powering up a dead car’s electrics from the outside

[Tim+]

An EV owner got caught out when their 12V battery died and the emergency
key wouldn’t open the door lock as the lock barrel hadn’t been connected up
in the factory.

Apparently the AA jacked up the near side front wheel, had a fiddle
underneath and were able to plug in a battery somewhere which provided
enough power to boot the system.

Now I know my emergency key works so I can alway open my bonnet it I get
caught out but it would be handy to know (if only to satisfy idle
curiosity) what circuit the AA man tapped into. As far as I’m away, no
wires were cut and they presumably plugged into the loom into a circuit
that is normally permanently live.

It was a 2020 “First edition” Kia Soul. Although it’s an EV, much of the
12V side of things is pretty similar to a regular car. What kind of
circuits accessible from underneath might be permanently live and hence,
useable to power up the 12V system?

Tim

[Brian]

Post by Tim+
An EV owner got caught out when their 12V battery died and the emergency
key wouldn’t open the door lock as the lock barrel hadn’t been connected up
in the factory.
Apparently the AA jacked up the near side front wheel, had a fiddle
underneath and were able to plug in a battery somewhere which provided
enough power to boot the system.
Now I know my emergency key works so I can alway open my bonnet it I get
caught out but it would be handy to know (if only to satisfy idle
curiosity) what circuit the AA man tapped into. As far as I’m away, no
wires were cut and they presumably plugged into the loom into a circuit
that is normally permanently live.
It was a 2020 “First edition” Kia Soul. Although it’s an EV, much of the
12V side of things is pretty similar to a regular car. What kind of
circuits accessible from underneath might be permanently live and hence,
useable to power up the 12V system?
Tim

My guess is they accessed the back of the fuse box somehow.

On my hybrid, there is a place under the bonnet to ‘jump start’ the 12v
system - it is (roughly) over the near side front wheel in a fuse box. I’ve
never checked if the wiring is visible behind the wheel arch shield.

[Tim+]

Post by Brian

Post by Tim+
An EV owner got caught out when their 12V battery died and the emergency
key wouldn’t open the door lock as the lock barrel hadn’t been connected up
in the factory.
Apparently the AA jacked up the near side front wheel, had a fiddle
underneath and were able to plug in a battery somewhere which provided
enough power to boot the system.
Now I know my emergency key works so I can alway open my bonnet it I get
caught out but it would be handy to know (if only to satisfy idle
curiosity) what circuit the AA man tapped into. As far as I’m away, no
wires were cut and they presumably plugged into the loom into a circuit
that is normally permanently live.
It was a 2020 “First edition” Kia Soul. Although it’s an EV, much of the
12V side of things is pretty similar to a regular car. What kind of
circuits accessible from underneath might be permanently live and hence,
useable to power up the 12V system?
Tim

My guess is they accessed the back of the fuse box somehow.
On my hybrid, there is a place under the bonnet to ‘jump start’ the 12v
system - it is (roughly) over the near side front wheel in a fuse box. I’ve
never checked if the wiring is visible behind the wheel arch shield.

I don’t think so. I have the same car and there’s no way you can access the
fusebox from underneath.

Tim

[Peter Hill]

Post by Tim+

Post by Brian

Post by Tim+
An EV owner got caught out when their 12V battery died and the emergency
key wouldn’t open the door lock as the lock barrel hadn’t been connected up
in the factory.
Apparently the AA jacked up the near side front wheel, had a fiddle
underneath and were able to plug in a battery somewhere which provided
enough power to boot the system.
Now I know my emergency key works so I can alway open my bonnet it I get
caught out but it would be handy to know (if only to satisfy idle
curiosity) what circuit the AA man tapped into. As far as I’m away, no
wires were cut and they presumably plugged into the loom into a circuit
that is normally permanently live.
It was a 2020 “First edition” Kia Soul. Although it’s an EV, much of the
12V side of things is pretty similar to a regular car. What kind of
circuits accessible from underneath might be permanently live and hence,
useable to power up the 12V system?
Tim

My guess is they accessed the back of the fuse box somehow.
On my hybrid, there is a place under the bonnet to ‘jump start’ the 12v
system - it is (roughly) over the near side front wheel in a fuse box. I’ve
never checked if the wiring is visible behind the wheel arch shield.

I don’t think so. I have the same car and there’s no way you can access the
fusebox from underneath.
Tim

Is this a car where they build the car around the 12V battery in the wing?

[Tim+]

Post by Peter Hill

Post by Tim+

Post by Brian

Post by Tim+
An EV owner got caught out when their 12V battery died and the emergency
key wouldn’t open the door lock as the lock barrel hadn’t been connected up
in the factory.
Apparently the AA jacked up the near side front wheel, had a fiddle
underneath and were able to plug in a battery somewhere which provided
enough power to boot the system.
Now I know my emergency key works so I can alway open my bonnet it I get
caught out but it would be handy to know (if only to satisfy idle
curiosity) what circuit the AA man tapped into. As far as I’m away, no
wires were cut and they presumably plugged into the loom into a circuit
that is normally permanently live.
It was a 2020 “First edition” Kia Soul. Although it’s an EV, much of the
12V side of things is pretty similar to a regular car. What kind of
circuits accessible from underneath might be permanently live and hence,
useable to power up the 12V system?
Tim

My guess is they accessed the back of the fuse box somehow.
On my hybrid, there is a place under the bonnet to ‘jump start’ the 12v
system - it is (roughly) over the near side front wheel in a fuse box. I’ve
never checked if the wiring is visible behind the wheel arch shield.

I don’t think so. I have the same car and there’s no way you can access the
fusebox from underneath.
Tim

Is this a car where they build the car around the 12V battery in the wing?

No, just towards the front of the engine compartment like many ICE
vehicles.

Tim

[Theo]

Post by Tim+
It was a 2020 “First edition” Kia Soul. Although it’s an EV, much of the
12V side of things is pretty similar to a regular car. What kind of
circuits accessible from underneath might be permanently live and hence,
useable to power up the 12V system?

Is there maybe access to something on Canbus that might have a 12V on the
connector? For example the body control ECU might be live if it's used for
the alarm. I doubt you'd get much current into it that way, but maybe
enough to hold up a weak but not 0V lead acid battery enough to open the
high voltage battery contactor?

Theo

[Tim+]

Post by Theo

Post by Tim+
It was a 2020 “First edition” Kia Soul. Although it’s an EV, much of the
12V side of things is pretty similar to a regular car. What kind of
circuits accessible from underneath might be permanently live and hence,
useable to power up the 12V system?

Is there maybe access to something on Canbus that might have a 12V on the
connector? For example the body control ECU might be live if it's used for
the alarm. I doubt you'd get much current into it that way, but maybe
enough to hold up a weak but not 0V lead acid battery enough to open the
high voltage battery contactor?
Theo

Sounds plausible. I don’t think it needs a huge current to boot things up.
When the weather is better I will have a rummage under my car.

Tim

[George Harrison]

Post by Tim+
An EV owner got caught out when their 12V battery died and the emergency
key wouldn’t open the door lock as the lock barrel hadn’t been connected up
in the factory.
Apparently the AA jacked up the near side front wheel, had a fiddle
underneath and were able to plug in a battery somewhere which provided
enough power to boot the system.

Not that vehicle, but I had a car with flat battery. Connected a charger
to the starter motor cable, which was accessible if you raised the car 2
inches, other end to engine block. Left it overnight. Lucky it was home,
not stuck in some narrow village road.