i understand all the math in the article but the initial question mentioned using the fifth wheel pigtail cable. your answer is very appropriate but it uses the fifth wheels shore power connection. this is the best way as it will power the 80 amp converter. but you might want to explain why this should be used and not existing 5th wheel pigtail.
to try to use the pigtail you would have to get the generator output transformed down from 120 vac to 12 vdc. but the pigtail would not support anything near 80 dc amps. some generators have a 12 dc output but again you would have to get an adapter to plug the pigtrail into it and again, no way to get anything near 80 dc amps.
You are correct. At most, a 7-way plug can support 5 to 10 amperes of charging current at 12 volts DC. Most of them that I’ve measured are transferring less than 5 amperes of charging current from the tow vehicle. That’s why I suggested a 15 to 50-amp adapter with a 12-gauge extension cord plugged into the generator’s 120-volt outlet. That’s the right way to utilize a small generator for RV battery charging.
I already have an article detailing why the 12-volt DC output on an inverter generator won’t work for charging RV house batteries. I’ll dig it out of my archives and post it here next week.
All great points! And couple of interesting notes: 1, the peak charging power of a lithium battery will occur at something less than the voltage at full charge voltage of 14.4-6 V, since the current (and power) drops off dramatically when the charger switches out of constant current mode. I’m not sure how big the effect is but it is interesting nonetheless, and 2, if the alternator of the tow vehicle could source 80 A and an Anderson connector and suitable gauge wire (like 2 AWG or larger!) was wired directly between the alternator and the battery bank, the lithium batteries could be charged with the tow vehicle’s engine.
i understand all the math in the article but the initial question mentioned using the fifth wheel pigtail cable. your answer is very appropriate but it uses the fifth wheels shore power connection. this is the best way as it will power the 80 amp converter. but you might want to explain why this should be used and not existing 5th wheel pigtail.
to try to use the pigtail you would have to get the generator output transformed down from 120 vac to 12 vdc. but the pigtail would not support anything near 80 dc amps. some generators have a 12 dc output but again you would have to get an adapter to plug the pigtrail into it and again, no way to get anything near 80 dc amps.
You are correct. At most, a 7-way plug can support 5 to 10 amperes of charging current at 12 volts DC. Most of them that I’ve measured are transferring less than 5 amperes of charging current from the tow vehicle. That’s why I suggested a 15 to 50-amp adapter with a 12-gauge extension cord plugged into the generator’s 120-volt outlet. That’s the right way to utilize a small generator for RV battery charging.
I already have an article detailing why the 12-volt DC output on an inverter generator won’t work for charging RV house batteries. I’ll dig it out of my archives and post it here next week.
All great points! And couple of interesting notes: 1, the peak charging power of a lithium battery will occur at something less than the voltage at full charge voltage of 14.4-6 V, since the current (and power) drops off dramatically when the charger switches out of constant current mode. I’m not sure how big the effect is but it is interesting nonetheless, and 2, if the alternator of the tow vehicle could source 80 A and an Anderson connector and suitable gauge wire (like 2 AWG or larger!) was wired directly between the alternator and the battery bank, the lithium batteries could be charged with the tow vehicle’s engine.