How to Best Charge Battery for Longest Life

[Reid]

I wish I could charge to just 70%, but then at the end of my ride I'd be at 15%-30% depending on the weather of the day. So I go to 80% so I end at roughly 30%-40% on average. Plus, I like the performance in the 50%+ area on my bike!

Opinion essay.

Our batteries require occasional balancing charges. Charge to 100%. If we do not balance charge on some sort of more or less regular basis,

then any weak sister among the cells is liable to reverse charge on a deep discharge and cause the pack to shut down.

Point: if battery pack makers designed the BMS for maximum life span of the pack's cells, that is, charging a "48V" pack NOT to 54.6V, but, instead, charging only to a lower terminal voltage, pack life would be extended greatly. We would not obsess about charging only to 80%, for instance...

Many of us do not need to milk maximum range from each pound of battery pack weight.

And for us (I think that might be almost all of us), a BMS set to a lower, battery-conserving terminal voltage, would automatically give us the best battery pack lifespan, and therefore, truer economy. If this meant, in effect, a pack five pounds heavier for a given, long milage range, so be it. That would be only about a ten percent bike increase in weight-penalty for a much longer pack life.

For myself, it does not matter. I pedal my bike manually as much as I can because it is both easy to pedal and I don't have to make long trips. My needs and likes are not yours, probably. And I do not even need to maximize pack life. I'll buy a new pack when my standard CCS pack becomes too low capacity.

But heck, lower charging equals longer pack life.

But the BMS at present only balances the cells of a pack when you give the pack a full and cell life-shortening, 4.20V-per-cell charge. 4.2V per cell is an energy density ideal. But at the great expense of cell lifespan.

Also, how often should a person who only charges to say, 80%, instead do a full charge for the cell balancing act that won't be done by 80% charging? How can he know he is adequately balancing cells if he is flying blind?

 

[MisterBritcom]

I charge to 80 or 85% for my daily commute and do a full balance charge about once a month. This is based on anecdotal evidence from other users and what I've read from more scientific articles on the subject.
If I used my battery less often, I'd balance charge four times a year.

 

[Slipperyrick]

I have a 4 mile commute and would be able to charge the battery everyday after the commute. Is it best to keep it topped off after every ride or wait until it's more depleted? I'm not sure if it's the number of charge cycles that is hardest on the battery or how much it has to charge each time. Any thoughts?

It is hard to define it exactly. Everything is moving along the curve on the graph. At some point of charging we have to consider it "1 cycle" but basically the current thinking is that charging it from 20% to 80% gives the best life span vs. useable capacity.

Partial charging is not as harmful as full charging. Deep discharging and full charging decreases cycle life. High discharge and high charge rate also decrease charge cycles.

In a nutshell, use the middle part of the pack unless you need extra capacity, in which case charge it all they way up. Use the Cycle Satiator to charge to 80% (or wherever) then use the Low Voltage Limit on the LCD display to control the depth of the discharge.

So with a 12.8 battery what would I charge it to to reach 80%?

 

[MisterBritcom]

So with a 12.8 battery what would I charge it to to reach 80%?

51.5 volts

 

[Slipperyrick]

I wish I could charge to just 70%, but then at the end of my ride I'd be at 15%-30% depending on the weather of the day. So I go to 80% so I end at roughly 30%-40% on average. Plus, I like the performance in the 50%+ area on my bike!

51.5

51.5 volts

Thank you! And am I correct in understanding I don't want it to go below 40 volts?

 

[MisterBritcom]

I believe 40 volts is 20%. If your bike is like my Crosscurrent S you'll notice the pedal assist and throttle functions start to drop off at about 46 volts. I assume the software is set up to ration power and extend range at lower charge levels.

 

[Slipperyrick]

I believe 40 volts is 20%. If your bike is like my Crosscurrent S you'll notice the pedal assist and throttle functions start to drop off at about 46 volts. I assume the software is set up to ration power and extend range at lower charge levels.

Excellent thanks for your help

 

[Bruce Arnold]

40 volts is too low. You would run a real risk of stressing your battery, which will affect battery life. 20% is 42V. I've gotten down to 42V twice. You have very little pedal assist or throttle at that point. At 44V you notice a huge drop in performance. Performance and voltage both plummet quickly from 44 to 42V. It's like that half-gallon fuel reserve on my old Honda 550K - don't plan on going very far with it. (Don't ask me how I know this.)

Practically speaking, I plan not to get below 46V. Partly because I prefer to have more of a reserve, just in case, and because performance moves from "meh, good enough but no zip" to "kinda sluggish."

However, some of us have gone into Settings and set 40V as the Minimum Cut-Off level.

Any lower is, frankly, nuts.

It seems that if you set it at 42, which ought to make sense, then the sluggishness at 46V is worse. There is unconfirmed speculation that the controller starts to cut back the current at some percentage above the MCO point to ration what remains. So I set it at 40 and just watch the volts myself.

 

[Asher]

Regarding preserving power.... Earlier I was critical of the CCS lack of a zero power mode, but perhaps that was unwarranted. A nice compromise is to set the speed limit below a speed you can pedal at without power, say 15+ mph. Then, the bike will only offer help when you're below that speed - chiefly accelerating from a stop or going uphill.

