80% charge level.

[The banjo]

I have just joined the forum and was reading a very good article on batteries & charging yesterday which basically stated that to prolong battery life it is best to charge a battery to 8o%. Does this 80% refer to the full charge voltage or the nominal voltage? My bike has a Samsung 14.5AH 36v, 520W, battery and 250watt motor. I would like to get my charging strategy organized up front.

 

[indianajo]

80% of full charge voltage. Full charge on nominal 36 v battery is 42 v according to electric-scooter.guide
so 80% would be 39.6 v I use a $12 timer to shut $25 charger off instead of a $200 multi-voltage charger. My luna battery is 3.7 years old and doing fine. I do full charge quarterly to balance stack voltage. Winter, below freezing, I store the battery under a heat pad in the garage.
I doubt if your battery is 520 w, that would be a 12.8 amp limit. Most controllers will put out more than that. I suspect your battery is 520 wh, which is 14.5 ah * 35.8 v .

 

[The banjo]

80% of full charge voltage. Full charge on nominal 36 v battery is 42 v according to electric-scooter.guide
so 80% would be 33.6 v I use a $12 timer to shut $25 charger off instead of a $200 multi-voltage charger. My luna battery is 3.7 years old and doing fine. I do full charge quarterly to balance stack voltage. Winter, below freezing, I store the battery under a heat pad in the garage.
I doubt if your battery is 520 w, that would be a 12.8 amp limit. Most controllers will put out more than that. I suspect your battery is 520 wh, which is 14.5 ah * 35.8 v .

This is what the bike specs quote : "Samsung 14.5AH 36v, 520W, charge capacity 70-140kms" . I think you are right - think they left the "Hr." component out.
I don't take any notice of claimed mileages per charge. I am goin to set the charger up on a mains timer also. My charger is marked 2 amp output.
Thanks for your input - appreciated.

 

[Pulsar]

I use a Luna digital charger and just select 80% and it does all the work. It also has selectable charge rates which is nice. I’ve seen folks use a digital volt meter to just shut charging down at a prescribed voltage if you want to baby sit charging? Luna charger is $100 and money well spent in my opinion considering our batteries are usually $500+.

 

[indianajo]

I use a Luna digital charger and just select 80% and it does all the work. It also has selectable charge rates which is nice. I’ve seen folks use a digital volt meter to just shut charging down at a prescribed voltage if you want to baby sit charging? Luna charger is $100 and money well spent in my opinion considering our batteries are usually $500

I bought one from Luna. It didn't work. No output. The $22 single voltage one from ebay does work.

 

[AguassissiM]

@The banjo

Welcome to the forums.

Have a look at this chart, hope it's helpful.

 

[The banjo]

Thanks for that. Saved it in my bike folder.

 

[6zfshdb]

There are several strategies used for battery maintenance. Many prefer to use the 80 / 20 rule and store at 40 - 60%. These measures do indeed prolong battery life. Unfortunately, it also has an effect on range. For casual short distance riding, this isn't a problem. For longer rides, losing 20% of your battery capacity can become an issue.

I usually do 50 or more miles on an average ride. I prefer to store my battery at 40-60% and charge to 100% just before heading out. I rarely discharge below 20% but rather than walk the last few miles back, I have gone as low as 10% on a couple of occasions.

My battery is 3.5 years old and a recent bench test shows it has lost 9% of it's original capacity. Just how much of that loss is from age rather than use is unknown. At that rate, I can expect it to give me another 4 years of usable life. By then, new lighter, higher capacity batteries will likely be available and I'll want to replace it anyway. It is also likely I will want a new bike by then as well. Conventional bikes can last for decades but e-bikes are far more complicated and have a considerably shorter lifespan. I see no sense in babying a battery to the point it outlasts the useful life of the bike.

Your personal charging strategy will depend a great deal on how you plan to use your bike and where you ride it.

Much has been posted here on EBR about battery care. By all means, do some searching and read on! In particular, check out the posts from our resident battery expert @Ravi Kempaiah.

Welcome to the forum and good luck with your bike!

 

[The banjo]

There are several strategies used for battery maintenance. Many prefer to use the 80 / 20 rule and store at 40 - 60%. These measures do indeed prolong battery life. Unfortunately, it also has an effect on range. For casual short distance riding, this isn't a problem. For longer rides, losing 20% of your battery capacity can become an issue.

I usually do 50 or more miles on an average ride. I prefer to store my battery at 40-60% and charge to 100% just before heading out. I rarely discharge below 20% but rather than walk the last few miles back, I have gone as low as 10% on a couple of occasions.

