Watching a Wallstreet Battery Die

[beachycove]

Well, this is a new one for me. Can anyone help?

A week ago, my Wallstreet main battery held a 2.5 - 3 hr charge. I used it on Friday last week, running from the battery at the pool while my daughter was swimming, then I came home and left the machine asleep for a day. The battery was about half charged when the powerbook was put to sleep.

Over the past weekend, I plugged the machine in and the battery refused to take a charge: it would charge only for a few seconds every 5 mins or so. Tried Battery Reset (which didn't even drain the thing) NUMEROUS times and the standard clearing of pram procedures, including an attempt at recalibration by running down the battery (that didn't work either, as the machine just shut down, even though the battery showed a quarter full).

So the battery was not responding to the computer. The computer itself seems to be running fine, as it will charge another, older battery that I use in the other bay. It's my best battery that is on the blink.

Then today, the battery just died: it will thankfully still show one light if I press the little button (meaning the cells are not all past recovery), but the Wallstreet will not only not charge it, but it does not recognize the battery any more: I now just get the "battery X" icon (I'm running 9.2).

Can someone explain what must have happened? It seems that the battery was going, going, and then it was gone, fizzled out. Is it most likely a bad cell, or most likely the electronics? And if the electronics, can I just solder in the necessary board from a scrap battery (I do have a couple of those)?

I'd like to save the battery if possible, as up to now it has worked very well, and the cells had (I thought) lots of life in them still.

Experienced advice appreciated!

:?:

 

[tomlee59]

First off, unlike Battery Recondition for NiCds, Battery Reset does not (nearly) zero out the charge in a lithium ion battery (fully discharging a lithium batt is a Very Bad Thing, as it turns out). Although lithium ion cells are free from the "memory" effect of NiCds, they do suffer from a form of digital memory problem if they are not regularly allowed to cycle fully. Basically, as the battery ages, the correlation between cell voltage (with and without load) and remaining operating time shifts. If you don't cycle the batt, the logic doesn't get updated. Battery Reset is supposed to take care of this. Since using it didn't fix your problem, one or more cells have just gone south, or there's a circuit problem, as you surmised.

It may be worthwhile trying various OF resets, which I believe work on the Wallstreet. Reset the power manager, etc. repeatedly. Maybe you'll get lucky...

If the cells have just aged to the end of life, then there's little you can do. But if it's a failure of the battery pack's smarts, then a board transplant may be worthwhile, given that you have a source of organ donors. Just work carefully, and avoid shorting the cells, if even briefly.

Btw, never solder directly to a lithium ion cell (you won't have to if you're just swapping boards, but I feel obligated to issue this safety tip nonetheless).

Good luck, and let us know how you make out.

 

[.]

Tomlee, I've heard the opposite with regard to Li-Ion batteries - that it's better to keep them charged and not let them discharge fully. Are you saying the ideal way to maintain a Li-Ion battery is to keep it charged up as much as possible, but to let it discharge fully every couple of weeks or something? Or what? I'm a little confused.

 

[tomlee59]

I'm not sure that you really read what I actually wrote: "Fully discharging a lithium battery is a Very Bad Thing" (see first sentence of my post).

By "fully cycle" (not "fully discharge") is meant that you run the laptop until it shuts *itself* off, and then you recharge. The shutting off occurs not when the battery is fully discharged -- the "smarts" inside the battery are specifically designed to prevent this. The point of my discussion about memory effects in lithium batteries is that, if you do not fully cycle (in the sense of the term just defined) the batt from time to time, the smarts can get confused about when it should shut off. This confusion results in a premature cutoff, long before the cells have actually discharged too far, and you will believe that your battery is no good when in fact the only problem is that the logic has made an erroneous decision.

Hope that this explanation clears things up a bit.

 

[Quadraman]

Lithium Ion batteries degrade over time. Even if they are brand new and never used, they still lose their capacity to hold a charge. I bought my laptop in 04 and it had 2.5 hours capacity then and barely has an hour now. This is why LiIon will never be viable in electric cars. The cost of replacing the battery pack every 4-5 years will cost you more than anything you save on fuel and maintenance costs.

 

[Bunsen]

Still better than the 1-3 year life of lead-acids

 

[beachycove]

Must be a bad cell. Battery is dead.

Ho hum.

 

[MrMacintosh]

Hmm, I had a similar experience with my iBook Clamshell. Here's the story, for what it's worth. I received an excellent battery with my clamshell - a BTI 4 hour battery. It ran great. I put the clamshell to sleep, and left it that way (not plugged in) for days. The battery was 'drained' when I next used the book. But, the iBook would charge the battery for about 5 minutes, then stop, no matter what I tried. (the usual resets, software, etc etc.) I assumed the battery was dead, so, naturally, I took it apart } . Well, it turned out that the cells were all fully charged - the controller in the battery was just messed up. My solution was to discharge the cells manually. I hooked up some DC motors from old VCRs to each pair, and when it was discharged, I moved to the next pair. This worked just fine, and I've actually been dumb enough to leave the thing in sleep again, so I've had to do this twice.

Anyway, perhaps it is worth cracking the battery open and taking a look with a voltmeter - it can't hurt too much, right?

Oh, and if you kill/blow up/burn/short anything, please don't blame me

Kyle-

 

[Quadraman]

Apple also used the cheapest cells available in the powerbook batteries. I think they used 1800mah rated cells, which are crap. There are up to 2800mah cells available if you want to upgrade your battery, but they aren't cheap. That's why some Mac vendors are advertising batteries with up to 40% greater battery life. All they did was upgrade the cells inside to more powerful ones.

