Can you run your PPC from off the back-up battery?

[famousdavis]

I've never had my main battery go to 0% before, but I've wondered what would happen if that occurred? Can I still use my iPAQ if power is drawn from the back-up battery? Or is the back-up battery only used to retain RAM contents?

[g0097]

Your device will proably hard reset itself after a minute. I have not done this myself but I am guessing that it is like taking out your battery out of your ipaq for over a minute. I would not do it! 8O

[Sven Johannsen]

The backup battery in most devices, whether real or a virtual one carved out of the main battery can keep your data for a reasonable amount of time, but you cannot run the device on it. Typically the unit will give some sort of severe power warning, that you don't see, and then go into a coma. Applying power and letting it charge a while, even after 8 hours has resurrected my Axim once or twice, with no loss of data. My 2215 has gotten to the point that powering on just displays the critical warning long enough for me to see it and then goes back to sleep. I've had that happen in the morning and not gotten to a charger till I got home that evening with no problem. (Just couldn't use the PPCs while they were in hibernation)

The trick on the Axim was having the faith that I had drained my battery when the power button did nothing. I had diagnosed that as a lockup before and hard reset the poor thing by pulling both batteries. I'll always wonder if all I had to do was charge it that time.

BTW, the Axim has a somewhat unique hard reset sequence. Pressing power and the reset brings you to an option screen that offers to hard reset or cancel. I have had to do that on occasion to recover from a state that not even a soft reset would work. Cancel brought me back to stable. Most other PPC seem to assume that if you are hard reseting, you mean to, no opt out.

[qmrq]

iPAQs drop to "reserve mode" or something when the battery gets low. From there you have 36 hours to connect to a power source before data is lost. I have a white paper on iPAQ batteries if you're interested.