Is there an auto-electrician in the house?

[Arrowfoot]

Given that all modern cars drain the battery slowly while standing idle, I also suspect your use of the vehicle is the problem.

In other words, battery use of designed in drain and one start per week is slightly greater than the amount of charge generated by the short journey.

I recall the days of our parents. Someone had to go out and start the engine and run it for 10 minutes or so once a week if the car was not in use. Though technology has improved I see that with our modern camera batteries - dead if not in use for along time.

 

[swee'pea99]

I'm far from an expert, but my thoughts are that it would depend if your cigarette socket is live when the ignition is off. If it isn't, I don't think it will work, and you'll need to wire back to the battery terminals, or other point before the ignition.

Just checked using a phone charger which has a little red light on, which has just confirmed that when the ignition's on the 12v socket is live, but when it's turned off, the little light goes out. Which as I understand it means I can't after all recharge the battery via that socket, right? I knew it all sounded too good to be true.

Looks like it would be quite a job to physically get leads from the interior to the battery - my idea of drilling holes in the back of the glove compartment just shows my ignorance. There's quite a lot of hardware between the glove box & the engine bay. Has anyone cracked this one, and if so, how did you manage it?

 

[JtB]

The reading I'm getting is millivolts rather than amps. Don't ask me why Scotty reckons that's the way to go about it - I just do what I'm told.

Can’t really tell what you’re testing but from the photo I’m guessing you’re measuring the voltage across a one ohm resistor in which case a 70mV reading will indicate a current of 70mA.

 

[swee'pea99]

Can’t really tell what you’re testing but from the photo I’m guessing you’re measuring the voltage across a one ohm resistor in which case a 70mV reading will indicate a current of 70mA.

Ah. Learn something new every day! Thanks. As it happens, I've just been out and today the readings are jumping all over the place, from c70 to around 120 - literally flickering constantly. I've just ordered a new 9v battery to rule out a dodgy meter. One step forward....

 

[Drago]

I use mine infrequently so have rigged up a plug in smart charger.

I also use a ctek battery monitor which connects to my tablet via bluetooth so I can see what state the battery is in without leaving the house.

 

[JtB]

Ah. Learn something new every day! Thanks. As it happens, I've just been out and today the readings are jumping all over the place, from c70 to around 120 - literally flickering constantly. I've just ordered a new 9v battery to rule out a dodgy meter. One step forward....

A quick search using Google reveals:

A normal amount of parasitic draw for newer cars is between 50-milliamp to 85-milliamp current draw. A normal amount of parasitic draw for older cars is a reading less than 50-milliamp. Anything past these amounts indicates an electrical issue.​

So your original 70mA measurement is in-spec for a newer car.

Not sure why you are measuring voltage across a resistor rather than measuring inline current, maybe it’s to protect the multimeter in case you inadvertently exceed the maximum current.

 

[Electric_Andy]

You can run power from your battery into the car; I did it to power my subwoofer which is in the boot. There is usually a gromet in the passenger side behind the glove box. There are already wires running through that so you can, if you're careful, poke more wires through where the existing loom runs. In my last car I did the same but got a garage to do it, and one of the men did it for me for free in his lunch break so it's not a big job. Depends on the model of car of course

 

[fossyant]

My solar charger has two crocodile clips on, I just clip to the battery, shut bonnet, open door, put solar panel on dash, shut door.

Or I did, tend to use the car a bit more now.

 

[numbnuts]

My solar charger has two crocodile clips on, I just clip to the battery, shut bonnet, open door, put solar panel on dash, shut door.

Or I did, tend to use the car a bit more now.

Bravo.....let's keep it simple

 

[swee'pea99]

A quick search using Google reveals:

A normal amount of parasitic draw for newer cars is between 50-milliamp to 85-milliamp current draw. A normal amount of parasitic draw for older cars is a reading less than 50-milliamp. Anything past these amounts indicates an electrical issue.​

So your original 70mA measurement is in-spec for a newer car.

Not sure why you are measuring voltage across a resistor rather than measuring inline current, maybe it’s to protect the multimeter in case you inadvertently exceed the maximum current.

BECAUSE THAT'S WHAT SCOTTY! SAID TO DO. Sorry, I've been watching him quite a bit lately. I don't understand this stuff, I chust vollow orders.

Re the milllwotsits, I was going by what Scotty says around 1.30+, that anything up to about 35 milliwotsits is to be expected, but above that you have a problem. What do I know?

Overall, I'm definitely leaning toward the solar charger option. Gut feeling, I do have a problem somewhere, but not a massive one (two & a half months on a charge) and it wouldn't take that much of a trickle to keep up with it.

