Thinkpads Forum

I'm wondering if a significant upgrade in capacity is possible by replacing the cells in a T6x battery. I've put the most power-hungry components I can find in to a T61/T60 hybrid and would like to get more life out of the battery if I can. It's not a brand new battery and already has 25% less capacity than it did new.

It appears to me that the originals cells are 2500-2600 MAh, and I'm guessing they're 18650 cells. 3000 MAh cells appear to exist. I'm wondering if using higher-capacity cells will cause a problem.

You can try it if they physically fit in the case, but be warned that if you open the circuit at any time the controller card will detect a problem and disable the battery, this safety feature is non-recoverable short of replacing the controller card, so you'll need to solder each new cell in the circuit before removing the one it replaces. I'd also recommend you get the new and old cells at an equal charge level before you begin, if one cell is dramatically different then the rest your battery may panic and shutdown. I've also heard that it's best to do this work at about 50% charge, but I'm not certain about any of that.

If you'd like a large box of batteries with disabled controller cards drop me a PM and we can discuss it, I'd say I probably have about 10-20, mixture of 6 and 9 cells and all have a disabled controller.

I know batteries are potentially dangerous and stuff, but the design of that controller sounds pretty extreme.

I'm not sure if I have a use for a box of dead batteries at the moment, but it does look like there are places that sell controllers to go with their cells, and that these controllers are not designed to fail permanently upon detecting an unsafe condition. These seem to be about the same price, if not cheaper than one cell, so it might make sense to just count on replacing the controller when rebuilding a battery.

Zak wrote:I know batteries are potentially dangerous and stuff, but the design of that controller sounds pretty extreme

The results of an incendiary failure in a LiON battery can also be fairly extreme, so the controllers are deliberately designed to take a very conservative approach to any abnormality in the battery of cells

Cheers,

Bill B.

Having the controller shut down is one thing, having it permanently shut down is another. Unless there's a federal or int'l safety requirement (and there isn't) then it's just a method of forcing users to but complete new batteries, rather than re-cell them.

I run into this with NiCd packs in my cameras' motor drives occasionally (dead cells). but at least they don't have controllers that render the whole thing useless.

cadillacmike68 wrote:Unless there's a federal or int'l safety requirement (and there isn't) then it's just a method of forcing users to but complete new batteries, rather than re-cell them.

There are stringent indeed air saftey requlations regarding the transport and use of LiON batteries.

Perhaps you'd prefer that consumer LiON batteries were just totally banned from aircraft, as that is pretty much the alterantive

Cheers,

Bill B.

cadillacmike68 wrote:Unless there's a federal or int'l safety requirement (and there isn't) then it's just a method of forcing users to but complete new batteries, rather than re-cell them.

bill bolton wrote:There are stringent indeed air saftey requlations regarding the transport and use of LiON batteries.
Perhaps you'd prefer that consumer LiON batteries were just totally banned from aircraft, as that is pretty much the alterantive
Cheers,
Bill B.

Those are air transportation rules. The airlines don't want people carrying multiple spare batteries crammed next to each other so they can short out their connectors on each other. I usually travel with 2 or 3 spare batteries but i keep them in separate plastic bags. They haven't melted or burned up the planes yet.

What I'm referring to is internal controllers that shut off on an Open, not a Closed circuit. Not necessary and to me just a way of forcing replacement. I've also had new batteries "die" sitting in a box at home while I've been deployed, possible due to a controller deciding it's time for me to buy a new one.

It reminds me of HP inkjet cartridges that were never used and still sealed, but not used for months or years, only to have users find out when they opened them to replace an empty one, that the item had a coded expiration date and it "expired" while never being used.

That ticked off a lot of HP users, and this is a similar item to me.

It seems to me that a failsafe with a manual reset, or a failsafe that retries after a set period of time would be equally safe. I'm more inclined to think that the failsafe with the permanent failure mode was the cheapest way to do it than that it was chosen to force users to buy new batteries when they don't need one or because it was necessary for safety.

Confirmed fact: These controllers have a thermal fuse that melts and shuts down the battery at a certain temp. They didn't want this to be temp because the risk of continued use on a battery that overheated increases the odds that the safety system may fail... and in normal use this fuse should never melt.

Unconfirmed fact: an open circuit will cause the controllers logic circuit to shut down. I'm not about to start clipping and resoldering connections just to confirm this, but I've read that the only way to replace a cell is to solder a new one in parallel, then remove the old one. The new cell has to be (about) the same charge level as the others in the battery too.

Theory: an out of spec voltage on one of the cells will cause the logic circuit to shut down, so an open circuit (0 volts), or adding a fully charged cell to a battery with discharged cells could be a problem.

TuuS wrote:Unconfirmed fact: an open circuit will cause the controllers logic circuit to shut down. I'm not about to start clipping and resoldering connections just to confirm this, but I've read that the only way to replace a cell is to solder a new one in parallel, then remove the old one. The new cell has to be (about) the same charge level as the others in the battery too.

I've read this as well, and every time I do, I imagine someone mopping my brow while I perform the procedure and screaming at them to clear the building. That, or a loud buzz as I accidentally touch the side while removing the bread basket.

Alas, the chip in my 4 cell already gave the died message, but something tells me that there's some hope for it someday.