Tapping 12V from the truck to charge Battle Borns

[howson]

Took a photo of some Anderson SB connectors SB50, 120, 175.
I tend to use a contact sized for next smaller welding wire for a snug wire fit in the contact, that's just my preference.
The 1st two are SB50 6 Awg contacts with 6 and 4 wire. Then SB120 4 Awg contact with 2 Awg welding wire.

I've debated using 2 Awg vs 4 Awg. I know to minimize voltage drop (a key consideration with a 12V system) and the distance I'm contemplating from alternator to Battle Borns, bigger is better. I'm not "sold" on either wire size (yet). Very interesting that you use 2 Awg welding wire in a 4 Awg Anderson contact. "Snug" means "good contact" if I'm understanding correctly.

I've got to research how the wires attach to the Renogy more to understand if there's a size limit. (Maybe 4 Awg is the largest it will accept--the point is I don't know at this time.)

I'm probably going to install this upgrade to my system in January, so I have time to mull it over.

Thanks, as always, Gene!

Howard

[gbkims]

I've debated using 2 Awg vs 4 Awg. I know to minimize voltage drop (a key consideration with a 12V system) and the distance I'm contemplating from alternator to Battle Borns, bigger is better. I'm not "sold" on either wire size (yet). Very interesting that you use 2 Awg welding wire in a 4 Awg Anderson contact. "Snug" means "good contact" if I'm understanding correctly.

I've got to research how the wires attach to the Renogy more to understand if there's a size limit. (Maybe 4 Awg is the largest it will accept--the point is I don't know at this time.)

I'm probably going to install this upgrade to my system in January, so I have time to mull it over.

Thanks, as always, Gene!

Howard

Howard,

I'd go with 4 Awg for this. I've used both sizes 2 & 4. 4 Awg would be much easier to run back from the engine area.

Renogy DCC50S Manual: Cable Sizing: 16' to 30' Recommended: 4 Awg

[howson]

Howard,

I'd go with 4 Awg for this. I've used both sizes 2 & 4. 4 Awg would be much easier to run back from the engine area.

Renogy DCC50S Manual: Cable Sizing: 16' to 30' Recommended: 4 Awg

I read through the manual and watched Will's video again. The diagram is getting easier to read so I'm probably getting close to having it right.

To all: This project is still very much in the planning stage so all questions, comments or recommendations are most welcome.

-Howard

[TucsonJim]

Howard, I'm really liking the new drawing. As Will explained, you need +12V DC into the DC to DC charger for it to work. So I can't imagine it wouldn't work if you used one of your upfitter switches to power it on when you need it.

[wygieman]

Just curious why you chose to use DC instead of AC? When I was trying to decide how to do a similar thing, I decided that using AC would solve the wire size problem. The truck has a built-in inverter good for 400 W which will charge around 35 Amps DC. The location under the rear seat is convenient also. You can use 14 AWG wire and put an appropriately sized charger in the battery compartment. Lots of AC wire connectors also in the marine world. If you want more charging power, upgrade the inverter and install a larger charger (or use the one you already have limited to the available current).

[howson]

Just curious why you chose to use DC instead of AC? When I was trying to decide how to do a similar thing, I decided that using AC would solve the wire size problem. The truck has a built-in inverter good for 400 W which will charge around 35 Amps DC. The location under the rear seat is convenient also. You can use 14 AWG wire and put an appropriately sized charger in the battery compartment. Lots of AC wire connectors also in the marine world. If you want more charging power, upgrade the inverter and install a larger charger (or use the one you already have limited to the available current).

Excellent question. Getting power across distances is easier with higher voltages (thus the reason for high voltage lines from the power company). Back when I was first putting together my system there was a similar discussion about running an inverter at the front of the truck (I believe it was Gyrogearloose that suggested it but I could be mistaken).