This is almost as good as having an unpowered option, though it (arguably) requires stopping the bike to navigate the tiny menu to change the speed limit.

 

[MisterBritcom]

Bruce is correct, 42 volts is 20%. I rarely get below 46 volts because of the loss of performance at that mark.

 

[Gator]

Reading my Ebike handbook, the manufacturer states that the battery should be fully charged and discharged 15 times before doing partial charges. Does anyone know the reason for this? I have timed my charges so that the battery does not stay on the charger too long. It fully charges in 4.5 hours usually.

 

[Bruce Arnold]

Reading my Ebike handbook, the manufacturer states that the battery should be fully charged and discharged 15 times before doing partial charges. Does anyone know the reason for this? I have timed my charges so that the battery does not stay on the charger too long. It fully charges in 4.5 hours usually.

Going below 20% is likely to overstress a battery no matter how new it is, so please consider this to be as "fully discharged" as you are going to go. In a pinch, you might go lower, but only with extreme caution about how much load you put on the battery. Acceleration, especially especially from a full stop, would be the most likely stressor.

There is anecdotal evidence - lots of it, from various fields that use Li-ion batteries - that a couple of cycles of a safely deep discharge followed by a full charge primes the battery to give its best performance. There is disagreement on this point here on EBR, so while my experience supports the practice, people I respect consider it nonsense. We'll never know for sure until someone with a proper testing facility does the study.

I think there would be unanimous agreement that 15 cycles would be overkill, kind of silly, and possibly detracting from the useful lifetime of the battery.

 

[jazz]

Even if you charged it up to 100% every time, a good pack should still last you at least 3 years and probably more. Replacing or rebuilding packs is getting cheaper every year. I suspect by 2021, they will be better if not cheaper batteries available. For now, just charge up your bike and use it. Don't worry about 70%, 80% or 20%. The only thing to remember is that if you are going to not use it for several weeks or months, leave it 1/2 charged and you will be fine.

In my experience it is best to use it and not stress over how you should charge the batteries so much.

I just rebuilt a battery pack I had for just over 5 years. Cost me $200 and time and I got an extra 2ah out of the same case. I always charged it to 100%, even when I left it during the winter. I got that bike & battery in 2013. I also have a 2014 ebike, still on the original battery always charged to 100%, and good. One of my electric motorcycles is 8 years old, original LifePo4 batteries, always charged to 100%, very little degradation so far.

 

[Asher]

Even if you charged it up to 100% every time, a good pack should still last you at least 3 years and probably more. Replacing or rebuilding packs is getting cheaper every year. I suspect by 2021, they will be better if not cheaper batteries available. For now, just charge up your bike and use it. Don't worry about 70%, 80% or 20%. The only thing to remember is that if you are going to not use it for several weeks or months, leave it 1/2 charged and you will be fine.

In my experience it is best to use it and not stress over how you should charge the batteries so much.

I just rebuilt a battery pack I had for just over 5 years. Cost me $200 and time and I got an extra 2ah out of the same case. I always charged it to 100%, even when I left it during the winter. I got that bike & battery in 2013. I also have a 2014 ebike, still on the original battery always charged to 100%, and good. One of my electric motorcycles is 8 years old, original LifePo4 batteries, always charged to 100%, very little degradation so far.

I looked into repacking services briefly, and there aren't many, maybe one in Nevada? Do you know of others?

Also, it may be a matter of time until high American labor costs and declining battery prices make repacking less competitive.

 

[Bruce Arnold]

I'm anticipating a couple of battery improvements that will make me want to buy a brand new battery when they come out.

The first one is battery packs with the new 21700 cells. Higher energy density, lower heat. This is an incremental change but I hope the ebike companies will adopt it.

The second one is supercapacitors in combination with Li-Ion cells. Supercaps can be quickly charged, have over a million re-charge cycles, and can support high current draw without degradation. Imagine being able to replace 25% of your wattage in 5 seconds. Low temps for charging and discharging. Configure the controller so that it draws on the supercap for acceleration and the chemical battery for cruising and your chemical battery will last a lot longer. The Fully Charged Show went to Estonia to talk to a company that is turning these puppies out for various kinds of use, including vehicular. It's only a matter of time before a smaller version perfect for ebikes is married to our existing batteries.

And I'm already saving for Juiced Bikes 52V 21Ah battery; if those two developments take time to emerge, I'm not going to kill my current battery before I get another one.

So I'm with Jazz on this one. My charger takes my battery up to 95%, and that's what I do, every time, without trying to cut it off at some lower percentage.

 

[Reid]

I rarely ride any great distance but, nonetheless,

I want that bike fully charged, just so it is as primed as possible, in case I were to want to travel relatively far.

Battery capacity lifespan is not as important to me as a full range always available. Even if I never use it.

From practical posts above it sounds like I don't need to worry that I will have an unsatisfactory battery pack within two years, at least. And that will be long enough for me. By then, better packs may be available. Better bikes, too.

