PowerBook 160 Repairs

[jmacz]

Googling for “104 thermistor” shows that would designate a thermistor with 100k ohm resistance at 25C, and you should be able to measure your existing one to get the dimensions for a replacement. The tricky part is figuring out the B value of the original, which describes the curve for how the resistance changes as the temperature changes.

Yeah, and I still don't know if it's even bad or whether I'm barking up the wrong tree. Did not dawn on me that it was a thermistor as the ones I had seen previously look more blobby capacitors than SMD resistors. Learn something new.

The OS clearly thinks the battery gets fully charged, I've tried a few battery utilities as well as the battery DA included in System 7.1.1, and all report 100% charge, and the battery tools that report voltage, show a reading around 7.1V when it reaches 100%. Yet, then running Battery Amnesia, it starts at around 50% with a 6.8V reading and then drops very fast (when charged from the laptop), dying within 15-30 minutes. When charged from an external charger and then running Battery Amnesia, it starts at 100% and drains over 90 minutes.

Maybe the issue is with whatever component is reading the battery voltage?

 

[mdeverhart]

When charged from an external charger and then running Battery Amnesia, it starts at 100% and drains over 90 minutes.

What battery voltage is reported when you charge using an external charger? What voltage do you read from the battery if you check it with a multimeter after charging with an external charger?

I’m wondering if the internal charger is stopping the charge early for some reason.

 

[croissantking]

Just for context (I am sure I mentioned this before) my PowerBook 180s don’t consistently charge up my rebuilt batteries properly. Just as you’ve found, they often will think the battery is fully charged even though it’s maybe at only at 50% capacity. Many times, pulling out the AC adapter and plugging it back in gets it to continue charging.

So whatever issue is causing yours to not want to take a charge seems endemic to the 160/180 series.

 

[3lectr1cPPC]

Have you tried leaving it plugged in overnight while powered off yet? That worked on my PowerBook 145 which would "charge" the battery up in about a minute (while not putting any actual charge into it).

 

[jmacz]

What battery voltage is reported when you charge using an external charger? What voltage do you read from the battery if you check it with a multimeter after charging with an external charger?

Was meaning to check this and charged my battery yesterday using the external charger but forgot to go back and look. Will need to look when I get home tonight.

I’m wondering if the internal charger is stopping the charge early for some reason.

Yup exactly. Just trying to figure out why.

Given there’s only two connections from the battery (positive and negative), the only sense the laptop has on charge state has to be voltage, so curious if the voltage monitoring mechanism is busted.

So whatever issue is causing yours to not want to take a charge seems endemic to the 160/180 series.

Hmm interesting. That kinda sucks.

Have you tried leaving it plugged in overnight while powered off yet? That worked on my PowerBook 145 which would "charge" the battery up in about a minute (while not putting any actual charge into it).

Yes, tried overnight and even longer. Doesn’t help. It’s really strange because if I charge via the laptop and watch the desk accessory gauge, it gets to 100% quickly and it should not do that. So the laptop clearly thinks it’s charged when it’s not.

 

[jmacz]

Charged via the Laptop

• Multimeter reading after leaving the battery in the laptop overnight (with laptop off): 6.8V
• Battery Amnesia initial reading: 6.7V, 100% capacity
• Drain Time: Usually ~20-30 minutes

Charged via External Apple Charger

• Multimeter reading: 7.1V
• Battery Amnesia initial reading: 6.7V, 100% capacity
• Drain Time: Usually ~90-100 minutes ..... but I got 129 minutes in the most recent test!!!

My wild guesses:

• Voltage monitoring issue - laptop isn't reading voltage from battery properly
• Thermistor issue - thermistor thinks temperature is too high and shuts down charging - although the laptop thinks the battery is at 100% whereas I would expect a thermistor related issue to just shut down charging and leave the battery capacity at a sub 100% value
• Charging current issue - maybe the current going to the battery is really low (ie. stuck in trickle charge) and thus it would take a very long time to charge (maybe I should leave the battery charging inside the laptop for a week and see if it does any better)?

Looks like there's some interesting state information provided by the Power Manager (according to Inside Macintosh documentation) including whether the battery is being charged at a high rate plus some error checks. Will try probing these.