Electric bike battery care

[6zfshdb]

Any thoughts here on the Satiator chargers? Are they worth using?

The Satiator is an excellent product although a bit pricey. There have been many posts on the product if you do a search. I own one but find myself using the OEM charger on a simple timer most of the time. It's fairly easy to estimate the charge time to get the % charge I want.

I would use the Satiator more but it doesn't play well with the BMS in my battery. Whenever I connect it, I get a message that says to "connect a battery" even though it is already connected. I have to discharge the battery slightly or connect the OEM charger first to get the Satiator to recognize it. Once I do this, the charger works fine. It's a pain though, so I wind up using the OEM charger instead.

Keep in mind, the problem is with my battery, not the Satiator. I'm not knocking the product in any way.

 

[Gionnirocket]

Never used one but from what I understand it is an excellent charger.
That said only owning one battery I can't justify the cost for my needs.
If you read other threads, such as this one, Battery Guide.... There are low tech alternatives such as the use of a timer.

 

[tomjasz]

I have several batteries making the Satiator invaluable. I can track the history of each battery.

 

[Handlebars]

I'm considering two ways of thinking about charging.
1. How a single cell's lifespan is affected by fully charging
2. How a battery pack of cells lifespan is affected by fully charging

If it were about a single cell I think I would always avoid fully charging it unless I value the playtime and performance more than the cell's lifespan. Say, if you give away your used batteries after you get the maximum performance out of them for a relatively short time.
With a battery pack it's not all that clear to me because "out of balance" becomes an issue.
I think I have that issue with my battery getting balanced because I see the fastest drop in voltage when it's 100% charged, but around perhaps 85% full I seem to get better mileage. I've never taken it below about 20%. I usually charge to 80% and do the long balancing charges once a month or so.
I've tried extra long charges, tried letting it have breaks to cool down, I even unplug it to see if it stays at 100% and then replugging.
The battery still does OK overall after daily use for 1 year in freezing weather and warm summer rides, have 2200 miles on it, not babying it when riding. 48V 17Ah gets me 36 miles on slightly hilly city riding/stop and go, if I take it to down to 20%.
It's seeing very quick drops from 100% that bothers me.

 

[Gionnirocket]

I'm considering two ways of thinking about charging.
1. How a single cell's lifespan is affected by fully charging
2. How a battery pack of cells lifespan is affected by fully charging

If it were about a single cell I think I would always avoid fully charging it unless I value the playtime and performance more than the cell's lifespan. Say, if you give away your used batteries after you get the maximum performance out of them for a relatively short time.
With a battery pack it's not all that clear to me because "out of balance" becomes an issue.
I think I have that issue with my battery getting balanced because I see the fastest drop in voltage when it's 100% charged, but around perhaps 85% full I seem to get better mileage. I've never taken it below about 20%. I usually charge to 80% and do the long balancing charges once a month or so.
I've tried extra long charges, tried letting it have breaks to cool down, I even unplug it to see if it stays at 100% and then replugging.
The battery still does OK overall after daily use for 1 year in freezing weather and warm summer rides, have 2200 miles on it, not babying it when riding. 17Ah gets me 36 miles on slightly hilly city riding/stop and go, if I take it to down to 20%.
It's seeing very quick drops from 100% that bothers me.

I don't know if I agree with your method to achieve a maximum balance charge and think that it can do more harm than good.
The correct way would be to use a very low amperage output charger, say 0.5a and let it reach 100% slowly.

I'll add... Most likely unnecessary.

 

[AHicks]

I don't know if I agree with your method to achieve a maximum balance charge and think that it can do more harm than good.
The correct way would be to use a very low amperage output charger, say 0.5a and let it reach 100% slowly.

I'll add... Most likely unnecessary.

If we are talking balance charging, I have a slightly different take. Very necessary... and should be done frequently when the bike is getting a lot of use. At least once a week.

 

[Gionnirocket]

If we are talking balance charging, I have a slightly different take. Very necessary... and should be done frequently when the bike is getting a lot of use. At least once a week.

No... I was referring to the method used, not the frequency.

 

[Handlebars]

I don't know if I agree with your method to achieve a maximum balance charge and think that it can do more harm than good.
The correct way would be to use a very low amperage output charger, say 0.5a and let it reach 100% slowly.

I'll add... Most likely unnecessary.

I'm using a 3 amp "Sans" charger. I should correct what I wrote to say I do not routinely stop the charge at 100% reading and then do more charging. Routinely, I would just let it do a long charge once a month or so, attempting to balance charge to full voltage. I've only unplugged and replugged a few times to see if that made any difference to the fast voltage drop from 100%. I do know that just charging to 100% does not bring the battery to full voltage but long charging does get very close.

 

[Handlebars]

No... I was referring to the method used, not the frequency.

What is your opinion, please, regarding best practice regarding the frequency of balance charging?

 

[Handlebars]

If we are talking balance charging, I have a slightly different take. Very necessary... and should be done frequently when the bike is getting a lot of use. At least once a week.

This is the area that is most unsure in my thinking. The lifespan graphs show single cell lifespan vs % of voltage ...100% charging gives you about 1/4 the lifespan of 80% charging, so I would just try to avoid 100 % charging in routine practice.
My guess is that with multi-cell packs all that changes and not balance charging regularly would bring degradation of at least some of the cells.
I haven't seen any charts showing the differences in pack lifespan between always 80% and always long balance charged, and the in-betweens.

 

[Gionnirocket]

There are so many variables when it comes to how a battery is used that I don't think myself as an authority on what everyone should do.
How low of a voltage you drop to and how fast you run it there along with operating temperature I would say are the key factors to consider.
The more aggressive you are with those, the more often I would fully charge to balance.

