Do's and Don'ts for e-bike battery care. What do you do to keep your battery performing at its best?

[RiderOnTheStorm]

What’s commonly known with lipos is:
Store 66% or so
Never charge or discharge a better that’s hot ( recently used/ charged)
Fast charging causes more heat so it’s a bit of a degrading thing.

Thanks for the guidance. You mentioned LiPo batteries. Do these behave similarly to Lithium-Ion batteries which are generally fitted on eMTBs?

 

[Ark]

Thanks for the guidance. You mentioned LiPo batteries. Do these behave similarly to Lithium-Ion batteries which are generally fitted on eMTBs?

LIPO drop voltage quicker as the battery discharge and they aren't as energy dense

also they are pretty much guaranteed to catch fire when overcharged where as a Li-On will likely just swell a bit

Note how quick LI-PO goes from swelling to fire

 

[RiderOnTheStorm]

Yep that's scary stuff Glad that ebike batteries use Lithium-Ion which seem safer than Li-Po.

The MBA article I linked earlier mentionned that "Expert consensus is that the worst thing you can do to your e-bike’s battery is damage it in a crash or purposely tamper with it... Crashes happen, but the battery packs are designed to protect the cells inside."

So, as far as battery care goes, besides avoiding to drop the battery, what should be done after a bike crash if the battery housing or battery cover has been hit?

Is the best practice to just replace the battery after a serious crash? Can a battery be tested after a crash for any internal damages that would make it unsafe to use over time? How to check it?

 

[RiderOnTheStorm]

Regarding battery storage for weeks or months, keeping a charge around 50 to 70% seems to be the guideline.

But what if your battery is fully charged and you're unable to ride your bike and drain the battery to a storage-friendly charge.

Are there any electrical devices or tools that can be used to discharge a battery to an acceptable level for storage? Any such thing as a commercial battery dis-charger? Other thoughts?

 

[billium]

Actually, all you would need is a 99p 560 Ohm, 5 Watt resistor from Maplin if they were still around!

That would discharge at roughly 0.01 Amps and 2.5 watts - slow enough to not generate too much heat.
If you have 700WH battery and want to lose 300WH it would take about 120 hours or 5 days at that rate.

But having said that, I don't recommend it unless you know what you are doing - and by asking you probably don't!
Too much could go wrong if you connect the wrong terminals on the battery and they all have more than two.

Having someone ride the bike in Turbo for 15 mins is a quicker, cheaper and safer strategy.

 

[RiderOnTheStorm]

Having someone ride the bike in Turbo for 15 mins is a quicker, cheaper and safer strategy.

Good advice, completely agree. Better be safe than sorry! Just surprised though by the lack of ebike chargers with a "storage discharging" function, since batteries have become such a prominent power source for our electric vehicles

 

[Alexbn921]

Is the best practice to just replace the battery after a serious crash? Can a battery be tested after a crash for any internal damages that would make it unsafe to use over time? How to check it?

It's protected by the frame and then it has it's own protective case and then the induvial cells are in metal cans.

A crash would have to eject the battery and significantly damage the case or snap the frame at the battery before I would consider replacing it.

If my battery was charger to 100% and needed storage, I would find some way to ride the bike, unless it's broken and waiting on parts or something. You could also swap the battery into a friends frame just to drain.

Using a resister is a good way, but I won't recommend it to someone that doesn't really understand what they are doing. Shorting the positive to the negative with the wrong setup could literally catch on fire or fry the battery.

 

[RiderOnTheStorm]

If my battery was charger to 100% and needed storage, I would find some way to ride the bike, unless it's broken and waiting on parts or something. You could also swap the battery into a friends frame just to drain.

Good idea to swap the battery to another bike so it can be drained... safely

 

[RiderOnTheStorm]

On the battery performance topic, I was wondering how to best troubleshoot battery health degradations?

For example, if you notice a significant drop in your riding range over a period of time (seeing less autonomy for the same ride over time), are there battery health checks that someone can do at home to help pinpoint an actual battery issue or just regular wear, which can obviously be expected as the battery ages.

With bosch batteries, I found that LBS/bosch dealers can run an e-bike diagnostic tool and check number of charging cycles, cell voltages, temps, etc.

I just had such diagnostic report printed for my bikes but couldn't figure out how to determine my battery health status, battery degradation % and what autonomy or range I should expect for a given assistance mode. Could this be calculated or estimated based on battery characteristics and diagnostic data?

 

[RiderOnTheStorm]

It's protected by the frame and then it has it's own protective case and then the induvial cells are in metal cans.

A crash would have to eject the battery and significantly damage the case or snap the frame at the battery before I would consider replacing it.

