Toshiba satellite a120 battery hack

[Metiz]

I bought a satellite pro a120 from a friend of mine but the battery's pretty dead. I've ordered some new lithium cells so I can get a decent charge again. While reading up on the subject I came across several mentions of flash chips on the battery PCB that will besically shut down the battery when power is completely removed, so even if I'd put new cell in, the battery would remain "dead".

I found some vague references that might suggest older Toshiba's don't have that problem, but nothing solid. So before taking out the original cells: does anyone know if this battery is protected or how I can identify said chip so I can make sure not to unhook the things before putting the new cells in place?

Thanks.

[UAirLtd]

Can't say for sure specifically what battery protection features that specific battery pack has, but ALL lithium ion laptop battery packs have a protection circuit. When you open up the battery, the protection circuit should be fairly obvious, it'll be small board with a few components on it. It'll usually be where the battery contacts are connected, or attached to one end of the battery pack.

A side note: I hope you purchased cells with solder-tabs pre-attached, or you're going to have one hell of a time trying to connect all your cells together!

[Metiz]

Thanks for the answer. I know about the board, the question is: if I completely disconnect them from a power source (current lithium cells), will it cease to function altogether, even after replacing the cells.
And no, no solder tabs. I like a challenge. Also: ducttape

[st2000]

I know you're not going to like this, but I would suggest you recycle the old pack and buy a new one.

LION batteries are not all that safe. Think of what happens when you leave Lithium out in the open on a humid day. What about when you pack the batteries back into the case? There is probably a thermal sensor that is used to signal end of charge. If you forget that, you might have a dangerous situation literally sitting in your lap. With regards to the charging circuit which might contain a processor and non-volatile memory - what usually happens is that the processor will track the age of the battery and report on the charge remaining accordingly. It's not a sure thing that swapping in new LION will not work. In fact I suspect it will. But it might take a few charge cycles until you see the "new" expected life behavior. As for discharging LION. Never do this. This is why you seldom see LION by themselves. They are almost always in a pack where special circuits shutdown the battery before they are completely discharged. Such is how I would expect your laptop battery pack to behave.

BTW, it's probably not the computer telling you how much time you have left to run your computer. It's probably the processor inside the battery pack. That's why there are so many terminals. Some are for power. Some are (probably) for safety. And some are (probably) so the computer can talk to the processor inside the pack. I think if you wikipedia SBus you can find out more about this.

BTW, I might try rebuilding a pack (I've never done it). But I would never take such a pack into a closed space like an airplane.

-good luck

Edit: added later

A side note: I hope you purchased cells with solder-tabs pre-attached, or you're going to have one hell of a time trying to connect all your cells together!

I'm sure UAir knows this, you'll need a spot welder. We had one at my old work. Not much to them - but very specialized as for their intended purpose. Do not subject the LION cell to anything out of the ordinary! Like trying to solder wire to them! At best - if they have an internal thermal fuse - they will stop working. At worst - well, recall what I said about Lithium on a humid day.

[GaspingSpark]

Some laptops have a battery calibration utility built into the BIOS. My old ASUS laptop does. It runs a full charge cycle and then when the battery is fully charged it asks you to disconnect the AC adapter. Then it analyzes the battery's discharge curve until it runs out of power. It updates the chip on the battery with the proper calibration.

[st2000]

Some laptops have a battery calibration utility built into the BIOS.

No kidding? I never knew that. I learned something new. Thanks GS.

[Metiz]

Thanks for the reply, st2000.

I'm aware of the risks and I am willing to take them. As long as the risk is that I mess up, I'm ok with it. If there was like a 1 in 10 chance the cells would catch on fire, regardless of how I treated them I would think twice. I don't have a spot welder (I do have a microwave oven transformer so I suppose I could build one). Is it impossible to safely solder tabs? for example, if I get a flat copper strip and punch an hole in it, add some soldering flux on the lithium cells, place the strips and just quickly add a blob of solder, that won't work? If it won't: I do have ductape:P If I add enough of it so the cells will fit snugly into the case, I don't forsee any problems realy.

[st2000]

Is it impossible to safely solder tabs? for example

You can try. I remember reading that LION cells included some sort of thermal fuse. Remember a years back when laptops were catching on file? Something about dropping them in a certain way caused the cells to short out. And I think there was a well know battery manufacture that had to recall cells for similar reasons.

http://www.cbsnews.com/2100-205_162-1894909.html

If you already have batteries w/o tabs I think I would look for a way to pack them with a spring to keep them in contact with each other. Maybe plastic tubes. All the while pay attention to not alter the thermal relation ship between the batteries and the thermal couple should there be one pack with the older batteries. To the extent you cut holes in the plastic tubes. (I would be very very suspicious if you don't find a thermal couple packed with the original batteries.)

-good luck

[k-ww]

If you are going to try to solder tabs on the LION batteries:

1) sandpaper the ends of the batteries - sometimes the plating dosn't solder well.

2) put flux on the battery terminals

3) tin the ends of the wires/foil you are soldering on the battery

4) use a big/high wattage iron/soldering gun

5) heat the wire with the iron/gun, then press it against the battery terminal,
untill the solder melts against the battery terminal [not more than 10 sec.]
(better a short high burst of heat, than a long low one when soldering batteries.)

6) do this step outdoors, if possible, and have a metal bucket & some sand/
cat litter handy. dump the battery into the can in case it starts to burn
& dump the sand on top of it / don't use water!

[st2000]

don't use water!

Good point kww! I do have to admit - the Li + water experiment was a high point of my high school chem class. What we are worried about here Metiz is that Li + H2O will produce Hydrogen gas. You know. Think Hindenburg. (Li is normally stored in an oil.)