Regarding the Ford OEM inverter, I'd have to change it as it is a cheap square wave unit. If I upgraded the unit I'd have to ensure Ford's OEM wiring is adequate to handle an inverter with more capability. Then, of course, every conversion from DC to AC has a loss involved. Additionally, if it means I have to convert yet again from AC to DC at the camper that's too much for a mere 40 amps. For the one-time nuisance of installing the right size wire for the DC I'd rather do that.

If you're suggesting leaving the power going to the camper as AC...honestly, I'm not sure where the input from the truck inverter would be integrated into the camper's system. The Victron in the camper is in inverter mode and supplying AC power to the camper while I am towing. Supplying 12vDC to the existing circuit I understand--how to tie in another 110vAC source? Is it even possible? gbkims ? TucsonJim ?

[TucsonJim]

If you're suggesting leaving the power going to the camper as AC...honestly, I'm not sure where the input from the truck inverter would be integrated into the camper's system. The Victron in the camper is in inverter mode and supplying AC power to the camper while I am towing. Supplying 12vDC to the existing circuit I understand--how to tie in another 110vAC source? Is it even possible? gbkims ? TucsonJim ?

It is certainly doable.

According to this video from Ford, the inverter outlet is capable of 400 watts while idling, but 300 watts while driving:

https://www.youtube.com/watch?v=b3Sw3NUj8wo

I would think a battery charger should do fine on this type of inverter. It does not need a pure sine wave like some sensitive devices.

You'd have to use an extension cord to get the AC power back to the battery compartment of the trailer. Before proceeding with trying to figure out a route for the wires, I'd run a test. I'd put a battery charger in the battery compartment and hook it up to partially discharged battery. Then run an extension cord from one of your truck's outlets to the battery charger. Put the truck in drive and see if anything trips. There's no sense proceeding if the inverter won't power the charger.

Jim

[howson]

I would think a battery charger should do fine on this type of inverter. It does not need a pure sine wave like some sensitive devices.

I never thought of a battery charger--that is a self-limiting device. All I have is a "normal" car battery charger--not sure if it can be used with LifePo4 batteries. I'm also unsure if the battery charger can be connected while using the Victron in inverter mode.

Regardless, I'd like to stay away from adding yet another device in the camper. (I am considering a solar controller and a few panels to augment the DC input, too, in the future). For now I'm leaning towards letting the battery management system in the Battle Borns (BBs) do their job of taking care of the battery state of charge. The attractive attribute of the Renogy is that it will take care of limiting how much current is sent to the BBs from the truck--an extremely important consideration (to me).

I fully understand the concept of using a higher voltage to transmit power over distance, but given the relatively low power (480W=12V*40A) that I'm looking to get from the truck, for now I'm still thinking of staying with the DC circuit.

Very thought provoking conversation (at least it made me think!) so definitely appreciate everyone's input.

[ncitro]

My understanding is the built in BMS should negate the need for any concerns on the charger output. I am using the LIon brand batteries, but I spoke with them extensively about charger settings for the batteries and they assured me to just set it to fixed voltage and their BMS will taper the current accordingly. Based on their recommendation I turned up my voltage, but they said if I only had a traditional battery charger they would function with its lower voltage, albeit at a slower than optimal charge. I would imagine Battleborns BMS should function similarly.

As for how the inverter would handle the presence of an additional charger, it should not mind at all. That is essentially what a solar charge controller is to it, an additional battery charger. That is also how it would see the Renogy as well. Think of it as a DC to DC battery charger.

I hear you about less things in the trailer, but do see the advantages of running 110 to the trailer.

Another option would be you could install a transfer switch on the main shore power line. One side goes to your shore power inlet and the other goes to the inverter in the pickup. When you start the truck and connect the trucks inverter it should provide 110v to the input of the inverter which will activate its charger. The problem here would be you would need to set the Victron to expect the proper input current from the truck, which would not be much. Given you are running your fridge and various loads off of the inverter already, I don not think the stock inverter in the truck would keep up with that draw and charge the trailer batteries. Not to mention the loss of inverting the trucks 12v, and then converting it back to 12v in the trailer lol.

