I am considering a van or a light truck large enough to hold my tiny off-grid home and with the surface area to hold 6 kW of solar panels.
I would use the vehicle battery for both driving and powering my home needs. So I need to charge and draw power from the EV battery.
Most of my home power needs would be met by 12 VDC. An instant tankless hot water heater would required the HV. A smaller heat pump may work off 12 VDC but maybe a higher DC voltage would be required for a bigger unit. I would need to use 120 VAC only occasionally for appliances that don't come in a DC version.
When I mentioned using a buffer battery, I had in mind a relatively small battery that could trickle charge when solar power is low until enough power builds up to transfer to the EV battery. The buffer battery would also serve to collect solar power when it is not possible to simultaneously charge the EV while driving (or while shore charging).
Most
light trucks seem to have very accessible electronics. Connecting directly to HV battery or BMS is no problem as can be seen in this example image...
Even though access is easy, the light truck electronics are proprietary and understanding their behaviour would the challenging part.
The
Ford e-Transit has an integrated battery and BMS like most small cars. But, it seems the HV systems could still be accessed from points under the hood as seen here...
There are many companies that do EV conversions using Tesla battery packs and motors. Such conversions of
Ram Promaster are common, and this would be a viable EV for my use case. This is the reason I had mentioned Tesla swaps before.
There seems to more information available on Tesla battery packs, so this type of vehicle could be more easily hacked.
I'm learning more about the
e-Transit, so considering it as a candidate...
A) The EV is off and NOT connected to a charger.
The e-Transit has an option for a 2.4 kW inverter that can be used while stopped or driving. So it seems that the HV battery contactors could be kept closed all the time to access HV without some hacky trickery.
Because of this, I am feeling more confident that it would be possible to solar charge the HV directly while e-Transit is parked.
B) The EV is off and charging from shore power.
I'm gonna forget about trying to charge from solar and shore power simultaneously for now. It's not critical for me to be able to do so.
A mechanical switch to disconnect solar when the charge port is accessed would prevent this from happening.
C) The EV is on and possibly being driven.
I wonder how the vehicle control systems handle simultaneous draw from motor and with the unpredictable draw of up to 2.4 kW from the built-in inverter. For example, if the accelerator pedal is floored and a 2.4 kW appliance is simultaneous turned on, would the control system simply reduce power to the motor (thereby reduce acceleration rate) to comply with the max current draw reported by the BMS?
I also wonder if the control systems (as they are) would be able to handle unpredictable extra current from solar panels. For example, if the brake pedal would be floored and max regen power produced, say 60 kW, and suddenly you emerge from a tunnel into the sun and solar power jumps from 0 W to 6 kW, would the regen power be reduced to comply with the max in-current reported by the BMS?
Any thought?
Thanks!