trailer brake batteries self charge?

[gerard]

Do the batteries that activate the emergency brakes on trailers self charge when hooked up to a tow vehicle or should you throw a charger on them periodically? Can you just check the voltage with a multi tester and if it's within specs it's ok?

 

[cowboydoc]

All the trailers I have had Gerard they do self charge. You can test them with a battery voltage tester. Just make sure and set it to the proper volt for your battery. If it shows a charge you are ok. Where you may want to check it is if you only use the trailer a couple times a year.

 

[gerard]

thanx - that was what I was wondering, never really checked and the horse trailer does go through some long time periods between uses.

 

[Charlie_Iliff]

Gerard:
You usually can tell if the trailer is wired to charge the battery from the tow vehicle because there will be a little box containing a diode pack in with the battery, wired between the tow vehicle and the trailer battery. If you just hard wire the trailer battery to the tow vehicle 12 volt, the trailer battery will try to help start the tow vehicle and can fry the wiring unless there is a diode in the truck wiring. I don't know if new trucks automatically have that in their harness, but none of the older nehicles I've worked with had them.