A couple of weeks ago, I shared about my HP-110 (or Portable Plus) laptop (see link below). I didn’t address the battery question at the time for the sake of clarity and also because I needed some time to rebuild a battery pack, as close to the original design as possible. Before getting into some details, I want to share my surprise. Indeed, I’ve expected a well-integrated battery pack, à-la HP. And it is not what I found. Therefore, I am wondering if this is an after-market battery? But at the same time, it seems too elaborate for that. I do not know. What I did notice though, is that in the service manual of the previous version (not the + model), the battery depiction resembles more to three D-cell batteries packed together. Maybe an HP employee/expert can shed some light on this. Nonetheless, the battery – an SLA (Sealed Lead Acid) battery – was dead. Without load, it had barely a voltage of 0.9, which was not a good omen.
Indeed, after trying charging it for a day with a 6V/1A charger, it didn’t keep any of it. So, it was good for a replacement. Of course, HP parts cannot be bought anymore, and the few articles found on the web claiming that you could still source them in some random stores turned out to be dead ends to me. The original battery in my system has a Panasonic LCR6V2.4P at its core (6V, 2.4Ah/20HR. cycle use: 7.3~7.5V, standby use: 6.8~6.9V, Initial current < 0.8A). You can still easily find equivalent models in any battery store. One important detail is the geometry of the leads (or connectors). Indeed, the odd montage HP seemed to use requires to pick the right one: with the leads aligned and not offset. What HP did next, is to fit snug this battery in the battery compartment using a rubber pad. Nothing really odd about it until this point. But, they also stick an epoxy board with two screws sticking out of them on one side of the battery. This board is held in place with double-sided tape.
The screws are positioned in such a way that they align, once the battery is shoveled into the case, with two double leads coming out from the motherboard. These are screwed onto the board with the screws and nuts. But this doesn’t make a circuit. So, in addition, the positive lead of the battery, which by geometry is at 90 degrees and at the other side from the screws, is connected to the “positive” screw using a thin metal strip, glued all along the side of the battery. It is then covered with some sort of electric tape for isolation. The same trick is used for the negative lead, but since it is much closer to its screw, the metal strip is very short. Add to this some padding between the leads, and you have an idea of how this pack looks. This design works well but seems a bit off compared to the classic HP build.
Regardless, I had to rebuild a similar package. I decided to drop the original metal strips since they were too damaged during the dismounting (that glue is really strong, and the strips are thin). I’ve decided to used adhesive copper tape to replace the metal strips. Instead of using plain copper tape and cover it with electric tape, I’ve preferred using some Tapewire (other brands exist for sure). These tapes are used in priority to wire speakers by running and sticking the tape wires onto the walls. The tape is covered with an insulator that one can paint over easily. The tape is thin enough so it is not visible, and in this particular use case, it doesn’t prevent the battery to fit into its compartment. The gauge of the tapes is enough to supply the required current to the computer, so all went well. Because this particular tape model has two separate conductors, I could split it into two strips and use one for the long positive trip and the other for the short negative one. Everything worked well, and my HP-110 is ready to go all over the world … if needed. Last but not the least, if you plan to fiddle with an HP-110 battery pack, think to remove the battery jumper (on OFF position) on the motherboard.