120V Level 1 Charge rates

[GizmoEV]

I can now confirm that the on board charger, OBC, in the 2016 Kia Soul EV+ can charge at a faster rate than 12A when fed 120V. I also found that the Kia supplied level 1 EVSE charges slightly faster than the Panasonic (Nissan Leaf) EVSEUpgrade one I purchased when on the default 12A setting for 120V. Note that in the US that a circuit is not supposed to have more current draw than 80% of its rating when the current will be continuous as happens when charging an EV. This means that a 15A circuit should not have more than 12A on it which is why the EVSE that comes with the car is limited to 12A.

There has been a question about whether the OBC will draw more than 12A on 120V if given the signal that more than 12A is available. Earlier I was lead to believe that it would limit it self to 12A, which didn't make any sense to me since the OBC is a 6.6kW charger which would mean that it would have to draw 27.5A on 240V to reach that power. I suspect that 27.5A is also the limit on 120V too but I have not been able to verify that yet.

Why does this matter? If you live in a home without an available 240V dedicated circuit but you have a 120V one available you could install a high current Level 1 EVSE and shorten the charge time significantly. Also, when traveling, 20A and 30A 120V outlets are common at RV parks. If you had a portable EVSE which could be programmed up to 16A for a 20A circuit or 24A for a 30A circuit you could significantly reduce your charge time. Of course you need to understand the risks of charging at a current too high for the circuit, plug, and breaker you are connecting too. For example, I charged at 20A on a 240V 50A RV pedestal and found that the 50A breaker was warm. I would not want to charge at a higher rate than that since obviously the breaker had degraded over time from the elements. The breaker contacts were probably not clean thus increasing their resistance.

Here is the data I collected. Input voltage to the EVSE is 120VAC

Time      Current setting (A)    Measured (A)  % of expected time
7:40                                                   Expected
8:10        12                       11.0              106.5
8:40        12                       10.4              113.0
5:55        16                       14.3               77.2

21:00                                                  Expected
11:50       20                       18.4               56.3

The first 12A setting was the KIA EVSE. The 20A current setting was done at a different time with the car battery at a different SOC than the first ones.

 

[BigEdgar]

Thanks for the info, David. To clarify, were all of the measurements you provided below taken using the Kia EVSE? IOW, are you saying that the Kia Level 1 EVSE can charge at 18.4 amps if given the right combination of circuit amperage and (presumably low) battery SOC?

 

[GizmoEV]

No, I'm saying that the on board charger (OBC) can charge at higher rates than 12A on 120V if the EVSE sends the right pilot signal to the car. From what EVSEupgrade says the Kia supplied EVSE can only do 12A, even if they modify it for you for 240V. Only the first 12A setting in the chart was the KIA EVSE used to show that the car charges slightly faster with it than the Panasonic EVSEUpgrade one, also on the 12A setting.

As for SOC of the battery, for the charge rates we are talking about the SOC doesn't matter until right near the end like less than 5% to go.

 

[GizmoEV]

I recently built a wide-voltage 50A OpenEVSE and programmed it to allow 30A on 120V to test the Soul EV OBC at higher currents than just 16A or the 20A I was able to test with another EVSE. For those wondering I used a 50A circuit for this test through a 50A receptacle. With the EVSE set to 30A the car drew 28.7A on 115.1VAC input according to Torque Pro. This is inline with what the OpenEVSE reported though I haven't calibrated the EVSE yet. It appears to read about an amp low. I think the Torque Pro value is accurate since when I have compared it to my clamp meter on the circuit in the past readings were usually within 0.1A of each other.

In summary, the Kia Soul EV can charge at the OBC's full current even when on a 120V line, just make sure that the circuit and EVSE can handle it safely.

Now when I travel where there are no charge stations available but there is a TT-30 plug like at RV camps I can charge at 24A rather than be stuck at 16A. That is better than a 50% improvement in charging rate since the parasitic loads won't significantly increase.