Alternator Charging ? Again
I need to use the truck to recharge the batteries for the truck camper when off grid because there is no room for a generator, and solar can't always keep up. I know you are supposed to upgrade to...
Forum Discussion
Roadking284 wrote:
To BFL13 I agree with YC1. I am a mechanic and your alternator should put out between 13.5 to 14.5v. If your truck battery is not holding a little better than 12v.,then it also can be pulling amps for it. You need to get your battery load tested. Most local autoparts stores will do this for free. Its the ONLY way to test a battery correctly.
Getting back to your alternator: The nature of the way modern alternators work combined with a regulator should produce a steady amp rating at idle. It will go a bit higher at 2000 rpm but there shouldn't be that great of a difference. Start by getting both your batteries load tested and put a meter across your pos and neg truck battery post 1st with engine off key off, then during idle. check voltage. if you do not see and increase in the voltage from 12 to 13.5 after starting at idle replace the alternator.
As far as your original question, I've never seen anyone direct wire a camper battery off a alternator. It should work ok with the heavier gauge (thicker) wiring. Install a heavy duty in line fuse rated for the circuit just to protect the alternator. You can get them at places like Northern tool.
Good luck, and please post follow up after you check a few things!
When the truck is not on, the engine battery posts read around 12.5 volts usually. (parasite loads) The battery is newish and all cells are in the 1.275 area. When the truck is started, the battery post voltages go to 14.5 volts but soon after settle at around 14 volts.
It is when I put the extra load of the inverter running a charger on the truck battery as described, that the truck voltage gets low. If the load is not too much it will hang there steady at say 12.2 volts, but if I add more by using a bigger charger, the truck voltage can't hold and it starts to drop off.
You can see this on the dash voltage needle as it normally is at 12 o clock at 14v but then hangs steady at about 11 o clock with the 35 amper, but then with more load it drops around to the left dropping through 9 o clock and heading for 6 o clock. Before it gets to there, I shut it all down of course.
Does that still indicate a problem? Thanks.
