Cold weather - almost didn't make it back!

[Telkwa]

My Haibike HardNine 1.0 is only 400Wh battery. It has three boost settings. Eco, Std. and High. My wife's Liv Amiti-E also has three boost settings and a 400Wh battery. She weighs a lot less than I do so her battery goes almost twice as far.

Our usual ride is 20 miles RT on a local rails-to-trails. We go one direction in Std. boost and return on High boost. We've been going out early in the mornings. Average air temp probably mid 50's to low 60's this summer. I'd usually get back to the car with 35 - 40% battery left.

It's getting cold here in the PNW. This morning it was about 48 deg.

I almost didn't get back to the car. The display started blinking at 10%. I went back to Std. boost and shifted down a few gears. Made it to the car with 7% left.

I'm gonna make a blanket out of some Reflectix material. Wrap the battery and see if it makes any difference. I sure hope the battery's not failing! It's only been cycled about 150 times.

 

[Nova Haibike]

You can check your battery's condition.

 

[rich c]

Is the battery warm when you start out? I'd suggest you practice a little better battery management as it gets colder. I ride Eco as much as I can when I'm fresh and that also helps to build up body heat. If going down hills, I shut off the motor. There are also hypermiling techniques of hard pedaling for 10 seconds, then coasting at least 10. To be conservative, I estimate the battery with 1/2 the normal range when it gets cold. Makes sense you almost didn't make it if you usually have 35-40% normally left over. Most cold weather covers are made of neoprene.

 

[Telkwa]

Thanks a million for the tip!

I plugged the batteries in as soon as we got home. The charger indicated it was done by the time I did the following...

The first time I held the button down I didn't wait quite long enough. Tried again.

The sequence goes something like this. For the first 5 seconds or so the lights come on to indicate charge. In this case, all four lights came on. Then they went out. It seemed like forever, but at about 25 seconds the first LED started blinking. This went on for about 2 or 3 seconds. Then the LED went out. I kept my finger on the button. A few seconds later all four LEDs came on solid.

So that indicates less than 100 cycles, and 75 to 100% capacity. Yay!

I built a little blanket with some Reflectix and duct tape. I'll report back in a coupla days, weather permitting. Cold and fog is one thing, but if it's raining we probably won't go.

 

[rich c]

You might get some tips from this post. https://electricbikereview.com/forums/threads/winter-battery-cover-flir-one-measurements.3457/

 

[Telkwa]

rich c, I was writing while you were writing. The bikes stay in the garage overnite, then it's about ten minutes drive to the rails-trails trailhead. I guess we could keep the batteries in the car with us.

 

[Mr. Coffee]

@Ravi Kempaiah can weigh in on this, but I'd be mighty careful about charging a battery that is cold.

If you are going to make a cozy for your battery, I'd think that neoprene or fleece would be a better material than reflectix, since i suspect that conductive heat losses far exceed radiative heat loss from a battery most of the time. I could be wrong on that point, though. It might be clever to make pockets in the cozy where you could use hot hands hand warmers to keep the battery warm -- but you'd want to make sure that the hand warmers were never in contact with the battery.

 

[larry-new]

Get it charged a.s.a.p. Worst condition for a battery is depleted.

 

[Telkwa]

I consider the Reflectix as an experiment, using what I could find in the shop that I didn't mind cutting up. Had to try something before we went out again. Neoprene would be awesome, but I don't have a partial sheet nor a stout sewing machine.

Hadn't pondered conductive vs. radiative.

The bikes get plugged in as soon as we get home. I've got a Kill-A-Watt meter. A month ago I started plugging both bike chargers in via the KAW to see how much it took to recharge. Set the KAW to record cumulative KWh. The average was right around .51, .52 KHw. Yesterday it was .69. Interesting, though I'm not sure exactly what that means. I guess it means more electrons are wasted in the process of providing power?

Some of you guys are really into this subject. Does someone make neoprene covers? If you're rolling your own, any construction tips would be appreciated.

 

[rich c]

I consider the Reflectix as an experiment, using what I could find in the shop that I didn't mind cutting up. Had to try something before we went out again. Neoprene would be awesome, but I don't have a partial sheet nor a stout sewing machine.

