Turning on a Jornada 820 without working battery

Hi there

I have a Hewlett Packard Jornada 820, and unfortunately the battery has now packed it in altogether. I'd like to try to turn the machine back on just to see if it still works, after it fell and.. uh.. sorta broke. [Image 1] [Image 2] It doesn't turn on and previously didn't turn on because the battery was dead, and they don't run without them.

The motherboard still looks very much intact, which gives me hope that it could possibly be repurposed as a desktop-type PC through it's VGA and single USB output (which in theory, should work with a USB hub).

Is it at all possible to force it to turn on purely on AC power?

Thanks, sorry that I broke it and probably made everyone here cringe in terror and shock

Edit Oh my gosh, that's so creative of you guys to have the ActiveSync loading GIF as the submitting post GIF.

Edited by JustARegularNerd 2018-10-13 1:47 PM

The J820 will run fine with the AC adapter.

Edit: Man, quite a bit of damage - I'll be surprised if the display still works!
Ah... I see now. Good luck.

Edited by Mjolnir 2018-10-13 6:10 PM

Just ran a test on a J820 that came as 'parts' when I bought my good ones. It's display is broken and the keyboard is loose. I hooked it up to a monitor and an AC adapter (it does put charge in its battery) and did a reset - nothing. The problem is that without a monitor I can't tell if the operating system is running and to get VGA out, AFIK, you need to run the 'HP Show' application.

Okay then, that's a bit of a shame. I was hoping it would 'clone' the built-in LCD to the VGA output by default. The LCD on my one looks fine though, I can't see any internal leaks or cracks. Perhaps if I set HP Show as a startup application?

Also, the battery is totally dead, to the extent where having it in there with the AC adapter does nothing because it just won't hold a charge at all. The light on the front doesn't even turn on. That's why I'm wondering if there's any possible way to 'trick' the computer into starting without the battery (e.g. shorting two different pins)

Edited by JustARegularNerd 2018-10-14 1:40 AM

Have you tried a hard reset? You will lose all data on the device that's not part of the operating system. The J820 will start and run fine without either battery - you must of course save your data externally.








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Very nice!

Thanks. Forgive the dust - I was in my 'junk' room.

no worries, we all must have a form of mancave...

Yeah, my "mancave" will need a hazmat crew to clean up.

I think male population is like that in one way or the other.
-stingraze

Just a thought, why don't you upconvert from 5V -> whatever the J820 battery voltage, with correct amerage. That way, it will be a safety measure. Rebuilding cells are very dangerous if you don't know what you are doing.

-stingraze

I recently managed to acquire a Jornada 820 in mint condition with a working (!) battery. Keeping it plugged in 24/7 atm to make sure it never falls under the threshold voltage, that happened with my first one sadly. My plan is to hook up my logic analyzer and sniff around a bit and documenting it.

Ideally then it would be possible to build a replacement battery that will be recognized by the 820, but the most important thing would be having the protocol preserved.

Excited to hear this. offer one piece of advice also... Mine was plugged in for about 20 years almost continuously and the battery did die out and now receive the dreaded no main battery detected error message in windows ce. In short, make haste please

That reminds me of me making a graph of Sigmarion 3 battery discharge. (x and y inverted, lol) long time ago, circa 2007.)

One tip: Li-ion batteries like to be discharged too.
If it holds charge too much it gets "pregnant" as we say here in Japan.

There is a trustworthy re-celler here in Japan that I've always wanted to use to recell my Li-ion batteries... haha