Li-polymer laptop cells replacement

[matttelz]

Hey all,

Quick question here. I have a 2020 asus g14 and right now it's undergoing repair. I have to replace the screen because it randomly died. Well it got me thinking of doing other improvements. The battery is a 76wh lipo and hwinfo says it has a 29.9% wear level...pretty bad for only being a few years old. I'm considering either finding a replacement on ebay, which is around $35 but no brand name....or what I could do is buy the extra battery to have and take a stab at doing some surgery on the existing battery. I'm wondering if I can swap out the individual Li-polymer cells...what's odd is the laptop also has an addition 2-4mm of thickness so technically I could possibly add bigger cells to get more wh if possible also. Wondering if anyone has done something like this. Also what is the best place to get raw Li-polymer cells from? Seems eBay is a bit sparse and they favor smaller cells. I'm looking at 4400-5000mah cells each.


Heres the replacement battery type: https://www.ebay.com/itm/2564771160...2adkWcYQ3O&var=&widget_ver=artemis&media=COPY

 

[sunshine_eggo]

I've torn down laptop batteries. It's a chore, and it's hard to do neatly and cleanly to where it actually goes back together nicely.

IMHO, your life will be WAY better if you just replace it.

 

[SparkyJJO]

Build a LFP battery for it, suitcase style. Won't have to charge for days

 

[robbob2112]

If there is extra space in the laptop around the battery it is either need for some arcane reason OR the laptop was sold with different size batteries and you got the small one. IF you can find your brand/series laptop with a larger battery listed you can probably just do a drop in replacement.

If you can't you should only replace the battery with what you have. Here is why, if you replace with larger capacity cells suddenly the charge circuit has to work longer to top them up from empty and now it generates extra heat. Extra heat is the enemy of all laptops and will cause premature failure of something else.

Screen wise - do you regularly use the laptop with the screen closed? If so that heat I was talking about can cause a discoloration on the screen and also cause it to fail. Depends on the fans and how well they work. Laptop vendors have a tendancy to turn the fans off at certain times to make it more quiet but everything runs better if the fan keeps running on at least low all the time. So you might want to look at tuning the fan profile to prevent it from ever going off while power is applied.

 

[matttelz]

I've torn down laptop batteries. It's a chore, and it's hard to do neatly and cleanly to where it actually goes back together nicely.

IMHO, your life will be WAY better if you just replace it.

Yea, I don't have a TON of time on my hands but I have plenty if I were to experiment on a 2nd battery... The current battery works, I only get ~5-6 hours of battery life whereas before I was getting 9-10Hrs with the same power draw. I'm typically 8-12W draw on battery.

If there is extra space in the laptop around the battery it is either need for some arcane reason OR the laptop was sold with different size batteries and you got the small one. IF you can find your brand/series laptop with a larger battery listed you can probably just do a drop in replacement.

If you can't you should only replace the battery with what you have. Here is why, if you replace with larger capacity cells suddenly the charge circuit has to work longer to top them up from empty and now it generates extra heat. Extra heat is the enemy of all laptops and will cause premature failure of something else.

Screen wise - do you regularly use the laptop with the screen closed? If so that heat I was talking about can cause a discoloration on the screen and also cause it to fail. Depends on the fans and how well they work. Laptop vendors have a tendancy to turn the fans off at certain times to make it more quiet but everything runs better if the fan keeps running on at least low all the time. So you might want to look at tuning the fan profile to prevent it from ever going off while power is applied.

So my rough numbers are as follows: Existing battery dimensions are L73.9mm x W284mm x D8.13mm. I believe the cells are encased in a frame so there might be extra room around the cells if I get rid of the frame after I tear down a second one... if that's the case it looks like there's some 5000mAh lipo cells available that should fit... Going from 4800mAh to 5000mAh might be negligible for the amount of time this project might take...still might be fun though...
Honestly... I think it might be my own doing with the screen... The laptop is Always open but hot air still finds its way to the bottom of the screen... however... I say it might be my fault because I had the FHD screen that's 120Hz and I overclocked it to 144Hz... I didn't have it on that all the time but recently I noticed a few flickering horizontal bars at the bottom of the task bar... then all of a sudden just the top of the screen works... so yea, it might have been from the overclock. Won't do that again. I've ordered a replacement QHD screen so technically it should be higher Pixel density and colors should technically be more accurate so excited for that.

