Charging question - don't overcharge?

[Mr. Coffee]

Punk rock drivel.

"There is no such thing as exaggerated art. There is salvation only in the extremes."

--Salvadore Dali

Now, personally I think that Dali was a complete nutjob, but in this particular case he did have a point.

 

[Mr. Coffee]

Mr. Coffee: I do not think anyone negates the 20-80% rule. Only my 72 km ride of today required 86% of the battery charge to complete my trip. Should I really go on any ride with two or three heavy batteries?

No. But when you can and aren't planning a longer day your batteries will last much longer if you charge to 80 percent.

There are three reasons I think that we don't have legions of e-bike riders with dying batteries and perfectly good bikes:

1. Most people don't ride hard enough and far enough for it to matter very much.
2. A lot of folks who bought a lower-cost bike in the past probably outgrew it pretty soon and upgraded to a better bike and newer batteries.
3. The population of e-bikers is growing very rapidly. This means that as a total of the present e-biker population, the ones who have had an e-bike for more than three years are a small minority.

One thing we should keep in mind, this is an enthusiast forum. 99 percent of e-bikers out there wouldn't be interested in it and in what we have to say. I suppose they are too busy riding their bikes, in which case I think a lot of the posters here have much to learn from that 99 percent.

 

[Elkman]

Battery manufacturers tend to recommend having a battery ast 50% charge if it is not going to be used for months. Batteries are rated for XXX charge cycles and going from 20 to 100 SOC is one cycle as is going from 70 to 100 SOC. The more one does short charges to "top off" the battery the shorter its life overall.

For my part I can ride my bike with the power turned off and so I do not worry about heading out with 30% SOC or less.

 

[Stefan Mikes]

But when you can and aren't planning a longer day your batteries will last much longer if you charge to 80 percent.

I was trying that scheme out with my everyday e-bike (Vado SL) when I only owned a single Range Extender. I kept the main battery below 80% and instructed the system to only be discharging the Range Extender. As the outcome of that policy, the Range Extender was always at some SoC between 20 and 80%. When the Range Extender was just in its low state of charge, the disaster struck.

A close member of my was suddenly transported to a hospital because of a serious medical condition. I had to drop everything and start riding between home, the hospital, and her home to manage many things necessary. On low charge of my SL batteries. My notes remind me it was a very cold day (7 C perceived as 3 C) with strong wind of 25 km/h. Eventually, I had to ride for 74 km, a big part of the trip against the headwind. As I had to reduce the assistance greatly, I was crawling upwind so slowly a countryside "grandpa" on a ruined bike could take me over! The ride needed 275 Wh, was very slow, and I barely made it on batteries.

Not again. No one knows what Future holds. Any of my two e-bikes has to be ready for a long and fast trip in case of need. I will not be spending hours to recharge all batteries necessary for my long weekend rides either.

 

[Stefan Mikes]

This very morning, I learned one of my closest friends got hospitalized in Warsaw.
I wouldn't ride very far without at least two big Vado batteries charged to 100% and at the ready!

 

[AHicks]

No. But when you can and aren't planning a longer day your batteries will last much longer if you charge to 80 percent.

There are three reasons I think that we don't have legions of e-bike riders with dying batteries and perfectly good bikes:

1. Most people don't ride hard enough and far enough for it to matter very much.
2. A lot of folks who bought a lower-cost bike in the past probably outgrew it pretty soon and upgraded to a better bike and newer batteries.
3. The population of e-bikers is growing very rapidly. This means that as a total of the present e-biker population, the ones who have had an e-bike for more than three years are a small minority.

One thing we should keep in mind, this is an enthusiast forum. 99 percent of e-bikers out there wouldn't be interested in it and in what we have to say. I suppose they are too busy riding their bikes, in which case I think a lot of the posters here have much to learn from that 99 percent.

Kudos Mr. Coffee. Well thought out and said. -Al

 

[Nomad]

actually my charger shuts off and wont start again unless you plug in the battery again or the power to it is turned off and back on. it has to get a signal from the battery to start again.

actually if there is power to it can and usually does after prolonged use even if its high-quality system thou prolonged use could be a extreme amount of time if it can turn itself off and on at some point it will fail and do one or the other when it not supposed to

 

[m@Robertson]

--> Is this as bad as charging to 100% and leaving it there for 5 days?

No thats absolutely fine. And if you are going to charge to 100%, thats how to do it without consequences. The accelerated degradation to the cells happens over time and, if there is no time then you are fine. Less time is better, but 5 hours isn't going to end the world.

 

[m@Robertson]

Batteries are rated for XXX charge cycles and going from 20 to 100 SOC is one cycle as is going from 70 to 100 SOC. The more one does short charges to "top off" the battery the shorter its life overall.

No thats not true. A partial charge cycle is just that: Partial. Here follow this link:

BU-808: How to Prolong Lithium-based Batteries

BU meta description needed...

batteryuniversity.com

Look at Table 2: Depth of Discharge. This addresses the specific thing you are talking about. It is the reason for the '20' part of the 80/20 "rule".

To quote from the caption under the table

A partial discharge reduces stress and prolongs battery life, so does a partial charge...