You can run power from your battery into the car; I did it to power my subwoofer which is in the boot. There is usually a gromet in the passenger side behind the glove box. There are already wires running through that so you can, if you're careful, poke more wires through where the existing loom runs. In my last car I did the same but got a garage to do it, and one of the men did it for me for free in his lunch break so it's not a big job. Depends on the model of car of course

Brilliant! That sounds like a hole in one to me.

My solar charger has two crocodile clips on, I just clip to the battery, shut bonnet, open door, put solar panel on dash, shut door.

Did you have it permanently like that, with, presumably, a bit of lead showing between door and bonnet? Or did you set it up then remove it? Have to say, I'm minded to try to track down this 'ere grommet...

I'm baffled by the apparent clash between Google and SCOTTY! on whether there is actually an issue. SCOTTY! would seem to suggest yes; google no. But either way, I suspect I will have a problem, simply because the car lies idle for so much of the time. But it at least sounds like there might be a quick 'n (relatively) easy solution.

Thanks all.

 

[fossyant]

It's a 30 second job to remove the panel - if you car is likely to be parked up, then shove it on (wire will show) then if you want to use it, then just pop the bonnet. Mine used to sit Monday to Friday !

 

[raleighnut]

BECAUSE THAT'S WHAT SCOTTY! SAID TO DO. Sorry, I've been watching him quite a bit lately. I don't understand this stuff, I chust vollow orders.

Re the milllwotsits, I was going by what Scotty says around 1.30+, that anything up to about 35 milliwotsits is to be expected, but above that you have a problem. What do I know?

Overall, I'm definitely leaning toward the solar charger option. Gut feeling, I do have a problem somewhere, but not a massive one (two & a half months on a charge) and it wouldn't take that much of a trickle to keep up with it.

Brilliant! That sounds like a hole in one to me.

Did you have it permanently like that, with, presumably, a bit of lead showing between door and bonnet? Or did you set it up then remove it? Have to say, I'm minded to try to track down this 'ere grommet...

I'm baffled by the apparent clash between Google and SCOTTY! on whether there is actually an issue. SCOTTY! would seem to suggest yes; google no. But either way, I suspect I will have a problem, simply because the car lies idle for so much of the time. But it at least sounds like there might be a quick 'n (relatively) easy solution.

Thanks all.

TBH I've watched some of this Scotty Kilmer channel and most of it is drivel, i wouldn't trust him to work on a wheelbarrow.

With modern cars that have alarms and 'keyless entry' etc those systems are on all the time so are drawing power from the battery which will over time flatten it.

As for 'tracking down this 'ere grommet the easiest place to start is the 'firewall' or bulkhead under the bonnet, you'll see where the wiring loom disapears into the cabin far more obviously than grovelling around behind the dash/in the footwell then just poke a 2 core wire in alongside the loom. The location of the grommet on the bulkhead will give you a clue as to where to find it inside the car.

 

[swee'pea99]

As for 'tracking down this 'ere grommet the easiest place to start is the 'firewall' or bulkhead under the bonnet,

I think I've found it - right in the middle of this pic:

Or, for a closer-upview:

The ribbed 'tube' goes through a hole...I reckon it's full of wires.

 

[Jenkins]

Just checked using a phone charger which has a little red light on, which has just confirmed that when the ignition's on the 12v socket is live, but when it's turned off, the little light goes out. Which as I understand it means I can't after all recharge the battery via that socket, right? I knew it all sounded too good to be true.

Looks like it would be quite a job to physically get leads from the interior to the battery - my idea of drilling holes in the back of the glove compartment just shows my ignorance. There's quite a lot of hardware between the glove box & the engine bay. Has anyone cracked this one, and if so, how did you manage it?

I'm in a similar position to you as I hardly use the car over the winter so the idea of a solar trickle charger appeals to me. There's an AA branded one which apparently can charge via the EOBD port on the car and comes with all the cables - it is available cheaper than in the link below...
AA 12V Car Solar Battery Charger 4.8W AA1432 - For Vehicles And Caravans - Battery Connectors Included : Amazon.co.uk: Automotive

 

[swee'pea99]

I'm in a similar position to you as I hardly use the car over the winter so the idea of a solar trickle charger appeals to me. There's an AA branded one which apparently can charge via the EOBD port on the car and comes with all the cables - it is available cheaper than in the link below...
AA 12V Car Solar Battery Charger 4.8W AA1432 - For Vehicles And Caravans - Battery Connectors Included : Amazon.co.uk: Automotive

Interesting. Especially the idea of charging via the OBDII port, which I've never heard of, but which sounds like the smart option. Googling suggests this is doable, and if it works is surely the easiest (and potentially very neat) solution.