denwood
Well-known member
Interesting problem showed up last night with the house to garage wiring. I have been charging the EV at 120V (16amps) but after doing some research, found out that there is a small efficiency gain to be made going to 240V. This is because there is some charging "overhead" to run the charger/electronics etc. which may be in the 250 watt range. So there is some advantage to charging faster at 240V as that "overhead" is running for less time.
The EVSE I purchased can do 16 amps at 120V, or 16 amps at 240V. My garage service is only 30 amps, so I figured this would work fine. After adding a 20 amp breaker to the shop, and a Nema 6-20 receptacle, I figured all good.
Last night, during the first 3 hour timed charge (cheaper overnight), the charging apparently stopped. It took me a bit to figure out that one leg of my 240V service was out. Part of the shop was powered including lights...so it was not obvious. The EVSE was just clicking on and off..which is what is supposed to do if there is a power issue.
This is the first time I've seen this kind of issue, but it was related to high resistance on one leg of the 240V at the house feed to the garage. The 30 amp fuse was only seeing 16 amps, but the resistance issue caused it to gradually overheat..and it did it's job (thank goodness) and blew. After bending the fuse tabs on the holder (for better contact), cleaning all connections, and cleaning and torquing the power leads to the fuse holder, I confirmed with an IR temp gun (after an hour charging the EV) that the heat issue was resolved.
I guess the lesson is that it may not be a bad idea to check your panel with an IR gun under high load! This problem has likely been there for some time..it's just that I haven't pulling 16 amps on both legs of the shop for longer period before. In any case, charging the LEAF exposed a wiring issue that was likely slowly getting worse over the years on the garage feed
Note that the fuses in there for the pic are not 30amps..they are 20s. I'm actually using 30 amps fuses as per the garage spec.
This the EVSE I'm using:
The EVSE I purchased can do 16 amps at 120V, or 16 amps at 240V. My garage service is only 30 amps, so I figured this would work fine. After adding a 20 amp breaker to the shop, and a Nema 6-20 receptacle, I figured all good.
Last night, during the first 3 hour timed charge (cheaper overnight), the charging apparently stopped. It took me a bit to figure out that one leg of my 240V service was out. Part of the shop was powered including lights...so it was not obvious. The EVSE was just clicking on and off..which is what is supposed to do if there is a power issue.
This is the first time I've seen this kind of issue, but it was related to high resistance on one leg of the 240V at the house feed to the garage. The 30 amp fuse was only seeing 16 amps, but the resistance issue caused it to gradually overheat..and it did it's job (thank goodness) and blew. After bending the fuse tabs on the holder (for better contact), cleaning all connections, and cleaning and torquing the power leads to the fuse holder, I confirmed with an IR temp gun (after an hour charging the EV) that the heat issue was resolved.
I guess the lesson is that it may not be a bad idea to check your panel with an IR gun under high load! This problem has likely been there for some time..it's just that I haven't pulling 16 amps on both legs of the shop for longer period before. In any case, charging the LEAF exposed a wiring issue that was likely slowly getting worse over the years on the garage feed
Note that the fuses in there for the pic are not 30amps..they are 20s. I'm actually using 30 amps fuses as per the garage spec.
This the EVSE I'm using: