Scheduled charging pre face lift

[Pebblefeline]

Highly technical solution while waiting for my ohme install. works perfectly

 

[slmorgan42]

Very neat. Was that an amazon buy

 

[MickeySw]

Highly technical solution while waiting for my ohme install. works perfectly

There is no issue using an AC timer to start the process but it’s not advisable to cut the power while charging is still ongoing.

 

[Pebblefeline]

20 quid from screw fix

In terms of stopping charging whats the danger of killing the power?

I may need to change my habits………..

 

[MickeySw]

20 quid from screw fix

In terms of stopping charging whats the danger of killing the power?

I may need to change my habits………..

Generally speaking if you mechanically interrupt electrical current you create an arc that is bad for the contacts.

The on board charger on an EV (or CCU in MG terminology) is designed to safely dissipate energy before the contacts are opened, simply cutting the power may create energy surges that can damage (expensive) electronics.

Some owners out there will say that they have been using mechanical timers for years without apparent issues but IMHO using a 20 quid timer to charge a 20 grand EV is false economy.

 

[Pebblefeline]

That’s genuinely useful thanks. I will use it to start a charge and then stop the charge manually.
Thanks for the advice

 

[Geoffers]

Been doing it this way for years, admittedly with an electronic 16A timer. Not much choice if you want to make use of cheap rate electricity over night and only need to use a granny charger.

 

[MickeySw]

Not much choice if you want to make use of cheap rate electricity over night and only need to use a granny charger.

That depends on the ‘granny’ and your DIY skill. It is possible (I have done it myself) to interrupt the low voltage control lines to allow scheduled charging based on the idea below.

 

[shpub]

Been doing it this way for years, admittedly with an electronic 16A timer. Not much choice if you want to make use of cheap rate electricity over night and only need to use a granny charger.

What is even stranger is that the instructions for most granny chargers is switch off the AC power first and then unplug the type2 plug. Using a time switch is just another way of following these instructions.

My experience with mechanical timers is not good as switching contacts are not that reliable. They can get worn and start to arc and then burn out. I tend to steer clear of them. I've used electronic ones ( they typically use a relay though and not a solid state switch) and my current favourite is a 63A wifi enabled Tuya RCBO installed into the garage distribution box. Checks for leakage, over voltage and other stuff as well. Controls a socket specifically for the granny. Has an app to set on and off remotely and stores consumption data.

I would not recommend taking a granny apart - they are usually fitted with anti tamper screws anyway - and there is little space inside them to do anything. It voids any warranty as well. The external timer is really the easiest and safest solution.

Equally I would not worry about switching a granny with a timer. The current is far far less (10A) than from a charge point (32A) as shown in the video and is also AC which not so destructive as DC. Even if you disconnect the car from the granny yourself, you should, according to the instructions, switch the power off first. So no different from letting a timer do it.

The switched mode power supplies themselves are designed to cope with problems in the AC supply such as brownouts, surges, over voltages and so on.

 

[MickeySw]

What is even stranger is that the instructions for most granny chargers is switch off the AC power first and then unplug the type2 plug.

Simple reason, you can’t unplug a type2 on the car side while charging is ongoing

Using a time switch is just another way of following these instructions.

Correct, but IMHO the manual should mention to stop an active charging session before removing any cables

 

[shpub]

Correct, but IMHO the manual should mention to stop an active charging session before removing any cables

I am confused as does this mean that you can stop a charging session from the car?

My MG manual says power off the charger and then you can remove the cable. No mention of being able to stop a session.

To be honest I could not find anything in the MG user manual that would allow me to terminate the charge from the car end. It could well be hiding. Thinking back, I always have to go the charger to stop the session or switch off the power. Unless I am missing something, on a PFL MG5 I don't think you can stop a session from the car. Only from the charger. So with a granny it is back to switching off as there is no alternative.

What am I doing wrong if it is possible?

 

[Verdigris]

I've clearly been doing it "wrong" as well. IME the only ways to unlock the cable from the car is to either charge to 100% or unplug the charger.

 

[MickeySw]

Hard to believe but I take your word for it that on a PFL one cannot stop a charging session from the car.

Can you pause the session by opening the door as @Coulomb mentioned? At least that would stop the DC current before shutting off the granny…

 

[Verdigris]

Maybe if you open the door for long enough it will disconnect but I just wait long enough for it to show the numbers and then shut the door. I'll have an experiment, next time I charge.

 

[shpub]

Tried that and nothing happened. Car said I'm still charging. Plug unlocked though.... I also wonder as your car has the latest EVCC Tesla upgrade which controls all this whether the upgrade also changes this behaviour? Like Verdigris, time for an experiment.

 

[johnb80]

Generally speaking if you mechanically interrupt electrical current you create an arc that is bad for the contacts.

The on board charger on an EV (or CCU in MG terminology) is designed to safely dissipate energy before the contacts are opened, simply cutting the power may create energy surges that can damage (expensive) electronics.

Some owners out there will say that they have been using mechanical timers for years without apparent issues but IMHO using a 20 quid timer to charge a 20 grand EV is false economy.

Every wallbox on the market has mechanical relays in there to switch current to the EV, they can (and do) open under load creating the exact same conditions that you say damage the cars electronics (mechanical contact opening under load). Yet, you don't hear of wallboxes wrecking car electronics?
I accept that most of the time a gracious stop to the charging will take place i.e. charge rate reduced by pilot signal but that isn't always the case.

 

[MickeySw]

Every wallbox on the market has mechanical relays in there to switch current to the EV, they can (and do) open under load creating the exact same conditions that you say damage the cars electronics (mechanical contact opening under load). Yet, you don't hear of wallboxes wrecking car electronics?
I accept that most of the time a gracious stop to the charging will take place i.e. charge rate reduced by pilot signal but that isn't always the case.

The negative effects of disconnecting under load are rarely instant therefore you won’t ‘hear of wallboxes wrecking car electronics’.

Of course nowadays components are designed to withstand a number of power surges (that’s why I used the word ‘may’) and the likes but everything has a limit, ‘death of thousands cuts’ comes to mind.

We have to agree to disagree but IMHO the safest way to schedule a charge on a PFL MG5 is using a wall box that is capable of doing so.

 

[johnb80]

The negative effects of disconnecting under load are rarely instant therefore you won’t ‘hear of wallboxes wrecking car electronics’.

There will be good input protection too on the onboard charger.

Of course nowadays components are designed to withstand a number of power surges (that’s why I used the word ‘may’) and the likes but everything has a limit, ‘death of thousands cuts’ comes to mind.

The component themselves do usually have a good tolerance for abuse if decent quality. The whole unit will be well protected on the input side. I seriously doubt using a timer operated micro switch is going to cause any issues.

I’m We have to agree to disagree

I can go with that, you’re wrong ???

but IMHO the safest way to schedule a charge on a PFL MG5 is using a wall box that is capable of doing so.

Absolutely 100% BUT, the timer should be ok too.

 

[dragon2611]

I've clearly been doing it "wrong" as well. IME the only ways to unlock the cable from the car is to either charge to 100% or unplug the charger.

Try the unlock button on the keyfob that usually releases the cable for me unless the cars throwing a hissy fit