I think your best bet would be some kind of DC to DC charger, either the Renogy or something else. I have heard good things about the CTek but have not bitten the bullet to try it yet. You have it a lot easier than those of us in fifth wheels. I have fished a couple of cables from the truck through the pin box to the battery area for my Ford Trailer TPMS and I would not want to repeat it with some big welding wire for the batteries.

[howson]

I have fished a couple of cables from the truck through the pin box to the battery area for my Ford Trailer TPMS and I would not want to repeat it with some big welding wire for the batteries.

But I'm jealous of all that storage room you have in what I think is called the basement for "stuff". I am limited to just the pass-thru and there are some components under the hutch--but that location is too full of items as it is.

Another thought-provoking post. Thanks.

[ncitro]

But I'm jealous of all that storage room you have in what I think is called the basement for "stuff". I am limited to just the pass-thru and there are some components under the hutch--but that location is too full of items as it is.

Another thought-provoking post. Thanks.

It is what sold me on the fifth wheel over the travel trailer for sure. We have the old style 28bh with a rear storage compartment as well.

[wygieman]

If you did go AC, I don’t think you would need any additional devices, just a connection to the inverter/charger. I don’t know about the Victron but on my GoPower, it can be set so that the AC passes through up to a specifiable level and then the inverter will kick in to augment the AC if demand is higher than the level set. It will also charge the batteries if more power is available than demand. The setup on my unit is somewhat complicated but the victron is much higher end and may be smarter about everything. Also I don’t know how the Ford truck limits the current to the inverter but I suspect it is smart about it like it is on the tow cable (a regulator not a fuse). That is speculation but easily tested. No extra conversion losses and no significant voltage drop which will translate into lost charging amps if you require a DC-DC converter.

[Bigjaike]

I read through the manual and watched Will's video again. The diagram is getting easier to read so I'm probably getting close to having it right.

To all: This project is still very much in the planning stage so all questions, comments or recommendations are most welcome.

-Howard

Howard,

I like what you are going to do and I am looking at the same thing. I think I will be putting the DC-DC charger in my front compartment to minimize the output side length to the batteries and just put in a switch connected to my RV batteries to turn it on. I would also be putting in another breaker at the hitch point to protect the wires going thru the cap. I think this will give me more than enough amps to run the fridge going down the road and not drain my batteries. Thanks for the wiring setup, hope you don't mind if I copy it.

Monty

[howson]

Howard,

I like what you are going to do and I am looking at the same thing. I think I will be putting the DC-DC charger in my front compartment to minimize the output side length to the batteries and just put in a switch connected to my RV batteries to turn it on. I would also be putting in another breaker at the hitch point to protect the wires going thru the cap. I think this will give me more than enough amps to run the fridge going down the road and not drain my batteries. Thanks for the wiring setup, hope you don't mind if I copy it.

Monty

Not at all--just keep in mind the system as drawn is untested. I have several other projects to complete before tackling this project. Right now looks like mid to late January. if you get it done before me, ***please*** share lessons learned.

[howson]

Howard,

I like what you are going to do and I am looking at the same thing. I think I will be putting the DC-DC charger in my front compartment to minimize the output side length to the batteries and just put in a switch connected to my RV batteries to turn it on. I would also be putting in another breaker at the hitch point to protect the wires going thru the cap. I think this will give me more than enough amps to run the fridge going down the road and not drain my batteries. Thanks for the wiring setup, hope you don't mind if I copy it.

Monty

You've sparked a thought, Monty. For the D+ ignition cable signal why not use the 12v from the truck's 7-pin charging line? It's already there in the camper and (at least on my '17 Ford) it is only active when the driver's door is closed and the truck is in drive. Should be perfect for the purpose.

Putting the DC-DC charger in the camper solves a lot of other issues, too. I like it!