Car battery charger that turns 115ac into cigarette lighter charger; how to do?

My trunk light was on all night and my car almost started. It just needed a little more. I bought a tiny battery that inserts into the cigarette lighter but it does not work in more severe discharges. The car is in the garage with plenty of 115ac power. The problem is I cannot open the hood by myself so I cannot give it a battery charger usual charge. I would like a device that I can plug into the wall outlet and plug into the cigarette lighter to charge the battery. It cannot be so strong as to blow the fuse. I cannot find a bigger device for sale.

What can be done or made?

If you can get to the starter motor main cable or alternator output terminal from underneath the vehicle, you may be able to charge the battery from there, if you have enough room for the alligator clips.

How come you can't open the hood?

That is not useful to me.

Thank you anyway.

It can be done, up to the current limit of the cigarette lighter fuse in the vehicle. Recent vehicles have larger current capability. Could be anything from 7amps to 20 amps capability.

You can buy a cigarette light plug and connect it (observing proper polarity) to your charger. Remember current maximum. A 10 to 15 amp charger will likely be okay.

that simple?

Thank you. Is it that simple? I have a multi meter, spare cigar plug, and charger that can do 2, 10 or more Amps. So I stick in the plug to be certain of polarity, attach enough wire of #14 or bigger, and clip the charger onto the plug? Is it that simple?

Something like this:
Amazon.com: Battery Tender Cigarette Lighter Adapter: Automotive
may be of help, if you can remove the 2-pin plug on the end.

Use a multi-meter to check which wire is positive & negative. The centre pin is usually positive in the majority of vehicle's sockets.

EDIT: info already posted whilst typing this post..

SsgKen said:

Thank you. Is it that simple? I have a multi meter, spare cigar plug, and charger that can do 2, 10 or more Amps. So I stick in the plug to be certain of polarity, attach enough wire of #14 or bigger, and clip the charger onto the plug? Is it that simple?

Click to expand...

Yes, but I wouldn't go above 10 Amps.
You will likely need to have the key turned to the accessory position too, unless the socket has a permanent supply.

final

Hi,
Let's see; I cut off the end of this old cell phone charger. Plug it in and test polarity, then hook it up to a charger? This paticular plug has a red LED so it may have a one way diode. I will check.

**broken link removed**

There will probably be a PCB inside that plug, to drop the voltage down to the suitable cell phone charging voltage.

Ideally, you need to get to the centre & side contacts directly.

Beware using the cigarette lighter socket.
One of my cars, a Ford Mondeo, switches off the the power to the socket when the key is removed from the ignition switch.

If this happens in you car, the charger will not work unless the ignition is set to the aux position to power the radio etc.

JimB

SsgKen said:

Hi,
Let's see; I cut off the end of this old cell phone charger. Plug it in and test polarity, then hook it up to a charger? This paticular plug has a red LED so it may have a one way diode. I will check.

**broken link removed**

Click to expand...

Cell phone charger is not just a plug. They usually have electronics in the plug assembly that converters 12-15vdc to 5vdc for phone. The one in your picture is this type.

not quite done

I thought of that over lunch. I am sure the voltage reducer is in the plug. I will have to go into the garage into the giant box of old wires. I am sure I have a better plug somewhere.

I can always buy one, but I have saved so many of these little gadgets, I would hate to buy one and then find one just kicking around.

I will write again when I find the right plug. Thanks one and all.

If you can find one like that in the link below, your job will be much easier:
https://www.shokaifareast.com/images/Misc_Products/lighter_plug1.JPG

thank you

One good picture deserves another

**broken link removed**

I put this in some of my websites at dawn tomorrow.

cigarette lighter plug found

I found my plug off of my 1.8 Watt Solar Battery Maintainer available many places. I tried it in the car and got a 14.2 volt reading just after starting. The exposed part was the positive. It is here

**broken link removed**

Look at the lower left part of the picture. There is an exposed plug which is positive and a hidden negative wire.

What would be the best way to expose the hidden negative wire inside the rubber cover?

Hello again Ken.

Do you also have the wire assembly, in the picture, with the crocodile clips?

If so, connect that to the cigarette lighter plug and check continuity with a multimeter. (Do not plug it into the vehicle yet) The centre connection on the cigarette lighter plug is positive and the contacts on the outside are negative. Please check to make sure, because both adapter cables are 'keyed' to connect correctly to the solar charger cable - this means the exposed positive pin, on each adapter cable, connects to the shrouded female connector on the solar charger cable positive. As you can now probably see, the shrouded female connector in each adapter cable plug is negative...connecting two adapter cables together will end up with a reversal of polarity. I think you will find that connecting a cigarette lighter plug adapter cable and a crocodile clip adapter cable together will give continuity, from the cigarette lighter plug tip to the black crocodile clip and the same with the side contacts to the red clip. If you want to test this on the vehicle, connect both adapter cables together and insert the plug into the cig lighter socket - check with the meter on voltage and you'll likely have -12.6v or something similar - but please make sure the clips are separated sufficiently otherwise, you will run the risk of shorting them out and blowing a fuse.

If you don't have the croc clip adapter cable, you will need some crimp connectors, crimping pliers and some wire. You'll need to crimp a female connector onto a wire for the battery charger positive connection and a male onto a wire for the negative.

Female crimp connector:
https://media.digikey.com/photos/Molex/19039-0006.jpg

Male crimp connector:
https://media.digikey.com/photos/Molex/19034-0009.jpg

HTH.

thank you

I will look for the rest of the assembly. I was thinking of just stripping back the wire insulation. maintaining proper polarity, and setting it up.
I think the PV panel and clips are on the boat yet.

You could snip off the original connector and use the adapter solely for this current problem, or you could keep it as-is and utilise a couple of crimp connectors & wire, to make your own charging lead, keeping the adapter lead still intact and able to be used for it's original purpose.

HTH.