LEAF L1 Trickle Charging current

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Randy

Well-known member
Joined
Apr 22, 2010
Messages
2,175
Location
San Diego, CA
Tonight while "Trickle" charging my LEAF at L1, I inserted a "Kill-a-watt" device to measure the current.

It moves around a bit at first as the handshaking occurs, but once the dust settles, it read about 11.5 amps steady-state.

Since my EVSE inspection went well on Friday, I'm hoping that my 2nd meter will be installed in a few days and I can fire up the L2 charging....

RedRandy
 
Randy said:
Tonight while "Trickle" charging my LEAF at L1, I inserted a "Kill-a-watt" device to measure the current.

It moves around a bit at first as the handshaking occurs, but once the dust settles, it read about 11.5 amps steady-state.

Since my EVSE inspection went well on Friday, I'm hoping that my 2nd meter will be installed in a few days and I can fire up the L2 charging....

RedRandy

Can you guesstimate how many miles you're gaining per hour of L1 charging?
 
I guess I haven't measured it that precisely, but I thought it was around 5 miles of additional range per hour of L1 charging...

Another data point is that when I press the power button on the Kill-a-watt it reads about 1300 watts, give or take.

With 100% efficiency, and assuming that 4.3 miles per kwh is an average that I see a lot on my car, then one hour of L1 charging would be 1.3 kwh.

1 hour of charging would equate to 5.5 miles at 100% efficiency (4.3 x 1.3). So maybe 5 miles is not so far out of line....
 
I'll do some checking, but it is a 20amp GFCI circuit in the garage with a short run to the main panel.

I have an external voltmeter that I'll test with to verify.
 
Randy said:
I'll do some checking, but it is a 20amp GFCI circuit in the garage with a short run to the main panel.

I have an external voltmeter that I'll test with to verify.
Might be interesting to measure the voltage on a separate circuit (but the same leg of your 240V feed) to see if the voltage sag is detectable there, too. I wouldn't expect a 12GA / 20A circuit to sag under 12A of load... Have a rough estimate of the length of your run?

For example, a 20ft run of 12GA with 12A of load on it should only see a voltage drop of about 1V.
 
garygid said:
4 volts loss through house wiring (and possibly "poor" connections) when drawing 11.5 amps?


Not every house has a 120V even at the panel. I see some with 130! and some at 113 or so.
 
Randy, Thanks for this info!

FWIW, its normal to see a voltage drop with the meter at these current levels and i don't see anything of concern here.
 
That is too much voltage drop. Chances are, you have a poor connection somewhere. Either to the breaker box or to the EVSE. And that poor connection may overheat and become a fire hazard.

With 20 ft. of 12 gauge wire, while pulling 12 amps you should only be losing about 1 volt. (Google "voltage drop calculator")
 
I am not charging tonight, but I plan on looking into this two different ways.

I am going to take the same measurement on a different circuit with only 3 feet of wire to the main panel.

I am also going to measure the drop on that tested outlet with a stand alone meter to see if my $17 Kill-a-watt device is telling me the truth.

I don't have any tell-tale signs of loose connections, other than this voltage drop number from the Kill-a-watt, but I'm going to look into it...
 
The meter does not need to be "accurate" to show a 4v drop in voltage when the current turns on. 105 to 101 or 117 to 113 does not mean much.

Checking for a similar voltage drop "upstream" should help locate the problem.

Something should be getting hot, but it MIGHT be the breaker itself. However connections to (and behind) the sockets in the wall are most suspect.
 
planet4ever said:
Did anybody notice that Randy said it was a GFCI circuit? I thought that we had been advised not to use GFCI outside the EVSE. Is there a possibility that is where the voltage drop is occurring?
Could be the Kill-a-Watt itself as well - though I know people have used it to measure similar sized loads before...

Anyway, confirming the voltage using a volt meter in the other socket will quickly confirm...
 
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