Electric bike battery care

[Ravi Kempaiah]

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.

Thanks for your comment, Al!
E-bikes have a much lower power draw compared to RC batteries. RC planes or Drones draw 5C to 10C regularly and in contrast, E-bikes are 0.25C.
Even if you ran 1300W Bafang BBS-HD, unless you completely deplete the battery in 1hr, you are still below 1C.
EM3ev recommends the following:

EM3ev 52V (14S5P) Jumbo Shark Ebike Battery | EM3ev

em3ev.com

So, if your bike has 35E then running 1000W should not stress the cells too much. If you have 30Q cells, then you can safely draw 1300W and still be <0.9C.
On top of that, if you have a decent BMS, then there is not much to worry in terms of balancing.

 

[AHicks]

Ravi, I doubt seriously that many Bike manf's selling in the mid to low price points (where I would typically buy) are using top quality cells like those that EM3ev are using. I'm fine with that idea, because my controllers are set to limit amps to 30 or less anyway. This is the comment that's most helpful - "unless you completely deplete the battery in 1hr, you are still below 1C". That pulls this into proper perspective here.

Thanks again, -Al

 

[billium]

Interesting thread.
Having just got a new white box bike ( Ride1Up 700) , I do want to maintain my new battery - don't charge it hot, maintain at 70-80% and minimize time at 100%.
But I know that I will soon forget about it.

So, I have built some smart home routines to keep it simple I use Alexa but Google home would probably work similarly. Here is what I did:

Got a "Smart Plug" - $15-$20 and plugged the charger into it.
Then I set up some Alexa Routines on my phone which are simple lists of commands that Alexa issues to the Plug.
So, I get home after a good ride, I see my display says 12%, turn the bike off and plug it in to the now unpowered charger.
Once inside I say " Alexa, charge bike at 10%"
This runs the routine of the same name which does the following:

• Tells Alexa to speak the words" Charging bike at 10% to 80%"
• waits 1hour ( for battery to cool down)
• turns on charger
• waits for 3.5 hrs ( while ON - so charges for 3.5 hrs which gets it to 70-80%)
• turns off charger

If I expect to go on a long ride tomorrow and want 100% charge, I also tell Alexa, "Alexa, top off battery" which does the following:

• Tells Alexa to speak the words " Charging bike for 90 minutes starting at 6am"
• waits until 6am tomorrow
• turns on charger
• waits for 90 minutes ( charging)
• turns off charger
• Tells Alexa to speak the words " Bike fully charged"

Add as many routines as you need for different battery levels that require different charge times.

Bill

 

[Ravi Kempaiah]

If I expect to go on a long ride tomorrow and want 100% charge, I also tell Alexa, "Alexa, top off battery" which does the following:

• Tells Alexa to speak the words " Charging bike for 90 minutes starting at 6am"
• waits until 6am tomorrow
• turns on charger
• waits for 90 minutes ( charging)
• turns off charger
• Tells Alexa to speak the words " Bike fully charged"

Add as many routines as you need for different battery levels that require different charge times.

This is fascinating! and certainly a smart way to do.
Instead of the E-bike battery, for me, it is the Instant pot + morning breakfast.
The night before I ut some oatmeal, chia seeds, hemp seeds, and almond milk into the Instant pot, and when I wake up, within 15 mins, breakfast is ready.

The kind of things you can do with Alexa or Google nest is amazing.

 

[Gionnirocket]

This is fascinating! and certainly a smart way to do.
Instead of the E-bike battery, for me, it is the Instant pot + morning breakfast.
The night before I ut some oatmeal, chia seeds, hemp seeds, and almond milk into the Instant pot, and when I wake up, within 15 mins, breakfast is ready.

The kind of things you can do with Alexa or Google nest is amazing.

I've been using home automation/monitoring since the early 1990's and it is definitely a useful technology.
But I'll be damn'd if I'm going to put a listening device in my home. I have no problem opening an app and tapping run macro.

 

[Ravi Kempaiah]

But I'll be damn'd if I'm going to put a listening device in my home.

