Quote:
Originally Posted by 4Callahans
hello eagleback. my 2019 Ram 2500 w/ Cummings TD may or may not have two alternators. if it has 1 are you thinking my truck won't keep my residential fridge running interrupted on an 8-9 hour drive?
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regarding the powering of the 5th wheel with power from the tow vehicle
the limiting factor isn't how much electricity the tow vehicle can make; the limiting factor is the wiring which gets the power to the 5th wheel
for example
The 7pin connector is fused with a 40amp fuse (meaning that the 5th wheel is going to be getting a fair amount less then 40amps at 12 volts). So at the limit of popping the fuse your tow vehicle can give 40 x 12 = 480 watts of power.
Your fridge is 110volt; lets guess that it uses 5 amps when running. So that fridge is using 110 x 5 = 550 watts of power.
The above numbers have the 5th using 70 watts more power then the tow vehicle can provide at the limit of the fuse.
In reality, that 7 pin is outputting a lot less then 40amps; tow vehicles aren't providing a pile of power to the trailer and a 110volt load quickly consumes more watts then a 12volt system can generate.
To the 8-9 hour towing question
If the fridge uses 5amps@110volt(550watts) running 70% of the time and the tow vehicle outputs 30amps@12volts(360wattts) 100% of the time.
Over 9 hrs you will consume (550x(9x.7))=3463amp/hrs and produce (360x9)=3240amp/hrs. Meaning your battery only has to provide 223amp/hrs.
A fully charged deep cycle should handle that without issue; but you'll be down say 30%.