Battery Charge Limit ~ Voltage

[Brian_Gregory]

If I tell my Laptop 13 to only charge to 70% is that going to stop it charging its battery to over 4.2V per cell?
I do not like the idea of trusting that a battery manufacturer claims its cells can stand 4.4V without danger or harm to their life. Most normal cells that are only charged to 4.2V last much longer if not kept charged to nearly 4.2V too much.

[inffy]

No it wont change that. It only sets the limit how far the battery charges

[MJ1]

Not sure what percentage 4.2v would be.
Are you on linux?
You can try upower -e then upower -i [battery_path]. It should give you both the current percentage and current voltage, so you can then find the place it hits 4.2v.

@inffy

No it wont change that. It only sets the limit how far the battery charges

Charge percentage is directly related to voltage.

@Brian_Gregory

I do not like the idea of trusting that a battery manufacturer claims its cells can stand 4.4V without danger or harm to their life.

High voltage li-ions are made by all the major li-ion manufacturers. Furthermore, they are in millions upon million of mobile phones at this point. We’d know by now if it couldn’t be done safely. These are not just normal 4.2v cells which are overcharged, rather they are designed for higher voltage.

But of course you will get longer life from your battery by limiting charge. Arguablely less important in a Framework since we can replace the battery easily & at a reasonable price. Unlike most other laptops and especially mobile phones.

[amoun]

Yes that will work

I set mine to be approx 4.1V per cell via 78% in the BIOS

The Charge Level in HWiNFO shows 78.6% ~ reads high in Windows @ 79% (2 sig figs) and low in Ubuntu at 78% (Int)

I use HWiNFO and have a small window showing the state of the battery.

You can see my BCLevel is shown as 78.6% in HWiNFO64 and max voltage is under 16.4V i.e. 4.1V for each cell

After 20min

It may be safer, though I doubt that and neither has it helped my battery wear. I have a 12.5% wear after only 103 cycles, whereas the specs are 20% after 1000 cycles. I use my laptop plugged in 99% of the time and have reset the BMS a few times with a ‘full’ discharge and 100% charge.

This is a 28 month old 1165GT

You will also see I have edited the title as [Charge Limit] was vague and can cover many queries. I hope that’s OK.

Someone searching for just Charge + Limit would get this

https://community.frame.work/search?q=Charge%20LImit

Searching for

Search results for 'Charge LImit Voltage' - Framework Community will get this topic

[Brian_Gregory]

Thanks for all replies.
I think I will stick with my current policy of keeping the battery at 70% a lot of the time.

@MJ1

Are you on linux?

No, Windows 11.

@amoun

… and neither has it helped my battery wear. I have a 12.5% wear after only 103 cycles, whereas the specs are 20% after 1000 cycles.

It seems more likely to me that the manufacturer has been overconfident in the specification of their cells.

[Adrian_Joachim]

@Brian_Gregory

If I tell my Laptop 13 to only charge to 70% is that going to stop it charging its battery to over 4.2V per cell?

Charge limits on laptops are usually based on capacity not voltage, so it’ll charge till the bms thinks it’s at 70% of what it thinks the current capacity is. One side-effect of that is that it’ll gradually loose track of what 100% is because it never hits the top and probably very rarely the bottom.

[Kyle_Reis]

@amoun

I have a 12.5% wear after only 103 cycles, whereas the specs are 20% after 1000 cycles.

@Brian_Gregory

It seems more likely to me that the manufacturer has been overconfident in the specification of their cells.

Battery degradation tends to be very non-linear with the first 50 cycles often having a lot of wear. I’ve seen batteries drop to 95% capacity in the first 50 cycles but still have 90% capacity after 500 cycles.

12.5% at 103 cycles maybe seems slightly higher than I’d expect, but may well be within the normal range and doesn’t necessarily indicate that 20% at 1000 cycles on average is overconfident.

[amoun]

@Kyle_Reis

Battery degradation tends to be very non-linear with the first 50 cycles often having a lot of wear.

Yes that’s what I read but it was under 4% for 100 then went to 6% and then 12% in a week or two

@Adrian_Joachim

@Brian_Gregory

If I tell my Laptop 13 to only charge to 70% is that going to stop it charging its battery to over 4.2V per cell?

Charge limits on laptops are usually based on capacity not voltage, so it’ll charge till the bms thinks it’s at 70% of what it thinks the current capacity is. One side-effect of that is that it’ll gradually loose track of what 100% is because it never hits the top and probably very rarely the bottom.

The wording is crucial. Yes the limits are ‘set’ by capacity. However although the applied voltage to charge may be 17.2v the load of the battery, in my case at 78% brings that voltage down to 16.4v. And with me using plugged in most of the time the voltage stays at just under 16.4v pretty much all the time.

Still if I allow the battery charge to drop the voltage will go up to 17.2v untill the set charge level is reached.

So @Brian_Gregory yes the battery voltage will be limited to 4.1v if I use the laptop plugged in and charged to ‘my’ set limit.

if on the other hand I charge it on and off, no matter what the BCL it will be charged with 17.2V until it reaches the 78% in my case or the 70% it that was the choice.

[Adrian_Joachim]

@amoun

The wording is crucial. Yes the limits are ‘set’ by capacity. However although the applied voltage to charge may be 17.2v the load of the battery, in my case at 78% brings that voltage down to 16.4v. And with me using plugged in most of the time the voltage stays at just under 16.4v pretty much all the time.

