Cheap 1500W 12V inverter, BEV charging?

Had an extended power outage this week due to severe storms, so purchased an inexpensive 12V, 1500 Watt inverter from Harbor Freight to keep fridge running in the house. The inverter worked great, connected directly to the 12V battery of my '06 Highlander Hybrid with 3 foot 2/0 AWG cables, and fridge was connected to the inverter AC outlet using an extension cord. Fridge takes from 350 to 750 watts, so at most was drawing around 60A from the 12V battery and Highlander DC to DC converter. The gas engine kicked on periodically to keep the HV battery charged, while the fridge compressor also turned on/off giving the car battery a chance to recover.

I got thinking this could work to charge my BEV in case I didn't have the range to make it to an outlet. My answer is no.

- First issue is the BEV 120V charger requires a neutral tied to ground. I read how cheaper inverters have two 60V hot legs instead of a single 120V leg and neutral. The AC ground plug on my inverter connects to the chassis, so using a neutral bond plug would either short out one 60V leg, or tie the AC side to the car's chassis, bypassing any isolation inside the inverter between AC and DC. An isolation transformer might fix this, but these are way more expensive than the inverter.

- Second the inverter outputs a modified sine wave, so not sure how this might affect the BEV's charging system.

- Third, my i3 draws around 1350 watts (I think) for level 1 charging, that's up to 112A at 12V which is close to the Highlander's 120A DC to DC fuse limit. Running constantly for several hours at this amperage would likely kill the 12V battery and/or overheat/damage the Highlander 12V charging system. The i3 has a low power level 1 option which might work, but also extends the charging time.

 

Assuming there's a way to prevent a ground fault, I'm still thinking even low power level 1 charging will push the limit of the Highlander Hybrid DC to DC converter. Would be best to use something like the1500W Toyot OEM inverter installed in newer top end models and that draws power directly form the HV battery.

DC-AC Inverters | Toyota Industries Corporation



PlugOut Power inverters could also provide enough power from a Hybrid vehicle to charge an EV, but I never liked the idea of having wires connected to the HV battery sitting in the trunk.

HOME | PlugOut Power, Generator for hybrid vehicles | United States

 

I'm going to say Do Not Use a 12V DC to 120V AC inverter on a hybrid vehicle to charge a BEV. After doing some reading on other forums, sounds like the DC to DC converter can source around 100A peak and perhaps 60A continuous. That works out to around 600 Watts on the AC side when factoring losses, less than half the power needed for Level 1 charging.

For reference another excellent video form Weber Automotive.