Charging 6 volt car battery

[yopappamon]

We just put my 93 year old father in an assisted living. Just getting too old to drive and live alone. I'm trying to move his 1940 Ford coupe to clean out his storage unit and the battery was low. It's a 6 volt battery. With all the electronics and battery chargers I have, there is nothing to charge 6 volts.

I have a black and decker 12 volt charger that limits current to 2, 6, or 10 amps. Could I use that on the 2 amp setting and just carefully watched the voltage?

 

[fechter]

Possibly, but you might damage the charger if it is not true constant current. I remember when a lot of chargers had a 6v/12v switch.

You should go for around 7v charging.

 

[SamTexas]

Look around in your house you might find a 9V or 12V ac/dc adapter with a low current, most of them are less than 1A. And yes, watch the voltage to be on the safe side.

 

[NeilP]

12 volt charger and a resistor/ light bulb string to drop the voltage?

 

[marty]

Do you have a RC charger? Some of them have settings to charge all different types of batteries.

 

[SamTexas]

12 volt charger and a resistor/ light bulb string to drop the voltage?

No that won't work. As the battery voltage increases, the battery takes more and more of the shared voltage.

 

[NeilP]

By the sound of it, this is a one off issue to move the car. If a bit of adjustment to the string as the battery charges is required, then so what? if this was for a long term charging solution then the answer is buyign a 6volt charger..since it is just to get the car started, then I think it is the ideal solution.
Can even start off the charge cycle with the 12 volt charger set on its highest power setting and the voltage across the battery reduced by a few bulbs/ resistors..as battery charges..drop the charger output power..Most car chargers have a high / low switch which usually just changes the output voltage

 

[SamTexas]

By the sound of it, this is a one off issue to move the car. If a bit of adjustment to the string as the battery charges is required, then so what?

Agreed. But then why bother with the resistor or light bulb in the first place?

 

[yopappamon]

The charger is too smart. It wouldn't stay on when I tried it.

I'll try the light bulb idea next.

I do have and adjustable wall wart, but that might take forever to charge.

 

[NeilP]

Agreed. But then why bother with the resistor or light bulb in the first place?

to try and drop the voltage across the battery from 14 or 15 volts that it would be putting out, down to a more reasonable level.

No idea how many bulbs will be needed but there si only one way to find out. Connect it up, monitor the current flow and the voltage across the battery

If not a bulb, an old resistive element style electric heater..hair drier..anything with a resistive loading

 

[dnmun]

my charger will charge 6V. go to harbor freight and buy one that puts out 6V/12V. they also have chargers that will assist cranking, so you could use that @6V to overcome the feedback that tries to keep it off for low voltage. once the car starts then it will charge itself from the generator. if the gas is old you should prime the carb with fresh gas when cranking. should start.

 

[SamTexas]

That's why I suggest him to use a 9 or 12V ac/dc adapter with low current. Most of them are "dumb" so they don't care about the voltage of the load.

 

[NeilP]

Ah, never seen or tried a 'smart' lead acid charger. only ever had the basic transformer /rectifier types

 

[yopappamon]

I took a second look at my rc charger and it does have a lead setting. I missed that the first time I looked earlier.

It's now charging at 1.5 amps since my 12v supply to the rc is only 2 amps.

The gas should be good, he drove it pretty regular up until this fall. I might need some starting fluid.

Thanks for the help, all!