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Lithium Polymer battery for PB100 (and maybe portable)

techknight

Well-known member
Thats kind of oddball.... That leaves alot of room for error because the computer cant really use the battery pack as a part of the load if the AC Adatper gets weak. Not to mention switching. 

I would say use a boost converter, but we would need a clear way to tell if your into charge mode or not. Since, the load and charge are on the same terminals. could create this weird feedback scenario. 

 
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360alaska

Well-known member
Thats kind of oddball.... That leaves alot of room for error because the computer cant really use the battery pack as a part of the load if the AC Adatper gets weak. Not to mention switching. 

I would say use a boost converter, but we would need a clear way to tell if your into charge mode or not. Since, the load and charge are on the same terminals. could create this weird feedback scenario. 
Exactly! This is the only way I know how to make it work, but for a computer model that has not had any working batteries for sale in quite a while it's probably not a big deal to have to shut down before disconnecting, if you don't it's not like the computer is damaged or anything. Maybe I can use a small supercap, but how would I isolate it from the comparitor? I've thought about connecting an AND gate to the Status pins on each charger so the relay will open when both chargers give the signal but this battery is good enough.

 
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techknight

Well-known member
Well as long as it works properly and there are no ill-side effects, then its fine I suppose. 

I dont use my portable machines enough to warrant replacement batteries, at least not yet. Only functional batteries I have left are my Portable batteries, and I just float them every few months so they dont go bad, I havent used any of the machines for a few years now. 

 

Fizzbinn

Well-known member
Got my PB 100 battery from @360alaska this weekend and after replacing a failed fuse he helped me identify (that I didn’t realize was bad) I’m wire free on a 30 year old laptop! So cool!
 

A847A9EB-C53A-4481-A5FC-7D2A4C83642E.jpeg

 

sutekh

Well-known member
Very cool! I developed something similar for my Duo (separate thread over in the PowerBook forum), but although that platform has some of its own unique challenges (ID chips, current regulated charging algorithms, etc.), one critical factor made the single port charge / discharge steering easier than what you've overcome here: When plugged into the charger, the Duo's battery terminals see ~20vdc, which gets pulled down by a NiMh when inserted. That allowed for simple diode steering into a battery-internal Li-Ion 3S CC/CV charger (which requires a source voltage over ~13.5vdc to engage) when plugged into AC, but it isn't engaged by the battery alone when it's discharging and AC is unplugged. I have a functional 18650-based pack, but am not nearly brave enough to try selling them :)

I'm now in the process of developing a 2S pack with its own power-path steering circuity for my PowerBook 180c, and while in some ways its characteristics are more conducive (7.5vdc OE charged voltage is a great fit for a 2S Li-Ion's 7.4vdc), the single port charge / discharge switching is more complicated. I'm using a 2S CC/CV charge board (similar to the 3S part I used in the Duo pack), but with only 7.5vdc from the wall charger, a boost converter is necessary in this application (or a split as you've done, very creative!) I can't just let the Li-Ion cells / BMS back feed into the boost converter, and with a common charge / discharge port, some sort of sensing / switching is necessary to prevent that (as you're obviously well aware).

Ingenious approach with the split cells, comparator, and electro-mechanical relay. Love seeing resto-mod projects like this leveraging modern tech to augment these old 68Ks :) In my case, I'm planning to use an LT1494 (or similar) current-sensing opamp to drive the gate on a FET powering the internal boost converter / 2S charger only if current is flowing into to pack. Bench testing currently on-going with a thread to follow if it goes anywhere... 

 
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360alaska

Well-known member
Thank you for your encouragement! There was a bit of trial and error and research involved. I'm going to try and use the other half of the comparitor to release the relay when both charging ICs signal complete.

 
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360alaska

Well-known member
Here is my final design:
Capture4.JPG

I added the two 10m pullup resistors and two extra transistors to function as an AND gate to overide the latched comparitor and release the relay when charging is complete. This will also necessitate a small pcb redesign:


IMG_3919.jpg
 

KnobsNSwitches

Well-known member
Fantastic, I could not find this thread before...another ebay customer here, eagerly awaiting my replacement battery. (first one had some kind of relay issue, 360alaska was easy to work with.)

I wish i'd know this was here, would have been glad to contact 360alaska directly instead of thru ebay...

Such a cool product and design.
 
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