Thanks Terry, Just been looking at a dcdc charger, Can’t understand why one is $400 (Victron) and another $120 and works at lower voltage? Makes me wonder about build quality of the cheap one. Thoughts? Cheers Coop
And the victron one. I run lithium in car lithium in camper and 2nd enerdrive one in car one in camper. Its wired dcdc to car one then out car lithium to camper dcdc then camper battery. is that good. or should I run another cable from crank battery to dcdc in camper?
Thanks for the video, all good points. As _my_ best practice, I would put the DC/DC charger as close to the engine as practical - in this case near the tongue of the trailer. Specify the cabling to the 2nd battery properly to minimize voltage drop - the current will be limited and easier to manage. That voltage drop can be compensated for by the DC/DC charger when equipped with a battery voltage sense lead. Also, pay attention to the ambient temperature when under the hood.
Moving the DCDC Charger closer to the start battery in the vehicle moves the problem from the input to the output and will result in slower charging of the caravan battery and not fully charging in a reasonable time if at all due to cable voltage drop - also what about if its a combined DCDC and Solar charger - the panels are on the caravan not the vehicle. The DCDC Chargers are (or should be ) designed to overcome the input cable loss not the output. This is the whole point of this Video.
@@timterry8714 The point of the DC-DC charger is to limit current draw on the input while, as you state, boost the voltage to properly charge the AUX battery. This does not eliminate the need to properly engineer the system with adequate cable size, which is arguably easier to do on the caravan chassis. When I said "near the tongue of the trailer", I meant ON the trailer chassis, just toward the front. Thanks for the video
I can't imagine running such a long thick cable. Not to mention having so little control over charging rates if the battery state(s) are non-optimal. At that point we might as well just connect the vehicle battery bus to an inverter controlled by the ignition and run AC to the trailer instead of DC. Then just have a programmable AC charger in the trailer. Victron sells several whos amperages can be programmed. Problem solved, and much smaller cables can be used. -Matt
Thanks Matt. Its quite the norm here to run 10mm sq cable to the caravan battery and it works fine as long as the DCDC Charger has the ability to compensate for the cable loss as most good quality chargers do - which is the point of this video. Good luck trying to find somewhere to mount an inverter in a modern 4WD tow vehicle these days in close proximity to the battery. There is little space for anything to be installed much less a bulky inverter.
@@timterry8714 The amperages you were throwing do not represent very much power, less than 500W. How quickly do you want the trailer to be able to charge ? From the diagrams it looked like 250W was fine for your purposes. That's like 1A @ 240VAC or 2A @ 120VAC. 1mm^2 (17 AWG) cable to the trailer and a tiny little inline glass fuse. Judging from a quick amazon search, we're talking quite small... about the size of a small paperback book it looks like, for something in the 250W range. Perhaps not entirely suitable buta commercial version wouldn't be much different. Also, don't a lot of these vehicles already come with inverters as stock these days? Well, think about it. It seems silly to run such a low voltage 10+ meters. -Matt
Yes you could do it that way. Then run a standard mains power charger in the caravan. However virtually every caravan and camper here have dcdc chargers installed and that's the point of this video.
Thanks Terry,
Just been looking at a dcdc charger,
Can’t understand why one is $400 (Victron) and another $120 and works at lower voltage?
Makes me wonder about build quality of the cheap one.
Thoughts?
Cheers
Coop
And the victron one. I run lithium in car lithium in camper and 2nd enerdrive one in car one in camper. Its wired dcdc to car one then out car lithium to camper dcdc then camper battery. is that good. or should I run another cable from crank battery to dcdc in camper?
I personally would cable each independently directly to the start battery
@@timterry8714 I was thinking that. as I run a 90 ltr fridge in the tray of dmax
You did not show enerdrive. Thats what I have. Is it good one ?
It was just a quick list of a bunch of random chargers. I just a look and the minimum input is 10.5v for the Enerdrive.
Thanks for the video, all good points.
As _my_ best practice, I would put the DC/DC charger as close to the engine as practical - in this case near the tongue of the trailer. Specify the cabling to the 2nd battery properly to minimize voltage drop - the current will be limited and easier to manage. That voltage drop can be compensated for by the DC/DC charger when equipped with a battery voltage sense lead.
Also, pay attention to the ambient temperature when under the hood.
Moving the DCDC Charger closer to the start battery in the vehicle moves the problem from the input to the output and will result in slower charging of the caravan battery and not fully charging in a reasonable time if at all due to cable voltage drop - also what about if its a combined DCDC and Solar charger - the panels are on the caravan not the vehicle. The DCDC Chargers are (or should be ) designed to overcome the input cable loss not the output. This is the whole point of this Video.
@@timterry8714 The point of the DC-DC charger is to limit current draw on the input while, as you state, boost the voltage to properly charge the AUX battery. This does not eliminate the need to properly engineer the system with adequate cable size, which is arguably easier to do on the caravan chassis. When I said "near the tongue of the trailer", I meant ON the trailer chassis, just toward the front.
Thanks for the video
I can't imagine running such a long thick cable. Not to mention having so little control over charging rates if the battery state(s) are non-optimal. At that point we might as well just connect the vehicle battery bus to an inverter controlled by the ignition and run AC to the trailer instead of DC. Then just have a programmable AC charger in the trailer. Victron sells several whos amperages can be programmed. Problem solved, and much smaller cables can be used.
-Matt
Thanks Matt. Its quite the norm here to run 10mm sq cable to the caravan battery and it works fine as long as the DCDC Charger has the ability to compensate for the cable loss as most good quality chargers do - which is the point of this video. Good luck trying to find somewhere to mount an inverter in a modern 4WD tow vehicle these days in close proximity to the battery. There is little space for anything to be installed much less a bulky inverter.
@@timterry8714 The amperages you were throwing do not represent very much power, less than 500W. How quickly do you want the trailer to be able to charge ? From the diagrams it looked like 250W was fine for your purposes. That's like 1A @ 240VAC or 2A @ 120VAC. 1mm^2 (17 AWG) cable to the trailer and a tiny little inline glass fuse.
Judging from a quick amazon search, we're talking quite small... about the size of a small paperback book it looks like, for something in the 250W range. Perhaps not entirely suitable buta commercial version wouldn't be much different.
Also, don't a lot of these vehicles already come with inverters as stock these days?
Well, think about it. It seems silly to run such a low voltage 10+ meters.
-Matt
Yes you could do it that way. Then run a standard mains power charger in the caravan. However virtually every caravan and camper here have dcdc chargers installed and that's the point of this video.