Okay riddle me this batman!

[deeuubee]

Yes, I can see how a DC-DC converter would be better for charging the battery directly, but

Isn't the 7-pin connector just supplying ~12-13V battery to his inverter/charger?
The size of which would determine the battery charge rate?

Whether or not there was any output from the alternator would be dependent on battery voltage.
Yes/No?

[Extreme]

Great...now I have to worry about Burning out my trucks alternator while driving?

[deeuubee]

No, the purpose of the smart alternator is to supply what ever extra power can't be supplied by the battery.
If the battery meets all the output, the alternator puts out very little.
The 7-pin plug is fused at 30 amps, but due to the size and length of the wire, you'll probably never see more than 8-ish amps to the trailer.

My truck has all kinds of Fu-Fu crap on it; electric defrost, heated seats, heated steering wheel, heated mirrors, auxiliary lights, and my gotta have it coffee maker.
The 8 or so amps from your trailer won't make a dent in it.

If you wanted to get the maximum amperage out of your alternator, then you would definitely need a DC-DC converter.
Plus much larger wires run all the way back to wherever you put the converter.

[Extreme]

Thank you....one less thing to worry about. I am totally new with all this.

[SolarPoweredRV]

Yes, I can see how a DC-DC converter would be better for charging the battery directly, but

Isn't the 7-pin connector just supplying ~12-13V battery to his inverter/charger?
The size of which would determine the battery charge rate?

Whether or not there was any output from the alternator would be dependent on battery voltage.
Yes/No?

The 7-pin connector supplies 12 volts from the truck to the camper's battery. This 12 volts is what keeps your camper battery from discharging while you are traveling (usually there are 12v items that are turned on even when you are not in the camper). Often, this 12 volts from the truck will charge up your battery while you travel between destinations, unfortunately, if you have items like a residential refrigerator, or your battery is a long distance from the front of your truck, the 12v 7-pin connector does not carry enough energy (amperage) to charge the battery while you travel.

This can also be the case if you have LiFePo4 batteries installed in your coach, because, the voltage of the LiFePo4 batteries when 50% discharged is higher than Lead Acid batteries that are discharged to 50%. Consequently, the Alternator in your truck does not know that extra power is needed to charge up the LiFePo4 batteries and you could arrive at your destination with your coach batteries not fully charged up after a full days drive. This is the reason you want to add a DC to DC converter to your truck. The DC-DC converter will increase the 12 volts coming from the truck to a higher voltage (14.4 to 14.8) that can charge your LiFePo4 batteries while driving (in this case the DC to DC converter simply acts to step-up the truck's voltage to a voltage that will charge the LiFePo4 batteries).

Note: the Inverter/Charger does not charge the batteries unless it is plugged into Shore Power. Shore Power is what activates the "Charger" portion of the Inverter/Charger. If Shore Power is not available then the Inverter works to create 120 volts form the 12 volt battery(ies) to supply 120 volts to the coach (usually a Residential Refrigerator while traveling).

[SolarPoweredRV]

No, the purpose of the smart alternator is to supply what ever extra power can't be supplied by the battery.
If the battery meets all the output, the alternator puts out very little.
The 7-pin plug is fused at 30 amps, but due to the size and length of the wire, you'll probably never see more than 8-ish amps to the trailer.

My truck has all kinds of Fu-Fu crap on it; electric defrost, heated seats, heated steering wheel, heated mirrors, auxiliary lights, and my gotta have it coffee maker.
The 8 or so amps from your trailer won't make a dent in it.

If you wanted to get the maximum amperage out of your alternator, then you would definitely need a DC-DC converter.
Plus much larger wires run all the way back to wherever you put the converter.

The wires coming from the 7-pin connector go directly to the battery, not the converter. The 12 volt 7-pin connection from the truck to the camper is designed to charge up the Lead Acid battery in the camper. The way your truck's alternator is triggered to send volts back to the camper is through the voltage reading, if your camper battery is sitting at 11.9 volts your alternator is triggered to send ~14.4 volts back to the camper battery (indirectly) until the camper battery is close to 13.2 volts (fully charged Lead Acid battery) then the alternator shuts off and will cycle on and off keeping the voltage between 13.2 and 14.4 volts.

A Lead Acid battery in a camper can be charged with the truck because the voltage supplied by the alternator is significantly higher than the low voltage of the LA battery (14.4 vs 11.9). A LiFePo4 battery in a camper is less likely to be charged by the truck's alternator because the voltage of a LiFePo4 battery is closer to (or above) the 13.2 volts of a fully charged LA battery, even if the LiFePo4 battery is 80% discharged (this is due to the LA battery's lowering voltage as it discharges versus the LiFePo4's voltage remaining relatively high until a sharp drop-off after 90% discharge).

Note: Above, I indicated that the Alternator sends power to the Camper based on the voltage in the camper battery. While this is true, it happens indirectly. In actuality, what happens is that the truck's battery supplies power to the camper's battery (via the 7-pin connector) and the alternator senses a lower battery voltage in the truck's own battery (due to the draw from the camper) and the alternator turns on to keep the truck's battery charged. The alternator's only job is to keep the truck battery fully charged.

