Electric bike battery care

[Gionnirocket]

Yes, the 4 major OEMs all have active BMS balancing... I can't comment on the other white-box brands.

Coolio... that's good to know. Something important to consider when making a purchase.

 

[AHicks]

Yes, the 4 major OEMs all have active BMS balancing... I can't comment on the other white-box brands.

Fine, if you have a high end bike, you don't need to balance charge - if - you believe the "active" charging equipment is getting the job done for you.

For the rest of us more common folk, we DO need to charge to 100% on occasion.

So with your exception noted, does that work for you FlatSix?

 

[pmcdonald]

Fine, if you have a high end bike, you don't need to balance charge - if - you believe the "active" charging equipment is getting the job done for you.

For the rest of us more common folk, we DO need to charge to 100% on occasion.

So with your exception noted, does that work for you FlatSix?

I'm not sure what there is to debate here.

If you plan on hanging on to your bike for a decade or are a high milage rider and aim to maximise the battery life try and follow the 80-20 rule and every now and then take it to 100.

If not just ride and charge it like you rented it.

Is there anything more we need to discuss here?

 

[AHicks]

I'm not sure what there is to debate here.

If you plan on hanging on to your bike for a decade or are a high milage rider and aim to maximise the battery life try and follow the 80-20 rule and every now and then take it to 100.

If not just ride and charge it like you rented it.

Is there anything more we need to discuss here?

No, not really. Maybe that there is a tendency to overthink the topic a bit. That, and much of the talk regarding the benefits of charging to 80% fail to mention the need to also consider maintaining cell balance. Possibly assuming we are all using high end systems, when it's very clear (or it should be) many of us are not.

 

[Gionnirocket]

You do need to occasionally balance your battery pack by charging to 100% if your pack utilizes passive balancing... but there are a few things to take in to consideration. The cheaper the cells/battery probably the more important it is and less so with a well made pack that has stable name brand cells that are properly matched by manufacturer date and internal resistance. Also how the battery is used will determine if you should balance more often. For example a small battery that is fully drained under heavy load quickly will generate more heat and this will cause internal resistance variations and require a more stringent balancing regime..similar to those used in RC hobby applications.
But as in my case where my battery is a bit oversized I'm burning <5%/hour during a typical daily two hour ride as well as protecting the battery from direct sunlight... my pack is never above ambient temperature and balancing once every fifteen or so 40% - 80% charge cycles I feel is more than adequate.
Temperature is a batteries biggest enemy. . . and that's all I gotta say about that.

 

[Ravi Kempaiah]

No, not really. Maybe that there is a tendency to overthink the topic a bit. That, and much of the talk regarding the benefits of charging to 80% fail to mention the need to also consider maintaining cell balance. Possibly assuming we are all using high end systems, when it's very clear (or it should be) many of us are not.

At this point, you like to charge your batteries to 100%, no problem, you may do it as you wish.
Technology has developed quite a bit in the last 3-4 years. Balancing can be initiated at a much lower voltage (say 80% or 90% of the upper voltage cutoff point). Not every pack needs to be charged to 100% for balancing purposes. In fact, out of respect and not to initiate endless debate, I did not say it before but it is incorrect to say that balancing happens at 100%, in 99% of the devices that use low-cost passive balancing circuit, it occurs at around 95%. There are different shades of passive and active balancing as well. Not every balancing circuit is the same!
I am in regular touch with Bosch and Shimano engineers and those packs have active balancing.
Using thermistors is another common feature. Bosch even registers the max/min temperature the pack experiences and this data is available for diagnostic purposes. Shimano batteries are also very well built. They do have active balancing.
As @Gionnirocket mentioned, if the cells in the pack are matched for internal resistance, a high-quality BMS board is used for monitoring the cell health, then the pack doesn't go out of balance. If it goes out of balance every month, then there is something wrong with the battery or it is not the right battery for that application.

 

[Over50]

... Using thermistors is another common feature. Bosch even registers the max/min temperature the pack experiences and this data is available for diagnostic purposes ...

