Installed an onboard charger and wondered where to install the negative lead. l guessed right.
Correct however you also set the minimum voltage charge start parameters and topped off voltage charges of the Victron in conventional charge mode. The Victron also takes the readings for the trailer SOC and auto shuts off charging when they are 100% SOC. So that's why this gets confusing.You want smart. That way it can properly charge your batteries through the various modes. Otherwise it just outputs a constant voltage.
I would disable. That’s meant for sprinters and other types of European vehicles that have alternators that will reduce output/voltage at certain times.Actually need to correct my explanation. According to Victron it's identified as "Smart Alternator" setting where voltage always fluctuates. Not sure if that's the same as the built in IBS System.
I have a similar setup, but using the Renogy 60A DCDC. I also put in a 300A continuous duty solenoid that is triggered by ignition on. It’ll get changed over to an Aux switch once I get around to installing those.Great information on this thread. I installed a Blue Sea Systems Single MRBF Terminal Fuse Block - 5191 and a 60A fuse for my Renogy 40A DC-DC charger in our Airstream trailer on the 8MM stud. I pulled two 4 ga. welding cable to the bumper and terminated it on an Anderson SB120 connector inside a Trailer Vision housing. I considered using the frame as the ground instead of pulling a dedicated cable but read about voltage drop issues so decided against it.
I pulled an extra smaller gauge wire for the ignition signal wire and connected it to an Aux switch programmed to disconnect when the truck is off.
This was part of a bigger project installing a Battle Born GC3 and Victron MultiPlus II 120x2 50A inverter, charger in the Airstream.
Henrys, the problem is lithium batteries have a different charging profile than the AGM / Lead Acid batteries in your truck.My truck has dual alternators so I'm not real concerned with limiting current to 40-60A and will be charging a 600AH lithium bank so I need quite a bit more current. Has anyone just directly connected the truck system to their RV with a solenoid like this guy did with his RV? I figured the current will be limited by wire size/length anyway. I'd like to get around 100-120A charging without having to spend lots of $ on DC-DC chargers (I don't have much room for them anyway with a compact truck-camper).
I'll second what Jeff said above. You truck batteries direct to your trailer batteries is going to end up with your trailer charging your truck more often than not. If you want a huge amount of power going from the truck to the trailer use more than one DC-DC (I suggest the Renogy, again because they're "affordable" and they work well), and either multiple wire runs or one larger wire run. Also make sure you disconnect your trailer's charge line on the 7-pin when you install a DC-DC charger.My truck has dual alternators so I'm not real concerned with limiting current to 40-60A and will be charging a 600AH lithium bank so I need quite a bit more current. Has anyone just directly connected the truck system to their RV with a solenoid like this guy did with his RV? I figured the current will be limited by wire size/length anyway. I'd like to get around 100-120A charging without having to spend lots of $ on DC-DC chargers (I don't have much room for them anyway with a compact truck-camper).
Why do you need to disconnect your trailer's charge line on the 7-pin when you install a DC-DC charger? I’m getting my parts together to install the Renorgy DC -DC 40 amp to recharge my 2 lead acid batteries. Great thread I have gained some knowledgeI'll second what Jeff said above. You truck batteries direct to your trailer batteries is going to end up with your trailer charging your truck more often than not. If you want a huge amount of power going from the truck to the trailer use more than one DC-DC (I suggest the Renogy, again because they're "affordable" and they work well), and either multiple wire runs or one larger wire run. Also make sure you disconnect your trailer's charge line on the 7-pin when you install a DC-DC charger.
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.Why do you need to disconnect your trailer's charge line on the 7-pin when you install a DC-DC charger? I’m getting my parts together to install the Renorgy DC -DC 40 amp to recharge my 2 lead acid batteries. Great thread I have gained some knowledge
Ahhh! I see what mean. Nice drawing it helps a lot. Thank you for your time.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 sharing. I have a very similar setup (minus the DC-DC charger side). My issue is I have a slide-in truck camper with very limited space and DC-DC chargers take up a ton of room and generate a lot of heat. However, I just realized Sterling makes an IP66 rated waterproof 120A DC-DC charger for marine application. I could mount that outside my camper giving me a lot more room to work with.For your info here's the diagram for my entire system. The DCDC is bottom left to bottom center.
Wow interesting. So you're saving some $ on wiring because you can keep the DC side really short and 12V inverters are really cheap.I went the DC-AC-DC charger route. My RV came with a gen transfer switch but no generator. I installed a 2kw inverter behind the rear seat of the truck (2awg), then ran an extension cord (12 awg) to the back of the truck. The other end of the extension cord went to the transfer switch.. The inverter came with a remote switch that allows me to turn on or off on the fly from the drivers seat. I set multiplus to 10 amp current limit; truck inverter powers the rv and multi charges the batteries up to 1200watts. The 10 amp current limit pulls right at 100 amps of DC from the truck. Dual alts keep the voltage above 13.6. Really helps when low and its raining/no solar coming in on drive days.
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.Why do you need to disconnect your trailer's charge line on the 7-pin when you install a DC-DC charger? I’m getting my parts together to install the Renorgy DC -DC 40 amp to recharge my 2 lead acid batteries. Great thread I have gained some knowledge
Interesting way to do it. You're probably losing a bit of efficiency in the back and forth conversion, but I doubt it's much. Plus you have a big inverter in the truck now.I went the DC-AC-DC charger route. My RV came with a gen transfer switch but no generator. I installed a 2kw inverter behind the rear seat of the truck (2awg), then ran an extension cord (12 awg) to the back of the truck. The other end of the extension cord went to the transfer switch.. The inverter came with a remote switch that allows me to turn on or off on the fly from the drivers seat. I set multiplus to 10 amp current limit; truck inverter powers the rv and multi charges the batteries up to 1200watts. The 10 amp current limit pulls right at 100 amps of DC from the truck. Dual alts keep the voltage above 13.6. Really helps when low and its raining/no solar coming in on drive days.