Being a Z88 user, I found your article about using the “Renewal RAY-O-VAC” rechargeable battery very useful. I think this provides a GOOD solution for low cost operation. I’d like to share with others my Z88 battery experiences.
I often take long airplane journeys requiring a computer totally dependent upon its batteries. I balance the benefits of a modern notebook with really great software against my lighter Z88. The Z88 is better suited for the long journeys because its batteries last longer and can be changed on the fly. For a long journey, these advantages can outweigh the Z88’s limited primitive software, limited storage, and the nuisance of cable file transfer.
For a long journey, the Z88 battery life wins hands down. I get 4 – 6 hours from the one set before getting the low battery message. I have read that battery life can be safely extended by ignoring the low battery message and waiting until the screen starts to blank. Being conservative, I never tried this.
Actual usage time is indefinite as the batteries can be changed on the fly. A capacitor in the Z88 retains all memories for several minutes without the batteries. This feature allows, when the low battery message appears, battery replacement and continued operation. By carrying enough spare batteries, battery life on a long trip is not an issue.
I have experimented with several techniques to reduce battery cost. Nicads were tried, but are not satisfactory. With 4 AA Nicads (6 volts) the low battery message is always on. I also tried 5 smaller (6 volts) Nicads. I quickly abandoned Nicads because of their short storage life and no real low battery warning. Nicads are risky, too easy to lose the Z88s stored data.
My best solution is using a 4 D cells (6 volts) external battery pack, slightly larger than the size of the Z88’s AC adapter. D cells cost about the same as the required AA batteries and provide a quantum increase in battery life. I purchased from Radio Shack a 4 D cell battery holder and a plug to fit the Z88’s power jack, fabricating the necessary cable. The AA’s in the Z88 serve as back up.
I have used this set up on long trips and have never exhausted the D cells, I strongly recommend this external pack. I like to plan on using the rechargeable Renewal batteries for shorter trips to obtain portability at minimum cost. My approach for longer trips when a recharge is not an option is to still use the external battery pack.
Chairman’s thoughts on this:-
Many thanks for the letter and the information on the RENEWAL batteries.
On the practical side, the number of times that you can recharge the RENEWAL batteries is in proportion to the amount of discharge, the less the discharge the more times it can be recharged. The spec. sheet I got from the company suggested that the 25 times of cycling could be extended to 100 if the discharge was not too great. I called their 800 number and I could not get a technician that could or would give that in an answer that I could relate to voltage. But I got the impression that it was along the lines of 85% of the full charge voltage. 5 volts to turn on the low battery signal means that likely the batteries are discharged to about 83% of their full charge voltage so the low battery light is a good time to change batteries. 0/0.