For the last 20 years I have used Gerbing heated gloves (and socks) in the winter. Apart from one claim under warranty when the wires broke, they served me well. With improvements in technology I felt it was time to consider battery alternatives so I no longer walk away from the bike with the cables still plugged in!
So earlier this year I bought the Racer Connetic 4 battery heated gloves. These are 7V. They have 3 heat settings plus a boost and true to the French manufacturer's claims they last 3 hours on heat 3 and 1.5 hours on boost. In addition, each glove has 2 connectors thus doubling the active timescales if extra batteries are bought. The ambient temperature of late has been 5 deg C and heat 3 is just sufficient to keep your hands warm, so Boost has not been needed.
While the batteries do not cause a problem inside their pouches, clearly you sacrifice "feel" of the grips to a certain extent. The version I bought has limited protection (e.g. knuckles) in the event of a spill. However, other versions are available with the extra protection.
Here is a link to my pair:-
FYI I also have the Hondaline heated grips - [perhaps someone can explain to me why with these and the Oxford grips, the left hand grip is always hotter? This has been the case on a number of bikes I have owned.]
Paul