Minor CCU connection problem

[OriginalBigAl]

Our guests have just left after having charged to 100% last evening, This was at the 10kW rate with sporadic cut-offs and resets but eventually getting there, air temp 20°C, EVSE getting up above 59°C.
This morning I wanted to put in around 40 kWh. Started at the 10kW rate but it shut down and restarted a few times before putting in 19 kWh. (air temp 17°C, start temp 30°C, stopped at 58°C). I then stopped it and changed the car screen setting to 8 amp and restarted. On 3 phase this gave a total input of 2kWh. Changed the setting to 16 amp and again restarted and got a total of 3.74 kW or 1,24 kW per phase or around 1/3 max value. The charge has continued unabated and the temp has dropped to 52°C.
Prognosis: at least I think the car is fine and not causing the charge cut-offs.
In all the above cases the EVSE was getting warm but not ( by touch ) to reported values.
So either the thermistor is faulty and sending values to the microchip which are wrong or the microchip is faulty and not interpretating those values correctly.
Or everything is correct and a fault in the contactors is actually making them too hot, and its shutting down as it should.
I have been looking at replacement units as a straight swap, but I want to throw out an idea to the forum. What if...... instead of getting a 11kW box I got a 22kW version , but keep the same RCD, wiring etc. The car would still only draw 10.2 kW but instead of running at its maximum capacity the EVSE would only be at half its potential capacity and should as a result be less temperamental. Well , that's the theory, If any one can see a fault in this I am all ears. I could uprate all the RCDs , breakers, and change to 6mm² cables, but for the moment that is impractical.

 

[Everest]

What if...... instead of getting a 11kw box I got a 22kw version , but keep the same RCD, wiring etc. The car would still only draw 10.2 kw but instead of running at its maximum capacity the Evse would only be at half its potential capacity and should as a result be less temperamental. Well , that's the theory, If any one can see a fault in this I am all ears. I could uprate all the RCDs , breakers , change to 6mm cables , but for the moment that is impractical

My 2p worth... generally I'm all for running electronic equipment at less than maximum rated values as a 'mechanical sympathy' gesture towards longevity. But, I wouldn't classify an EVSE as something that is working any harder at 22kW compared than 11kW - specifically for the reason that the 'power' is switched via a contactor, rather than (say) a solar inverter which is passing large currents through semiconductors (be they IGBT's / Mosfets etc.).

Sure, the wires and rating of the contactor may be meatier in a 22kW EVSE than an 11kW EVSE, but if the 11kW EVSE is getting hot that's a fault with the design of the EVSE IMHO.

Guess it will come down to the differential in cost and likelihood of you (or a guest) having a vehicle that can charge at 22kW as to whether the 'upgrade' is worth a punt.

Alternatively (and for less cost), what about a portable super-granny charger I mentioned in that other thread that could handle 7kW (single phase) via a commando socket?

 

[OriginalBigAl]

The 7kW super granny is on my ,list of things to do, when I sort out the bit of a disaster we call the third house.
I agree something has gone "pop" in the 11kW EVSE, whether or not its getting as hot as it reports is doubtful. Warm, yes, 60°C hot, no. So its how its detected and interpreted that's the issue , the false interpretation triggering the cut-off. Bad design , poor quality PCB . failed solder , bridged chip. Who knows? I can still use it overnight at the lower rate so there is no rush , and it is an easy job to replace like for like , but it is cutting into the savings from buying diesel if you need to replace the EVSE every two years.
If the larger capacity EVSE is designed to run at 22kW and I'm only taking 11 kW then the internal heat produced should be less , and hopefully a longer longevity. I am just trying to find out all the pros and cons of such a move even though I don't intend to pull 22kW ( or even try ) at all in the future. So its not really future proofing as we commonly know it.

 

[Everest]

If the larger capacity Evse is designed to run at 22kw and I'm only taking 11 kw then the internal heat produced should be less

Guess depends where the heat is coming from. Is the existing EVSE still under warranty? If not and you are up to taking it apart then it's likely repairable (assuming one's knowledge of electronics goes beyond knowing the difference between a thyristor and thermistor, that is ).

Do you have, or know someone who has, a FLIR camera? - that would be the safest method to identify the hotspot - if indeed there is one. If not, my tried-and-tested method would be to run it with case open (keeping the cats at bay), then turn off all power and quickly use one of the 10 digital thermometers you have (5 on each hand) to feel for the heat source.

If it's not as hot as it thinks it is, then pop over to Tandy to buy a new thermistor or add a series resistor, as @Coulomb suggested, as a workaround.

 

[Coulomb]

Yes, no need to shell out for a 22 kW EVSE. That will be an expensive monster, and you have have trouble getting an electrician to install it on an 11 kW circuit. In the future, someone might plug in a 22 kW vehicle. I guess all that will happen is that the breaker will trip, but that's not good for the on-board charger in the car.

As Everest says above, get it fixed or replaced under warranty, or get it repaired, repairing it yourself if you're up to it.

 

[tsedge]

I believe that the latest Zappis are 7kW/22kW single/multiphase capable. So you can install on any supply but they are built to take a lot of load.

Of course, Zappis are expensive but they also seem generally reliable. Mine hasn't missed a beat in nearly 3 years.