Read post #37. You skipped standby entirely. For most people leisure camping off grid, practicality beats frugality and the Amp Hour is king. Fuel cost varies enough (seasonal, regional, etc) to be a wash IMO but electrical power is always precious. Also no mention in your cost comparison of the expense of a fuel pump, which the Everest Star doesn't need.
Agreed, standby consumption is important. It is highly dependent on the vehicle and the usage situation, so it is difficult to make any single prediction
Assuming a duty cycle of 50% (very light heating load). The D2 will spend 30 minutes of every hour in standby. Now, the number of times the heater enters/exits standby is important for this calculation. However it will very greatly depending on the size of the space, and how well it is insulated. In my Sprinter with D2, and no window covering (well insulated otherwise), a hysteresis cycle usually takes 30 minutes. So lets use 30 minutes for the calculations (It matches the 50% cycle). So there will be 2 start stop cycles per hour. A well insulated van could very well see hysteresis on a 1 hour cycle.
The additional power usage from standby will be the sum of the start/stop and standby fan.
The fan usage will be counted in the standby time.
One start cycle consists of:
Glow plug (140 seconds) 6A (it doesn't pull this continuously though?)
One stop cycle:
Glow plug, 40 seconds
So 2 cycles is 180 seconds x2 x 6A=0.6AH It is actually less, as the glow plugs power drops once it reaches temperature. I have not measured it, but a rough guess is the average current would be half the max current?
The standby time is 30 minutes per hour in this case, so standby fan power would be 0.5hr x 0.4A = 0.2AH
So the standby power usage would conservatively be 0.8AH per hour. Though depending on hysteresis time and glow plug current, it could be as low as 0.35AH per hour. Definitely noticeable, but not extreme. Over a 24 hour period that would be 19.2 to 8.4AH.
I have not looked into the details, but how long does the Everest unit run the fan before and after burner ignition? It probably isn't long enough to matter, but it will affect power consumption in a high cycling situation.
I have found the D2 to run pretty much continually any time exterior temps are 30F or more below the setpoint in my van (at night). During the day, with direct sun, I find that the heater will run much less if at all. At some point the D2 will actually exit standby. This occurs when the interior is a certain number of degrees above the setpoint.
The real advantage of the D2/D4 in this situation is there will likely be a smaller temperature swing. For some the lack of cycling would be helpful from a noise standpoint as well.
For those with limited charging or battery capacity I can see the appeal of the Everest unit. Of course we could take it to the next level and go with a fan-less catalytic unit as discusses earlier in the thread.
Power usage is very important to the off-grid lifestyle. But in a mobile and/or full-time (especially a small van) application, comfort, size, etc are important considerations as well.
For those without a propane system, and who are working with an existing layout, the D2/D4 heaters have advantages in size and usability. If I was replacing an existing propane furnace installation, I would probably go with a Everest unit for simplicity of installation.