[deeuubee]

@SolarPoweredRV - Thanks for the clarification. I was confusing the connection of the inverter/charger and truck to the RV battery.
I was considering Solar to charge during travels, but sun time is so limited up here in New England. I'm now thinking the DC-DC converter is a better way to go.

[iproff1]

So I finally got everything concerning my Lithium Battery, Inverter/Charger and Monitor for my 2021 Imagine 2500rl that I pick up from Lazydays in Tucson Arizona. Yup traveling 500 miles from LA to Tucson for a dozen reasons but mostly because the Southern California Grand Design Dealers out here are a total joke. I could write a book on how terrible they are but lets move on.....

On a more happier note I pick up our 2021 Imagine 2500rl in mid April in which the dealership (Lazydays) is installing a 32" Fireplace, 2 sets of RV Locks, a 12V 206Ah LiFePO4 Lithium Iron Phosphate Battery, Xantrex inverter/charger controller, Xantrex Bluetooth monitor and a Partridge in a Pear Tree.

Just kidding about the last part. Why this equipment (you ask) its because they will only warranty the items they sell.
And to be honest with you I just want to get this all done and start camping. I will retire from the Press Enterprise Newspaper on June 4th and will turn 71 this year and I just want to live a little with my lovely wife (Honey) and our 2 Golden Retrievers.

But this would not be a posting from me if I didn't have a question (see that's what Newbies do).
So let's say I'm dry camping for a couple of days and I run my Lithium 206Ah battery down to 60% full.
If I take the rig on a 4 hour drive at 60 mph to our next camping spot how much do you think the battery would be charged up to?
Keeping in mind it started the ride at only being 60% fully charged. Any way that's the question for the day!
Thanks everyone for all the great help on the battery in the past posts.....

You will love the Xantrex system we had one on our boat with 2 golf cart batteries 225 amp hrs. Voltage is not what you need to be concerned with it's amp hours. Your shunt on the Xantex will measure amps out and amps in. The Xantex charger depending on your model could charge at 50 amp hrs but as the battery bank gets closer to fully charged the amp hrs drops a lot. Also a battery should not be charged at to high an amp hr rate or you will damage the battery. Your battery will tell you the max rate, the battery supplied with my camper is 12 amp hrs not very much at all. If your TV is only putting 10 amps to your RV after 4 hours you have only put 40 amp hrs back into the battery. The Xantex is one of the best battery management systems there is our golf cart batteries lasted 9 years because of that system.

[LanerC]

So I finally got everything concerning my Lithium Battery, Inverter/Charger and Monitor for my 2021 Imagine 2500rl that I pick up from Lazydays in Tucson Arizona. Yup traveling 500 miles from LA to Tucson for a dozen reasons but mostly because the Southern California Grand Design Dealers out here are a total joke. I could write a book on how terrible they are but lets move on.....

On a more happier note I pick up our 2021 Imagine 2500rl in mid April in which the dealership (Lazydays) is installing a 32" Fireplace, 2 sets of RV Locks, a 12V 206Ah LiFePO4 Lithium Iron Phosphate Battery, Xantrex inverter/charger controller, Xantrex Bluetooth monitor and a Partridge in a Pear Tree.

Just kidding about the last part. Why this equipment (you ask) its because they will only warranty the items they sell.
And to be honest with you I just want to get this all done and start camping. I will retire from the Press Enterprise Newspaper on June 4th and will turn 71 this year and I just want to live a little with my lovely wife (Honey) and our 2 Golden Retrievers.

But this would not be a posting from me if I didn't have a question (see that's what Newbies do).
So let's say I'm dry camping for a couple of days and I run my Lithium 206Ah battery down to 60% full.
If I take the rig on a 4 hour drive at 60 mph to our next camping spot how much do you think the battery would be charged up to?
Keeping in mind it started the ride at only being 60% fully charged. Any way that's the question for the day!
Thanks everyone for all the great help on the battery in the past posts.....

60% if you are not running a residential refer.

[notlostatall]

So I finally got everything concerning my Lithium Battery, Inverter/Charger and Monitor for my 2021 Imagine 2500rl that I pick up from Lazydays in Tucson Arizona. Yup traveling 500 miles from LA to Tucson
So let's say I'm dry camping for a couple of days and I run my Lithium 206Ah battery down to 60% full.
If I take the rig on a 4 hour drive at 60 mph to our next camping spot how much do you think the battery would be charged up to?
Keeping in mind it started the ride at only being 60% fully charged. Any way that's the question for the day!
Thanks everyone for all the great help on the battery in the past posts.....

There's no good way to answer your question without knowing what electrical load you will have while driving. But as you've probably already been told, your tow vehicle will not really run much of anything, or help your batteries as you're driving down the road. Even with a large alternator, your cables and connectors to the trailer are not made to supply much current.