My battery is 3.5 years old and a recent bench test shows it has lost 9% of it's original capacity. Just how much of that loss is from age rather than use is unknown. At that rate, I can expect it to give me another 4 years of usable life. By then, new lighter, higher capacity batteries will likely be available and I'll want to replace it anyway. It is also likely I will want a new bike by then as well. Conventional bikes can last for decades but e-bikes are far more complicated and have a considerably shorter lifespan. I see no sense in babying a battery to the point it outlasts the useful life of the bike.

Your personal charging strategy will depend a great deal on how you plan to use your bike and where you ride it.

Much has been posted here on EBR about battery care. By all means, do some searching and read on! In particular, check out the posts from our resident battery expert @Ravi Kempaiah.

Welcome to the forum and good luck with your bike!

I usually ride my bike 6 to 12 kms. a day which I think is enough to keep me going. I am a very active 77 years old. The battery at the moment is showing 35.9 volts. Is it time to give it its second 12 hour charge?
On a second point. How do I thank all responders to my original question without answering everyone individually

 

[6zfshdb]

On a second point. How do I thank all responders to my original question without answering everyone individually

Just click the "Like" symbol in the lower right of each response you find useful.

 

[harryS]

I usually ride my bike 6 to 12 kms. a day which I think is enough to keep me going. I am a very active 77 years old. The battery at the moment is showing 35.9 volts. Is it time to give it its second 12 hour charge?

Yes, for me, it would be time to recharge. You're at 45%, and you don't help your battery by running it lower..

A second 12 hour charge is too long if you want to be at 80%. Your battery will be fully charged at 100% after 3-4 hours. I say that because most chargers are 2 amps, so you get 2AH per hour. You're at 45%, so you've used about 7AH out of your battery. So 3.5 hours to recharge. Do you see how the math works?

Give it two hours of charge time. Check the voltage and reference the above chart. Add more time as needed,.

 

[RunForTheHills]

Battery obsession is a modern day problem and not just with bikes. Personally, I try not to leave it at 100% over night, but I do charge it up to 100% before a longer ride as @6zfshdb suggested. I have left it at 100% overnight occasionally though. If that means that I get 5% less battery life, I guess my somewhat lazy approach will cost me an extra $30 - $40 as I will have to buy a new battery a little bit sooner.

 

[harryS]

Wanted to give Mr. Banjo some pointers about this 80 percent stuff. I don't have big enough batteries to even give up 10%,. I charge mine full after every ride.

 

[The banjo]

Battery obsession is a modern day problem and not just with bikes. Personally, I try not to leave it at 100% over night, but I do charge it up to 100% before a longer ride as @6zfshdb suggested. I have left it at 100% overnight occasionally though. If that means that I get 5% less battery life, I guess my somewhat lazy approach will cost me an extra $30 - $40 as I will have to buy a new battery a little bit sooner.

Thanks for the input. There are 4 pages of the manual dedicated to battery care & maintenance. It says "you will need to cycle charge the battery for 12 hrs. for the first three charges. This will ensure the battery can hold the correct amount of charge"
What they mean by "cycle charge" I'm not sure. It is just a simple 42 Volt 2.0 amp. charger with a small red "charging" light which turns green when fully charged. The charger paperwork says it is a "switch mode power supply" I put it on a timer which shut off after 12 hrs. So- assuming that I know less than the author of the instructions I just stick to their instructions. I think there would be a more sophisticated charger available. I e-mailed Luna in the States - they don't make a 240 V charger and a 110v to 240 V step up transformer would cost as much as the charger & its postage. I am impressed with this forum so will follow it.

 

[RunForTheHills]

Most chargers do not have a lot of intelligence. The battery management system (BMS) is built into the battery. The BMS should try to balance the cells if you leave the battery on the charger for an extended period of time. I am not sure why you would need to do that for three charges in a row though. Once a month should be enough. Lithium-ion batteries do not have a memory effect.

 

[Mike_V]

I have just joined the forum and was reading a very good article on batteries & charging yesterday which basically stated that to prolong battery life it is best to charge a battery to 8o%. Does this 80% refer to the full charge voltage or the nominal voltage? My bike has a Samsung 14.5AH 36v, 520W, battery and 250watt motor. I would like to get my charging strategy organized up front.