Hadn't pondered conductive vs. radiative.

The bikes get plugged in as soon as we get home. I've got a Kill-A-Watt meter. A month ago I started plugging both bike chargers in via the KAW to see how much it took to recharge. Set the KAW to record cumulative KWh. The average was right around .51, .52 KHw. Yesterday it was .69. Interesting, though I'm not sure exactly what that means. I guess it means more electrons are wasted in the process of providing power?

Some of you guys are really into this subject. Does someone make neoprene covers? If you're rolling your own, any construction tips would be appreciated.

I tried to find a post where @Ravi Kempaiah made his own neoprene cover. Maybe with this bump he'll chime in. I'm not a fan of charging a pack immediately after a ride. Maybe it doesn't make any difference, but my thought process is that it just had a pretty good workout and a little cooling down wouldn't hurt. I usually wait a minimum of 2 hours if I can.

 

[Mr. Coffee]

I tried to find a post where @Ravi Kempaiah made his own neoprene cover. Maybe with this bump he'll chime in. I'm not a fan of charging a pack immediately after a ride. Maybe it doesn't make any difference, but my thought process is that it just had a pretty good workout and a little cooling down wouldn't hurt. I usually wait a minimum of 2 hours if I can.

My understanding is that charging a lithium battery that is very cold can permanently damage the battery. Best to let the battery warm up to room temperature before charging.

 

[indianajo]

I'm wrapping my battery with that closed cell white foam they wrap televisions etc with. I fold it up and tape it with shipping tape. The wires come out a hole in the bottom. Then I wrap that in an aluminum frame that screws to the bike frame and makes theft time consuming. The bike sits out a lot at stores restaurants and other public destinations, locked to a pole gas meter or live conduit. The battery wrapped up looks like nothing anybody has ever seen.

 

[Ravi Kempaiah]

Thanks a million for the tip!

I plugged the batteries in as soon as we got home. The charger indicated it was done by the time I did the following...

The first time I held the button down I didn't wait quite long enough. Tried again.

The sequence goes something like this. For the first 5 seconds or so the lights come on to indicate charge. In this case, all four lights came on. Then they went out. It seemed like forever, but at about 25 seconds the first LED started blinking. This went on for about 2 or 3 seconds. Then the LED went out. I kept my finger on the button. A few seconds later all four LEDs came on solid.

So that indicates less than 100 cycles, and 75 to 100% capacity. Yay!

I built a little blanket with some Reflectix and duct tape. I'll report back in a coupla days, weather permitting. Cold and fog is one thing, but if it's raining we probably won't go.

@Telkwa

You may want to purchase one of these: https://www.fahrer-berlin.de/en/e-bike/akku-cover/akku-cover-yamaha-rahmen/a-240/
Batteries work best when the temp is around 60-90'F.

Simple reason behind loss of range is = as the temp drops, the electrolyte inside the cell thickens/solifies and then Li-ions have to push through a thick slurry instead of liquidy stuff, just like how we would expend more energy to walk in quick sand vs regular water.

Thanks @rich c and @Mr. Coffee !

They are right! the best way to charge is when the cell is not too hot or cold. it's ok to drain the battery all the way down to 5%, it's just that you won't be able to eek out much power once it dips below 10%.

It's a well known fact in the electric car community that active thermal management is essential for the longevity of the battery.

 

[gljoe]

Get it charged a.s.a.p. Worst condition for a battery is depleted.

Is this correct?
I know you shouldn't let a battery stand for an extended period at a low voltage as it will slowly self discharge and going tooooo low is bad.
But if a battery has discharged down to say 5-10% , is leaving it in this condition (say for a week before you charge and use it again) the 'worst condition' ??

 

[WalkinTarget]

7% ? Hell, you had another 5% til you had to worry !! I rolled into my driveway on 1% last month, and I hopefully do not go any lower than that. Having the 500w on my Haibike is a treat, but having the Bikespeed RS is an invitation to get yourself in mileage trouble.

