Shouldn't be a problem on N900, no matter of normal battery (single cell) or dual one (as it's in parallel) - at least, when you plan to not leave it for months without use AND battery isn't many years old.

Problems happens, sometimes, in notebook batteries, because they have cells connected in series. This way, cells that age too much can enter reversed voltage (-) state during usage, and leak/self destruct.

In N900, we're running from a single-cell voltage ranges, so there is no such risk. Even dual-cell scuds/polarcells/etc are safe, as due to parallel configuration, weakened battery just decrease package total capacity, without possibility to enter reversed voltage.

Using ~3450 mAh dual-scud (bluedream) setup, on low usage, device last a week (or 2-2.5 days on very heavy usage ), so 6.8 Ah battery should give a 2 weeks runtime, or solid few days of heavy (ab)using.

Yea, that's why it is possible with xephyr and Easy Debian, but not with Maemo itself. Well, technically, Maemo *should* be able to forward own things at 800x480 too, but due to some twirls in Maemo's X, it doesn't work, and no one investigated enough to determine why.

/Estel