FS: Jornada 728s, 720, J728 ROM and power adapters.

Jax, I realize this is a little off the thread here but was wondering if you had any info on the innards of the battery for the J720? I would like to make myself a high capacity pack as I use it for hours on end and am often away from an outlet for days at a time.

As you have rebuilt these packs I was wondering if you could help.

Is a charging circuit or regulator built directly into the pack and if so are the two ground pins on the connector common or is one a safety like in cellphone batteries?

I would just take mine apart but as it still works good I would rather leave that until necessary.

Also I would be interested to know how much it would cost to get one of your rebuilds shipped to Ontario?

Thanx for any help you can give me.

hi OneDumbTrucker, all you need is two high capacity 2400 mAh cells, from batteryspace.com. just exchange the cells (you will need to solder, careful!). that's all. and yes of course it is a li-ion battery pack so it has a circuit / regulator built in the pack. the connector can have a lot of pins, be happy that the jornada has only three (easier to charge the battery in an external charger - but anyway it exists officially too, no need to build one).

You need two 18650 sized li-ion cells. Highest capacity you can find. And you should try hard to find ones with solder tabs if you can, unless you really know what you're doing with batteries. Even with then, it's not something I recommend you try on your own.
A lithium fire is very dangerious, as it burns on contact with water (Including that in the air or on your hands.)

I'll have to get back to you on the price of a rebuilt battery.

Oh, and the Jornada 720 is still available.

easy to order tabbed ones from batteryspace.com. everyone can do the battery cell replacement who can solder properly and is *careful*.

I won't tell you that you can't do it yourself, only that I don't recommend it.
Overheating a cell (Say with, oh, I don't know, a soldering iron) is a great way to bring about an explosion and a fire that you can't put out with water.

Don't worry about the safety factor, I am an electronics engineering technologist and have had much practice with making homebuilt battery packs. I was only wondering about whether the j720 pack has any other circuitry in it other than just the batterys and connectors as I didn't want to take mine apart if I didn't have to.
A lot of cell phone lithium cells have an over current protection built into them and I wasn't sure whether the j720 batt was the same or whether I could just direct wire a couple 3.6V Lithium cells.

Thanx for the help everyone, and hopefully Jax when I get back from England I will have the money to buy a rebuilt battery pack as I would really like to have a spare or two.

of course the jornada battery is the same. it is the same li-ion type battery...
oh and the cells themselves don't have anything, the pack has the additional circuitries. this is why you need to keep the pack and not just put two cells in the jornada you definitely need to solder them in the pack.
good luck.

Edited by cmonex 2006-07-26 7:04 PM