Replacement for a PDA Li-ion battery 1

[HolyBear]

I have three old PDAs I want to donate to a local hospital so the interns can hopefully put them to some good use.

They run on 1000mAh Li-ion batteries, but all three batteries are dead as doornails, so I'm looking into ways to replace them. The PDAs are so old, you can't just buy replacements anymore.

The two options I have considered are: building new Li-ion batteries or building a battery pack into the PDA that holds 3 AAA-batteries, and I'm wondering which would be easier and more importantly safer, as I won't be using them myself.

If I take apart the original batteries and replace the Li-ion cell with a comparable cell, should I be worried about the charging mechanism and how the battery interacts? I'm not very knowledgeable about Li-ion and don't want the batteries to be unsafe. I've heard the charging needs to be precise and the last thing the interns would need is the battery exploding!

I've already hooked up a battery pack to the PDA just to test it, and with normal alkaline batteries the PDA did power up, but only for about 20 seconds, then stopped working. I'm assuming this is because alkaline batteries aren't stable enough for the PDA. If I were to use NiMh rechargeable batteries, shouldn't that power the PDA about as well as the original Li-ion battery? The AAA batteries could then be charged in a simple charger as opposed to the PDA's charger.

Any insight would be greatly appreciated.
I'd just like for these old compaqs to be of some help to the interns as medical databases and such.

 

[davidh729]

It may actually be safer to put li-ion cells back in the PDA's. If the units have internal charging circuits and they ever get plugged in while the primary packs are installed you could end up with a really bad failure mode.
I would recommend that you not try and replace the batteries with something other than the original. Since you'll be liable for it's safety.

However, replacing a lithium-ion battery in a system designed that is already designed to use lithium technology is relatively straight forward. If you use a battery that is the same chemistry and has at least the capacity and current cpacbility of the old battery.

Dave Hyman
iRobot Corp

http://www.irobot.com

 

[HolyBear]

Sorry to bring this up again, but after a long, long search it has been established that there are no replacement batteries to be found.

I can't find anyone to refurbish the cells in the batteries either, as li-ion is so potentially aggressive/explosive.

Now, allow me to ask a possibly very stupid question:
If I take a battery for another PDA that comes with wires, also li-ion, also 3.8 mv, also 1000mAh (or a little more, preferably) and connect the wires to the correct poles, shouldn't that function in the same way?