It's definitely reassuring that batteries have many physical protection layers even down to the cell level. I suspect that a bike crash would have to be very serious to require a battery replacement.... and then probably also a bike replacement!

 

[BIG-DUKE-6]

Now that I’ve discharged my first charge down to 20% I’ve decided to run my charger through a timer . It’s set up to run from 12:00 am to 12:30 am every night of the week.

Not only will this keep the battery cool but will keep the battery at about 50%-70% . I usually ride twice a week . Wednesday after work and a longer ride on the weekends so this is more than enough charge.

Obviously epic rides will require more charge as needed . This should extend the life of the battery significantly.

 

[audistwo]

With regards to knowing what you're doing.
I've experienced a relatively small cell exploded. It's not something you'd want to experience. I was lucky and the only long lasting effect is tinnitus in my left ear.
This was due to the working procedure being incorrect at the time, for a new product we were using.

 

[MountainBoy]

Now that I’ve discharged my first charge down to 20% I’ve decided to run my charger through a timer . It’s set up to run from 12:00 am to 12:30 am every night of the week.

Not only will this keep the battery cool but will keep the battery at about 50%-70% . I usually ride twice a week . Wednesday after work and a longer ride on the weekends so this is more than enough charge.

Obviously epic rides will require more charge as needed . This should extend the life of the battery significantly.

I don't know the temperature of the room where you charge your eBike, but it's actually good for the battery to be a little warm, rather than a little cool, when charging. Sure, heat is the enemy, but so is the cold. Ideal cell temperatures for charging are around 80 degrees F.

Also, the BMS (battery management system) needs the battery to periodically visit the top and bottom 15% of the battery's state of charge in order to remain calibrated and display the correct state of charge. The issue of yo-yoing the battery in the middle for long periods is the BMS's estimation of the state of charge can drift over time and become wildly inaccurate. In an extreme case, the BMS could report that you are at 70% state of charge, but the battery could find itself flat after only using 25% of its capacity.

 

[MountainBoy]

On the battery performance topic, I was wondering how to best troubleshoot battery health degradations?

For example, if you notice a significant drop in your riding range over a period of time (seeing less autonomy for the same ride over time), are there battery health checks that someone can do at home to help pinpoint an actual battery issue or just regular wear, which can obviously be expected as the battery ages.

With bosch batteries, I found that LBS/bosch dealers can run an e-bike diagnostic tool and check number of charging cycles, cell voltages, temps, etc.

I just had such diagnostic report printed for my bikes but couldn't figure out how to determine my battery health status, battery degradation % and what autonomy or range I should expect for a given assistance mode. Could this be calculated or estimated based on battery characteristics and diagnostic data?

If I noticed my battery losing capacity, I would fully charge it and take it on a long ride. eBike manufacturers are not very good about providing the end user with good diagnostics because that could increase their warranty expense.

I just go with a top tier manufacturer and don't worry about it.

 

[BIG-DUKE-6]

I don't know the temperature of the room where you charge your eBike, but it's actually good for the battery to be a little warm, rather than a little cool, when charging. Sure, heat is the enemy, but so is the cold. Ideal cell temperatures for charging are around 80 degrees F.

Also, the BMS (battery management system) needs the battery to periodically visit the top and bottom 15% of the battery's state of charge in order to remain calibrated and display the correct state of charge. The issue of yo-yoing the battery in the middle for long periods is the BMS's estimation of the state of charge can drift over time and become wildly inaccurate. In an extreme case, the BMS could report that you are at 70% state of charge, but the battery could find itself flat after only using 25% of its capacity.

The temp was directed to the temp of the battery while charging. You do make a valid point. I will definitely put that into the rotation. Thanks

 

[RiderOnTheStorm]

Also, the BMS (battery management system) needs the battery to periodically visit the top and bottom 15% of the battery's state of charge in order to remain calibrated and display the correct state of charge.

You bring up a good point. From what I have gathered and tried so far, my simplified routine looks like this:

1. Charge to 80% (if not going to storage), or exceptionally charge to 100% before a long ride.
2. Ride, and keep riding without recharging until discharged to 15-20%
3. Recharge to 80% (if not going to storage) or to 100% for long rides. Then repeat to #2.
4. If going to storage (for 2+ weeks) recharge only to 50-60% and verify/top off the charge level every 6 months.

YMMV of course. I think this pattern should help maximize my battery's useful life. Thoughts/comments based on your experience?

