PowerBook 160 Repairs

[jmacz]

These were prebuilt packs with AA NiCDs. Finding NiCD A cells was harder so I punted for now. NiMH A cells are available on Mouser but a little pricey.

I grabbed 75 celsius thermal fuses off Amazon.

 

[3lectr1cPPC]

Would A cells fit? You mentioned the dimensions of the original cells earlier - is that A size?

 

[jmacz]

The original cells were A size so yes they would fit. But it would be a much tighter fit. Length wise A and AA are the same (50mm). But diameter wise the A is 17mm whereas the AA is 14mm. So the AAs are much more forgiving routing the wires etc whereas the A would be a really tight fit when putting it back together.

 

[3lectr1cPPC]

Good to know. I have cracked an aftermarket pack over (and it uses A cells) but wasn’t sure if the OEM pack did. Aftermarket pack is from 2004 but the cells are already leaking…

 

[jmacz]

Well, results are mediocre I think... I fully charged the battery and then left the machine running with full brightness, sleep disabled, configured to not allow the SCSI2SD to sleep. But I wasn't using it - left it sitting there at full brightness. Lasted about 1 hour 20 minutes. It's fine for now, at least I have something functional and it's not like I'm going to be heavily using this PowerBook.

I did run into another issue though. Even before I started mucking with the battery, the drive (SCSI2SD) was flaking out a bit. Every so often, it would not detect on boot. This afternoon as I was installing a fresh System 7.1.1 on it, it wasn't detecting for a while. But I was eventually able to do the install. Just tried booting again after letting it sit for a bit and I cannot get the drive to detect at all on boot... just getting the question mark disk icon. Will have to take this apart and figure out what's going on with it.

 

[jmacz]

My spare ZuluSCSI laptop version is working fine. Not sure what's wrong with this SCSI2SD. Will have to play with it later.

 

[jmacz]

Not lasting long enough under load. Going to try A size NiCDs next.

 

[jmacz]

I used battery amnesia to fully drain the battery. Right before system shutdown, battery amnesia was reporting a voltage reading of 5.66V from the battery. Then the power shut off. With the battery out of the laptop and no load, it reads about 6.09V. I then booted with the power supply and inserted the battery to charge it. The battery meter (I'm using both the battery desk accessory as well as a utility called mybattery - made by the same author as battery amnesia) and it's showing the battery is half full, voltage is up at 6.14V and starts climbing. Strange.

I think I had read that capacities aside, the difference between an A battery, AA battery, and AAA battery is voltage drop under load. It could well be that with the AA, the voltage is dropping enough where the system shuts off. Maybe there's less of a drop with an A size cell?

I found some new Sanyo A size NiCDs online, 1700 mAH. So a pack with two parallel sets should provide 3400mAH total capacity which is larger than the stock 2800mAH. Fairly pricey ($3/each).

 

[croissantking]

I used battery amnesia to fully drain the battery. Right before system shutdown, battery amnesia was reporting a voltage reading of 5.66V from the battery. Then the power shut off. With the battery out of the laptop and no load, it reads about 6.09V. I then booted with the power supply and inserted the battery to charge it. The battery meter (I'm using both the battery desk accessory as well as a utility called mybattery - made by the same author as battery amnesia) and it's showing the battery is half full, voltage is up at 6.14V and starts climbing. Strange.

I think I had read that capacities aside, the difference between an A battery, AA battery, and AAA battery is voltage drop under load. It could well be that with the AA, the voltage is dropping enough where the system shuts off. Maybe there's less of a drop with an A size cell?

I found some new Sanyo A size NiCDs online, 1700 mAH. So a pack with two parallel sets should provide 3400mAH total capacity which is larger than the stock 2800mAH. Fairly pricey ($3/each).

Just for reference, this is the design I went for in two of my rebuilds using 4/3 A NiMH cells. I had planned to use 10x A cells but had trouble with fitment as I didn’t have access to a spot welder at the time. Clearance is very tight with the original configuration so getting the cells welded together tightly is crucial and you just can’t achieve that when you solder them together.

Performance is OK, they sometimes don’t seem to fully charge up so runtime feels a bit inconsistent. One of the packs seems to work a bit better than the other in terms of runtime despite being the same design. These cells are definitely not premium quality however I used the same type of A cells originally designated for this battery in my PB1400c with very good results.

There doesn’t seem to be a lot of choice as regards purchasing new A or 4/3A size NiMH cells in the UK. It was either getting these ones for about £2-3 off a seller on eBay or paying upwards of £10 each for them for brand name cells from RS Components, Mouser etc.

 

[jmacz]

Ah.. I just got the the 10 "A" cells yesterday. Gonna give it a try this weekend. They are NiCDs.

 

[jmacz]

Just closing the loop on this. My rebuilt battery pack with "A" sized cells (10 of them) is working fine, as long as it's charged externally via an external charger. I am getting about 80-90 minutes of use out of a fully charged battery which seems fine.

Charging within the laptop doesn't work however and I'm not sure why.

The battery pack (fully charged externally) powers the laptop so I know all the connections are fine. Charging via the laptop however delivers some charge but it stops charging with the system saying it's at 100% but it's clearly not. The battery isn't smart, it only has power and ground connections, so all status monitoring is being done via the voltage. I don't know why it doesn't charge properly via the laptop. It can't be a faulty voltage detection either as the voltage is detected just fine when the battery has been charged externally. All I can think of is some diode that allows power to flow from the power adapter into the battery is malfunctioning .. assuming it's a diode since power going the other way (from battery to the system) is fine.

 

[croissantking]

Just closing the loop on this. My rebuilt battery pack with "A" sized cells (10 of them) is working fine, as long as it's charged externally via an external charger. I am getting about 80-90 minutes of use out of a fully charged battery which seems fine.

Charging within the laptop doesn't work however and I'm not sure why.

The battery pack (fully charged externally) powers the laptop so I know all the connections are fine. Charging via the laptop however delivers some charge but it stops charging with the system saying it's at 100% but it's clearly not. The battery isn't smart, it only has power and ground connections, so all status monitoring is being done via the voltage. I don't know why it doesn't charge properly via the laptop. It can't be a faulty voltage detection either as the voltage is detected just fine when the battery has been charged externally. All I can think of is some diode that allows power to flow from the power adapter into the battery is malfunctioning .. assuming it's a diode since power going the other way (from battery to the system) is fine.

Just a wild thought but diode D15 often fails on these machines, near the power jack. Worth a check?

 

[jmacz]

Just a wild thought but diode D15 often fails on these machines, near the power jack. Worth a check?

Thanks for the lead. Will check it out.