Any numbers on extended battery life with not full charging?

[rich c]

It's commonly considered the perfect battery pack treatment to not charge to 100%. How much extra life do we get with the 80% charge? Every charge I've done on my Bosch packs is till the charger shuts off. Two packs are on model two 2016 Haibikes, so assume the packs were made in late 2015. 5 years and they seem just fine. Could I have expected 10 year life if I had not charged them fully each time? Any research with a life vs full charging cycles?

 

[Ravi Kempaiah]

It's commonly considered the perfect battery pack treatment to not charge to 100%. How much extra life do we get with the 80% charge? Every charge I've done on my Bosch packs is till the charger shuts off. Two packs are on model two 2016 Haibikes, so assume the packs were made in late 2015. 5 years and they seem just fine. Could I have expected 10 year life if I had not charged them fully each time? Any research with a life vs full charging cycles?

It depends a lot on your mileage. if you are doing <3000 miles a year, then you won't notice it.
But if you were doing 8,000+ miles a year, for sure you will notice it. If you are charging and fully depleting the battery on a daily basis, in about 1 year, you will notice a drop in range.

Let's say you have about 4000 miles in 2 years, that means roughly 100 cycles if we assume 40 mile range. The drop in capacity becomes pronounced after about 250 cycles. It is not a linear drop.

If you plug in your bike to the Bosch diagnostic tool, you get a report mentioning the number of charge cycles and battery health. Have you tried doing that?

 

[Alex M]

How much extra life do we get with the 80% charge? Every charge I've done on my Bosch packs is till the charger shuts off. Two packs are on model two 2016 Haibikes, so assume the packs were made in late 2015. 5 years and they seem just fine. Could I have expected 10 year life if I had not charged them fully each time? Any research with a life vs full charging cycles?

Plenty of research.

Nissan Leaf battery, DST - dynamic stress test reflecting capacity loss.
In theory - yes, you could double the life of your Bosch by running 85-25% instead of 100-25%.
But there are many variables, I wrote about this in another post couple days ago.
There is balancing - unlikely you will get it right when charging to 85% only. Unbalanced pack will show signs of decay sooner. For this reason, I would charge it to at least 90%.
Also, it's aging with time even when you're not using it, this process begins on the day one and never stops. So you might get 8 years at 85-25 cycle VS 4 years at 100-25 (assuming same annual mileage), but only 10 years vs 6, i.e. less than a double.

Note that 85-25 means you're using mere 60% of nominal capacity, while at 100-25 it's 75%, so your range will be a bit shorter.

 

[rich c]

It depends a lot on your mileage. if you are doing <3000 miles a year, then you won't notice it.
But if you were doing 8,000+ miles a year, for sure you will notice it. If you are charging and fully depleting the battery on a daily basis, in about 1 year, you will notice a drop in range.

Let's say you have about 4000 miles in 2 years, that means roughly 100 cycles if we assume 40 mile range. The drop in capacity becomes pronounced after about 250 cycles. It is not a linear drop.

If you plug in your bike to the Bosch diagnostic tool, you get a report mentioning the number of charge cycles and battery health. Have you tried doing that?

Thanks Ravi, I've never had the bikes back to the dealer since the day I road them out of Lenny's on Nov 2016 and Mar 2017. I've put on about 1,500 miles a year on each since then, so no wonder I haven't noticed anything. Just curious since the 80% mantra is relayed so often.

 

[Deleted member 4210]

It's commonly considered the perfect battery pack treatment to not charge to 100%. How much extra life do we get with the 80% charge? Every charge I've done on my Bosch packs is till the charger shuts off. Two packs are on model two 2016 Haibikes, so assume the packs were made in late 2015. 5 years and they seem just fine. Could I have expected 10 year life if I had not charged them fully each time? Any research with a life vs full charging cycles?

