[VHFcontesting] Alternator/VR question for rovers or auto guys

[Jarred Jackson]

I finally ran a charging cable from my car battery (2012 Ford Edge) to the auxiliary batteries in the back of the car. The system consists for a 100A fuse mounted at the battery, cable to the rear of the passenger compartment, a marine style manual disconnect switch and  two 6V 210Ah golf cart batteries in series. The plan is to disconnect the aux. batteries when the car is turned off and when starting. I cant use 6m for anything other than local contacts when the car is running, so often need to turn it off.


After getting all of this wired up yesterday, I was happy to see voltage climb to 14V on the aux. batteries and everything looked good. I left the car idling in the driveway and returned 20 minutes later to see voltage at 12.8V. Thinking I popped the 100A fuse in the charging line, I checked under the hood and saw the car battery at 12.9V and the fuse looked fine.  I turned off the car and turned it back on and voltage came back to 13.8V for maybe 10 minutes, then dropped to 12.7V. At this point there is NO load on the aux. batteries at all (the main fuse for the amp rack and radio gear is pulled). The mobile radio in the car (simply plugged into the accessory port of the car) showed 12.4V.


This morning, the car has been idling for 30 minutes and voltage is good at 13.9V. The car battery is at about 14.1V and everything looks good. No change in setup from yesterday. However yesterday was a hot day and the hood was closed when idling (which is probably not a good idea for various reasons). Today is cooler and the hood is open as I take measurements. Is it possible that the voltage regulator doesn't like heat and simply keeping the hood cracked open will solve this problem? Or maybe there is something else I dont understand. A search of the internet says I need to replace my alternator. I am not so sure.


Any rovers or car guys have any thoughts on the cause?


Thanks,


Jarred - KF2MR