And the data in the table bears this out. This is how my 2015 battery pack has had over 2,000 'cycles'. I am charging at home from 55.4v and draining it down to about 53v, lets say. Then I charge at work and get it up to around 56v, and take the long way home after work. Its down to 52v and I charge it back up again at home and repeat the cycle. If I have to run an errand during the workday, I'll hook up the charger in the morning at a higher amperage rate, then run the errand, and when I get back I hook it back up again. Also at a higher amp rate that will let me do a nice long ride again in the evening. And the last part of that same caption quoted above:

... Elevated temperature and high currents also affect cycle life

So when I say I am charging at higher amp rates, because of the above I charge at very low rates, so for me a high amp rate is going to be about 1 amp. Maybe 2. Thats the other part about charging: Heat is the biggest enemy so if you can do it, do your charging at low amp rates that do not heat up the battery. Everyone wants fast charging but its bad for the cells. I know I can charge my 32ah pack at 0.20 amps typically to be at a good level to go back home at the end of the day.

If you are just a weekend recreational rider this is overkill. If you ride every day and the bicycle is a tool for daily transportation, these benefits magnify significantly. Not many people here charge 2 or 3 times a day, I bet.

 

[fooferdoggie]

actually if there is power to it can and usually does after prolonged use even if its high-quality system thou prolonged use could be a extreme amount of time if it can turn itself off and on at some point it will fail and do one or the other when it not supposed to

But it does not. The charger waits for a connection before it will turn on. In fact you can’t even get the Bosch battery to change with a grin charger without some extra effort. The battery does not put out power till it receives a signal.

 

[tomjasz]

extra effort.

?

 

[fooferdoggie]

If you are just a weekend recreational rider this is overkill. If you ride every day and the bicycle is a tool for daily transportation, these benefits magnify significantly. Not many people here charge 2 or 3 times a day, I bet.

2 or three times a day how many miles do you ride? that would be about 120 to 150 miles a day for me.

 

[Stefan Mikes]

2 or three times a day how many miles do you ride? that would be about 120 to 150 miles a day for me.

Not if he rides a 1500 W motor in the full Turbo

 

[Nomad]

But it does not. The charger waits for a connection before it will turn on. In fact you can’t even get the Bosch battery to change with a grin charger without some extra effort. The battery does not put out power till it receives a signal.

ever seen an alternator over charge a battery it happens it's a system that designed not to do that but certain failures will cause that the point is leaving it plugged in for long periods after it's charged is a total unnecessary risk

 

[fooferdoggie]

ever seen an alternator over charge a battery it happens it's a system that designed not to do that but certain failures will cause that the point is leaving it plugged in for long periods after it's charged is a total unnecessary risk

thats where well designed system takes care of that. the battery turns off when its done charging. if you put a volt meter on it it will read zero. the charger also shuts off. its always good to disconnect the two but its not like msot setups either.

 

[m@Robertson]

2 or three times a day how many miles do you ride? that would be about 120 to 150 miles a day for me.

Remember what I'm saying above: As part of the practice of long term management, I am charging at lower amp rates. Before some knucklehead (not you) starts rending their garments and screaming about how difficult it is to do that, I just park the bike in my garage (I have one at work as well as at home) and there's a charger sitting there already, waiting to be plugged in. Look at the display in the photo above. I am charging at 0.20 amps. Only pushing about 11 watts. If you follow the science about batteries you know that fast charging generates heat, and heat is bad for battery life. Slow charging solves this, and since I have known down-time, I also know how low I can go and still maintain my desired charge level. Plus, truth be told, the 80/20 rule is better served by treating it as 80/40. Since as quoted by the source above, partial charges are better for the pack. I don't wait until its drained. If I park where there is a charger I plug in.

Remember also I am riding a cargo bike and oftentimes hauling stuff. Just my lock, for instance, is 14 lbs but thats what you do if your bike is transportation and you have to lock it up outside at stores every day. I spent this last Sunday riding a total of about 35 miles, with half of that loaded down with bricks and bicycle parts I was moving to storage (not the same day as the pic below, which Google tells me was on July 30).

Not if he rides a 1500 W motor in the full Turbo

On my Bullitt which is 2wd together as a pair the two motors working together eat about 450w.

Lets not forget this is no foo-foo boytoy bike. It has a job. It carries things. It does work. If all you know is what you own, you are ill-equipped to understand the needs of working ebikes. But if you pay attention, and apply yourself, and keep your mouth shut and your ears open... You can't help but learn.

 

[BioWheel]

I left my SL charging for a week and now Blevo says I can go 300 miles in ECO mode.

 

[Catalyzt]

Thanks for the replies. Of course, I'm asking this question after I had the first situation where I intentionally left both bikes 100% charged for 10 days.

Reason: Fear of blackouts. If the power died while I was out of town, and it was 100 degrees indoors, my wife and dogs could lie on a yoga pad on the floor being cooled by a trusty little USB fan hooked up to the battery-- one of those ridiculous pieces of junk one occasionally buys online that actually seems to last forever-- and keep her phone charged so she could call me to complain.

I hated doing it, but every day, the news was screaming "Rolling blackouts! Rolling blackouts!"

I am very good about not charging in the heat. And I could swear that I get better mileage from my battery on super hot days when I stop to let it cool off periodically, though that is completely unscientific. The range indicator seems to recover after I've rested in the shade for five minutes... or maybe it's just my range anxiety!

 

[dodgeman]

I can’t imagine having the battery charged 100% for 10 days is going to hurt anything. 10 weeks would be more of a problem.

 

[AHicks]

I can’t imagine having the battery charged 100% for 10 days is going to hurt anything. 10 weeks would be more of a problem.

As long as you don't make a habit out of it...... Sometimes ya gotta do what ya gotta do!