Just got a Bosch diagnostic report yesterday on the Powerpack 500 that came with my Allant. 42 full charge cycles, max battery temp 96F, min battery temp 49F and duration in thermal protection 0 minutes. Delivered Ah over lifetime 513.

 

[Gionnirocket]

Just got a Bosch diagnostic report yesterday on the Powerpack 500 that came with my Allant. 42 full charge cycles, max battery temp 96F, min battery temp 49F and duration in thermal protection 0 minutes. Delivered Ah over lifetime 513.

Curious.... If you used your battery as I do basically charging to 80% then running down to 40% ...How would it register each charge? As a cycle or would it take 2.5 charges to register as a cycle?

 

[Over50]

I think you're close on the latter. They explain it somewhat here:

eBike batteries: Long range, low weight, easy charging

The high-quality, long-lasting eBike batteries from Bosch have the highest energy density with a small size and light weight. The Bosch PowerTube is fully integrated in the frame. Different capacities offer the right choice for replacement and spare batteries.

www.bosch-ebike.com

Refill your energy tank in no time​

Charge times and service life​

A charge cycle refers to the full recharging of a battery in a single charging session or several partial charging sessions. The charging time depends on the capacity of the battery and of the charger: with the Standard Charger, the PowerPack 500 and PowerTube 500 require approx. two hours for half a charge, and approx. 4.5 hours to fully charge. Charging with the Fast Charger is quicker, with only approx. 1 hour needed to half-charge the PowerTube 500 and PowerPack 500 – the perfect solution when on the road – and only three hours to fully recharge these battery packs. The service life of Bosch rechargeable batteries is influenced mainly by the type and duration of use. Like every lithium-ion battery, a Bosch rechargeable battery also ages over time, even if you do not use it.

 

[Sierratim]

Curious.... If you used your battery as I do basically charging to 80% then running down to 40% ...How would it register each charge? As a cycle or would it take 2.5 charges to register as a cycle?

I checked my Specialized Vado 5 for this; it registers a charge cycle for each 100% charge. So recharging a a battery that is at 40% charge won't necessairly count as a charge cycle but the next time you charge from 60% or less it will count as a full cycle. YRMV.

 

[AHicks]

At this point, you like to charge your batteries to 100%, no problem, you may do it as you wish.
Technology has developed quite a bit in the last 3-4 years. Balancing can be initiated at a much lower voltage (say 80% or 90% of the upper voltage cutoff point). Not every pack needs to be charged to 100% for balancing purposes. In fact, out of respect and not to initiate endless debate, I did not say it before but it is incorrect to say that balancing happens at 100%, in 99% of the devices that use low-cost passive balancing circuit, it occurs at around 95%. There are different shades of passive and active balancing as well. Not every balancing circuit is the same!
I am in regular touch with Bosch and Shimano engineers and those packs have active balancing.
Using thermistors is another common feature. Bosch even registers the max/min temperature the pack experiences and this data is available for diagnostic purposes. Shimano batteries are also very well built. They do have active balancing.
As @Gionnirocket mentioned, if the cells in the pack are matched for internal resistance, a high-quality BMS board is used for monitoring the cell health, then the pack doesn't go out of balance. If it goes out of balance every month, then there is something wrong with the battery or it is not the right battery for that application.

It looks like, if I'm understanding what you've written here, MOST of us are on bikes (including those with "white box" chargers, BMS, and batteries, NOT just the high end Shimano, Brose, etc bikes) that will not get a balance charge if the charge is stopped at 80%. That was/is my primary point here, the one that started all this. If you tell me that not every pack needs to be charged to 100%, I'm fine with that. The deal is, for our purposes here, I'm not interested in the exceptions - or where "state of the art" is. I'm interested in how to best deal with all of the others - the MAJORITY of the E-BIKE battery packs in use today.

From there, not going to split hairs regarding when the balance cycle starts. For my purposes, I see little difference if that happens at 95 or 100%. I use the 100% for clarity among those that are riding bikes today. Not all of us have high end bikes, nor are we electrical engineers that are able to comprehend or even interested in reading technical mumbo jumbo. I'm advocating for the MAJORITY of riders here. Trying to give them something simple THAT WORKS.

