I have an EB70 which “Appears” to have charging issues. With the EB70 discharged, I connected to my automobile (12V system) and EB70 appears to charge great (about 105 watts). I have a Toyota Hylander Hybrid. When I’m parked the engine is usually off so car battery alternator is not running. When I start driving the input to the EB70 drops to 50-60 watts. It consistently does this.
I would think when driving with engine on (alternator charging car battery) the input voltage will go up from about 12V to 13+ volts. I have not measured the actual voltage to the input of the Bluetti but with the assumption of the input voltage increasing the EB70 appears to throttle back the input current to the system. I’m not sure how the MPPT controller on this system works. I would hope when it reaches the max current it doesn’t throttle back as a step function!
If I have a defective unit, I will replace (warranty). If it is a design issue with the EB70 MPPT controller I will return unit.
If you are in the last 20% of the battery state of charge, the MPPT slows the rate of charge by tapering to 0 at the end.
Without knowing what voltage your vehicle charging port is outputting , it sounds like you are not receiving full voltage. You will need about 13.5 or higher to get the 100 watts or so you are looking for. If you can, try your unit in another vehicle for comparison
You read 13.7 volts from the Toyota and this is the vehicle that charges slower. You state the Ford charging faster so it would be interesting to measure the Ford voltage as well which I would think would be higher enabling the more rapid charging.
The only two variables are the voltage and amperage of the electricity reaching the EB70. Since you do receive a higher charging rate on one vehicle than the other while using the same 12 volt adapter cable, the cable can be ruled out as an issue. I suspect you will find higher voltage coming from the Ford with the engine operating.
Is the distance from the vehicle battery to the 12 volt car socket location about the same in both vehicles? For example, if one socket is in the rear of one vehicle and one socket is in the front area, that will have an effect as well.