EVSE With Adjustable Amps

[awefulspeller]

Has anyone tried to use a Level 1 EVSE with an adjustable amp setting? Last night was my fourth time towing my FFE because I ran out of battery. It doesn't look like I'm going to change my habits, so I think it is a good idea to carry a portable generator, in case of emergency.

I want a 1000w generator and a Level 1 EVSE running at 6amps. They make them small/light enough to fit under the hood. But, I've read that some EVs will not charge at low amps.

Does anyone know if the FFE will accept 120v 6amps or maybe 8 amps?

Linked to adjustable EVSE: https://www.amazon.com/gp/product/B08LM ... G7J0&psc=1

[Anti_Climax]

The car limits itself to the current value the EVSE "advertises" through the pilot pin. So it's less a matter of the car pulling too much and more a matter of the car being willing to go as low as 6A.

The J1772 spec allows for signalling down to 6A but that is in the context of 240V, so it isn't necessarily going to accept that range

I have a dual voltage charger that should let me drop the output to 6A, so I can try to test it, but I would strongly suggest shooting a bit higher on the generator, at least enough to do 12A+ on 120V.

I suggest that because there is a minimum power draw to run the various car systems while it's charging - not as much as having the car actually running, but still a measurable amount. If that is say 200W, you barely notice with a 6kW+ charger but it would be a significant chunk of that 1000W.

I'd try to get a reading on the DCDC converter (the amount of power being sent elsewhere) and compare that to the power in and out of the on board charger, but I don't think it will output that data after the other stuff "turns off"

If nothing else, I can look at the raw state of charge over some set amount of time. If I do that for more than one power level I should be able to work out that minimum draw.

I should also note that the car will not pull more than 12A at 120V even if the charger offers it more, which is unfortunate as 16A is absolutely a possibility from 120V outlets - but they probably didn't want to deal with the folks that put 20A outlets on 15A breakers...

[awefulspeller]

Thank you for the response. You provided a lot of helpful information, and I appreciate it.

As much as I would like to see the volts coming off the DC-DC converter, I will pass on that for now and order the adjustable EVSE. I want another 120v EVSE, and I'm going to end up purchasing it regardless of whether the 6amp option works or not.

After reading your post, I agree with you about the minimum generator power of ~1.5k.

There is a severe shortage of the Honda EU220i generators - the ones small enough to fit under the hood, although it only has a 120v outlet. I wonder if I can find a generator with similar dimensions, about the same power output, but 240v out?

[Anti_Climax]

The EU220i and many other brands support parallel operation. You have a cable that cross connects and lets the two inverters sync up but in opposition to double the voltage, or in step to double the possible current at the same voltage.

You may be able to find one of a similar size that has a higher voltage but unlikely if the current isn't dropped proportionately. That is to say, if the voltage doubles you potentially need 2X the windings on the generating coil but at the same thickness (since the current is the same) and potentially need 2x as much inverter hardware for the higher voltage output (that isn't a given though). But in that case you have the same current, double the voltage so double the power and the actual motor has to be twice as powerful to drive it. Every 1kW of output needs a minimum of about 1 1/3 HP from the crankshaft and if they don't build in some extra margin they won't last long - in addition to getting really hot and loud.

I tried to set my EVSE down to 6A and it would not charge - BUT I have to stress that I can't be sure the EVSE was behaving the way it should. I was doing it with some units my company makes that I know will start sessions even when they only have 120V in, but I need to re-verify with some other folks all the various bits I need to flip to truly set it to a 6A minimum.

Once I confirm that I will give it another go. It should have said "I'll" look at the DCDC info - I'm actually quite curious to work out what the various background loads are anyhow.

[triangles]

120V @ 6A would be painfully slow. I can also confirm it won't do more than 12A @ 120V It's a shame as I had a 30A 120V generator. If you still need me to verify I can see if it would charge that low. I tried it years ago and I don't remember what the minimum was. I want to say it was 5A but I honestly don't remember.

[Anti_Climax]

I'm still working on that one here. Was it 5A at 120V or 240V?

[triangles]

I though we were talking about 120V here?

[Anti_Climax]

We were talking about 120V, just didn't know if the 5A you mentioned was confirmed at 120 or 240.

[triangles]

if I remember I will confirm both this evening.

[triangles]

Confirmed at least with my '14 FFE and JuiceBox EVSE: 5A is the minimum current for both 120V and 240V. When I set current on the EVSE to 4A the car will not engage at either voltage. Set to 5A and it starts charging.

Interestingly, my FFE got pissed when I went from 240 to 120 without unplugging from the car. The charge ring was flashing quickly, and would not charge. I had to unplug and replug before it was happy again. When i switched back to 240 without unplugging from the car, my FFE did not complain.

Since I also have a model 3, it would be nice to charge both the model 3 and my FFE with the same EVSE without having to remove the tesla adapter. It's pretty low on my priority list, but if I ever get around to it I plan to build an arduino based EVSE with 2 of J1772 plugs. I am thinking of having 2 operating modes. Mode 1 would split the max current so I can charge both vehicles simultaneously (50A circuit so each car could get max 20A). Mode 2 would power Plug A first then power Plug B. If Plug A requests power it would interrupt Plug B. This should be fairly easy to implement as long as the arduino has enough IO.

FWIW you could charge at 6A @120V but that is only 720W. If it is cold out I'm not sure how much if any range you would add, as there are 900W of heaters in the coolant loop (3x 300W). Neglecting any power used to charge 12V battery, run pumps, heaters, etc and assuming 90% charge efficiency and 300Wh/mi energy consumption, you are looking at barely over 2 miles of range per hour of charging. 720Wx0.9/300Wh/mi=2.16mi/hr charging. Real world probably less than 2 mi/hr. So yeah... not really practical unless you have lots of time to kill.