PowerBook 500 Series Battery Rebuild Failure (Oops, all dead EMMs!)

[3lectr1cPPC]

I've got two working right now (or, last time I tested them anyway), but still with the problem where they only run for half as long as they should. I think I just need to use different cells. I have one more non-rebuilt battery which I need to crack open. When I get around to it, I'm going to try using the correct A cells and spot weld them together myself.

 

[jmacz]

Just charged both batteries and ran Battery Amnesia. Came in at 141 minutes to drain both batteries. This is about 60 minutes shorter than what @croissantking got and I think less than what I previously got as well. But there was one difference... my 540c currently has a spinning hard disk in it (removed the ZuluSCSI as I needed it for another laptop). I'm sure that uses more power than an emulator.

 

[jmacz]

LOL... argh. My "A" cell pack has zero errors. My "AA" cell pack has an error that is uncorrectable (Lind, EMMpathy). Given it charges ok, I'm just going to leave it for now. I don't feel like opening it again to replace the memory chip.

 

[alexGS]

LOL... argh. My "A" cell pack has zero errors. My "AA" cell pack has an error that is uncorrectable (Lind, EMMpathy). Given it charges ok, I'm just going to leave it for now. I don't feel like opening it again to replace the memory chip.

It was wonderful to fix that error by replacing the memory chip, I really appreciate that advice (a while ago now), thank you I hoped it might resolve some of the quirks and allow it to calculate a correct dt/dT rather than “No”. Mind you, probably wouldn’t stop it running dead flat!

croissantking - yes I think I love my 540c, my favourite Mac, but it is difficult when the result is to destroy perfectly good cells. Yes, I think they would have been left discharged. I try to exercise it every month, or two…

 

[croissantking]

It's clear to me at this point that the EMM is a very poorly designed BMS. Drains the cells flat on its own, constantly produces EEPROM errors such that there are two aftermarket tools to fix this, and on top of all that seemingly just likes to drop totally dead. I had one do the same thing (way back at the start of this thread).
These 500 batteries have got to be up in the "terrible BMS hall of fame", right next to the IBM ThinkPad 600 battery...

Better than the 3400c, though!

Would an external battery charger help? Then just leave them with a constant trickle. Or even just leaving the PowerBook plugged in to achieve the same (although I don’t trust the stock AC adapter very much and would be wary of doing this).

 

[jmacz]

Just charged both batteries and ran Battery Amnesia. Came in at 141 minutes to drain both batteries. This is about 60 minutes shorter than what @croissantking got and I think less than what I previously got as well. But there was one difference... my 540c currently has a spinning hard disk in it (removed the ZuluSCSI as I needed it for another laptop). I'm sure that uses more power than an emulator.

FYI, this was with a linear straight curve from 100% to 0%.

If you look at the curve that @croissantking, it was an S curve. In my previous tests, cases where I see that S curve I do much better in terms of duration. Without the S (ie. a straight linear line down), I get a lot less. I don't know why it flattens out sometimes.

I'm running another test right now and I'm going to come in less than the previous 141 minutes (by a significant margin). But this time during the test, I'm hearing hard drive activity. I'm not sure why that is since Battery Amnesia is the only thing running. I didn't hear this during the last test.

 

[jmacz]

I'm running another test right now and I'm going to come in less than the previous 141 minutes (by a significant margin). But this time during the test, I'm hearing hard drive activity. I'm not sure why that is since Battery Amnesia is the only thing running. I didn't hear this during the last test.

Made it to 133 minutes. So that not far off from last time. But not the 160-180 minutes I saw before with the SCSI emulator.

 

[croissantking]

But this time during the test, I'm hearing hard drive activity. I'm not sure why that is since Battery Amnesia is the only thing running. I didn't hear this during the last test.

I always hear hard drive activity (my SCSI emulators have a piezo buzzer fitted) - I thought this was a feature of Battery Amnesia to use as much power as possible.

 

[jmacz]

I always hear hard drive activity (my SCSI emulators have a piezo buzzer fitted) - I thought this was a feature of Battery Amnesia to use as much power as possible.

Not sure why I didn’t hear anything the first time.

 

[3lectr1cPPC]

Oh good lord, this is some of the most brittle plastic I’ve seen.

My other three 500 series batteries were all a fight to get open. The plastics were still very pliable. This thing? Totally different story. This is the only of the three with these purple cells inside - it’s labeled EMM-P so I’m guessing these are Panasonic cells. That would solve the mystery of who made the 5300 series battery cells.
I’m not actually rebuilding this battery right now. I just wanted to get the cells out so the EMM and ribbon are safe for a future rebuild. I’m going to try to source some individual A cells and spot weld a pack together, rather than using the prebuilt pack I did for the other two (which doesn’t work very well).

This battery was made in Mexico rather than Japan like my other batteries. Clearly the plastics vendor was different!

 

[croissantking]

Oh good lord, this is some of the most brittle plastic I’ve seen.
View attachment 98722
My other three 500 series batteries were all a fight to get open. The plastics were still very pliable. This thing? Totally different story. This is the only of the three with these purple cells inside - it’s labeled EMM-P so I’m guessing these are Panasonic cells. That would solve the mystery of who made the 5300 series battery cells.
I’m not actually rebuilding this battery right now. I just wanted to get the cells out so the EMM and ribbon are safe for a future rebuild. I’m going to try to source some individual A cells and spot weld a pack together, rather than using the prebuilt pack I did for the other two (which doesn’t work very well).

This battery was made in Mexico rather than Japan like my other batteries. Clearly the plastics vendor was different!