 

[BIG-DUKE-6]

You bring up a good point. From what I have gathered and tried so far, my simplified routine looks like this:

1. Charge to 80% (if not going to storage), or exceptionally charge to 100% before a long ride.
2. Ride, and keep riding without recharging until discharged to 15-20%
3. Recharge to 80% (if not going to storage) or to 100% for long rides. Then repeat to #2.
4. If going to storage (for 2+ weeks) recharge only to 50-60% and verify/top off the charge level every 6 months.

YMMV of course. I think this pattern should help maximize my battery's useful life. Thoughts/comments based on your experience?

Overall , this is my main goal. What I don’t want to do is fry my battery to 100% after every 90 minute ride .

 

[BIG-DUKE-6]

I am adding a 100% charge once a month for battery memory

 

[MountainBoy]

You bring up a good point. From what I have gathered and tried so far, my simplified routine looks like this:

1. Charge to 80% (if not going to storage), or exceptionally charge to 100% before a long ride.
2. Ride, and keep riding without recharging until discharged to 15-20%
3. Recharge to 80% (if not going to storage) or to 100% for long rides. Then repeat to #2.
4. If going to storage (for 2+ weeks) recharge only to 50-60% and verify/top off the charge level every 6 months.

YMMV of course. I think this pattern should help maximize my battery's useful life. Thoughts/comments based on your experience?

That sounds reasonable and, although it's splitting hairs, I don't think discharging it to 15-20%, over multiple rides, is necessarily something to shoot for. It's probably better to just charge it back to 70-80%, even if you've only discharged it to 40% and you know you could squeeze one more ride out of it without issue. Obviously, a periodic trip down to 10-15% could be beneficial to the accuracy of the BMS.

A battery used like that, and avoiding charging/discharging the battery when it's too hot or cold, could last a surprising amount of time and number of charge cycles

 

[billium]

You bring up a good point. From what I have gathered and tried so far, my simplified routine looks like this:

1. Charge to 80% (if not going to storage), or exceptionally charge to 100% before a long ride.
2. Ride, and keep riding without recharging until discharged to 15-20%
3. Recharge to 80% (if not going to storage) or to 100% for long rides. Then repeat to #2.
4. If going to storage (for 2+ weeks) recharge only to 50-60% and verify/top off the charge level every 6 months.

YMMV of course. I think this pattern should help maximize my battery's useful life. Thoughts/comments based on your experience?

I agree but would modify #1 to account for the cumulative impact of staying at 100%. Best way is to use some kind of timer to charge the last 20% just before your ride - i.e. not the day before

1. Charge to 75-80% (if not going to storage), or exceptionally charge to 100% just before a long ride.

 

[RiderOnTheStorm]

Thanks everyone for all your tips and best practices to get the most out of our ebike batteries. Good to hear that with proper care we can extend the lifespan of our batteries, and enjoy our eMTBs for a longer time!

 

[RiderOnTheStorm]

eBike manufacturers are not very good about providing the end user with good diagnostics because that could increase their warranty expense.

Yep, when I look at the Bosch Powertube diagnostic report that I received from my LBS, under battery status, I can only see:

-battery voltage
-battery charge level %
-number of full charge cycles

How can I determine my battery's health status from this data?

 

[MountainBoy]

Yep, when I look at the Bosch Powertube diagnostic report that I received from my LBS, under battery status, I can only see:

-battery voltage
-battery charge level %
-number of full charge cycles

How can I determine my battery's health status from this data?

You can't.

But I wouldn't sweat the details, it's all about whether it has enough capacity to keep you happy.

 

[RiderOnTheStorm]

I agree, capacity can be a good indicator to determine the battery health status, battery heat maybe another one.

To check my battery heath status, I was thinking about comparing the battery's factory/ design capacity with the full charge capacity or usable capacity if the latter can be measured?

For example, for a Bosch Powertube 625Wh, the design capacity is 16.7 Ah from manufacturer data. Over time, I suspect my full charge or usable capacity (in Ah) would decrease. So, calculating the delta between these two values could possibly indicate my battery health status.

Another thought, may be just compare the original battery voltage when charged at 100% (e.g 37.2V) with the actual voltage I get now when the battery is charged at 100% (e.g. 36 V) and see how the latter Voltage changes over time.

So here, (36 ÷ 37.2) x 100 would give me a current battery health status of 97% or a degradation of 3%. Does this make sense?

 

[BIG-DUKE-6]

I think this is the only way to check the actual health of the battery. All others have too many variables to calculate in .

 

[MountainBoy]

I agree, capacity can be a good indicator to determine the battery health status, battery heat maybe another one.

To check my battery heath status, I was thinking about comparing the battery's factory/ design capacity with the full charge capacity or usable capacity if the latter can be measured?

