Mamiya 6 long exposures and battery life

[jspha]

I'd like to do some very long exposure night photography with my Mamiya 6 (~3-5 hours). My reading suggests that this works just fine with bulb mode, but as the shutter is electronic it can be a drain on the battery.

The M6 manual mentions the "Emergency Winding-Stop Release Button" and states

If the batteries have been depleted - especially when the power on-off lever has been set to the OFF position during long exposures (at "B" ; 4 seconds or 2 seconds) - the winding-stop prevents the film from being wound. If this happens, push the emergency advance/stop release button with a pen or other pointed object as shown above. The advance/stop is then released, allowing the film to be wound. Please note that that particular frame will be poorly exposed.
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There's a lot to unpack here both due to the complexity and due to risk of bad translation.

My question is: is it possible to start the exposure in bulb mode, turn off the camera, and then finish the exposure hours later potentially by using the emergency release button? If so, what is the actual sequence of events to accomplish it? What are the tradeoffs? (loss of IQ? damage to camera?)

If not, are there any other techniques to save battery life while performing very long exposures on an M6?

Thanks!

 

[tedr1]

I do not have experience with the M6 however using basic principals there are two issues:

1. drain on the battery due to an internal meter.

2. drain on the battery due to the shutter remaining open in B mode.

The fact there is a power on off switch suggests that the meter causes battery drain however we don't know how fast the meter drains the battery.

It may be possible for the shutter to remain open in B without consuming power, this would be the ideal situation.

In your situation I would run some experiments to see how long a battery lasts: with the shutter closed and the power switch is left on; and when the shutter is open in B with the power switch off. I think this would give direct access to the important facts.