If you're telling me that the battery that came with my RAD, my Rize, and the others purchased in the last few years, don't need to be balance charged, all due respect, but I'd be suspicious of that idea. That said, I do have an open mind on the topic. I'd like to know that packs assembled from the popular cell makers (eg Samsung, LG, and Panasonic) have reached a state of the art where balance charging is no longer considered necessary when determining "best practices". Pretty interested in your thoughts there. Is MY battery pack included when you mention "not every pack needs to be charged to 100% for balancing purposes"? Follow what I'm saying? Let's focus on the majority of the packs in use. NOT the exceptions.

Thanks for contributing! -Al

 

[FlatSix911]

Ravi can best answer the specific questions regarding your eBikes.
For most users here are a few best practices.... hope this helps other EBR members.

 

[AHicks]

Useful tips, but not one word regarding balancing, which should be at least mentioned in any conversation regarding "best practices". Which is my other point....

 

[pmcdonald]

Useful tips, but not one word regarding balancing, which should be at least mentioned in any conversation regarding "best practices". Which is my other point....

So why not just charge to 100% every few cycles?

A little perspective.. your battery life is likely to be the least of your worries.

Run the math down. In my case I get 85km per full charge cycle. Even if I abuse my battery and only get 400 cycles that's 34k of life. I commute about 5k a year, and hope to get a minimum of 5 years from the bike. If I get 34k from the original components I'll be stoked! (At the upper end of the cycle count that's a very academic 136k of range.)

Now look at the reliability of ebikes: https://electricbikereview.com/forums/threads/spring-2020-ebike-reliability-survey-results.33641/. The evidence suggests a major electrical component on our bikes will fail long before our batteries expire from exhaustion. That was the case with my 5 year old BH.

Who here has truly run their batteries down? And how many miles did it take to get there?

 

[AHicks]

So why not just charge to 100% every few cycles?

I believe, personally, that's an excellent plan. If you do that, and follow that with a short ride, even if it's the next day, I don't see the harm in the 100% charge. What you want to avoid is leaving it at 100% for an extended period of time. And I also agree on the point regarding how many charges you get on a pack, even with some abuse, is likely way more than "enough" for the vast majority of e-bike riders.

The issues above, I think, are from those that don't like to hear about charging over 80%, saying they aren't necessary. Further, it seems like those pushing the 80% plan rarely mention balancing. Clearly, I struggle with both.

Getting 85km on a charge is doing a pretty good job! I know some report better, but again, many/most of us don't do as well.

You do read about some that are running their batteries down to the point the LBC (low battery cut off) shuts them off. Newbies usually, testing to see how far they can go on a charge/what they can get away with. -Al

 

[Ravi Kempaiah]

but not one word regarding balancing, which should be at least mentioned in any conversation regarding "best practices". Which is my other point....

I believe you come from RC toys or a similar hobby background. Balancing is needed when you use LiPo packs with no BMS. There are lots of LiPo hobbyists (Drones, RC planes, cars, etc.), and many of those LiPo packs have no BMS and you need a balance charger.
The whole idea of BMS is to minimize worrying about low voltage, high voltage cutoffs, balancing, temperature, etc.
Electric cars have even more advanced BMS with an active balancing circuit and you don't need to charge your car to 100% to balance those 1000's cells.

When it comes to E-bikes, the power draw is pretty low compared to LiPo cells used in RC toys or Drones and the cells should not go out of balance very often. Even if it does, the BMS should be able to handle that.

For those who are interested in learning more on this topic, a nice primer by Jehu Garcia explains some of the topics mentioned in this thread.

 

[Ravi Kempaiah]

Ravi can best answer the specific questions regarding your eBikes.
For most users here are a few best practices.... hope this helps other EBR members.

View attachment 73618

If folks can understand just this chart, then can forget everything else about battery care.

This was produced by the University of Michigan battery research institute and the scientists know what they are talking about.

 

[AHicks]

Ravi-
Guilty as charged. A very long time RC hobbyist, (though few in the hobby would call what I do "toys") dating back into the late 60's and early 70's.

