Looks fine though:
I would replace the relay and the small inverter with a battery to battery charger, between the starter and house batteries. Then you can eliminate the transfer switch and connect shore power directly to the large inverter.
I really wanted to use the Sterling B2B 120A charger
but it's lithium charge profile is not adjustable and doesn't quite fit my cells. At least according to AMSolar's recommended charging profile
Sterling B2B 13.8V 13.8V
AMSolar Recommendation 14.0V 13.3V
Also, I considered just connecting through a BlueSea ML-ACR
or similar engine-on enabled solenoid/relay but during extended drives holding the battery bank at a greater than 14.0V is probably not very good for the pack. If I did go with something like the ML-ACR I could put a switch on the dash and just disconnect the batteries during long drives.
By forcing all charging through the MS2000 I have complete control over the voltages and currents sent to the battery pack. The Sterling B2B doesn't provide this flexibility nor does any other B2B charger that I know off. And obviously a relay/solenoid such as the ML-ACR doesn't allow changing the voltage/current seen by the house battery.
But then I also question is this really that big of an issue. If I just connect the house bank to the vehicle battery and I never disconnect it on long drives how much actual damage will it do? How long will it actually shorten my house battery's life?
There is not much data out there to answer this type of question which motivates me to just follow a cautious and approved approach of charging only via chargers that have programmable charging curves.
If you want to heat water while driving, use a 12V heating element instead of a 120V one. This should be slightly more efficient and might provide better protection for your starter battery.
I'm planning on a 120V due to the ease of availability, for example a quick search on Amazon finds this one
. Correct me if I'm wrong but wouldn't a 12V heating element require some significant wires? 1000W / 12V = 83.3 Amps. Also, how would a 12V element provide protection for my starter battery? Heating element is planned to be powered by the lithium pack.
I will purchase a 12V brick for my laptop so that I don't have to turn on the inverter just for computer charging. This is a little bit more efficient with less inverter usage (wear and tear, heat and noise). Likewise for the camera?
A 12V brick would be ideal but the only ones I have seen
for the Apple line of laptops do not look well made nor have many reviews.
I think that the engine run signal on the Transit is ground switching and only 300 mA. You need to activate a little relay to get a positive signal. See the BEMM.
You are correct, here is the relevant text from the BEMM:
Pin 3 - Engine Run signal will only support a sense line or relay control.
This engine run signal is ground switching (max current sink 250mA), it provides no positive output (open circuit) and is only active when the engine is running.
The signal will not be present when:
• Key states - OFF (0), Accessory (1), Run but Engine OFF (2), Crank (3).
• Engine running but load is greater than 250mA (driving two or more relays in error).
The fitment of the Auxiliary Fuse Panel will provide a power +12V side for the relay (although connection to the engine run pin is still required). See Auxiliary Fuse Panel circuit diagram later in this section.
If a positive (+12V) engine run signal is required, it can be done by using the switched ground to control an ignition fed relay, to give this output.
But follow this advice at your own peril, I am no expert at this. My van still hasn't arrived yet and I am just in the planning stage myself.
We're in the same boat. Thanks for the taking the time to offer your thoughts.
No need for the transfer switch. Use a manual selector switch to select either shore power or vehicle powered inverter "shore power".
I was thinking if it was automatic that would be nice, that's why I put the auto transfer switch in there. But I don't plan on being plugged in very often so maybe a BlueSea rotator switch
would be a better option. Any reason why you prefer to manually have to switch it over?
Is the vehicle powered inverter pure sine? It should be.
Yes. Although I still need to find an inverter that automatically turns on when 12V is applied. Or do all inverters behave like that?
The induction cooktop forces you have the 2000 watt house inverter. Other loads would not require that large an inverter. Portable propane two burner stove instead of induction cooktop? Less money and can be used outside on picnic table.
I don't have a desire to store propane inside the van. That was the main motivation for going all electric. Induction cooktop
can still be used outside although it would need to be via an extension cord.
My question is if you expect to regularly use shore power? Otherwise, I'd suspect that you might have trouble keeping up with your loads.
I don't plan on regularly using shore power but I do tend to drive a lot. My hope is that with at least 100W of solar on the roof and driving a couple of hours every other day I will be okay. I suppose I should do some more calculations to verify this.