Dc to dc charging tie into 3500 battery/alternator

[Nifty07]

I fitted lithium in tub and ran 2 gauge (35mm) from Uber the bonnet to the dc2dc charger. Using 200amp circuit breaker on positive battery. Neg cable connected to neg post of battery.

The dc2dc is fitted in tub next to battery. It has 70amp breaker on input, output and 40amp on solar input. I used the 2 gauge wire to the lithium battery.

I also use the ignition sense on the dc2dc which is connected to the ignition power found near the spare wheel.

then I run two Anderson connectors using 6 gauge (16mm). One via a 300 amp continuous rated solenoid (ignition sense) and the other from the lithium battery (100amp circuit breaker).

Red Anderson for solar input (I really fitted a grey one and labelled it solar).

been running for three years and the trailer dc2dc charger gives full 40amps charge to lithium in trailer.

Please be aware that if you have four lithium batteries rated at 100 amp hour, the max current you should draw is 100amp (NOT 4*100= 400 amp). You run the risk of blowing your BMS and lithium batteries if you draw more than 100amp in this example.

 

[Electronut]

I just finished tying in my Tocas 50amp thermal circuit breaker into the HAPP system of my 2500. I've had great success installing these in my previous truck I was using to pull our Airstream. The beauty as well is there are no fuses to deal with and if you want to cut power for any reason it's just a flick of the switch under the truck hood or from the opposite end where the same fuse is sitting near my 500aH Battleborn Lithium Battery bank. Was pretty easy to run the 25ft pair of 6AWG welding cable wrapped in black insulation from hood to the rear. Plenty room and routing options. Very clean install. Especially since my 2500 is lifted which just allowed me to use a body dolly to slide along underneath as I routed and secured the cables. At the rear of the truck I ended up having the line run right out of the hole where you insert the tool for dropping the spare tire. Plenty room to have exit there and still spacing for the tool insertion plus is perfectly placed being it's right at 7 way plug. I was concerned how I was going to exit at the bumper so glad I figured this exit design. Just have to finish the plug termination at the bumper tomorrow.

I have a Victron Orion Smart 30amp 12v/12v DC to DC charger. Works awesome. Fully automatic and operates by detecting voltages off the trucks electronics so only runs in the higher voltage ranges you can customize.

 

[jsalbre]

Please be aware that if you have four lithium batteries rated at 100 amp hour, the max current you should draw is 100amp (NOT 4*100= 400 amp). You run the risk of blowing your BMS and lithium batteries if you draw more than 100amp in this example.

This definitely depends entirely on the batteries you’re using (mostly the internal BMS) and if you’re running them in series or parallel. If you have 4 100A batteries that can be discharged at 1C (100A for a 100A battery) and they’re wired in parallel then you should have no issue drawing 400A from them. I’m currently running a pair of 200Ah 12v batteries in parallel (providing 200Ah total) that can discharge continuously at .75C (150A) each and I have no problem pulling 300A from them. The same applies for charging. They have a .25C (50A) charge rate so I can charge the pair at 100A (though usually charge at 80A to increase the battery lifespan and keep heat down).

If I were to have the same batteries in series (thus providing 200Ah@24v) I’d be limited to 150A discharge and 50A charge.

 

[JABAR357]

Disconnecting the 7 Pin is recommended if you’re charging Lithium batteries due to the higher voltage charging profile. If you’re charging lead acid which are the same as your truck, it’s not a problem.

Just make sure you follow Renogy’s instructions on pg. 18-19 in the manual regarding the DIP switch settings for lead acid and to connect an alternator (ignition) wire to terminal D+ on the DC-DC charger. I plan to use the RAM’s AUX switch set to disconnect when engine is off. This way I can control when the Renogy is engaged and not have to worry about that I forgot to turn it off once we stop.

I was wondering & confused about the voltage, Planned on testing on a buddy’s truck to see what would happen. Yes, I’m charging lead acid batteries. I was going adding a relay wired to an Aux switch to control my connection. I have been rethinking It will be cheaper just to wire the aux switch to the D+ being I’m running a switched circuit to control my service lights I have added to the RV. I did not want to use the trailer lights to trigger the D+. Thanks for your input.

 

[Carneros]

If you don't disconnect it you'll be feeding power back through it to the truck when the DCDC is on, because it'll be putting out higher voltage than the truck is. On an additional note, I recommend not connecting the ground that goes from the DCDC to the truck to anything on the trailer except for the DCDC. If the ground between the DCDC and the truck were to become disconnected and you have the DCDC grounded to the trailer then the electricity would try to follow the little 7pin ground, which would burn up quite quickly.

For your info here's the diagram for my entire system. The DCDC is bottom left to bottom center.

