wiring question

[AC]

I'm installing a Tekonsha battery switch in my truck and am wondering if I can come off of the B+ on the back of the alternator instead of the battery terminal. Would this be any different? It sure would make things easier. AC

 

[B.G. Smith]

If you are going to use the switch to charge the battery in your slide in and the switch is off when the engine is off it should work fine hooked to the alternator lead. That lead is #6 wire and goes through a 140 amp fuse into the PDC. bg

 

[AC]

Ok sounds good! I ran the rest of the wiring back to the bumper and have some sodering to do yet but otherwise it's coming along good. All I need to do is pull the existing 14 gauge wire out of the plug and hook my 10 gauge up and then run this final piece hooking it in to the alternator. Thanks for the reply, AC

 

[B.G. Smith]

One thing that I didn't mention and you probably already have covered is that you should have a fuse in the line immediately off the alternator to protect the new wiring you are running. You indicate 10 ga. wire so a 30 amp fuse would cover it. bg

 

[AC]

Thanks again! I have it all mounted up and the 30 amp fuse too. AC

 

[AC]

Too much voltage

That didn't work. I ran all the wiring for the battery switch except for the connection to the power source. With the truck off I measured 12. 8 volts at the B+ terminal on the back of the alternator. When I hooked it up to the battery switch and fired up the truck I was getting 33 volts at the camper Obviously I had bypassed the voltage regulator. At that point I got out my hack saw and cut the end off of the bolt that holds the battery cable down. That way I could take the bolt off and connect directly to the + poll of the battery. 13. 8 volts at the camper now AC

 

[B.G. Smith]

Don't understand what could have happened. The alternator output is controlled by the computer, it reads voltage from the truck batteries and regulates the output voltage accordingly. The voltage should be about 14. 5 volts when the truck is first started and then drop to 13. 8 volts or so after it has run a few minutes. With the B+ disconnected and the field connected it is capable of going much higher than 14. 5 volts depending on how fast it is being turned and how much voltage is being applied to the field. I think I would check the 140 amp fuse and connections where the B+ 6 gauge wire enters the PDC. bg

 

[AC]

In rereading this thread I think I see now where I went wrong. I hooked on at the back of the aternator. I think you meant for me to come off of the PDC. Oh well, she's hooked up and working good now AC

 

[klenger]

33 volts from the alternator could be usefull for charging an RV battery with a 24 volt solar controller inline at the RV battery. A system like that would eliminate any voltage drop from alternator to RV battery that exists with a conventional 12 volt setup.

 

[AC]

I'm not familiar with solar controllers. Is that a battery isolator unit that goes with a solar panel? AC

 

[klenger]

A solar contoller regulates the voltage from solar panel(s) so that it does not overcharge the batteries.