Mac Daniel's Advice

Field Testing the Carpenter's PB 100 Fix

Manuel Mejia Jr - 2000.05.09

A few weeks ago, I overcame what apparently is the most common problem with aging PowerBook 100s - the short charge and life span of the PB 100's lead acid battery. I had my father, a retired carpenter, create a wooden adapter that goes into the battery compartment. The adapter allows me to use common 7.2 volt R/C car battery packs to run the computer. To learn more about how to build such an adapter, refer to the plan that accompanies this article.

In recent weeks, I have field tested the adapter. I find that the PB 100 will run with its backlight on with no other attachments (like the floppy drive) plugged in for about 70 minutes before shutting down. Unlike the old lead acid battery pack, you will not have much time between the initial warning that you are low on power and shut down. The NiCad 7.2 cell pack delivers a constant level of voltage to the PB 100 for those 60-70 minutes before heating up a few degrees and then losing its charge. Once the initial warning comes up, you have about 25 seconds to save your work and quit your application.

The standard battery monitor that is part of System 7.0.1 does not give the user adequate warning about the approaching loss of power. The desk accessory just tells you that you have full power until just before the battery pack is exhausted. Since such short notice is of limited use, I deleted the battery desk accessory from the hard drive and rely on my watch and the first stage warning of imminent power loss from the PB 100.

Since the publication of the initial Carpenter's article, I have gotten email asking why I did not choose to wire a new set of batteries into the battery compartment of the PB 100. I have reviewed various comments about rebuilding existing PB 100 battery packs so that they will function again. I felt that this solution required too much effort for a pack that is likely to wear out not long after it has been rebuilt.

I also have no desire to open up my PB 100's outer casing so that I could access the battery compartment. The device is very delicate once opened up, and I did not want to risk damaging the machine.

For those who need more than 60-70 minutes of run time on the PB 100 using a wood adapter, all you need to do is wire additional 7.2 volt battery packs in parallel to one Tamya plug. Each pack that is added will add another hour of operating time following the conditions I stated previously. Another option that one can use is to carry spare 7.2 volt battery packs with you and swap out power sources as they are used up.

For those PB 100 users wanting to use the AC plug connector rather than the wood block, this should work providing that you can find a spare plug. Those plugs may be a bit hard to come by. I had only 2 and both are attached to working power supplies. In the final analysis, the wood plug was the easiest way for me to make my PB 100 mobile again and free it from is fate as a desktop computer - forever dependent on a wall outlet for power.

Manuel Mejia Jr is familiar with Mac IIs, LCs, and older PowerBooks. He uses his Mac LC, PowerBook 145B, and PB 100 with System 7.1 on a regular basis and recently added a Mac Plus running System 6 to his collection. He's quite familiar with both System 6 and System 7. He also owns the Pina books on repairing compact Macs from 128k through the SE. You can read more about Manuel's computers in Manuel Mejia Jr's Four Old Macs.

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