SolarDaveGreen
Posts: 4
Joined: Mon Sep 12, 2022 9:04 am

Onboard Charger Testing

I am working through my second onboard charger failure.

Here's a tip for diagnosing a blown fuse in the onboard charger. I actually did this the first time the onboard charger failed, and it seems pretty reliable (though not infallible).

I opened up my Leviton Electric Vehicle Supply Equipment (EVSE) J1772 "Charger" and used a clamp-on ammeter to measure amps on each of the two hot wires going to the car. (Be careful if you do this. Bad things can happen if you touch the internal parts. Deadly things.)

Then I had a friend plug and unplug the J1772 nozzle.

One wire caused the ammeter to momentarily show current.

The other was absolutely dead.

Sure enough, when I got into the onboard charger and tested the fuses, the fuse was blown on the "leg" that showed no current flow.

I expect there is some "capacitor pre-charging" going on when the charger starts and if the fuse on either leg is intact, that brief current flow will show on the meter.

I have done the test again since the charger stopped working the second time, and THIS time, there is current on both legs going to the car. In other words, something inside the charger has failed, not the fuses.
alflash
Posts: 189
Joined: Sun Sep 03, 2017 3:46 pm
Location: Ukraine
Contact: Website YouTube

Re: Onboard Charger Testing

SolarDaveGreen wrote: Fri Sep 23, 2022 7:13 am I am working through my second onboard charger failure.

Here's a tip for diagnosing a blown fuse in the onboard charger. I actually did this the first time the onboard charger failed, and it seems pretty reliable (though not infallible).

I opened up my Leviton Electric Vehicle Supply Equipment (EVSE) J1772 "Charger" and used a clamp-on ammeter to measure amps on each of the two hot wires going to the car. (Be careful if you do this. Bad things can happen if you touch the internal parts. Deadly things.)

Then I had a friend plug and unplug the J1772 nozzle.

One wire caused the ammeter to momentarily show current.

The other was absolutely dead.

Sure enough, when I got into the onboard charger and tested the fuses, the fuse was blown on the "leg" that showed no current flow.

I expect there is some "capacitor pre-charging" going on when the charger starts and if the fuse on either leg is intact, that brief current flow will show on the meter.

I have done the test again since the charger stopped working the second time, and THIS time, there is current on both legs going to the car. In other words, something inside the charger has failed, not the fuses.
HV Charging may not work for other reasons (not only due to a malfunction of the onboard charger). It is necessary to read the Tesla system fault codes, collect its data and analyze them.
Otherwise, it becomes like fortune telling.

Remote diagnostics are available, for example as described in https://www.myrav4ev.com/forum/viewtopic.php?t=2530 and/or https://www.myrav4ev.com/forum/viewtopic.php?p=29931 #p29931
Russian fascists are killing the civilian population of Ukraine.

Return to “Technical Rav4 EV Discussions”