I don't have a lot of world-changing things going on at my house .
So, I am ok with Alexa or Siri listening to some sounds and performing some tasks as needed.

 

[Gionnirocket]

I have an HTC U11 which was the first phone to come with Alexa... and the first app that I deleted on initial boot up.
Not paranoid just don't think it adds that much convenience for the privacy granted. I guess I've been doing it with taps for so long that speaking requires more effort for me.
How many ads do you see for oatmeal, chia seeds, hemp seeds, and almond milk?

 

[FlatSix911]

Interesting thread.
Having just got a new white box bike ( Ride1Up 700) , I do want to maintain my new battery - don't charge it hot, maintain at 70-80% and minimize time at 100%.
But I know that I will soon forget about it. So, I have built some smart home routines to keep it simple I use Alexa but Google home would probably work similarly. Here is what I did:

Got a "Smart Plug" - $15-$20 and plugged the charger into it.
Then I set up some Alexa Routines on my phone which are simple lists of commands that Alexa issues to the Plug.
So, I get home after a good ride, I see my display says 12%, turn the bike off and plug it in to the now unpowered charger.
Once inside I say " Alexa, charge bike at 10%"
This runs the routine of the same name which does the following:

• Tells Alexa to speak the words" Charging bike at 10% to 80%"
• waits 1hour ( for battery to cool down)
• turns on charger
• waits for 3.5 hrs ( while ON - so charges for 3.5 hrs which gets it to 70-80%)
• turns off charger

If I expect to go on a long ride tomorrow and want 100% charge, I also tell Alexa, "Alexa, top off battery" which does the following:

• Tells Alexa to speak the words " Charging bike for 90 minutes starting at 6am"
• waits until 6am tomorrow
• turns on charger
• waits for 90 minutes ( charging)
• turns off charger
• Tells Alexa to speak the words " Bike fully charged"

Add as many routines as you need for different battery levels that require different charge times.

Bill

I also use Alexa and a smart plug to control the charging of the battery and monitor the energy usage rate.

Beastron S31 S31-Red Wi-Fi Smart Plug Outlet, Works with Alexa, Timer Switch Socket, Energy Meter, Wireless Remote Control Your Electronics from Smartphone or Tablet, Red - - AmazonSmile

 

[Gionnirocket]

Hi Alexa... Please disclose my personal information/preferences to anyone willing to pay.... and anyone that asks once the inevitable hack occurs. Then turn on the light that I'm sitting next to

 

[FlatSix911]

Hi Alexa... Please disclose my personal information/preferences to anyone willing to pay.... and anyone that asks once the inevitable hack occurs. Then turn on the light that I'm sitting next to

The moral of this story... never put Alexa in your bedroom!

 

[Gionnirocket]

The moral of this story... never put Alexa in your bedroom!

But that's where I have most of my home automation!

 

[Oski1997]

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.

Ravi, I recently bought a Yamaha Civante ebike. I bought an extra battery ($900) so I can save money in the long-run. My thinking is “if I spend $900 today, I shouldn’t need to buy another battery in a long time because I’m using a 75-25% rule” (i know it’s 80-20 but at $900/battery, I’m being more conservative). I’ve read that I can better maximize the cycles of a Lithium Ion battery if I use it from 75% down to 25% than if I used it from 70-20% because more damage can be done by charging below 20% (I hope that’s right). Do you agree? If not, I think I’d rather charge my batteries 70% down to 20% because less heat is produced by the battery if I stop charging at 70%. Since my bike can utilize active balancing at a lower threshold than 95%, do you happen to know what the threshold is for a 500wh Yamaha battery? If it’s 90%, then I’m not doing my batteries any good by only charging up to 75%. If it’s impossible to find out, then I’ll just charge to 100% 2x/year. Thanks in advance for your thoughts.

 

[Ravi Kempaiah]

Since my bike can utilize active balancing at a lower threshold than 95%, do you happen to know what the threshold is for a 500wh Yamaha battery?