Not charging to 100% is a great way to shorten the life of the battery, as your individual cell voltages will never get properly and fully balanced with each other. Supposedly cycle satiators do that, but I know two customers who killed off their expensive samsung and panasonic batteries by trying to do it on their own, using a timer or other guessitmate measures at when they reached "80%' or something thereabouts. Their batteries lasted about 18 - 20 months in each case. Not fully depleting the battery can certainly help, as the charger is starting to charge at a point where it doesn't affect the life as much as a full depletion. People are often citing Tesla's charge process for ebike batteries, but Tesla's charging software and pack design is significantly more sophisticated than anything you'd ever find on products for ebikes. Just not worth the effort to get cute with battery charging.

 

[RabH]

When I was cycling at the weekend only (pre lockdown) I would charge to around 80% and the day before I was going on a trip I would charge to between 95-98%, every once in a while I charge it fully! My bike is now 27 months old and has covered 9,700 miles, the ride control app shows my battery health at 97 from 143 cycles! When the bike was new my range in eco mode in the factory setting was 85 miles and is currently showing a range of 81 miles, I haven't noticed any degradation as yet but its not very old so I'm not sure if this info helps in any way!

 

[Sierratim]

It's commonly considered the perfect battery pack treatment to not charge to 100%. How much extra life do we get with the 80% charge? Every charge I've done on my Bosch packs is till the charger shuts off. Two packs are on model two 2016 Haibikes, so assume the packs were made in late 2015. 5 years and they seem just fine. Could I have expected 10 year life if I had not charged them fully each time? Any research with a life vs full charging cycles?

Battery University has a number of good articles on lithium battery life vs charge levels. Here's a couple to start with;

Charging Lithium-Ion Batteries

Review simple guidelines for charging Lithium-based batteries and prolong battery life such as; a portable device should be turned off while charging and more.

batteryuniversity.com

BU-808: How to Prolong Lithium-based Batteries

BU meta description needed...

batteryuniversity.com

Basically, limiting the charge and discharge voltages to a narrower range will increase battery life but of course limit battery capacity. This can be dramatic with very limited SoC range, but from a practical standpoint limiting your battery to a range of 80% max - 20% min will achieve a good balance between maximizing both battery life and capacity. How much longer might the battery last? Battery University offers this somewhat complicated answer;

85–25% SoC has 2,000 cycles to 90% capacity. Uses 60% of battery capacity. This is double the life of a battery cycled 100-25% SoC.

I personally choose not to worry about this. My battery pack has a 300 cycle warranty to a minimum 75% capacity meaning that after about 8 years of my typical use the battery will still be able to deliver 75% of its original 600wh capacity. I could extend this with special charging limits, but 8 years is good enough for me, esp considering that I'm in my 70's...

BTW - battery storage conditions also have a sizable impact on battery life. Temperature and SoC are reported to be the most important variables. Keeping the battery at room temps and at about 50% SoC in storage is recommended.

 

[Alex M]

Battery University has a number of good articles on lithium battery life vs charge levels. Here's a couple to start with;

Charging Lithium-Ion Batteries

Review simple guidelines for charging Lithium-based batteries and prolong battery life such as; a portable device should be turned off while charging and more.

batteryuniversity.com

BU-808: How to Prolong Lithium-based Batteries

BU meta description needed...

batteryuniversity.com

Basically, limiting the charge and discharge voltages to a narrower range will increase battery life but of course limit battery capacity. This can be dramatic with very limited SoC range, but from a practical standpoint limiting your battery to a range of 80% max - 20% min will achieve a good balance between maximizing both battery life and capacity. How much longer might the battery last? Battery University offers this somewhat complicated answer;

View attachment 57528

Yes. Battery U is a good source. I tried to link this graph earlier, it showed in Preview but disappeared later.

Cycling close to the middle is the key - but e-bike pack is different from Nissan Leaf, there is a balancing issue, so it's better to charge it higher than 85%.
Not discharging all the way to the bottom still helps, and so does prolonged storage with 40-60% charge VS 90-100% (say, one week or longer) .

80% is not a mantra, it's the truth, but for an e-bike pack this isn't a good idea because of the balancing.

Note that these graphs are at 20C (68F), this is what battery wants. Higher temps of operation and storage will shorten the life.