I'm waiting for my new screen to arrive to confirm the issue was just the screen. IF its not then my computer is toast even though it still works with an external monitor...so there might be no reason to do a battery mod. If the new screen does work, then yes I'll likely dive into the battery mod...

 

[matttelz]

Ended up getting this item: https://www.ebay.com/itm/275955893594

I kinda doubt its a genuine Asus product, probably some knockoff but we shall see. I'll capacity test the new battery and if its crap I'll just tear down that one over my existing battery. Whichever has better capacity will win and the loser will get torn down. I'll capacity test each existing cell to see if they're matched or if one is pulling down the rest of the battery. I also have my eye on these cells: https://www.ebay.com/itm/176467660530
I think those cells will obviously be thicker than the current battery by 1-2mm but should technically fit in a 4S configuration. Once I do the battery teardown I'll have a better idea of what I'm dealing with and how difficult it might be to replace the individual cells. Stay tuned!

 

[matttelz]

SO I'm trying to understand Li-Polymer more... It seems like most of my knowledge comes from all the youtube videos of people putting screwdrivers through them and having them explode with frightening consequences...
I can't believe a genuine laptop battery just ends up with 30% degradation after 3 years... I can only think of a few scenarios that would lead to this: 1) Charge rate is too fast 2) Too many cycles 3) Kept the battery at 100% too long 4) Discharge is over 1C
I think I did a decent job of keeping the battery charged at either 60% or 80% for a long time but there was the occasional trip where I'd charge to 100%. I rarely dropped the battery under 10% also... So other than NEVER charging it to 100% I'm not sure how I'll keep the new battery from degrading soo quick again... other than maybe hoping to have better cells...

 

[SparkyJJO]

I'm not sure why some last forever and others don't. I had an old IBM T61 that the original battery lasted for years, and when I sold it, it still had probably 75% or so of its usable capacity left (just estimated based on runtime). My old Dell work laptop that they just upgraded was 5 years old and I got hours of life out of it when I needed it, even though I used it left fully charged and plugged in most of the time. But I've had others that only had minutes of runtime after only a couple years. No idea.

 

[robbob2112]

The batteries in laptops are more than just cells, there is a small circuit board in there that monitors the overall battery and cell voltages and keeps things in balance and not bursting into flames. The board is in the battery verse the laptop so it gets replaced with the cells. The cells in a laptop battery should be a matched set with as close to the same internal impedance as possible.

From my days doing electronics repair I can say that with heat and age capacitors and resistors can change values throwing things out a bit over time. And, it depends on the cost of the laptop as to how close they try to match the cells... cheap latop the don't care so much as the $4000 beast that the customer is going to work to death in the warranty period.

I would also lay odds that the more expensive laptops have active balancing going on where the cheap ones don't. I know the newer ones use a flat pouch cell similar to what is in your phone where the thicker/cheaper/older ones all use round cells similar in size to a AA with welded tabs.

 

[sunshine_eggo]

SO I'm trying to understand Li-Polymer more... It seems like most of my knowledge comes from all the youtube videos of people putting screwdrivers through them and having them explode with frightening consequences...
I can't believe a genuine laptop battery just ends up with 30% degradation after 3 years... I can only think of a few scenarios that would lead to this: 1) Charge rate is too fast 2) Too many cycles 3) Kept the battery at 100% too long 4) Discharge is over 1C rated.

Yep. Same reasons for any Lithium chemistry.

LiPo has very low cycle life compared to LFP. 300-500 cycles is pretty common, and they don't benefit as readily from "short cycling" as other chemistries. It's not uncommon for some manufacturers to tweak the chemistry to 4.25 and 4.30V charge level to squeeze a little more capacity out of them at the expense of cycle life.

