I have to agree. I received a Chumby for Christmas and promptly put a fresh alkaline 9V battery in it. My Chumby is sitting on my nightstand, plugged in and on while I am now several hundred miles away until tomorrow morning. With all the posts lately I have had a few restless nights wondering if my apartment will be in ashes. I called the office this morning and had them go in and pull the plug. It was an interesting conversation trying to explain why I needed them to do this. I sure hope we get some definative answers soon.

I have been running a 9volt in my chumby for a fe weeks now. I have had no problem so far, and I cant remember which thread it was, but I believe bunnie said that the 9volt in the current release chumbys (not the Alpha Prototype) is safe. Don't quote me until I can find the original quote myself.
I dont expect any answers from the folks at chumby for a few days due to the holidays, but I am sure they will give a solid answer soon.

There is a high-impedance path between the DC input and the battery input. The path consists of the reverse leakage through schottky diodes, less than a microamp. There is also some charge storage on the node as well (about 10 uF).

The reason why you see 11.5V is because reverse leakage through the battery voltage measurement circuitry will slowly charge up the 10uF of capacitance from charge sharing of voltage from the regular DC input line. The amount of reverse leakage and charge sharing is very tiny, but even a tiny current over a long period of time will charge a capacitor and therefore when you put your probes across the node you will see that charge.

If you install a regular 9V battery, this tiny leakage current will not charge the battery. Therefore, any standard 9V non-rechargeable battery would be fine to put inside the chumby device. You do not need a special rechargeable battery for safety.

As alluded to before, there is a pair of diodes that help the power management for the chumby. The diodes sit between the power supply, the battery, and the power input to the core board in "Y" topology. Therefore, if the power is lost, the battery will take over as the voltage supply. Primarily, the battery is there to keep the cryptoprocessor/alarm power manager IC alive in the case of a power outage, so that the chumby will wake you up if the power goes out. A more detailed discussion of this functionality is happening in the "Hardware" section, although most of the power management features being discussed are due out in a firmware update soon.

This is both good and bad news.
I am very happy to be wrong about this from a safety point of view.
Unfortunately no matter what battery is in use it will drain rather quickly and not be able to rebound when power is applied.
since the chumby is NOT charging the battery.
If a power outage is longer than 1/2 hour or so the battery will be drained.

Can the system be set up so that if power is lost and a switch to backup 9V happens that the chumby drops into a power saving mode?
That would be a sort of consolation since the battery is not being charged.
Using a rechargeable cell would certainly be a greener thing to do.

Yaesumofo

Bunnie, thank you for your response. So with the current firmware the Chumby should stay on if power is removed but a fresh 9V battery is installed? I plan on getting one of those rechargeable photo frame batteries as mentioned in another post to keep my Chumby alive for an extended time during a power outage.

For now, the chumby will stay powered on with the 9V battery installed but don't count on that behavior, it will change soon.

However, the rechargeable photo frame battery plugs into the DC input, so it looks exactly like the wall adapter to the chumby--so your idea will still work, and work even better, because if you accidentally knock the DC input connector out (it happens) the chumby will still stay on thanks to the 9V and gives you a moment to plug the external pack back in.