Battery solenoid isolator

Mine is charged through a solenoid which is activated by the ignition. Several years ago it stopped charging the house battery. The problem was worn out contacts in the solenoid. Replaced it and all is fine.

The solenoid had been installed upside down. I mounted the new one right side up. It has been good ever since. Don't know if that caused the problem or not.

If you can measure the voltage across the solenoid contacts with the engine running, it should be close to zero.

Had similar problem -- my solenoid was in engine compartment - my fix was to run a wire from E350 fuse panel through a rubber grommet on fire wall to the solenoid. I purchased one of those piggy back fuses and used the radio slot as it is energized when the ignition key is turned on. 5 minute DIY job.

Thanks for the replies, I like that Sure Power battery separator. I'll have to pull the instrument cluster and trace the solenoid power wire back to its origin. If I can’t find the source, then I'll run a new power wire from the fuse box.

alternativeclimate wrote:
Thanks for the replies, I like that Sure Power battery separator. I'll have to pull the instrument cluster and trace the solenoid power wire back to its origin. If I can’t find the source, then I'll run a new power wire from the fuse box.

If the solenoid is bad running a new wire to it won't help.

I can actuate the solenoid manually with a battery charger applying power to the small side post terminal. The solenoid will click and if the engine is running, the alternator current flows to the battery.

The oem wire coming from the fire wall to the side post terminal has no power, even if the engine has been running for a half hour...I’m thinking that it may be wired into the ignition switch since none of the fuses are bad at the fuse box, but if that’s the case how come I don’t have any other issues...