 

[Alex M]

When I was cycling at the weekend only (pre lockdown) I would charge to around 80% and the day before I was going on a trip I would charge to between 95-98%, every once in a while I charge it fully!

I would tune this process up a little.
80% is a bit high for storage, optimal SOC in this case is 40-60%.

 

[RabH]

I would tune this process up a little.
80% is a bit high for storage, optimal SOC in this case is 40-60%.

The bike gets used every week so I'm assuming this wouldn't matter? its not like its sitting for weeks without use!

 

[FlatSix911]

It's commonly considered the perfect battery pack treatment to not charge to 100%. How much extra life do we get with the 80% charge?

Every charge I've done on my Bosch packs is till the charger shuts off. Two packs are on model two 2016 Haibikes, so assume the packs were made in late 2015. 5 years and they seem just fine.

Could I have expected 10 year life if I had not charged them fully each time? Any research with a life vs full charging cycles?

Here is a simple graph to help answer your question... you will triple the number of useful cycles (500 vs 1.500)

 

[zzRider]

Will a "smart" charger with over/under charging circuitry avoid some of these issues?

 

[Sierratim]

A programmable, or smart, charger can be setup so the charger cuts off before 100% SoC. A charger like Grin Tech's Satiator will dom this., https://www.ebikes.ca/product-info/cycle-satiator.html .

The lower cut off is up to you, you need to stop riding with assist when your battery gets to 20-25%.

 

[gringo]

I'm trying to use the timer method to charge a Bosch battery to roughly 80% while attached to bike (with purion) . Unfortunately, when doing this, the bike lights and Purion system turn on when the power switches off.

Is there any way to avoid this? Or is charging off the bike the only way to go ?


If I let it charge to 100% the Bosch System automatically shuts off. It would be nice if it did this whenever the power is cut before 100% charge rather than switching on the lights and draining the battery further.

 

[Dallant]

I just have to trust that Bosch has designed my battery/charger combination to do what’s right. The charger (or the battery) shuts down just when the fifth LED blinks off. If I’m supposed to stop the charger as soon as the fifth one just starts blinking, I would hope to hell Bosch would say so!

 

[Dallant]

I'm trying to use the timer method to charge a Bosch battery to roughly 80% while attached to bike (with purion) . Unfortunately, when doing this, the bike lights and Purion system turn on when the power switches off.

Is there any way to avoid this? Or is charging off the bike the only way to go ?


If I let it charge to 100% the Bosch System automatically shuts off. It would be nice if it did this whenever the power is cut before 100% charge rather than switching on the lights and draining the battery further.

Hmm, I only charged my Allant+7 Bosch battery once while in the bike and don’t remember the light being on.

 

[gringo]

Well...I just tried it again and this time the lights did not come on. I must have accidentally turned on the power last time. Disregard my question... sorry for my confusion!

You make a good point, perhaps just charge all the way and let Bosch battery management do it's thing.

 

[Bruce Arnold]

If I understand all this correctly, it's not necessary to balance the cells every time you charge. You could do the 20-80 thing most of the time, and a full charge once a month to get things balanced, and be alright.

So much of the problem with charging to 100% is leaving the battery in a fully-charged state for some period of time. If you top off to 100% before going for a nice long ride, you're not going to do any major damage. Maybe that's your once-a-month balancing session.

My charger from Juiced Bikes goes to 95%. This is as true for the 52V Scorpion battery as it was for the 48V CCS battery. What is said so seldom, is that every bit less than 100% still helps the battery's longevity. It doesn't have to be 80%. There's no magic in that figure. You will get more cycles doing a 20-80% thing, but you will also get more cycles doing 30-95%, just not as many more. So I often go ahead and charge to the full 95% that my charger gives me. Hopefully, the BMS is balancing the cells when I do that.

 

[FlatSix911]

Lithium cells only need to be balanced once or twice a year based on the number of full cycles.

The rest of the time you would benefit from charging to 80% to achieve the maximum number of cycles.

 

[-sandro-]

Lithium cells only need to be balanced once or twice a year based on the number of full cycles.

The rest of the time you would benefit from charging to 80% to achieve the maximum number of cycles.

Source for balancing thing?