10% per year actually sounds really good to me.

I think I did a decent job of keeping the battery charged at either 60% or 80% for a long time but there was the occasional trip where I'd charge to 100%. I rarely dropped the battery under 10% also... So other than NEVER charging it to 100% I'm not sure how I'll keep the new battery from degrading soo quick again... other than maybe hoping to have better cells...

Sometimes happiness is about adjusting your expectations. A $40 battery lasts you 3 years. Winner, winner, chicken dinner.

 

[yodamota]

For battery life I use Coconut battery app. works alright
I also look at ifixit for repair advice. Looks like the battery they recommend is 60 dollars on amazon. https://www.ifixit.com/Guide/Asus+ROG+Zephyrus+G14+Battery+Replacement/165021

Ive also used a program which will only allow the battery to charge to a set percentage(adjustable) It worked fine. I had it set to 80% for a while. Its called charge limiter.

Now I am at the moment where I am wondering what to do with the unit. 2018 Macbook air. Replace battery or upgrade? I don't know. My battery has lasted 1221 cycles, and is at around 70% capacity. so 6 years and still 70% capacity. The unit will also shut off at 30% state of charge.

Where are you getting that your battery is 29% degraded?

 

[matttelz]

I just started using Ghelper which is actually pretty awesome... I can set the charge limit to anything I want. It's a really light application. Fortunately for me the new screen works perfect so now my laptop is back to working just fine. I'm using HWInfo to monitor my battery. That's where its reading 29% wear.. also the Windows battery report is saying: 76K mWh designed capacity, 53K usable... On to discovering what I can do with this battery now!

 

[matttelz]

OK so I have the new battery. Good news is it only came with 4% wear. Bad news is its showing a lower capacity of 66wh instead of 74wh but it supposedly is a genuine asus battery.

I've taken apart my original battery and the cells are much bigger but also thinner than I expected. They're 18.48wh rated so I'm looking for something similar. There's 5000mah cells I alluded to earlier. I ended up getting 2 so I'll see what those test out to be. I'm going to capacity test each of the stock cells to see what they come in at. Stay tuned.

 

[matttelz]

As I expected the 1st cell pulled 3343mah. This is within the wh that the battery monitor was telling me so everything appears to be correct. The cells are roughly 56mm x 133mm x 3-4mm. Overall the pack lays flat about ~8mm so I think I'll be able to get away with 9.5mm thick cells in the modded battery. I'm pretty sure the case has some wiggle room in the battery compartment so that should be great.


I should have the new cells this week so I'll do some capacity testing on those before I figure out how to mount and wire up the new cells.

 

[sunshine_eggo]

Oh god... you gave me a jump scare... that little chinese knock-off imax B6 charger... ugh... I have at least a dozen of them. Fine for little jobs like this, but I asked way too much of them...

 

[matttelz]

Oh god... you gave me a jump scare... that little chinese knock-off imax B6 charger... ugh... I have at least a dozen of them. Fine for little jobs like this, but I asked way too much of them...

Haha. Yes. It's been modded. I used to charge my 26ah lifepo4 with it. It's not very accurate voltage wise, about 0.1v off. I've tried to calibrate it but just haven't invested too much in it. I've replaced the banana plugs and hardwired a 5A power supply to it. I also swapped out the mosfet on the bottom of the board. Before it used to get pretty hot at 12V 3A but now it barely gets warm. I used to have a better capacity tester but in my haste I threw that one away so this b6 is what I've got... Lol. It charges and discharges quite nicely!

So I kind of highly doubt these cheap Li-polymer cells will actually pull 5000mah. Im expecting more like 4500mah maybe even 4300mah if I had to guess, so that's my current expectation... Based on how the 2 samples I purchased perform, I'll end up either trying to find different ones or just keeping the bms board on the original battery till I can find some better cells. I've got the entire battery disassembled and it should be very easy to wire up the new cells. I'm mildly concerned that the bms will store the rated capacity and not new capacity of the new cells once I swap them out so I may get an inaccurate battery life indicator...we shall see.