Thanks for this note.
I have not personally worked on Yamaha batteries, so I don't know the exact threshold at which the active balancing kicks in but I am experienced enough with Yamaha bikes to tell you that they are one of the best batteries on the market. I have ridden them for ~1000 miles. The BMS system is robust and it even goes to sleep mode if you don't use it for a few months.
The benefit of charging only 70% is so small. Because there is something called calendar aging apart from cycling. Whether we use the batteries or not, they are going to degrade. So, why not use them properly to get the best out of them.
If I was in your situation, I would do the following:

1. Charge to ~90 or 95% before each ride.
   Avoid situations where the batteries would sit with 100% SOC for many days.
2. Taking it down to the last 5% is not a problem (just don't let it sit at 5% SOC).
3. yamaha batteries are great. So, I would not worry about babying it too much.

 

[Oski1997]

Thanks for this note.
I have not personally worked on Yamaha batteries, so I don't know the exact threshold at which the active balancing kicks in but I am experienced enough with Yamaha bikes to tell you that they are one of the best batteries on the market. I have ridden them for ~1000 miles. The BMS system is robust and it even goes to sleep mode if you don't use it for a few months.
The benefit of charging only 70% is so small. Because there is something called calendar aging apart from cycling. Whether we use the batteries or not, they are going to degrade. So, why not use them properly to get the best out of them.
If I was in your situation, I would do the following:

1. Charge to ~90 or 95% before each ride.
   Avoid situations where the batteries would sit with 100% SOC for many days.
2. Taking it down to the last 5% is not a problem (just don't let it sit at 5% SOC).
3. yamaha batteries are great. So, I would not worry about babying it too much.

Thanks Ravi, I did have another concern. The 2nd battery literally sits on top of the battery on the top tube below the Civante letters in the pic (It’s in a bag and I use straps to keep it secure on the bike frame but on bumpy roads the battery sitting on top of the installed battery on the down tube does bump into it. I’m not sure how much of that the batteries could handle. There is very little room to put any good amount of rubber or something to help them not to bump into each other on rough roads. So, you gave me the idea to use them from 90% down to 10% on my 45+mile rides. Most of my rides are closer to 35 miles so I would generally use the batteries 80% to 20% (I can easily get a 50-mile range using the 2 highest settings so I would get more like 75 miles if i used the 2 lowest settings). Do you think if I alternated them monthly (so each battery is only used 6 months every other month in a year), this would help them last longer too? Thanks again for your thoughtful reply.

 

[AHicks]

Oski1997, if I may, just one question. Are you using the full capacity of one of these batteries completley, then plugging in the second in order to complete this one trip? -Al

 

[Oski1997]

Oski1997, if I may, just one question. Are you using the full capacity of one of these batteries completley, then plugging in the second in order to complete this one trip? -Al

No, I am currently charging both up to 80% and using them down to 30% so I can double the life of each battery. I figure if I spend the extra $900 today I’ll get an extended capacity so in the end I’ll save $900 (from not having to buy a 3rd battery later). I can go about 57 miles on 100% charge on one battery but I only use 50% on two batteries (I will now be going form 75% to 25% because I noticed the quick charge ended closer to 70%). But another member advised me that Yamaha makes one of the best batteries and BMS. He said I can use this battery 95% down to 5% with a negligible amount of capacity loss. Most of my rides are 35 miles so I plan on just using one battery around 75% down to 25%. And, on my rare 45+ miles I’ll use two batteries 90% down to 10% on one and 75%-25% on the second. Since these batteries are $900 each, I want to make sure I extend the life of each battery as much as possible now.

 

[AHicks]

Hopefully Ravi will confirm this, but buying that second 900 dollar battery now is only useful if you need the additional capacity that it will give you. Buying now, for the purpose of extending the life of each battery, is a false economy.

That second battery, even if you only rarely/never use it, is deteriorating all by itself.

Using up the first battery, assuming only that it will get the job done for you most of the time, THEN buying a replacement battery that will do the same, will let you get more use than buying both to begin with.