I tested just how bad it was last night on a short ride - I cruised at 21+ last night for 7 miles, burning thru 20% of my battery on the ride out, then took a much more leisurely ride back at 14mph, and I only used 10% of the battery. Speed is a lot of fun when you want to put on some miles, but running that Yamaha battery flat out just sucks the battery dry at a very prodigious pace.

 

[Ravi Kempaiah]

But if a battery has discharged down to say 5-10% , is leaving it in this condition (say for a week before you charge and use it again) the 'worst condition' ??

Simple answer = No!

Low charge = bad for cell health is a residual notion from the lead acid battery technology. Batteries from Yamaha, Brose, Bosch, Shimano have Low Voltage Cutoff point and they prevent any irreversible damage happening. Having said that, ideal would be to store your battery at 40-60%.

 

[Telkwa]

Thanks to everyone; let's keep the conversation going!

Just a quick review: my Haibike HardNine has a 400Wh battery, as does Patti's Liv Amiti-E+. Both bikes roll on ETRTO 622 rims. Her Serfas Krest FPS knobby tires are 52/622's and my Conti Trail King Protects are 54/622. I'm not scientific about air pressure. Patti likes her tires at about 50 psi, I tend towards 45 or so.

At the end of the ride during the summer her bike returned with 60 - 70% battery when I was at 35 - 40%. Similar Yamaha drivetrains so I assume that's mostly weight and wind resistance. Can one bike manufacturer tweak the controlling circuitry so it's more aggressive? Or do they get what they get from Yamaha, Bosch, etc.?

Went out yesterday morning. 45 deg. air temp. Home-brew Reflectix blanket over my battery. Kept the batteries in the car until reaching the trailhead. I rode just like all the previous trips - Std. boost 10 miles out, then Hi for the return. Back to the car with 15% remaining. Plugged the batteries in when we got home. The Kill-A-Watt meter said .62KWh cumulative when charging was complete. That's both bike chargers running thru the Kill-A-Watt meter. I haven't bothered to take individual readings. I'm assuming her battery is adversely affected like mine, but she's got so much more capacity at the end of the ride so it hasn't been an issue.

I probed under the Reflectix blanket with a fingertip when the battery was nearly charged. I was concerned about heat build-up when charging. The battery hardly felt warmer than ambient so no worries.

There's always been a lot of confusion about battery mgmt. Not that I'm an expert. People believe things that may be true for lead-acid, or NiMH, but not Li-Ion, etc. For instance, I know that running a typical lead-acid battery (like in your car) way down in freezing weather is bad. The electrolyte's composition changes and the battery is more susceptible to freeze damage. I don't know if that's also the case for Li-Ion?

I have a feeling there's also confusion about discharge states. I'm an 18650 Li-Ion flashlight fan so learned a bit along the way. Any flashlight worth its salt has protective circuitry inside that will not let the battery go below a certain level of discharge. Roughly 3 to 3.2 volts is the absolute low end for Li-Ion. It's dangerous to recharge a Li-Ion that's gone below 3V. The chances of fire or explosion go way up.

I guarantee you that the battery packs from reputable sources such as Yamaha and Bosch all have protective circuitry inside that will not allow discharge below whatever they decided was the cut-off. So when somebody writes to say their battery was at 1%, that is not at all the same thing as running a car battery down until it's so dead the horn won't honk. 1% means the protective circuitry is about to kick in and stop you from hurting the battery or yourself.

Don't want to, but probably gonna tweak the ride - start out in Eco for the first coupla miles, and do the 10 mile return in Std. instead of Hi. Patti's gonna leave me behind...

EDIT: Ravi wrote quickly while I took an hour.

 

[rich c]

Thanks to everyone; let's keep the conversation going!

Just a quick review: my Haibike HardNine has a 400Wh battery, as does Patti's Liv Amiti-E+. Both bikes roll on ETRTO 622 rims. Her Serfas Krest FPS knobby tires are 52/622's and my Conti Trail King Protects are 54/622. I'm not scientific about air pressure. Patti likes her tires at about 50 psi, I tend towards 45 or so.

