Fast charging 12v battery through home 7kW. Possible?

[Striker]

I had to charge my ICE 12v car battery yesterday. This entailed the use of a long extension lead for my garage to the front of the house, about 20 metres.

Although I am still awaiting for a ZS delivery, I do already have the 7kw home charger installed in the front porch. Is there an adapter of Type 2 to a 13A UK socket that can be bought and to be used safely?

I don't use the car often, so the 12v battery needs topping up once in a while.

I assume this can be also used for the ZS?

To answer your original question, the answer is no

There's a lot of comments above, but it's really quite straight forward. The 7kW wall socket you have is where the clever bits are,not the cable and the actual charger is in the car. The wall box and car communicate with each other through the "dumb" type 2 cable. Any sort of adaptor on the end of the type 2 cable would need to communicate with the wall box

Also, I'm pretty sure that the ZS Mk2 does top up it's 12V battery from the traction battery when switched off, I'm sure I remember threads in summer asking about this. The comments on here have me doubting that now!

 

[N2STY]

Also, I'm pretty sure that the ZS Mk2 does top up it's 12v battery from the traction battery when switched off, I'm sure I remember threads in summer asking about this. The comments on here have me doubting that now!

If you think about it when you switch car on without using brake it will tell you it not charging the battery because it's not in ready mode

 

[Striker]

If you think about it when you switch car on without using brake it will tell you it not charging the battery because it's not in ready mode

Is that talking about the 12V or the traction battery, I can't recall the message/

I thought that the 12V battery management was one of the Mk1 vs Mk2 improvements that people were happy about?

 

[N2STY]

Or look at 12v battery voltage in non ready mode it soon drops especially with fan on

 

[Striker]

Or look at 12v battery voltage in non ready mode it soon drops especially with fan on

Ah I get you, but can we be sure that off off, behaves the same was a stand by (not sure what that mode is called) in terms of 12V battery management?

I might have to do some testing!

 

[hmadsen]

My understanding (as per link below) is that there is just a resistor in the plug head, which tells the car what the cable is rated for or whether it's a V2L cable. No computer in the cable per se.

I guess plug in chargers with adjustable charging power (eg. 6/8/10/15a) would have a little "computer" to change the resistance value between the 2 signal wires.

Yes there is a resistor inside the cable this actually signals to both the charger and the car, what its rated for.

This is vital, because otherwise someone would try to charge a car that would accept 32A with a cable that only had enough copper to charge at 16A for example.

I have not heard of any direct cable where there is a type 2 plug in one end and some sort of wall connector to connect directly to for example a CEE plug.

This is why there is both an option for a Type2 to type 2 cable, and a granny charger.

The type 2 to type 2 is used for destination chargers and in this case, the charger circuit to initiate the charge is inside that one.

If you could just use a simple lead with a resistor to charge from some AC outlet in your house, there would be no need to have an actual granny charger at all, they could just give you that cable with a resistor that told the car to not take more than 6A

If you think about it when you switch car on without using brake it will tell you it not charging the battery because it's not in ready mode

Also, when switching the car off, there is at some point a "klonk", that is the relays disengaging the traction battery from the car.

This is a safety feature so that, if for example water gets into some wiring or electronics box, the car will not self ignite in your driveway, or garage, if the water short circuits something.

 

[Coulomb]

I guess plug in chargers with adjustable charging power (eg. 6/8/10/15a) would have a little "computer" to change the resistance value between the 2 signal wires.

[ Edit: Oops, didn't see the replies on the next page. Sigh. ]

No, the resistor is always fixed, and represents the maximum safe carrying current for the EVSE's (AC "charger's") cable (the copper wires, a function of their cross sectional area). Or of course the resistor could have the special value that means "turn on the V2L function", but it would never have that value in an EVSE's cable.

In an adjustable limit EVSE, there is a small computer that adjusts the duty cycle of a 1 kHz signal on the control pilot wire. That's what tells the car what the supply equipment limit is (usually, the cable back to the switchboard and its circuit breaker), though users sometimes make that limit lower for other reasons (e.g. to match excess solar generation power).

The resistor is a separate limit on the charge current, needed because some EVSEs are non-tethered. That means that for example a 32 A EVSE might get a 16 A cable plugged into it, in which case the 16 A limit of the cable has to override the signal on the control pilot wire, if it's over 16 A.

In all these cases, it is the On Board Charger (OBC, the actual AC charger in the car) that implements these limits. The on-board charger is usually also the same equipment that "runs in reverse" (causes the power flow to reverse) to become a V2L generator/inverter.