The only way this works is if your RV has a charge line correct? I just purchased a brake buddy classic and it comes with a 15amp charger that I connect to the towed vehicle's battery like you did but I don't think my 7 pin on the back of my RV has a 12v charge. So now I need to figure out what I need to do.
Depending on the towed vehicle, there may be more items that present a load while towing than the brake controller. Sometimes the ignition switch must be in accessory position, and while vehicles with this requirement typically must have fuses pulled (my Grand Am required 3 fuses to be pulled), having a battery charger may possibly eliminate that step. But each vehicle is different so this is not an accross-the-board recommendation. Otherwise, you could directly connect the brake controller to the 12V from the 6 or 7 pin connector, but it would require some re-wiring of the vehicle. I suppose though that wiring a charger in the engine compartment is far easier than trying to wire behind the dash. Finally, you could simply directly connect the 12V coach power directly to the towed vehicle battery and it would charge. However, this charger really is more like an isolator, preventing the towed vehicle battery from trying to charge back into the coach when the coach engine is off. And without an isolator, the higher charged battery (regardless of whether or not it is in the coach or towed vehicle) will attempt to charge the lower charged battery until they equalize. An example would be if the towed vehicle battery were completely discharged, and the engine is shut off the coach - say at a resturant, etc. If not isolated, the coach battery would be discharged until it's charge is equal to the towed vehicle battery. In a worst case scenario, that might mean the coach battery won't start the coach. If course, some coaches disconnect the charging circuit when the engine is off, but not always - depending on the RV mfg. So there are some valid reasons for this kind of charger, but the need varies depending on the setup.
not sure if you can use this for keeping your chassis battery charged? I think you also have a video out about the switch that will start your chassis battery if it is dead, I want to change mine and not sure what the amp rating I should use? Thanks
Probably not much difference. I did not take it apart to see what was inside. Anytime you introduce a higher voltage to a lead acid battery, it will charge.
I'm going to do something similar and need to ask you a question: If you use the 12V pin on the 6 pin connector, how is the charge controller grounded on the toad? I see you are connecting both pos and neg cables to the toad's battery, but I'm not understanding where the ground wire comes from before it goes from to the controller from the battery.
+martinedd The 6 pin connector's negative pin is grounded to the chassis. This ground is picked up by the charge controller as it's case is also grounded. For most projects, I have a corresponding webpage that goes into more detail, often including schematics. There is a schematic for the charger's wiring diagram at: www.rv-project.com/projects/toad2.php
Can't you just run a positive + wire (12 gauge) from the 7 pin plug on the coach to the 6 way plug (center) on the toad?? That wire is regulated from the coach. I just don't get what this thing does.
Yes it is possible you can charge your battery with 12V from the coach directly wired to the battery. However, this charger provides isolation and a fuse protected power source. Isolation is important because should the towed vehicle battery be bad, it could damage the coach battery. So it's really a matter of enhanced safety.
If there is any other device drawing power off the coach charge line, it will draw from both the chassis and toad battery. The coach line ties into the chassis electrical system via a fuse, so when the vehicle is turned off and the harness is connected, engine computers, running lights, or anything that might draw power could begin to discharge the toad battery. This device has diode protection which acts as a valve against reverse flow from the toad into the coach chassis.
What if I leave umbilical connected overnight? Will the road battery draw down the coach battery? Will the coach battery draw down the road battery? What about if the toad engine and rv engine are running at the same time? What do the alternators of each vehicle do at that point?