Can't think of many transport devices cheaper to run and more useful to my daily life than the CCS. Saves me two bills per month on insurance I don't need anymore. The battery pack life, whatever it works out to be, is a virtual gift.

I am today seven months into CCS ownership. I had a bit of a crash. I had an infant mortality (first week) battery pack failure quickly rectified by Juiced Bikes. I had a failure of the display that took a few weeks to get replaced. The bike works gangbusters.

 

[Bruce Arnold]

Totally agree, Reid. Also, even when I know I'm not going far, I enjoy the zippy performance of a charged-up battery, which is much more fun than the totally-adequate-gets-the-job-done-quite-handily performance between, say, 50 to 75% of battery capacity.

If we had the 52V jobs, this would be much less of an issue. Even one of those 52V, 13Ah batteries they're putting on the Scramblers would provide the thrill on most of my rides. (But I really want the 21Ah battery for my increasingly longer rides.)

 

[Slipperyrick]

I rarely ride any great distance but, nonetheless,

I want that bike fully charged, just so it is as primed as possible, in case I were to want to travel relatively far.

Battery capacity lifespan is not as important to me as a full range always available. Even if I never use it.

From practical posts above it sounds like I don't need to worry that I will have an unsatisfactory battery pack within two years, at least. And that will be long enough for me. By then, better packs may be available. Better bikes, too.

Can't think of many transport devices cheaper to run and more useful to my daily life than the CCS. Saves me two bills per month on insurance I don't need anymore. The battery pack life, whatever it works out to be, is a virtual gift.

I am today seven months into CCS ownership. I had a bit of a crash. I had an infant mortality (first week) battery pack failure quickly rectified by Juiced Bikes. I had a failure of the display that took a few weeks to get replaced. The bike works gangbusters. The bike is my preferred car (that word is short for carriage).

Battery pack life is not the priority so much as the CCS' life of always-ready assistance to help me get out and go, this horse power of a different color, this equitable electric equine that does not ask for sugar cubes or currying.

(over nine years ago)

(nineteen thirty-nine)

I forgive Ron Nelson his perjury, from

me,

a horse of a different color.

I had quite the experience yesterday. First commute home, taking a more bike friendly route. I took a left instead of a right, before you know it a 12 mile commute was 18. I just charged a full battery trying to figure out what I'd need to get home. I'm really happy I did, I had plenty of juice getting home.

 

[tomjasz]

I'm anticipating a couple of battery improvements that will make me want to buy a brand new battery when they come out.

The first one is battery packs with the new 21700 cells. Higher energy density, lower heat. This is an incremental change but I hope the ebike companies will adopt it.

The second one is supercapacitors in combination with Li-Ion cells. Supercaps can be quickly charged, have over a million re-charge cycles, and can support high current draw without degradation. Imagine being able to replace 25% of your wattage in 5 seconds. Low temps for charging and discharging. Configure the controller so that it draws on the supercap for acceleration and the chemical battery for cruising and your chemical battery will last a lot longer. The Fully Charged Show went to Estonia to talk to a company that is turning these puppies out for various kinds of use, including vehicular. It's only a matter of time before a smaller version perfect for ebikes is married to our existing batteries.

And I'm already saving for Juiced Bikes 52V 21Ah battery; if those two developments take time to emerge, I'm not going to kill my current battery before I get another one.

So I'm with Jazz on this one. My charger takes my battery up to 95%, and that's what I do, every time, without trying to cut it off at some lower percentage.

The data and research is pretty clear. If you’re happy with the life cycle you get out of a battery, then by all means follow Jazz’ logic. He makes sense. But grandpa here is very happy with 18650 cells, plenty of power, and 20%-80% charge zone works very well for me. My two first bikes have 36V batteries. Identical except by management. After 4 years the Satiator battery is as new. I followed the best information I could find. The other on my wife’s bike was charged willy nilly, no rhyme, reason or much attention. Just plug in the 2A fabless. It sags so badly only she can ride wit that battery. She always pedals here BBS01 with level 2(of 5) PAS. Now the same cells are half the cost, making fussing at her not worth the drama. But some want to extract the maximum effective use and some of us want to make the best possible use before recycling.

Now let me be clear. This does not make me a better rider, builder, or human being. Just another view. From a tight wad curmudgeon. We’re actually going the opposite of the market. Slowing our bikes down, building more 36v batteries, and packs as small as possible. Without stressing the pack under use. (I still have a 30+ MPH bike but I ride it only in light traffic days. These farmers around here are stupidly unaware of how to judge PTW speeds. Fooking left turns on me every time I’m running in a hurry in peak traffic.

I have 3 customers that use electrical timers and laugh at the cost of a Satiator. Fortunately the opinions haven’t turn bitter like politics. Great discussions here. The level of respect. Between posters is awesome.

 

[Asher]

Lol at infant mortality Reid.

Bruce, are these super capacitors in production with any ebikes or even cars?

We always hear about battery tech that is just around the corner, but never comes to fruition. 21700 of course is already available (see Luna Apex). The next change might be solid state batteries, which car companies are pushing into aggressively. Maybe 5 years from now.