time2roll wrote:
StirCrazy wrote:
Just a question, I understand how the smart alts in the new fords work, just had to diagnose my system to find a broen monitering wire , but just trying to wrap my head around this, if you have your charging system in tact and you have your camper pluged in and the batteries are down that would put a load on the trucks batteries and then the PCM would raise the voltage output from the altanator to charge the batteries untill that load is not detected any more, meaning the batteries are fully charged. the system doesnt say it takes 800 watts to start the truck so thats all I am putting back in. the new fords use a two wire feed back and command loop to controle the altanatore output depending on the Voltage read directly from the battery. so if you conect your batteries in the camper to the truck batteries then the overall voltage will be inbetween them and if thats the case then the system will ramp up the charge untill all the batteries are charged.
now if there is an isolater in there that could change things, and a DC_DC charger is starting to sound like it is a more efficient way to go but the responce from the altanatore should be the same either way , unless I am missing somthing like an isolator or somthing but that wouldmt make sence to have that thee when it is designed as a system to charge the camper batteries or such
Steve
Yes you have it right. The alternator does not know anything. Not the charge level in the start battery, not the accessory load. The alternator just produces the amps required to maintain the voltage set point directed by the vehicle computer.
The newest vehicles have tuned this voltage to optimize fuel economy vs just providing tons of voltage to make sure the battery is topped off quickly. So your RV battery may not receive the proper voltage at the end of a long #14 wire for any type of fast charging. The DC-DC charger will resolve this issue for the RV battery.
Diode isolator (motorhome) could drop another half volt, relay isolator (Ford truck, some MHs) will pass through full voltage.
I think that for sure you would need to change the factory charge wire to a larger guage. I was thinking in the 2/0 range back to my batteries in the camper. the only thing I kinda like about the dc to dc idea is you can limit the charge draw where if I just do a nice new charging line it will ramp the alt up to full output if nessasary which makes them run hot.
Steve