That said... And please someone correct me if I'm wrong.
I don't think most BMS's are that intelligent when it comes to balancing. From what I've seen they only have wires going to each series group, not each cell.. So at most it is balancing the series groups with each other, not individual cells. Still better than nothing, but not what most perceive.
Again, please correct me if I'm missing something here... but I know with hobby chargers and batteries each cell has its own pair of wires for balancing.

 

[AHicks]

I agree, just sharing what I've learned (the hard way).

My own opinion, so you can take it for what it's worth, is that there is nothing written in stone here. What you read about batteries may not have any direct correlation when it comes to our e-bike battery packs. Note very little is written about balance charging when discussing these "don't charge over 80%" theories. My opinions are based on what I've learned over the last 10-15 years using multi cell Lithium based technology in radio control "stuff". I do admit that max performance will be chosen over max possible lifespan every time here. If a battery is determined to be of "marginal" capacity it's pulled from service immediately.

 

[Gionnirocket]

The only way to have a better understanding would be an in depth study with multiple packs made with cells from the same lot and matched perfectly by internal resistance. Then run them identically but apply different charging practices and document the results.
Or
Charge up, go for a ride and say damn you my fickle Li-Ion friend

 

[6zfshdb]

Be it fact or fantasy, my philosophy on battery charging this this: When a Li-Ion battery "fails" it doesn't usually die completely all at once, it begins to lose capacity. If you're only charging to 80%, in effect, you've already lost 20%. Why not charge to 100% and enjoy the extra capacity while it lasts? In my case, I've been storing at 60 - 80% and charging to 100% just before a ride. My batteries are 3 years old now with no noticeable loss of capacity.

I almost always ride with 2 batteries. The combined capacity will get me 100 - 120 miles using PAS 1, which is more than I'm capable of riding in a day. The longest I've done so far is 68 miles. That means I can afford to lose almost 40% of total capacity without affecting my riding style. By that time, I'll likely be looking to replace the bike anyway, hopefully with one that has newer battery technology.

I see no sense in "babying" a battery to outlast the useful life of the bike.

 

[amosdecker]

I'm just south of you in Henderson and I wouldn't get an e-bike unless it was light enough for me to carry into the house, or, the battery is easily removable to store in the house. No way I'm leaving it in the 120F / 48.8C garage. That's like forgetting your laptop in your car in the garage - never going to happen.

A couple of systems that caught my eye while roaming around listed below. Onemotor looks like a great option. Though it will wear tires quicker, it solves the heat (and cold) problem as it's easily removable. The Brompton is in high demand, so don't expect to go online and purchase. Made in the UK, probably, maybe? a long wait list.

Onemotor

ff to around 5:05 in the below video for battery removal:

 

[Gionnirocket]

Be it fact or fantasy, my philosophy on battery charging this this: When a Li-Ion battery "fails" it doesn't usually die completely all at once, it begins to lose capacity. If you're only charging to 80%, in effect, you've already lost 20%. Why not charge to 100% and enjoy the extra capacity while it lasts? In my case, I've been storing at 60 - 80% and charging to 100% just before a ride. My batteries are 3 years old now with no noticeable loss of capacity.

I almost always ride with 2 batteries. The combined capacity will get me 100 - 120 miles using PAS 1, which is more than I'm capable of riding in a day. The longest I've done so far is 68 miles. That means I can afford to lose almost 40% of total capacity without affecting my riding style. By that time, I'll likely be looking to replace the bike anyway, hopefully with one that has newer battery technology.

I see no sense in "babying" a battery to outlast the useful life of the bike.

My take is to use the bike as I please and charge using the best practical practices. I would never sacrifice a rides enjoyment worrying about my battery.
Take my typical ride... I usually do about 20 miles a day and only burn a volt as I enjoy pedaling. If I use my battery between 40 - 80% (42.5V- 50.5V) I get a weeks rides per charge. It's really no inconvenience and I haven't lost anything by not charging to 100%... even more so now that I made my little solar charge controller hack to help me easily charge to whatever voltage I want.
I hoping this fall to take some weekend biking trips. At that point I'll charge to 100% daily and not lose any sleep.

 

[AHicks]

When it comes to a battery pack really heading south on me, what I notice first most often is that it will no longer balance charge. The charge light doesn't go out as soon as it normally does. That pack may even be warm to the touch. It's done. Don't try and save it. That's the stuff that causes fires....

For somebody that really knows what they are doing, they can go in, identify the bad cell(s) and replace them.

 

[cstoebe]

I use the Luna Charger ($85) for my2 48v ebikes. I don't overheat them by charging them to 80% at 1 amp, and they are alway cool to the touch. I live in Verrado, AZ and I set the garage thermostat to 95 in the summer as I'm not about to take the bikes inside. An alternative would be to just use a timer on the factory charger but you would have to monitor it. Getting more involved, the luna doesn't shut off at the 80% mark after the batteries become more unbalance (many charges) Then just charge them to 100% and that re-balances. Yeah, I'm probably overdoing it but it's a hobby.

 

[tomjasz]

For somebody that really knows what they are doing, they can go in, identify the bad cell(s) and replace them.

IMO a bad idea. Unless it's a relatively new pack. I have the tools, welder, tester, and experience but simply changing out what will likely be mismatched cells is risky.YMMV

 

[Gionnirocket]

IMO a bad idea. Unless it's a relatively new pack. I have the tools, welder, tester, and experience but simply changing out what will likely be mismatched cells is risky.YMMV

So very true. Not matching manufacturer, age and internal resistance is a recipe for disaster