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2023-11: Warosu is now out of extended maintenance.

/diy/ - Do It Yourself

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1370940 No.1370940 [Reply] [Original]

Hello /diy/,
I just replaced the 18650s in my old laptop battery pack. After the first charging (laptop said batteries had 0% charge) I went from 100% to 5% hibernate as suggested for calibration, but got only 1.5h of battery life. I was expecting >4. The batteries are genuine. The charging process stuck for quite a while at 99%-charging before saying 100%-fully charged. Then I discharged them to 5% and the computer went to hibernate. I'm discharging them for the second time now and it looks the same again.

How should I re-calibrate the pack? I'm guessing since I got the 18650 at half charge, that the laptop thinks that's the 0% charge. Any ideas?

>> No.1370945

>>1370940
Most laptops these days have what is called smart battery. There’s chip inside that counts charge-discharge cycles and lowers possible charge as it progressed. Replacing cells is first step, you have to reset chip (some of those are impossible to erase)

>> No.1370947

>>1370945
There is also another proposed solution to run the hard drive check from bios to completely drain the battery? Will that move the apparent 0% farther down to the actual 0%? Or do I need to reset the chip?

>> No.1370949

>>1370940
How did you connect the cells together?
If you directly soldered to the ends you probably damaged the cells.
If they were tabbed and the tabs aren't thick enough for the amps the laptop pulls the voltage the controller sees will plummet and it will think the cells are near depletion.
Likewise if the cells you bought were not up to the current draw of the laptop the same scenario will play out. Some 18650's can sustain half an amp while others can sustain 2 or 3 amps.

>> No.1370951

>>1370949
a company spot welded the cells into a pack, I just soldered the end wires to the metal strips (I didn't heat damage the cell). Cells are same spec (new ones only have +10% capacity)

>> No.1370952

>>1370951
I just connected the pack with the electronics

>> No.1370960

>>1370951
Awesome. Were the cells balanced before you soldered them to the controller and tried to charge it?

>> No.1370972
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1370972

>>1370960
Also did the controller have small wires going to connection points in between each cell. Ala this pic.

>> No.1370983

>>1370972
yep and yep, connected everything as was with the old cells.

ran the hardware diagnostics and the system still thinks it has old cells inside (it says they are degraded to 37% capacity and displays 600 cycles)

>> No.1370993

>>1370940
the battery controller board usually has flash to store info about the cells. you'll need to reset that to some sane value.

>> No.1371001 [DELETED] 

>>1370993
If that's even possible. He'd probably need a pic programmer minimum. It could probably be done in software but only the manufacture would know the correct addresses. What's the make and model?

>> No.1371005

OP here. Ok another question. How do the electronics know when the battery is fully charged? Do they measure the voltage or the amount of charge? How do the measure degradation of the cells?

>> No.1371021

I'll charge/discharge fully a few cycles to see if the diagnostics report a increase in capacity.

>> No.1371027

>>1371005
The controller monitors the current into and out of the battery and knows how much the batteries should take to charge. That's how it knows the degradation. They know how much energy they have left based on how much they charged vs used. Cycle it a few more times and see if life improves.

>> No.1371079

>>1370940
>1.5h of battery life. I was expecting >4
You used >4 amp hour cells?
What was the battery configuration? If it is just 3s1p or whatever it is for only one bank of cells the youre not going to get super high capacities using cheap cells

>> No.1371269

>>1371079
3s2p Sanyo 2.9Ah cells genuine

>> No.1371332

UPDATE:
after the second charge diagnostics of the battery capacity increased from 37% to 45%. After charging it to 100% again, I'm at 1h40min and 30% battery remaining.

It seems the electronics are cautious and increase max charge incrementally. Only 1 question remains. Will it allow it to charge over 100% (of the original battery pack capacity) because I have new cells with 10% more capacity. Either way it's a win. Will report back later if anyone is interested.

>> No.1371336

>>1371332
I read that on some batteries you need to solder new battery on while old was still connected.

>> No.1371358

>>1371336
I've read that that applies only to certain laptop brands. But it kills the battery pack completely, not just degrading it.

>> No.1371599

>>1371332
I'm interested, btw which laptop and pack is it?

>> No.1371939

>>1371599
hp tm2, standard pack, replaced the Samsung cells with Sanyo. After the 3rd full 100% -> 5% cycle the capacity went to 64%. Next cycle I went from 100% -> 20% then charged for 10% and went down to 5%. The battery didn't want to re-calibrate, because it detected it was charging. I'm guessing it has to be a full discharge without interruptions. Doing the next cycle now.

>> No.1371940

>>1371599
It seems to depend on the model of the pack, how it re-calibrates. I've read that some get 100% within the first 100% - 5% - 100% cycle.

>> No.1372142

I'd been thinking of doing a similar thing, except I'd be adding additional cells. Would it be possible to add them to the same controller that the laptop had beforehand? Is it also theoretically possible to use a controller from a different laptop battery?

