Car battery charge via towbar 12S connector

A better way is to fit one of the Lidl etc chargers in the car and provide a mains input. I've got that on the old Rover.

The permanent feed should be fused. I'm not sure that miscreants have any great knowledge of, or interest in, such matters. The results of their attempt would not be particularly spectacular, indeed they probably couldn't tell if it had worked.

Is your question, "Is it possible to charge a car battery via the

Personally, on the odd occasion it has been necessary, running a mains extension to the car, and putting the charger under the bonnet has worked fine.

Your proposal would increase the length of DC cable, both internal to the car, and possibly also externally, which is less than ideal, though not a job-stopper.

Why does the idea appeal to you?

Chris

I'm not sure what the fuse rating is. Say it's 10A (maybe 16A) and the charger can only do 6A. Then the fuse can't blow can it?

Yes.

That's what I'm doing now.

It appeals as it is easier to plug something into an exposed socket than to keep lifting the bonnet. It's the cold mornings that cause the starting troubles. Both battery and charging have been tested and are ok. There may of course be a permanent drain elsewhere.

This is certainly something that was fitted to my father's car in the

It would be most unlikely.

Chris

Grumps explained :

If it is wired to modern standards, then pin 4 should be fed via a relay that only energises when the engine is running/ the main battery is receiving a charge. Like wise pin 6 fridge supply, which is only live under the same circumstances.

Pin 4 is intended to charge the battery in the trailer.

My ciggy lighter socket is live all the time and I use a small maintenance charger which plugs in there. I have the charger mounted on the garage roof beam, with its 12v plug hanging ready to plug straight in as I stop.

Many years ago, I put a cigarette lighter plug on my battery charger so I could just plug it into the cigarette lighter socket, and leave it sitting in the dry car (in the footwell) whilst it was charging. That charger was only 4A max.

However, I don't recall ever needing to charge my own car batteries - it was always someone else's.

on 16/01/2012, Grumps supposed :

It should be a direct fused supply from the main battery. What I do is fuse one large cable at 30amps at the source, run that to a charge relay in the boot, then split it down to two supplies again fused, but at 15 or 20amp each for fridge and trailer battery charging. Large cable to avoid volts drop rather than rated for amps.

What temperature was the battery when it was tested? Really cold like it would be after standing overnight or just a few degrees warmer after starting and run to the garage to be tested?

When the battery was going in my car I knew it might be interesting starting if it was cold but just a few degrees warmer there wasn't a problem. Could almost use the ease, or not, of starting as a thermometer. B-)

Pin 4 is permanently live. However, and not relevant to the original question, latest caravan standards implement switching of this feed within the caravan in response to pin 6.

If pin 6 is energised, besides feeding the fridge itself, it initiates switching of the battery, isolating it from the load and connecting it to pin 4.

Chris

Rings a bell. I recall when I was young and penniless bump starting my Mini every morning there was a frost. I was hoping it would last until spring, and then I'd be all right all summer.

Then we had some snow. You can't bump start on snow :(

Andy

You can start the original 850 Mini by jacking up one front wheel, plonking it in top gear and 'spinning' the wheel by hand.

every

spring,

Makes it harder, but not impossible I would have through higher gear and don't drop the clutch?

Neat trick. Was going to say what wrong with the starting handle but then remembered the transverse engine. B-)

I guess that would still work for petrol engines today but possibly not on a diesel.

My dad had a Citroen GS and then a later model which I forget. You could use the wheel change spanner as a starting handle in both of these, and we did occasionally (damn hard work through).

Strangely, there was a starting handle conversion kit made. But you had to remove a wheel to use it, IIRC.

It would need to be a small engine.

Would that give any more leverage than simply using the tyre? And less chance of that assaulting you. ;-)

possibly

Not sure the size, as in cc, makes that much difference it's the compression ratio. 9:1 (ish) for a petrol, 20:1 (ish) for a diesel.

If I forget to operate the decompression lever on my single cylinder diesel genset and try to pull start it it's like yanking a rope attached to a boulder, it doesn't move once the slack has been taken up. The single cylinder 4 stroke petrol mower is a doodle.

It engaged with a dog on the crankshaft. Properly thought out, it was. And if it was hard work to start the engine by hand, IME, it needed a service.

I've hand started a 4 litre petrol engine in a Leylend FG550 truck. It was a low compression version of the Austin Princess engine, with a massive 6:1 compression ratio.

I've often hand started my Land Rover 2286cc petrol engine, too.