What I am saying is it will charge to wherever the voltage goes when it put 70% of the Wh in there that it thinks there are when full. It does not care where the voltage ends up after that (as long as it stays within limits).

If you set it to 70% (so about 42.7Wh assuming 100% healthy battery) and it thinks it has 20Wh now it’ll put another 22.7Wh in there and call it done. So with capacity drift the end voltage will drift too.

[Brian_Gregory]

@Adrian_Joachim

Charge limits on laptops are usually based on capacity not voltage, so it’ll charge till the bms thinks it’s at 70% of what it thinks the current capacity is. One side-effect of that is that it’ll gradually lose track of what 100% is because it never hits the top and probably very rarely the bottom.

I would hope a good BMS would use a combination of voltage and charge/discharge energy along with a typical discharge curve to estimate what it doesn’t know for sure. But you’re right, no matter how good it is, it’s likely to need occasional help in the form of a full charge and a deep discharge.
And I’m definitely not saying I’ll never ever charge it to 100% or discharge it down to near 0%.

[Adrian_Joachim]

@Brian_Gregory

I would hope a good BMS would use a combination of voltage and charge/discharge energy along with a typical discharge curve to estimate what it doesn’t know for sure.

The things are pretty smart these days but stupid real world physics are notoriously hard to model.

[Brian_Gregory]

@Kyle_Reis

Battery degradation tends to be very non-linear with the first 50 cycles often having a lot of wear. I’ve seen batteries drop to 95% capacity in the first 50 cycles but still have 90% capacity after 500 cycles.

12.5% at 103 cycles maybe seems slightly higher than I’d expect, but may well be within the normal range and doesn’t necessarily indicate that 20% at 1000 cycles on average is overconfident.

That’s good to know. Hopefully, my suggestion that “the manufacturer has been overconfident” is largely wrong.
I guess I’m jaded by having recently seen Chinese cells marked 8800mAh that are actually under 800mAh and light as a feather.

[Kyle_Reis]

@amoun

Yes that’s what I read but it was under 4% for 100 then went to 6% and then 12% in a week or two

The wear level estimates are also not particularly accurate (they are after all estimates). My prior Thinkpad at one point had the wear level do the opposite of yours and go from 15% to 8% in about a week.

@Brian_Gregory

That’s good to know. Hopefully, my suggestion that “the manufacturer has been overconfident” is largely wrong.
I guess I’m jaded by having recently seen Chinese cells marked 8800mAh that are actually under 800mAh and light as a feather.

Yeah, there are a lot of Chinese cells that are straight up fraud (or sometimes truthful about their capacity but have some other major compromises that make them not worth buying).

[amoun]

@Brian_Gregory

it’s likely to need occasional help in the form of a full charge and a deep discharge.

Yeap! that’s what I thought and kept a log for two years. For two years it when down most times I did a full recharge then it just went up.

There’s a whole topic on this issue, so no need to discuss this here.

See this after one year ~ follow the discussion for two years and there’s link to my daily data included. It’s on a ‘woodland’ server starting http://217. . . . . .

How's everyone's [55Wh] battery health and wear looking?

Hi and welcome to the forum. Here is a summary of the battery wear on my 1165 after 1 year. Initially I didn’t think much about it and didn’t know I could check it for a couple of months etc. which explains the lack of data in the following graph of the first six months. I had no idea of the cycles for months and the first few figure for wear were from the Windows powercfg.exe which showed a) the initial at 3.4% and the lowest at 2.9% I was concerned by the 7.4% after 3 months and so took th…

Leaving this thread now

Take care

[Adrian_Joachim]

@Brian_Gregory

I guess I’m jaded by having recently seen Chinese cells marked 8800mAh that are actually under 800mAh and light as a feather.

If they sell stuff that’s above the fanciest cells from actual manufacturers you can buy it’s pretty much always complete garbage.

[Brian_Gregory]

@Adrian_Joachim

If they sell stuff that’s above the fanciest cells from actual manufacturers you can buy it’s pretty much always complete garbage.

These were included with rechargeable torches (flashlights) I’d ordered.

[MJ1]

18650 batteries?
You shouldn’t use any questionable cells. They can be dangerous. Or any cell included with a cheap flashlight, unless the flashlight is from a known good quality brand. Convoy is one of the least expensive, which is still quality. Convoy Flashlight Store - aliexpress

You can also search for particular features you want in a flashlight here Parametrek Flashlights

For flashlight or battery questions reddit.com/r/flashlight (they are welcoming & friendly there).

If you do buy random cheap flashlights, either don’t get cells with them, or dispose of the included cells and use actual quality cells. If used with questionable flashlights they should be “protected” cells. Li-ion fires are nasty, not worth saving a buck.

@Brian_Gregory

Chinese cells marked 8800mAh that are actually under 800mAh and light as a feather.

The highest capacity 18650s were 3600mAh the last I looked. Anything higher is not currently available from any manufacturer. So a cell marked higher is lying & is usually just straight up dangerous junk.

[amoun]

Had decided not to continue this BCL Limit to voltage Topic as I considered it had all been said. However I hadn’t muted the topic, but will now as the discussion is now about batteries and quality and a depressing discussion talked about elsewhere and drags this topic off-topic.

Bye

[Adrian_Joachim]

@Brian_Gregory

These were included with rechargeable torches (flashlights) I’d ordered.

That does not inspire more confidence XD