charging car battery

forgotmyname

nobbysn*ts wrote: »

You can let us know how well the electronics cope with the load dump when you whip the battery lead off to put the meter in with the engines running. Should be a good little experiment for you.

Err whip the battery off with 70 amps going through the system. I think not.

I have a smartcharge system that will increase the alternators output to 18volts. I dont fancy going around the car replacing everything that didnt like running at 18volts.

A clamp meter is much safer.

Rover_Driver

Strider590 wrote: »

Get a multimeter on the battery terminals, if you read more than 12.8v with the engine running, then it is being charged by the alternator...... I've never known a car where the voltage did not rise with the engine running, so yes it does charge at idle.

It should always show about 14.4v with the engine running, but it is the current (amps) output that supplies the power not the voltage, and that is dependant on the alternator speed.

Strider590

Rover_Driver wrote: »

It should always show about 14.4v with the engine running, but it is the current (amps) output that supplies the power not the voltage, and that is dependant on the alternator speed.

And if the voltage from the alternator is higher than the battery voltage, then current must be flowing into the battery.......... Only if they were completely equal would there no zero current flow into or out of the battery.

Rover_Driver

Strider590 wrote: »

And if the voltage from the alternator is higher than the battery voltage, then current must be flowing into the battery..........

Current will be flowing at idle, and it should charge the battery, but it depends how much is being produced, how much is being used to run the engine etc. how much is left over to charge the battery, and how long it would take (how low the battery is).