I watched the video with an open mind, looking for some relevance that might sway my current opinion regarding the need to balance charge. The ONLY comment that might apply was something to the effect that if you "stay below the threshold of the lowest cell" when discharging, there is no need to balance charge. I struggle with that a bit, but then I'm used to using 40-60c batteries in RC as well. Pulling 6 cell 4500ma packs down in maybe 6-8 minutes of flight time is the norm (very high discharge/performance levels).

So let me ask you this. My bikes tend to use the biggest motors available, as I'm 300lbs and live in a coastal area with a lot of hills I have to deal with to go anywhere. Are you telling me I can pull 1500w (Bafang Ultra or MAC 12t) from a typical 48v battery, and "stay below the threshold of the lowest cell" in your experience? I really don't have the answer to that question, could use a hand. I also realize this is hardly the typical application.

Staying "below the discharge threshold of the weakest cell" is a new concept here. I struggle with that, but it sounds logical, especially regarding the more commonly seen motors (250-750w) used in our e-bikes.

I still see the need for occasional balancing, but I'll now admit it may not be necessary as frequently as I thought previously, especially with regard to lower wattage motors. Expecting a lifetime of service from an unbalanced battery is just beyond my comprehension. Regarding the 1000w+ bigger stuff, I will likely remain pretty vigilant - just cuz.

Thanks for your patience Ravi. Learned something new today. Much appreciated. -Al

 

[Gionnirocket]

Ravi-
Guilty as charged. A very long time RC hobbyist, (though few in the hobby would call what I do "toys") dating back into the late 60's and early 70's.

I watched the video with an open mind, looking for some relevance that might sway my current opinion regarding the need to balance charge. The ONLY comment that might apply was something to the effect that if you "stay below the threshold of the lowest cell" when discharging, there is no need to balance charge. I struggle with that a bit, but then I'm used to using 40-60c batteries in RC as well. Pulling 6 cell 4500ma packs down in maybe 6-8 minutes of flight time is the norm (very high discharge/performance levels).

So let me ask you this. My bikes tend to use the biggest motors available, as I'm 300lbs and live in a coastal area with a lot of hills I have to deal with to go anywhere. Are you telling me I can pull 1500w (Bafang Ultra or MAC 12t) from a typical 48v battery, and "stay below the threshold of the lowest cell" in your experience? I really don't have the answer to that question, could use a hand. I also realize this is hardly the typical application.

Staying "below the discharge threshold of the weakest cell" is a new concept here. I struggle with that, but it sounds logical, especially regarding the more commonly seen motors (250-750w) used in our e-bikes.

I still see the need for occasional balancing, but I'll now admit it may not be necessary as frequently as I thought previously, especially with regard to lower wattage motors. Expecting a lifetime of service from an unbalanced battery is just beyond my comprehension. Regarding the 1000w+ bigger stuff, I will likely remain pretty vigilant - just cuz.

Thanks for your patience Ravi. Learned something new today. Much appreciated. -Al

I knew you had to be a stuck RC'r

Let the angels sing

 

[Gionnirocket]

I believe you come from RC toys or a similar hobby background. Balancing is needed when you use LiPo packs with no BMS. There are lots of LiPo hobbyists (Drones, RC planes, cars, etc.), and many of those LiPo packs have no BMS and you need a balance charger.
The whole idea of BMS is to minimize worrying about low voltage, high voltage cutoffs, balancing, temperature, etc.
Electric cars have even more advanced BMS with an active balancing circuit and you don't need to charge your car to 100% to balance those 1000's cells.

When it comes to E-bikes, the power draw is pretty low compared to LiPo cells used in RC toys or Drones and the cells should not go out of balance very often. Even if it does, the BMS should be able to handle that.

For those who are interested in learning more on this topic, a nice primer by Jehu Garcia explains some of the topics mentioned in this thread.

Funny... I never saw this video but it is close to what I concluded by reading multiple tech docs and stated in post #65.
I would disagree in that basic balance charging can be implemented at such a low cost as it is in most less expensive batteries that Al and I are referring to, I don't see a down side in doing so and you should gain some output by occasionally topping off all cells equally.
Not having a BMS balance at all doesn't make sense to me as it is so inexpensive to have base passive balancing.