For example, for a Bosch Powertube 625Wh, the design capacity is 16.7 Ah from manufacturer data. Over time, I suspect my full charge or usable capacity (in Ah) would decrease. So, calculating the delta between these two values could possibly indicate my battery health status.

Another thought, may be just compare the original battery voltage when charged at 100% (e.g 37.2V) with the actual voltage I get now when the battery is charged at 100% (e.g. 36 V) and see how the latter Voltage changes over time.

So here, (36 ÷ 37.2) x 100 would give me a current battery health status of 97% or a degradation of 3%. Does this make sense?

I doubt the final 100% charge voltage is a reliable indicator or battery degradation because it's dependent upon the programming of the BMS and would vary from manufacturer to manufacturer. Also, I doubt if the peak voltage is linear with degradation.

I think if the manufacturer doesn't include the ability to read consumption (for example in Wh) and percent of charge.

This is what I like about the way Tesla reports battery state of charge (including range remaining). The BMS reports the amount of electricity used since last charge and will tell you to the nearest percentage point what the state of charge is (from 0% to 100%). The latter is an estimate, of course, based on the BMS tracking of voltage and energy consumed and is designed to have a "fudge factor" at the bottom (0%) so you don't accidentally run the battery flat because the state of charge estimate had drifted due to multiple partial charge cycles in the middle of the battery capacity.

Because the range remaining is based strictly on the EPA consumption rating, it's as reliable of an indicator of how much energy the battery can hold as is the percent charge. The range remaining is locked into the simple formula of energy remaining divided by Wh/mile of EPA consumption. This means if the car, when new, had 330 miles of range, and you charge it to 100% and it reports 327 miles of range, then you have less than 1% battery degradation.

Of course, the degradation of a Tesla battery is slower and much more predictable than that of an ebike battery because it has far more sophisticated temperature monitoring and regulation and the BMS is more sophisticated as well. But we could monitor the state of health of our ebike batteries much more closely if their manufacture used the same type of energy reporting as the Tesla uses for their cars. Instead, we get vague and highly variable estimates of range based upon whether the bike recently went up or down hill (amongst other variables).

I don't think there is an easy solution other than hacking the BMS system so you can peek under the hood or modifying the charge cord and installing a current measuring device on it. The latter is probably your best option. The most accurate measurement would require running the battery to zero and then measuring the amount of energy added energy by the time it had stopped charging. This figure would be very close to the total capacity but it's far from ideal in that it requires the complete discharge of the battery to start with.

I chose to not worry about battery health, beyond unplugging the charger before it finishes charging all the way (unless I will be going on a long ride that day). I have an eMTB and an eGravel and both batteries might outlast me!

 

[RiderOnTheStorm]

I don't think there is an easy solution other than hacking the BMS system so you can peek under the hood or modifying the charge cord and installing a current measuring device on it. The latter is probably your best option.

That makes a lot of sense, thanks. Sounds like getting an accurate reading of the battery's state of health can prove difficult if not supplied by the BMS.

 

[Ark]

I am adding a 100% charge once a month for battery memory

They don't have battery memory

 

[RiderOnTheStorm]

My attempt to summarize some key factors that affect the lifespan of our e-bike batteries. Being aware of these factors could certainly help increase the battery life expectancy in my opinion.

This non exhaustive recap is based on manufacturer guidelines and also forum feedback.

1. High usage. Lithium-Ion batteries have a limited number of charge-discharge cycles before they lose capacity to hold a charge and may need to be replaced. Typically between 500 and 1,000 cycles.
2. Poor charging habits such as improper charging or discharging, overcharging. If the battery is left to charge for too long, it can cause overheating and cell damage. Damage can also occur when the battery is left unused for extended periods to drain without being recharged.
3. Extreme temperatures. Damage can occur when the battery is used or charged in extreme high or low ambiant temperatures. Also, the temperature of the battery before, during, or after charging can indicate a problem.
4. Poor maintenance. Insufficient cleaning, premature wear & tear, water ingress, battery not replaced on time can impact the battery lifespan. Dirty electrical contacts can lead to poor charging.
5. Poor storage. A battery left in storage overcharged or fully charged will degrade faster. Batteries should be disconnected and stored in a protective case when not used for some time.
6. Safety. Using the wrong charger or a defective charger could damage the battery and cause a fire.

 

[Alexbn921]

Your order could be better.
1. Over discharging and letting it stay at 0% for any length of time.
2. Charging while hot, like immediately after I ride.
3. Storing at 100%, the hotter it is the worse this is.
Very few people will reach a cycle limit of a properly cared for battery. Approximately 12,000 miles to 500 cycles.
The battery CAN last the life of the bike.