X61s battery board reset

[pgoelz]

Hi all,

I tried my hand at rebuilding a couple X61s batteries with known good Sanyo cells from a battery store. All went well with my Chinese aftermarket battery even though I foolishly neglected to leave an external power source connected while the cells were disconnected. To get it running again, I just had to power the internal board externally by connecting a (current limited) voltage greater than the internal pack voltage to the battery output terminals, and that reset the monitor board and all was well.

But with a second genuine IBM battery (also foolishly unpowered during cell replacement) I was not so successful. I was unable to get the board powered up with any combination of internal or external power. In the end, I swapped the board out for the one from the aftermarket battery.

Does anyone know the secret to re-initializing an IBM battery monitor board that has had the battery cells disconnected without being externally powered? I would like to use this board because A) it does not trigger the "non-genuine IBM" warning and B) it does not slowly discharge the cells like the aftermarket battery does (about 1% per 1-2 days) even on AC power.

Interesting sidebar.... the rebuilt Chinese aftermarket battery seemed to work great for many months even though it slowly discharged and then recharged while on AC. I have the charge threshold set for charge start at 90% and charge stop at 95% and it does start and stop when the gauge indicates those values. However, today, I decided to run it on battery only to see how long it would run. It ran for a couple minutes, reporting about 85% remaining.... and then suddenly triggered the low battery warning (the battery gauge went to 10% at the same time) and hibernated a couple minutes later. Since this was a pack I had rebuilt, I was able to open it easily and measure the cells. They were all between 3.5V and 3.64V (unloaded). I found it interesting that they were that far out of balance, but an unloaded voltage of ~3.5V does sound consistent with the low battery warning, and the voltages would seem to indicate that I do not have a dead cell. Still not sure how they got that low that quickly, unless the battery monitor was severely mis-calibrated. I calibrated it when the pack was first rebuilt, but not since.

After I wrote that above, it dawned on me that perhaps my mistake was not charging all the way to 100%? I am wondering if the 100% charge point is determined by cell voltage, but less than 100% is (most likely) determined by the energy monitor. If the energy monitor circuit is off, the "95% charged" point could slowly walk downward due to inaccuracies. ??

TIA,
Paul

[twistero]

IIRC genuine IBM/Lenovo battery boards are unrecoverable after cutting power.

[pgoelz]

IIRC genuine IBM/Lenovo battery boards are unrecoverable after cutting power.

Well................ crap Live and learn, I guess.

Maybe I can find another dead IBM pack and try again with external power applied. Its kind of a toss up though. The Sanyo cells cost me about $40, which is about what a complete aftermarket Chinese pack would cost.

Paul

[twistero]

Well, you have to consider the reliability of the Sanyo cells you bought as well. Did you get them from a reliable seller? There are plenty of people openly selling second-hand cells recovered from used battery packs on those Chinese e-commerce sites. They do state the fact up front, but it's easy to imagine someone selling these old cells passing them as new.

[pgoelz]

Well, you have to consider the reliability of the Sanyo cells you bought as well. Did you get them from a reliable seller? There are plenty of people openly selling second-hand cells recovered from used battery packs on those Chinese e-commerce sites. They do state the fact up front, but it's easy to imagine someone selling these old cells passing them as new.

These were purchased (in person) from the local "Battery Giant" franchise. I have spoken to him at length and I believe him to be selling 100% genuine brand new (tabbed) Sanyo cells. These are the same cells they use internally to rebuild batteries.

I initiated a battery gauge reset on the suspect pack and when it started charging it went to 100% rapidly and then stayed there for at least an hour, still charging (indicating that the battery gauge was indeed wrong). It finally stopped charging and is now discharging. It seems to be dropping normally so far (it is currently down to 75% and still dropping appropriately).

After the reset, I'll leave it set to charge all the way to 100% and see if that avoids the battery gauge drift. I wish they would stop trying to monitor current in and out and just use battery voltage. It is not as accurate and any estimate of remaining run time would be just that... an estimate. But it sure would eliminate all this battery gauge drift nonsense.

Paul

[pgoelz]

Sorry guys.... I just realized I started this thread in the X41 forum instead of the intended X61 forum. I have bookmarks for both. They are adjacent and I clicked the wrong one

Moderators, please feel free to move it.

Thanks,
Paul

Admin note: Done!