Battery rebuild for J6xx and J7xx

I've done a battery rebuild tutorial which I think will be useful for anyone rocking a 20+ year old battery!



I couldn't get the video to embed properly

Fixed
It's [ video=https://youtu.be/PRGn7COoN1w] without the space between [ and video.

Good video as always. Takes me back. I used to do it a lot - I didn't have a spot welder though!

Thanks C:Amie!

I will make sure to remove the space next time!
Ah yes the spot welder is excellent especially as my soldering isn't very good

Huw

Just as a friendly warning to any newbies out there thinking that it's safer to use a spot welder. It isn't necessarily. The heat that can cause the battery to go, but so can piercing the casing and allowing oxygen in. Over volt the spot welder or linger on the tab for too long and it can over heat or melt the casing. If it does, the case ruptures and it starts a lithium fire. Fire extinguishers won't do a whole lot of good for a lithium fire until the lithium has reacted off. So have a bucket of sand handy to dump it in.
The advantage of the spot welder is that - if you know how to use it - there is far less lingering time compared to solder.

Go to 1:45 if you want to see what it looks like.


What I'm saying here is: be careful and I strongly recommend eye protection.

So I agree whole heartedly with fantablium. If you want to try it. Get pre-tabbed cells and solder the tab. Don't try and save the 50p for the un-tabbed ones.

Warning aside. This is well worth doing on any device. For those who do not understand. You can safely put any amperage (mAh) cells into the device, but the voltage must be the same. Higher amperage is what allowed fantablium to go from the 9 hours original life to 15+ hours.

This was a great video, and since I started not one, but two fires while trying to re-cell an Omnibook battery pack, I'm guessing spot-welding couldn't be worse.

A dilemma: fantablium has done due diligence and found acceptable batteries--the rub is that they aren't tabbed. Can anybody recommend quality, tabbed batteries?

Again, what a fine set of instructions, fantablium.

Jake

I got inspired by this video and rebuilt my 720's battery - thanks heaps fantablium! Bought 2 untabbed cells from a local vape shop and used aluminium foil for padding you recommended against. It's a sloppy job but it works.

Humm, using something conductive as a gap insulator wouldn't be my first choice. If it causes a short and that happens to ignite the cell. Aluminium burns at about 660c and lithium 600-1000c. So it could very easily go up with it.

Do you know what though. I'd have never have thought about picking up 18650's from a vape shop. Good tip.

As to where. Back in the day, I used to get them from RS e.g.:
https://uk.rs-online.com/web/p/speciality-size-rechargeable-batteries/8801551

Some good points C:Amie, the ideal might be to use the spot welder to weld to the tabs on some tabbed cells! The spot welder I bought does a timed discharge and wont do another until it is disconnected and reconnected, but if I do another video a bucket of sand and eye protection will defiantly be recommended, in the meantime I will add it to the description!

platform88 NOOOOOOOOOO! don't use aluminium foil, if you get a short foil ignites easily and will destroy your 720 and possibly your house!!!

@fantablium, I agree. The spot welder on tabs is certainly the safest option for novice users - but I can't see many novice uses wanting to buy a spot welder.

Having said that, they aren't too expensive

This is your one isn't it?

Solder on the tab would be my second choice, just don't linger on the tab too long.

That's why they make low temperature solder.

I get all my 18650s from a local Vape shop down the street. He has genuine great quality cells that I have weighed and then discharge tested for capacity. So inexpensive these days. I even recelled my Halo emergency jump start device them.

@Rich Haawley, it is, but that requires you to have a soldering iron with a temperature adjuster on it. Many people will only have (or only want to acquire) a cheap-o one that is binary state. So newbies still need to be careful with lingering the tip.

C:Amie,

That's basically the same one. There's a bunch that look very similar in appearance and function. I paid ~£40 for mine so I don't think that expensive. I only went for it as I intend to do quite a few battery rebuilds otherwise I would have got tabbed cells and soldered them.

@Rich Hawley what do you use for discharge testing? What weight should they be for 2500/3000Mah?
I'm not totally convinced the cells I bought are 3000Mah, from the results I'm getting I think they might be 2000 - 2500Mah

Edited by fantablium 2022-05-07 7:31 PM