>> No.1372335

>>1372142
OP here. It would by similar to my situation, where the new pack has a bigger capacity than the original. Didn't calibrate it past 100% yet, so stay tuned. I wouldn't suggest mixing controllers. What brand of laptop?

>> No.1372341

>>1372335
It's a Toshiba R930

>> No.1372346

>>1372335
Thanks, I'll be looking forward to it! definitely post a tutorial

>> No.1372570

>>1372346
There are 2 things that you need to worry about the most. First find out if you have one of those battery electronics that need to be powered constantly, even when replacing the cells. Because some can get unusable if you remove the voltage. Next tip is for soldering the cells. I assume you have a basic soldering iron. Then I suggest you find someone to spot weld some metal strips to your cells or connects them to a pack and then you can just attach wires to the strips at the end of the pack. don't solder near the actual cells, because heat can harm them and they have high thermal capacity, so you will either make unsafe cold welds or you will have to heat them up really high and long. After the welding is done, make sure the pieces aren't moving.

I'm still deciding if I should use hot glue or some silicone for that part. now it's held together temporarily by scotch tape. Any suggestions from others?

>>1372346
I didn't take pics, but there are many tutorials online.

>> No.1372740

>>1372570
Oh, I got it, I've read about it. Idk if I can find someone myself, but hopefully I could affix them in a 3D printed pack well enough... I plan to make a custom one in a completely 3D printed laptop chassis, since my ivy bridge i7 laptop still feels like it has life in it but is falling apart. I need to figure out how to replace the flex cables too.

>> No.1372828

>>1372740
If you have time on your hands, you could make your own spot welder. I can't stress enough how dangerous it is to have poor contacts between batteries. Charging currents can be ~1 amp, and if the joint is too small it heats up considerably, also heating the battery. Heat is a no-no for lithium batteries. And if your pack doesn't have a thermal sensor the whose thing can blow up.

>> No.1372830

>>1372828
>spot welder
https://www.youtube.com/watch?v=o1NFbchHeM8
>outline of the replacement process
https://www.youtube.com/watch?v=VrDnTXqoqjM

>> No.1373049

>>1372828
>>1372830
What's wrong with using electrical tape or self amalgamating tape instead of a spot welder? I'm interested in restoring laptop batteries.

>> No.1373229

>>1373049
Your batteries will shake, expand thermally. You can't ensure a perfect contact all the time.

>> No.1373443

>>1370940
Sorry for brainlet question, but...18650? I use these at work all the time, and i thought they wew weak in terms of max current.

So, I can power my laprop with these with enough cells to get the voltage right?

>> No.1373499

>>1373443
kek your tesla runs on 18650s

>> No.1373563

>>1373443
18650 is the size
some of them have like 30-40A discharge

>> No.1373648

>>1373499
My Tesla is reporting a malfunction in the battery. How hard would it be to diy replace it? I've done some soldering before on my Arduino.

>> No.1373770

>>1373648
It has a few more batteries than a laptop...

>> No.1373892

>>1373648
Imposdible, or damn near. You're dealing with like 300vdc, crazy dangerous to work on if you don't know what you're doing, also most of the time resetting the errors on a Tesla requires software that they only have at their service stations. Aren't almost all Teslas still under warranty?

>> No.1373947

>>1373892
Wish you said that earlier. Already opened up the main flux capacitor.

>> No.1374700

>>1373947
If you discharge 1.21 giggawatts into it, it should be enough to reset it.

>> No.1374838

>>1373648
You could but it would be dangerous, well beyond your skill level, stupid , time-consuming and potentially unnecessary as manufacturing faults are covered by an extended warranty. In other words you would do this for a good LARP

>> No.1375121

OP here, currently at 75% capacity. It seems that the battery will calibrate only if you don't interrupt the 100-0-100 cycle. Last 2 cycles I did some funky charging and discharging and it stayed at 64%, now I did it properly again and it increased. Finally put the casing back together and it looks almost like original.

>> No.1375357

>>1375121
Hi OP! Battery pack expansion guy here, learned a lot from what you posted, thanks lots, sorry for not responding before. Did the battery pack expand by the extra capacity of the new batteries, like it should have?

>> No.1375501

>>1375357
Last cycle dropped the capacity to 49%, I have no idea why. I'll use it normally from now on, only cycling 80-30 to keep the battery healthy. Maybe going 100-0 every month. I don't know how the electronics work or why is it behaving so strange. It is not degrading the batteries, it's just having trouble estimating the capacity. Maybe it's the extra .05V, maybe the extra 10% capacity of the replacement batteries. I don't actually care anymore, just hope it sets above 90% some day.

>> No.1375556

>>1375501
Damn :T sounds tricky.
What model was the laptop again?

>> No.1375743

>>1375556
HP touchsmart tm2