If you followed last days (from Monday actually) conversations on #omnimaga or #nspire-lua, you've probably noticed I was attempting to use a Nintendo DS battery pack instead of the AAA batteries (which are getting more expensive these days) and instead of the official battery pack, which is difficult to find in France. Just before telling you what I did, i'd like to be honest with you: you must not use/host/edit my pics without my permission. As some TI-Planet's pics were stolen and edited, I do not want this to happen to me.
Now, let's start off!
The official battery pack has the following characteristics: 3.7V and 1060mAh, so 3.92Wh. That battery is difficult to find in France (as I said 4 lines above) and really expensive: it's 1/4 of the price of a 2nd-hand TI-Nspire in France!
As some of you may not know, the battery pack can only be used on TI-Nspire TouchPad, which PCB includes a battery pack slot with 4 pins. If you have a Nspire ClickPad or don't even own a TI-Nspire, don't do what I did!!
If you're in that case, you will only have to use those expensive AAA batteries which are used by every manufacturer. These batteries have a life which depends of your use of the calculator. I personally belong to the intensive-users category..
It's when I found an old Nintendo DS Lite battery pack that I wondered if I could make it supply my TI-Nspire.. I didn't want to solder anything, so I just checked the thickness.... which is one of the problems: the NDS battery pack is thicker than the official battery pack. I had to push strongly on the back of the calc to close it more or less correctly...
As I didn't know what the 4 pins were used for, I decided to go on IRC and ask anyone.. Adriweb had a very pertinent answer: 2 +, 2 -.. One + for charging, one + to be used normally, one - to be charging and the last one to be used normally.
He was right! As I was sure that the pins, up to down, were ++--, I only used one wire for each sign, which means I have soldered only 2 wires to my battery pack.....
In order to know if it would be detected successfully by the calc, I prefered to keep the batteries inside and solder the battery pack like that: ++--. I then had a very strange message from the OS: In the "Status" menu, next to the battery pack icon, was blinking a "Warning" triangle. The pins aren't ++--, but --++... The OS detected the battery pack!! After having unsoldered and soldered correctly the battery pack, as well as removing the AAA batteries, it works!!
So here are some pictures of my experiment, with a Proof of Concept video, which is temporary because I need to use a real camera, not my phone