plan to get a bit less seat of the pants with this and tape a temperature probe onto the battery that I can monitor. If anyone is interested I will post the results back.
 
dont use handlebar heating. use heated gloves. way more efficient and comfortable. :wink:
 
Thanks for the suggestion. I've played with heated gloves for skiing for quite a few years. At the moment using bar mitts with liquid fuel handwarmers in them, work well, advantage is you can wear your summer cycling gloves at -20C.

[youtube]https://youtu.be/gDmiJ424U78?list=PLDXT34Ltvhm_lajF6yfU-ZNJE7TQVWeKm[/youtube]
 
As others have already mentioned, cooler temps reduce battery performance. I've done some tests on batteries for lights that indicated the energy used to heat the pack (if well insulated, so most the heat goes to the pack and not the environment) would be of net benefit (more energy available from the warm pack than lost to heat it from cold). Cant remember the exact numbers but form -20 to 10C was a ~30% difference in available energy, and warming it from -20 to 10C would require about half that. This was for a chemistry specifically meant for cold temperatures, so there may actually be greater benefit for the more typical 'lipo' chemistry on ebikes, and also discharged at just C20... so the capacity loss would be much higher at the C2 to 2C more typically seen in ebike use, while the same 10-15% of capacity would be required to get it above freezing... so yea... big benefits in warming a pack IMHO.

Also worth noting that while you loose some capacity at cold temps, you can also age the battery relatively quickly when charging at cold temps... personally im not surprised that tesla's heat their packs prior to fast charging... the faster the charge the more cold temperatures impact the cycle life. 50C is a little higher than I'd have thought/guessed, but anywhere between 25 and 45C wouldn't have been a surprise for me at all.

I've used pet bed warmers, and car seat warmers in my packs. Good ones come with built in over temp sensors (usually ~75C, so a bit too hot) but they're basically thin electric blankets that fit nicely between packs, so make good battery warmers. Where I live rarely goes below 5C, but for both charging and discharging warming the pack to ~15-20C makes a notable difference, and (to early to tell yet) should also extend the cycle life a bit, particularly when charging.

One final point on high temps - from what I've read 40-80C has the largest effect on calendar life when at high SOC... at mid levels the effect is far less pronounced. So if tesla keep their cells at ~4C SOC then 50C would be far less of a concern, at least compared to 4.2VDC...
 
Punx0r said:
Why would a reputable company like Sony, Panasonic etc when testing their cells according to recognised standards a) lie b) do so in a manner that makes their product appear to perform worse?

Did you previously advise Nissan on their Leaf packs? :D
Click to expand...

I LOL'd.
 
sn0wchyld said:
As others have already mentioned, cooler temps reduce battery performance. I've done some tests on batteries for lights that indicated the energy used to heat the pack (if well insulated, so most the heat goes to the pack and not the environment) would be of net benefit (more energy available from the warm pack than lost to heat it from cold). Cant remember the exact numbers but form -20 to 10C was a ~30% difference in available energy, and warming it from -20 to 10C would require about half that. This was for a chemistry specifically meant for cold temperatures, so there may actually be greater benefit for the more typical 'lipo' chemistry on ebikes, and also discharged at just C20... so the capacity loss would be much higher at the C2 to 2C more typically seen in ebike use, while the same 10-15% of capacity would be required to get it above freezing... so yea... big benefits in warming a pack IMHO.
Click to expand...

So to confirm... by looking at the lights on the battery that shows the charge of the battery you have seen that using the battery's own charge to heat the well insulated battery gives extra capacity right?

And that the extra capacity received in total is 2 times that used to heat the battery where half is used on the heating so half is left for extra range.

I would like to know if you have tried measuring the distance with unheated battery and heated battery under the same conditions.
Not sure if we can trust what those light are showing.

I dont have lights on my battery but the bars on the speedometer changes quickly depending on if you have using the throttle or not.
 
This graph from this paper says it all really.

285 Fig_3.JPG

https://www.endless-sphere.com/forums/download/file.php?id=260595
 
scootergrisen said:
sn0wchyld said:
As others have already mentioned, cooler temps reduce battery performance. I've done some tests on batteries for lights that indicated the energy used to heat the pack (if well insulated, so most the heat goes to the pack and not the environment) would be of net benefit (more energy available from the warm pack than lost to heat it from cold). Cant remember the exact numbers but form -20 to 10C was a ~30% difference in available energy, and warming it from -20 to 10C would require about half that. This was for a chemistry specifically meant for cold temperatures, so there may actually be greater benefit for the more typical 'lipo' chemistry on ebikes, and also discharged at just C20... so the capacity loss would be much higher at the C2 to 2C more typically seen in ebike use, while the same 10-15% of capacity would be required to get it above freezing... so yea... big benefits in warming a pack IMHO.
Click to expand...

So to confirm... by looking at the lights on the battery that shows the charge of the battery you have seen that using the battery's own charge to heat the well insulated battery gives extra capacity right?

And that the extra capacity received in total is 2 times that used to heat the battery where half is used on the heating so half is left for extra range.

I would like to know if you have tried measuring the distance with unheated battery and heated battery under the same conditions.
Not sure if we can trust what those light are showing.

I dont have lights on my battery but the bars on the speedometer changes quickly depending on if you have using the throttle or not.
Click to expand...

FOR lights... not looking AT lights. As in street lights... batteries in street lights. Measurement was done with a lab coulomb counter, to the uAh. Didn't measure distance because again... battery taken from a street light. no chance the little status LEDs sometimes used on batteries would be accurate enough, they're almost as likely to be affected by temperature as the battery itself... Battery in the above case was designed for a very different application (street lights), but the underlying benefits are almost certainly translatable, given the battery was actually designed for a very wide (including cold) operating window, more so than your average ebike battery.
 
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