|
Thanks everyone and thanks Karel for your comments. I think the expansion of the battery during charge-discharge should be okay. The battery is ~1.5 mm thinner than the original. There is room to expand lengthwise at least 5% towards the top and widthwise ~5% except at the point shown by the arrow where I had to shave a little off the screw spacer. The fit is not extremely tight due to the packaging with the folded excess edges and should allow for a few mm expansion even between this point and the opposite edge. But it could be of concern and after many hundred charge-discharge cycles could weaken the battery here. I will let you know if I ever have any problems.
Immediately after a charge cycle, I did not notice any significant expansion of the battery pack. If the battery were shorted however or the battery protection circuit failed for whatever reason, the temperature change could cause significant expansion more than what is allowed here and be dangerous. It is important to make sure the leads are correctly connected and insulated to prevent this possibility. The battery I ordered is UL listed so it should be okay. The circuit is the original circuit and I hope it has overtemp protection.
A less wide or less tall battery may have been a better fit but there are not too many commercially available batteries that I could find online with the parameters I was looking for.
As far as the mod goes. The case can be removed with a T-6 torx driver. A credit card slid a long the edges releases the tabs as in any small device. There is a speaker cable connected and a battery cable so do not pry the whole back cover off to quickly without disconnecting these first. See pictures for the plastic bits I removed. Additional pictures show placement of original battery and feint white lines around it where the removed walls used to be. Also the screw holes where a bracket was attached to hold the old batteries in place was removed. The last picture shows the batteries and circuit in place. I have cellophane tape covering all the exposed leads and anything that may short and also to hold the pieces down. I also used some electrical tape not shown to cover the same areas for extra protection.
So far I am getting about 20-21 hrs per charge with or without stylus removed. I think the orig is 2x 1100 mAh batteries so it should be 63% more use per charge. I think it seems to be about right although I was hoping for more.
Hope this helps and beware of chance of exploding battery.
|