Edit: Figured this isn't worth a new post. One thing I've noticed in my research is the 1C charge rate of most of these lipo cells.... However, is that 1C rating based on current capacity? The battery new supposedly was ~4700mAh which would give it around a 4.7A charging rate, however, I've tested 2 cells so far and they're in the 3400mAh range which is more than 1Ah less capacity, would the 1C charging rate apply to the current cell capacity? Therefore, I could only get a 3.4A charging rate instead of 4.7A????

 

[matttelz]

Quick update.
New cells are here. I ordered 2 so I can do testing. If they check out I'll order the final 2 cells. Here's my calculations.

Existing 2 cells of the original battery weigh 136g. Let's say the cells come out to be 4800mah cells on the original battery. That would be 261wh/kg. This appears to be roughly correct since the original battery said 74wh and had at least 25% wear which my capacity testing says they have 3500mah left which is about right. So the new cells weigh 74g each, total of 148g for both cells. If I use the same energy density I would get 9% more capacity just merely due to weight. Also, the cells are barely 1mm thiccccrrr than the original cells and they should easily fit with proper writing....


Overall pretty excited to give these cells a go. I almost have 1 fully charged up then I'll do some capacity testing.

 

[sunshine_eggo]

TEST! TEST! TEST!

 

[matttelz]

Well...One of my greatest fears came true this afternoon... I accidentally dropped one of my old Lipo cells when I was trying to move stuff... Bent over the aluminum tape and ended up denting the corner of the cell pretty good... What do I do with it now? The cell is clearly damaged, its not swelling, hissing, or becoming bloated but its definitely damaged. I removed it from my home and put it in a decent sized rock bed with nothing around it... we don't have any rain forecasted for the next week or so... I'm tempted to just leave it there indefinitely... Now how do I dispose of the cell? I'm fearful of taking it to like HD or Lowes...if that thing goes with other batteries it'll clear out the entire store... I don't feel like its terribly unsafe but I feel like I need to either slowly discharge the cell to 0 volts or short the heck out of the thing till it has no energy left...

 

[AntronX]

Take it outside and shoot it

 

[robbob2112]

I put a screw through the old cell from my cellphone. On cinderblocks... smoke, puffs, flames, it was fun for 20 minutes.

 

[matttelz]

Yea... I think I'll have to do something to get all the energy out. Thanks all.

Well, I expected slightly better numbers and unfortunately the first cell only pulled out 4300mAh. Now I only charged up to 4.2V and stopped when the charger was at 0.4A left but at most I'd expect maybe another 100mAh tops. So technically that's around 215wh/kg which I think is more in line with current technology for LiPo batteries. I think I'll still go ahead and test it out with 2 more cells and wrap up the battery and test it in my laptop. Should be a fun little project and we shall see what sort of battery life I get... I'll test the 2nd cell tomorrow and see what I get.

 

[yodamota]

no chance you have room for 2 - 100ah prismatic lfp cells in there.... haha i wish man!

 

[matttelz]

no chance you have room for 2 - 100ah prismatic lfp cells in there.... haha i wish man!

lol...i wish
I have to stay under the 100wH limit per FAA requirements since I take my laptop on travel quite often.

 

[matttelz]

Well I probably should have done my research before jumping to purchase the 2 cells... I did some math based on the information available and current cell offerings... this is what I come up with... I think the next best option is the YTKavq 106070 cells, Here.

I put together an excel chart and did my own calculations for gravimetric and volumetric densities to see if the claimed ratings are even possible... I think if a 10mm thick cell fits it should do the trick as a replacement for my laptop cells. The only thing I didn't include now as I'm thinking as I'm typing this, is I didn't include the original Asus cell capacity numbers... But I could again only go off of claimed and not actual tested capacity.




2nd battery came finished at 4457mAh, still well below reported. I may give this other 90g cell a try...