My 1 year laptop's batteries are not holding charge. Since I have some extra RJim 18650. I was wondering is it a good idea to replace the batteries. I am still trying to figure out how to open up the case without breaking it. Anyone has done it before? Thanks in advance.
Can you post a pic of your laptop battery? How to open it depends on the battery. Also you may want to just order some normal 18650 with tabs instead of using your protected ones. Of course it could also be the protection circuit. But good luck. :)
I've ripped apart at least a dozen laptop batteries to try and salvage cells.
I haven't seen any that can be non-destructively disassembled (ie unscrewed). I generally use a small chisel and hammer. I try to tap the chisel into the seam between the two halves just enough to pry them apart.
A couple were pretty easy to pop open and could have been put back together. The rest I had to totally trash.
If it doesn't work in your laptop, you don't have much to lose...
You won't be able to solder them .it's just impossible ,impractical and foolish to try ..take it to a batteries plus and let them build it for you with your cells if you want .
http://www.youtube.com/watch?v=Z7M9_YEqF6o
Sure it can be done Boaz.
If you take off the protection from protected cells you end up with cells that have allready tabs.
I once made a battery for a robot lawnmover, out of 21 protected 18650 TF-flames (3P/7S). Well, that's more than a year ago and that one works well.
I've successfully soldered pieces of wire and original tin contacts to battery operated drill replacement cells. So has my father. Unfortunately, those cells are/were pretty out of the ordinary, from my later experience, and from all the available info from the 'net.
If they can make some cells solder friendly by accident, why can't they make more of them solder friendly on purpose? :(
Viktor
The point of trying to rebuild a laptop battery may be moot. A friend of mine, just received a replacement laptop battery (6 cell) for his Compaq. $21.00 free shipping. That's $3.50 per cell, no fuss no muss. I didn't believe it so I checked, most laptop batteries can be had for $21-$25. Of course there is no telling how good they are, but they can't be THAT bad
Depends on where you live and what type of battery you want. My gf's laptop has a battery that's about $30 + $15 shipping to where we live. Still too 'spensive. I've got 6 brand new Ultrafires already waiting to be put in the laptop battery, but no way to weld them. And no time to play hit'n'miss much. Once I find time, they are going in as replacement cells.
Viktor
Thanks for all the replies. With 2 left thumbs, I think it will be safer for my family if I just buy the battery. 
That is sort of odd, laptop batteries usually last about 3 years, sometimes longer.
I kept the battery while it is plug-in, I use the computer like 7 hours daily(6 1/2 on BLF)
.
Laptop batteries for under 30$ where?
Eh :D?
They might last you 3 years if you dont cycle them much, most of the batteries, unless those made with Panasonic cells(at least in world of ThinkPads thats the case) will wear out rather quickly and around 100-150 cycles will start to drop their Wh quickly with every discharge cycle.
200 cycles for average laptops battery is alot, 300 cycles is mostly achievable only with best cells(again, Panasonics AFAIK) and only recently manufacturers have released batteries that should last up to 1000 cycles and even then its only because of built in battery craze in ultrabooks.
Cheapo consumer laptops, those priced at the very bottom have crappiest batteries that wont last you more than 6-12 months depending how harsh you are on them.
Always buy original manufacturers batteries, if they are too expensive try to look into manufacturers outlet online stores and buy refurbished/scratch and dent batteries from there.
Or use professional battery refill services.
My 2c.
Luckily battery in my laptop is in good condition, but I rarely use it because its Sanyo and those wear off quickly+I have Lenovo's Power Manager installed so I can easily set how far I want my battery to charge and discharge, very important thing to have, pitty its a rare option in laptops, theres also refresh function to revive when you see it has lost too many Wh's.
Sanyo batteries wear off quickly? My 14" Lenovo had 6 2400mAh Sanyos 3s2p config, they lasted 5 years. Entering 6 counting this year. Of course at year 6, the end of their days, I had to keep the laptop plugged in whenever I use it.
When it was salvaging time, I pried the batteries out, checked them all out and what do you know, all of them except one still have over 1000mAh capacity. Turns out one dud'ed out at 660mAh, this is the black sheep, otherwise I would still be able to use my laptop for over an hour without charging.
Considering the batteries drop their capacity to 40% in almost 6 years, that makes a drop of only 10% per year. Which, considering the heat and deep discharge conditioning of laptops, is unbelievably good.
Oh and don't buy those $30 laptop batteries, they have really crappy batteries inside, seriously... I've had many many chats with ebay vendors and all of them NEVER answer directly when asked the real capacity. Always answer "don't worry", "cheap price", "won't be same as original but not bad" etc etc.
Reading the negative/neutral reviews showed their real color - 10 minutes runtime then shutoff, not able to charge, bad runtime... the list goes on.
I also looked at replacement batteries at ebay, those tabbed ones... they also keep getting bad reviews... only around 800-1000mAh even though claiming 3800mAh etc. I'm betting these are the batteries that went into the $30 pack.
So if you're lucky and don't get any dud out of the 6 batt in the pack, you're probably only getting max around 1000mAh for that cheap $30 batteries. For just $20 you could buy three Panasonics and replace your old batteries (assuming you need 3s battery), and still get 2900mAh true capacity. Or for $40, get 5800mAh. For real.
Consider yourself lucky then :D
Most of the praise goes to Panasonic cells in Lenovo batteries.
There is considerable difference in quality between these two.
I have lost 10-15Wh(currently having 72Wh@100% charge) after 72 cycles of which only few have been from 100% down to 5%, the rest of cycles have been more like down to 30/40/50/60% from 90/80% or 100% when I first started using it.
I never charge it to 100% and as I said - only couple of times it has been discharged down to safest minimum, other times no lower than ~30% and up.
So as you see, even tho I havent taxed my Sanyo 9cell battery much it has lost bit of its capacity, unlike Panasonic 6 cell battery that Ive used in other ThinkPad that has had no reset(ie refresh) been done to it and has been used carelessly by computer illiterate student chick and has lost only couple of Wh after more than a year of use.
Go figure, you probably got rather good Sanyo battery, for the most its a lotery with Panasonic clearly winning in quality department :)
I agree that currently Panasonic has really good batteries... the NCRs, I think, is definitely be biggest bang for the buck for any battery you can get nowadays.
HRL technology means they won't explode when shorted too. HUGE PLUS THERE.
My laptop battery went to 50% health in the first year, and is stable there for 4 years now. Fujitsu Siemens 17" gamer laptop, at the time. Not the best of the best, but it can still run even some recent games. Battery was never it's strong point.
Viktor
Guess I've been lucky. Three laptops in 10 years, always getting daily use, I've only ever replaced one battery.
All Dells, BTW.
And what if they are reverse charged in multi cell setups? When HRL "kicks in", is the battery dead or still in working condition?