View attachment 55637

Thanks for posting this diagram. I'm currently installing the Renogy 60A DCDC charger for my truck camper. I hadn't thought about the 7-pin connector and whether that would be a problem or not. I'm a novice so am just muddling through all of this, but I've run all the wires and made the connection to my Lynx distributor (actually a modified Power-In) to 300ah LiFePo batteries. I have the D+ wire hooked up to the AUX switch to turn the charger on/off with ignition. I've got s couple of questions. Again I'm a newb at electrical, so talk to me like a 5 year old.

1. In your diagram, what does the Relay 300A CD accomplish?
2. According to RAM, if I have greater than a 50A load, I need to ground the DCDC to the engine block when using the HAPP. Did you do this? Looking at your diagram, you just ran to the battery. Is that better?
3. If the engine block is best, where is the connection point on the block?

Thanks for any help you can give me!

 

[jsalbre]

Thanks for posting this diagram. I'm currently installing the Renogy 60A DCDC charger for my truck camper. I hadn't thought about the 7-pin connector and whether that would be a problem or not. I'm a novice so am just muddling through all of this, but I've run all the wires and made the connection to my Lynx distributor (actually a modified Power-In) to 300ah LiFePo batteries. I have the D+ wire hooked up to the AUX switch to turn the charger on/off with ignition. I've got s couple of questions. Again I'm a newb at electrical, so talk to me like a 5 year old.

1. In your diagram, what does the Relay 300A CD accomplish?
2. According to RAM, if I have greater than a 50A load, I need to ground the DCDC to the engine block when using the HAPP. Did you do this? Looking at your diagram, you just ran to the battery. Is that better?
3. If the engine block is best, where is the connection point on the block?

Thanks for any help you can give me!

1. The 300A Relay/Solenoid is to cut power to the bumper connector when the ignition is off. I don't like having a heavy gauge direct to battery pair of contacts just hanging out when the truck is parked. I also intend to move the control of that relay to an Aux switch so that it's only powered uo when I tell it to be
2. I went direct to battery as the battery to engine block ground is smaller than my cables and the battery is the actual source of power in this system.
3. I couldn't tell you where to ground on the block.

 

[Carneros]

1. The 300A Relay/Solenoid is to cut power to the bumper connector when the ignition is off. I don't like having a heavy gauge direct to battery pair of contacts just hanging out when the truck is parked. I also intend to move the control of that relay to an Aux switch so that it's only powered uo when I tell it to be
2. I went direct to battery as the battery to engine block ground is smaller than my cables and the battery is the actual source of power in this system.
3. I couldn't tell you where to ground on the block.

So if I have the AUX switch wired up, I don't need the relay, correct?

What about the 7-pin charging at the same time that the DCDC is charging? Is that a problem? Is there some kind of loop or ground issue that I should be concerned about?

My plan was to connect the positive to the HAPP with an 80A terminal fuse and was hoping to just do a chassis ground because it's easy. Then I saw that Ram recommends anything greater than 50A (continuous load) be grounded to the engine block. That kinda sounds beyond my skill level, but maybe its not? Now I don't know what to do!

I'm using 2 gauge wire for all runs to/from the charger, btw.

Sorry for all of the questions! I just don't want to screw this up and destroy my truck or camper!

 

[jsalbre]

So if I have the AUX switch wired up, I don't need the relay, correct?

What about the 7-pin charging at the same time that the DCDC is charging? Is that a problem? Is there some kind of loop or ground issue that I should be concerned about?

My plan was to connect the positive to the HAPP with an 80A terminal fuse and was hoping to just do a chassis ground because it's easy. Then I saw that Ram recommends anything greater than 50A (continuous load) be grounded to the engine block. That kinda sounds beyond my skill level, but maybe its not? Now I don't know what to do!

I'm using 2 gauge wire for all runs to/from the charger, btw.

Sorry for all of the questions! I just don't want to screw this up and destroy my truck or camper!

You definitely still need the relay. The aux switch relays are only rated for 40A max, and that's not continuous. Your 60A DCDC can draw up to 90A.

The 7 pin charging needs to be disconnected if when the DCDC is connected as I mentioned in my original post you quoted.

Definitely don't ground to chassis, you'll risk burning up the chassis ground. Either go to the block or to the battery.

2AWG is what I ran for mine as well.

 

[Brutal_HO]

You definitely still need the relay. The aux switch relays are only rated for 40A max, and that's not continuous. Your 60A DCDC can draw up to 90A.

The 7 pin charging needs to be disconnected if when the DCDC is connected as I mentioned in my original post you quoted.

Definitely don't ground to chassis, you'll risk burning up the chassis ground. Either go to the block or to the battery.

2AWG is what I ran for mine as well.

I'm reading this that @Carneros connected D+ (ignition trigger) to the AUX, not DC+.

 

[jsalbre]

I'm reading this that @Carneros connected D+ (ignition trigger) to the AUX, not DC+.

Ahh yeah, I see that now. I was assuming the DC-DC charger was installed in a trailer, so I didn’t think the charger enable wire would be run from the trailer up to the truck.