At the end of the ride during the summer her bike returned with 60 - 70% battery when I was at 35 - 40%. Similar Yamaha drivetrains so I assume that's mostly weight and wind resistance. Can one bike manufacturer tweak the controlling circuitry so it's more aggressive? Or do they get what they get from Yamaha, Bosch, etc.?

Went out yesterday morning. 45 deg. air temp. Home-brew Reflectix blanket over my battery. Kept the batteries in the car until reaching the trailhead. I rode just like all the previous trips - Std. boost 10 miles out, then Hi for the return. Back to the car with 15% remaining. Plugged the batteries in when we got home. The Kill-A-Watt meter said .62KWh cumulative when charging was complete. That's both bike chargers running thru the Kill-A-Watt meter. I haven't bothered to take individual readings. I'm assuming her battery is adversely affected like mine, but she's got so much more capacity at the end of the ride so it hasn't been an issue.

I probed under the Reflectix blanket with a fingertip when the battery was nearly charged. I was concerned about heat build-up when charging. The battery hardly felt warmer than ambient so no worries.

There's always been a lot of confusion about battery mgmt. Not that I'm an expert. People believe things that may be true for lead-acid, or NiMH, but not Li-Ion, etc. For instance, I know that running a typical lead-acid battery (like in your car) way down in freezing weather is bad. The electrolyte's composition changes and the battery is more susceptible to freeze damage. I don't know if that's also the case for Li-Ion?

I have a feeling there's also confusion about discharge states. I'm an 18650 Li-Ion flashlight fan so learned a bit along the way. Any flashlight worth its salt has protective circuitry inside that will not let the battery go below a certain level of discharge. Roughly 3 to 3.2 volts is the absolute low end for Li-Ion. It's dangerous to recharge a Li-Ion that's gone below 3V. The chances of fire or explosion go way up.

I guarantee you that the battery packs from reputable sources such as Yamaha and Bosch all have protective circuitry inside that will not allow discharge below whatever they decided was the cut-off. So when somebody writes to say their battery was at 1%, that is not at all the same thing as running a car battery down until it's so dead the horn won't honk. 1% means the protective circuitry is about to kick in and stop you from hurting the battery or yourself.

Don't want to, but probably gonna tweak the ride - start out in Eco for the first coupla miles, and do the 10 mile return in Std. instead of Hi. Patti's gonna leave me behind...

EDIT: Ravi wrote quickly while I took an hour.

You mention weight, but what is the differential between you and Patti. Not sure if current draw is a straight line vs weight, or an exponential change. I know speed and wind resistance is an exponential difference. The biggest danger with a Li-ion pack is having the battery capacity drop below the battery management low limit. If you run it really low, then store for winter, you will have a brick in the spring since the pack will not take a charge because it is below the lower limit.

 

[Solom01]

So by now it has pretty much been drilled into me that the best way to maintain the battery is not to let it go below 20% or to charge it above 80%, which makes sense, but I have yet to see an answer to whether most chargers balance the battery cells at the start or end of the charging cycle. If it's at the end is it more harmful for battery health to not fully charge, but also not balance the battery or to go ahead and charge fully knowing it's not optimal but ensuring that the battery cells are balanced? Or should it be a combination of both, e.g., charge to 80% 4 out of 5 times and charge fully and balance the 5th time or something like that? One would think that the bike vendors would tell you this or know the answer, but I've never seen any of them or any of the bike reviews on the site mention this.

 

[Ravi Kempaiah]

but I have yet to see an answer to whether most chargers balance the battery cells at the start or end of the charging cycle.

@Solom01 ,

I think you are confusing RC chargers with Li-ion E-bike chargers.

In most of the well-engineered E-bike batteries, It is the duty of the BMS (battery management system) NOT the charger to balance cells.
Here is an example, Bosch uses a smart BMS that monitors over voltage , under voltage, temperature and cell balancing at all times (even when you are riding it) and throws an error if one of the cells is malfunctioning. So, in short, BMS balances the cells at all times NOT just at some specific points.

If you want to see the circuit board of a Bosch BMS, here it is:
https://endless-sphere.com/forums/viewtopic.php?t=79188