Slightly odd electrical poser

[swee'pea99]

Long story short, it would be handy to be able to give the battery the occasional few hours' boost without having to remove it from the car. No garage. So, I'm thinking, what's to stop me from using a battery charger in the house, with the current taken out to the battery in the car at the kerbside by a basic little two-core cable - maybe 1mm or so, even 0.5mm bell-wire....don't think chargers actually put out very much current. Is there any reason this wouldn't work? Thanks for your thoughts.

 

[Emanresu]

How about one of those in-car 12V DC to 240V AC inverter that run from the cigarette lighter socket. Then you could use the battery charger from inside the car.

 

[lazybloke]

I'd just run an extension lead out into the drive and leave the charger balanced on the cylinder head. Just be careful not to short the clamps when you lower the bonnet.

 

[Beebo]

Do you have to run this across a pavement or is the car on a drive way?
Running any cable over a pavement is probably not advised as you don’t want to trip people up.

 

[Electric_Andy]

If it's a very slow trickle charge then it would probably be on about 0.6amps and ~10 watts. That is what my motorcycle one used; it took nearly 3 days to fully charge a small car battery (but it was all I had at the time). So there wouldn't be much danger using 1mm wiring. I'd be more concerned about water ingress and/or damage to such a thin cable with a suitably thin insulating jacket. It is probbaly more safe than using an extention lead though; if that got water dropped on it then would probbaly trip your circuit breaker and be more of a fire risk. Cover the terminals with rubber or something; I have had a battery short in a car once and it nearly burnt the thing to the ground

 

[Electric_Andy]

Do you have to run this across a pavement or is the car on a drive way?
Running any cable over a pavement is probably not advised as you don’t want to trip people up.

Not sure you're allowed to either unless you're in the trade and have the appropriate license?

 

[Electric_Andy]

give the battery the occasional few hours' boost

sorry, see my original reply. You're not going to give it much of a boost in 3 hours with a trickle charger. A small car battery capacity is 50-65 amp hours IIRC. So you're going to be trickling it in at even 1amp it's going to take 10 hours just to charge the battery by 16%

 

[fossyant]

I assume the car is not moved for some time - how about a solar trickle charger. TBH, if the battery isn't lasting, it could be time for a new battery. My car doesn't move for weeks on end sometimes.

 

[ebikeerwidnes]

There are cable protectors that you can use to go from your house to your car

They are becoming more popular because people with electric cars need them to charge their car overnight even if they don;t have a driveway

 

[Low Gear Guy]

There may be power losses in the cable if there is a significant distance between the charger and the battery, particularly with a thin cable. This will cause a voltage drop between the power source and the battery.

 

[numbnuts]

I'm using a 100W 12v solar panel with regulator, keeps the battery well topped up even on a dull cloudy day

 

[swee'pea99]

Thanks all for all contributions.

There may be power losses in the cable if there is a significant distance between the charger and the battery, particularly with a thin cable. This will cause a voltage drop between the power source and the battery.

Hmmm. 1mm core cable maybe 7-8m long? Would this scupper the plan?

FWIW I was thinking in terms of running it overnight - thin cable across the pavement, held down by 2inch-wide tape. No way anyone could trip.

I wouldn't run mains electricity out into the street unsupervised, but it's hard to see the output from a battery charger doing anyone any harm.

I'm using a 100W 12v solar panel with regulator, keeps the battery well topped up even on a dull cloudy day

Hmmm, interesting. I did once try using a solar trickle charger, but TBH it wasn't a very high rating and I never noticed it make any difference at all. Do you keep it on the dashboard? Which one d'you have, if you don't mind me asking.

 

[Low Gear Guy]

There may be power losses in the cable if there is a significant distance between the charger and the battery, particularly with a thin cable. This will cause a voltage drop between the power source and the battery.

Edit: I once had a colleague that designed 12V lighting systems and he used to calculate voltage drops across the system

 

[numbnuts]

Hmmm, interesting. I did once try using a solar trickle charger, but TBH it wasn't a very high rating and I never noticed it make any difference at all. Do you keep it on the dashboard? Which one d'you have, if you don't mind me asking.

This one
https://www.ebay.co.uk/itm/22557909...BlJs0s0AUDaovdxc+OSSVuv4gT|tkp:Bk9SR4qGk6L8Yg
and this 10 amp
https://www.ebay.co.uk/itm/39430409...XPReag6M3z2Lfp5ciFLKeU3Q==|tkp:BlBMUKrpnaL8Yg
Hi it has to be wired to a permanent "live wire" most fag lighters in cars are not, I was lucky to have one in the rear on my car so used that.
You will have to find to make a connection to a live feed from your fuse box, it is not a hard job and should not cost a lot even in a garage.

 

[swee'pea99]

This one
https://www.ebay.co.uk/itm/225579091842?hash=item34858fc782:g:J9UAAOSw3GZknOuU&amdata=enc:AQAIAAAA4G/dsPO9gilM9YhgRxULCCTxSqThmjeKqwRvLhja3XJi3KZk9Hj2TI8usROVpYYGupqrWg7goffVRYcDRqvx8O1GyvH/VfZvkb7vwIBqGKU0ut7AMrF0sVmN4Op3NIm0dJtnB44dJaQ3EG2ff4JKRCg2zOqPmDcrb3GYzxrZzg4+t7d1oGB4ePX53rpGg2fPqCeFjHmvyoOP+G2UEo1FhdnAaiE9CAeFTn8ehAnZbcjl3l6xI4L6xVUjKNK+DYQOZN32JhFTQ5ln8GQYyRBlJs0s0AUDaovdxc+OSSVuv4gT|tkp:Bk9SR4qGk6L8Yg
and this 10 amp
https://www.ebay.co.uk/itm/394304096218?hash=item5bce5b07da:g:VA4AAOSwHfdjV6n-&amdata=enc:AQAIAAAAwEi08S4r/+LKyy17m8WUmTGANV7E7vImYyXU/aDZ4jWSCjZ3lNzKGmIt0FVOzf2xLRQo2iexOQqYojN+Bad/jALBxmzorO8P76kdGSrYlDY9Iu4Gg5L5/XCrTS1f4dDeeGHwY8iJoCgCHSaEeNh5aleAd/unIxY2iJC3v4b3JvCr2sp+/B85TU+iuzob+OhcnkObpLokaRrnS6C0+apipWL/PbsGCA52b/sTICMDfDXPReag6M3z2Lfp5ciFLKeU3Q==|tkp:BlBMUKrpnaL8Yg
Hi it has to be wired to a permanent "live wire" most fag lighters in cars are not, I was lucky to have one in the rear on my car so used that.
You will have to find to make a connection to a live feed from your fuse box, it is not a hard job and should not cost a lot even in a garage.

Thanks. Interesting. At the risk of sounding clueless (I'm clueless) do you know if this would work if I just wired it directly to the battery terminals? (I already a have a two-core wire going from the dashboard through to the battery, left over from my previous (ineffective) solar panel.)