 

[AH64ID]

I used one of the large bolts in front of the intake manifold for my winch ground. That would be a good place for the DC-DC charger ground.

I plan to run a 12/12-18 DC-DC charger on my 5th wheel and just use the 7 pin wiring. It’s the proper size and will be a lot more effective than just the 7-pin wiring, and won’t require any crazy mods.

Maybe down the road I’ll want more, but for now that’s plenty.

 

[jsalbre]

I used one of the large bolts in front of the intake manifold for my winch ground. That would be a good place for the DC-DC charger ground.

I plan to run a 12/12-18 DC-DC charger on my 5th wheel and just use the 7 pin wiring. It’s the proper size and will be a lot more effective than just the 7-pin wiring, and won’t require any crazy mods.

Maybe down the road I’ll want more, but for now that’s plenty.

That’s not a bad idea for a relatively small DCDC, and you’ll actually get a useful voltage going to your batteries.

I run my AC in the trailer off the inverter when I’m rolling down the road, so I want all the juice going to the batteries I can. I’ve actually considered adding a second 60A DCDC that would kick in during high amp draw as that would pretty much cover the AC load entirely.

 

[H3LZSN1P3R]

That’s not a bad idea for a relatively small DCDC, and you’ll actually get a useful voltage going to your batteries.

I run my AC in the trailer off the inverter when I’m rolling down the road, so I want all the juice going to the batteries I can. I’ve actually considered adding a second 60A DCDC that would kick in during high amp draw as that would pretty much cover the AC load entirely.

Why would you have the A/C on while driving? Or do you just mean when you stop along the road?

 

[jsalbre]

Why would you have the A/C on while driving? Or do you just mean when you stop along the road?

We tend to take longer trips vs quick weekend camping trips, so we’ve got medication, my wife’s makeup stuff, and other things that don’t like the heat along for the ride. Also, if we’re somewhere that it’s 100 degrees (F) outside it’s nicer to stop and make lunch in a 75 degree trailer than in a 120 degree one.

I can get about 9 hours of drive time with the AC running (assuming it’s about 95 outside and we set it to 75) off of my battery bank + the 60A DCDC and 800W of solar.

It’s a habit we picked up when we were full timing it and it stuck.

 

[H3LZSN1P3R]

We tend to take longer trips vs quick weekend camping trips, so we’ve got medication, my wife’s makeup stuff, and other things that don’t like the heat along for the ride. Also, if we’re somewhere that it’s 100 degrees (F) outside it’s nicer to stop and make lunch in a 75 degree trailer than in a 120 degree one.

I can get about 9 hours of drive time with the AC running (assuming it’s about 95 outside and we set it to 75) off of my battery bank + the 60A DCDC and 800W of solar.

It’s a habit we picked up when we were full timing it and it stuck.

Interesting, we dont have heat like that here so that would have never crossed my mind to do that. Not a bad solution.

Here i just keep my 3 roof vents open they have max air covers and the trailer stays pretty reasonable temp wise but we dont often exceed 85°

 

[jsalbre]

Interesting, we dont have heat like that here so that would have never crossed my mind to do that. Not a bad solution.

Here i just keep my 3 roof vents open they have max air covers and the trailer stays pretty reasonable temp wise but we dont often exceed 85°

It feels very “glamping”, but I’m already pulling 26’ of creature comforts with me, so I may as well just push it all the way. We treat our trailer more like a mobile hotel room than most I expect. If I want to “camp” I prefer my ground tent because I can fit it anywhere.

I’ll do the vents (also with Maxxair covers) if it’s not too hot. No reason to add the extra power draw if I don’t need it.

 

[Carneros]

Ahh yeah, I see that now. I was assuming the DC-DC charger was installed in a trailer, so I didn’t think the charger enable wire would be run from the trailer up to the truck.

That's right. It wouldn't be pulling any of the power through the line, it's just for the on/off switch.

 

[Carneros]

I used one of the large bolts in front of the intake manifold for my winch ground. That would be a good place for the DC-DC charger ground.

I plan to run a 12/12-18 DC-DC charger on my 5th wheel and just use the 7 pin wiring. It’s the proper size and will be a lot more effective than just the 7-pin wiring, and won’t require any crazy mods.

Maybe down the road I’ll want more, but for now that’s plenty.

Thanks, I'll check that out!

 

[Creeker]

Heh. Maybe Ram will do what Ford did and have the capability to deliver over 2kw of AC to the bed, and use that to power everything in a trailer I think one of the hybrids can do over 7kw, but I doubt it can tow much

BTW, for anyone looking at a DC to DC solution consider the Kisae DMT1250. Combo solar MPPT and DC to DC. Very nice; I installed one in a van I owned with lithiums and was very happy with it.

 

[Carneros]

One more stupid question. If I connect directly to the battery, for the negative would I put my ring terminal on top of the IBS? I don't see any other stud available.