 

[beachycove]

Hmm, I had a similar experience with my iBook Clamshell. Here's the story, for what it's worth. I received an excellent battery with my clamshell - a BTI 4 hour battery. It ran great. I put the clamshell to sleep, and left it that way (not plugged in) for days. The battery was 'drained' when I next used the book. But, the iBook would charge the battery for about 5 minutes, then stop, no matter what I tried. (the usual resets, software, etc etc.) I assumed the battery was dead, so, naturally, I took it apart } . Well, it turned out that the cells were all fully charged - the controller in the battery was just messed up. My solution was to discharge the cells manually. I hooked up some DC motors from old VCRs to each pair, and when it was discharged, I moved to the next pair. This worked just fine, and I've actually been dumb enough to leave the thing in sleep again, so I've had to do this twice.


Anyway, perhaps it is worth cracking the battery open and taking a look with a voltmeter - it can't hurt too much, right?

Oh, and if you kill/blow up/burn/short anything, please don't blame me

Kyle-

How does draining the cells reset the controller?

 

[JWG Design]

From what I can surmise from this discossion about Li-Ion batteries, there are the cells, which can have between 0-100% charge, and then there is the circuitry that allows something like a 10-100% charge. (I'm just guessing that 10% might be the safe bottom figure here, as TomLee mentioned that Li-Ion cells should never be fully discharged.)

So if the circuitry thinks that the battery is at 10%, it will turn off the Powerbook -- regardless of the actual charge left in the cells. If you plug in the 'book, then the battery will begin to charge, but probably stop when the cell charge reaches 100% or when the temp sensor tells it to stop.

If you open the battery and manually discharge the batteries with a motor (not all the way, mind you), then the cell charge will more closely match what the circuitry thinks it is at. Then your Powerbook should be able to full charge the battery withouth stopping prematurely. I don't think that this procedure "resets" anything -- just that it puts the cells and circuitry on the same page.

My Wallstreet has a similar problem. Putting the battery in the Powerbook, it will charge for about 5-10 seconds, then show a full 100% charge. If I unplug the power adapter, the Powerbook will immediately shut off. Removing the battery and pressing the button in it shows a single flashing LED. I could have sworn that this was the better of my two Wallstreet batteries, and now it is useless. Perhaps I could do a manual disharge to revive it. Any thoughts?

 

[Dookie]

maybe its the charging circuit board. I've read elsewhere that the charging boards tend to die.

 

[wally]

Aging (increased series resistance) is gradual. Open cells cause a sudden loss proportionately, like a drop to 1/2 or 2/3 capacity of what was expected. Shorted cells can cause those particular sudden onset symptoms. Lithiums can develop high resistance shorts (hundreds to thousands of ohms) that cause minimal heating but cause state of charge to drift out of balance. So after some time one section has low state of charge relative to other sections. It discharges first, and the other sections in series that are almost fully charged recharge first then stop the charge to avoid getting overcharged. The continued leakage in one section eventually gets its voltage so low that charging is inhibited altogether for safety reasons. Older battery pack designs have no cell equalization provisions and newer ones have limited ability to compensate for internal shorts. If you carefully open and measure cell group voltages in such a battery, one section will be really low compared with the others. Even if you were to surgically recharge just the low state of charge group, it would self discharge itself again requiring manual intervention. No cure except by recelling.

 

[Unknown_K]

How hard is it to recell a wallstreet battery? How much to the cells tend to cost?

 

[wally]

Easy for experts but unadvisable for safety reasons if you have to ask. The safety requirements are in the datasheets and application notes at the original cell manufacturer's websites and they are all fairy uniform across different Lithium Ion suppliers. The RC folks work with building their own packs and live to tell about it, but they also post pictures now and then of batteries that exploded and burned. You first have to develop skill working with live NiMH recelling with other laptops until you are CERTAIN you can work with live batteries without shorting. The lithiums need to be soldered while they have some charge in them. Attempting to fully drain them to zero voltage even just once for installation purposes dooms them to a premature death. The internal PTCs inside the Lithiums offer some degree of safety, but best to work out how not to short elsewhere. Then you need to verify preferably by a measurement that your soldering technique does not overheat the base of the solder tabs. Usually not a problem unless the tabs are really short from salvaged batteries, and your technique is slow. Staying below the boiling point of water at the cell surface (thermal runaway begins at approximately 100 C) would be good to avoid explosion. Cost can be free, from batteries on hand, up to the prices on batteryspace.com. If you need the gas gauge to work the replacement batteries need to be somewhat matched in voltage, capacity and internal resistance, however batteries salvaged from a single used working battery often meet this criteria, and new batteries purchased as a set probably will easily meet this. If the replacement batteries have greater capacity than the originals you probably will not realize this additional capacity unless you reprogram the EEPROM capacity constant in the battery manager board. To do this you first have to reverse engineer the battery manager chip identity and the safety chip identity and look at their spec sheets (which with some math will also tell you how well the cells need to be matched), but lacking this you can just use the replacement batteries at the original capacity limit. This means generally that the least expensive, lower capacity new battery cell choice is the one to buy unless you are up to reprogramming.

People can and do recell Lithium Ion packs of many different makes and have so described on their websites, so if you can stay in the safe zone it is doable, and if you exceed the safe zone the heat of soldering alone could cause an explosion and fire that you cannot stop. If you do not yet know your limitations for sure do not attempt it. Some things like NiMH are fun experiments but for Lithium you need to be sure of your technique.