Hoi Banjo !
Charge it up full, ride and repeat.
Because: ' Articles ' are old anecdotes about battery packs with various quality of manufacturing.
Here's the data: Negligible capacity loss for Samsung over hundreds of full cycles.
Ref. https://endless-sphere.com/forums/viewtopic.php?f=14&t=103092&start=425

 

[m@Robertson]

Hoi Banjo !
Charge it up full, ride and repeat.

That pretty much flies in the face of every resource, everywhere unless you put some context in. How long was the 100% charge held, for instance? If you charge to 100% and immediately go for a ride, there's far less damage to the internal cell chemistry than there is if you charge to 100% overnight and let it sit from 2am until noon when you go for your ride. Or 3 days later. What was the charge amperage? 1 amp? 5 amps? Do you think that matters? What was the discharge? a steady 1 amp? 30 amps? Do you think that matters?

This is a far more complex subject than you are letting on. I agree that if someone wants to go out and enjoy their ebike, they should. Charge the bejesus out of it. But be smart about it and don't piss away your investment. Li-ion batteries have a finite life cycle made shorter by certain behaviors. Blowing that off is not giving responsible advice.

EDIT: Spend just a bit of time reading the posts in that thread and you'll see even the test author is acknowledging these are lab tests and not real world tests. Its good data but not what @Mike_V is representing it to be. For the record I have a Samsung 25R pack whose life is well over 2000 cycles and still appears to be at full capacity... but I have specific charge protocols that are WAY more involved than normal people want to get into messing with to get a pack to live that long. I have another 25R pack not treated so well - and not built so well (thanks for nothing UPP Battery) that degraded significantly in an annoyingly short period of time.

 

[m@Robertson]

Thanks for the input. There are 4 pages of the manual dedicated to battery care & maintenance. It says "you will need to cycle charge the battery for 12 hrs. for the first three charges. This will ensure the battery can hold the correct amount of charge"
What they mean by "cycle charge" I'm not sure. It is just a simple 42 Volt 2.0 amp. charger with a small red "charging" light which turns green when fully charged. The charger paperwork says it is a "switch mode power supply" I put it on a timer which shut off after 12 hrs. So- assuming that I know less than the author of the instructions I just stick to their instructions. I think there would be a more sophisticated charger available. I e-mailed Luna in the States - they don't make a 240 V charger and a 110v to 240 V step up transformer would cost as much as the charger & its postage. I am impressed with this forum so will follow it.

I think I have a 240v capable option for you. Mean Well LED power supplies use CC+CV modes (whats commonly called smart charging) and will operate in a wide voltage range (90-305v) automatically. The units I made for my daughter and son-in-law in Belgium are the same ones I use in the USA. The only difference is the plug I put on the side that goes into the mains.

You can dial your current level, and your voltage level. Since its a potentiometer, you can adjust it to a different value if you feel like doing an 80% charge or a 100% balance charge. Speaking of which, the typical sequence is to do daily 80% charges, and then do a once-per-month 100% balance charge. And yes it usually lasts at least a couple hours when you have reached full voltage as a bank of cells can slowly trickle up to balance out with its siblings.

Here are the instructions on the charger. BTW I stopped using Luna chargers after the third failure (I charge a LOT so thats not as bad as it sounds). These Mean Wells I am talking about are normally used for municipal street sign applications so their MTBFs are in the (literally) hundreds of thousands of hours. No fans to go out. Rock solid for years of use.

An Ultra Reliable Ebike Battery Charger…

How about a charger – quickly adjustable for voltage and current – that is rated for hundreds of thousands of hours of use before it typically fails?

talesontwowheels.com

 

[harryS]

Banjo, If your battery has a balance BMS. then three long charges will ensure that it balances the battery. After that, it should stay in balance as long as you don't overload the motor, which overloads the battery. If you want only charge to 80%, then an occasional full charge is needed to rebalance the battery,

 

[The banjo]

Most chargers do not have a lot of intelligence. The battery management system (BMS) is built into the battery. The BMS should try to balance the cells if you leave the battery on the charger for an extended period of time. I am not sure why you would need to do that for three charges in a row though. Once a month should be enough. Lithium-ion batteries do not have a memory effect.

Yes I understand the BMS looks after things. There is so much info. on the web re. Li batteries it is mind boggling

Banjo, If your battery has a balance BMS. then three long charges will ensure that it balances the battery. After that, it should stay in balance as long as you don't overload the motor, which overloads the battery. If you want only charge to 80%, then an occasional full charge is needed to rebalance the battery,

I think it may have a balance feature - that's why they say to give it full charge the first three times.