 

[Oski1997]

Hopefully Ravi will confirm this, but buying that second 900 dollar battery now is only useful if you need the additional capacity that it will give you. Buying now, for the purpose of extending the life of each battery, is a false economy.

That second battery, even if you only rarely/never use it, is deteriorating all by itself.

Using up the first battery, assuming only that it will get the job done for you most of the time, THEN buying a replacement battery that will do the same, will let you get more use than buying both to begin with.

Hmmm, I found the graph below on capacity retention on Batteries that were used in 7 different scenarios (i.e. 100% down to 25%, 85%-25%, 75%-25%, etc). At least in this study, it showed that the light blue line (using a battery only 75-25%) would yield a sweet spot where a batteries capacity retention would be 87% after about 5400 cycles. Using a battery 100—25% yileded the worst retention of capacity of 77% after 4500 cycles. That’s why I thought it would be a good idea to use two batteries 75%-25% today instead of using one battery 95%-5% today and waiting till the range didn’t work anymore. I need a range of 40 miles for me to feel safe on most of my rides which would be about a 60% capacity on my Yamaha battery. So, maybe you’re right. Even If I used my battery 85%-25% (also on the graph), my battery would have a projected capacity retention value of 83% at around 5400 cycles. The question for me now is if I ride 64 miles per week (= 3,078 miles per year divided by 57 mile rides (my range with a 100% Yamaha battery) = 54 cycles per year), how many years would i have to get to 5400 cycles?. Wow, I wound have 100 years to use my battery 5,400 cycles (thats 54 cycles per year) for a total of 64 miles per week.

I really didn’t have to spend the extra $900 did I !?! LoL HaHaHa on me!

Ravy, are my calculations correct? I know my battery won’t last 100 years using it 54 cycles per year. But theoretically Is this correct?

 

[Ravi Kempaiah]

Do you think if I alternated them monthly (so each battery is only used 6 months every other month in a year), this would help them last longer too?

I agree with @AHicks . If you are not actively using the 2nd battery, then you may not see a huge benefit by alternating the batteries.
May I ask you this?
How many miles do you ride per year?
With proper care, Yamaha batteries can serve you well for 30,000 miles or more. So, that's like 3-4 years of heavy riding.
if you get 30 miles per charge cycle (cycling between 85% to 15% should give you 1500 usable cycles) and that's 30 X 1500 = 45,000 miles.
By alternating another battery, you can not prolong that number to 80,000 miles because of the inherent calendar aging.

 

[Oski1997]

I agree with @AHicks . If you are not actively using the 2nd battery, then you may not see a huge benefit by alternating the batteries.
May I ask you this?
How many miles do you ride per year?
With proper care, Yamaha batteries can serve you well for 30,000 miles or more. So, that's like 3-4 years of heavy riding.
if you get 30 miles per charge cycle (cycling between 85% to 15% should give you 1500 usable cycles) and that's 30 X 1500 = 45,000 miles.
By alternating another battery, you can not prolong that number to 80,000 miles because of the inherent calendar aging.

I get 55 miles per 100% charge (always using the two highest settings) and I ride about 65 miles per week. One ride is usually around 40 miles and the second around 25 miles. I really only need a 2nd battery once a month when we go on 55+ mile rides. So the 2nd battery is really only necessary on one ride a month. So, still worth it to me. I might’ve primarily bought the second battery to save money but in the end, I now realize i actually do need it for the monthly long and steep ride my friends and I do. And, missing out on those monthly would be a real bummer.

Thank you for your thoughtful reply Ravi. I now see that I can get 1,500 usable cycles out of my battery (using them 85%-15%). Since I only use about 54 cycles per year (each cycle produces 57 miles of riding for me), that equates to about 28 years of riding my bike. I now see that the main benefit I will get from having the 2nd battery has nothing to do with extending the battery life but in the fact that I get to enjoy the long (55+ miles)/steep rides I do once a month with my friends.

The good news is that I also found out that I won’t be needing to buy a 3rd battery for 28 years LoL. Is that right Ravi???