X61s battery board reset
Posted: Tue Sep 18, 2012 10:35 am
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
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
Live and learn, I guess.