Dc to DC Converter Between TV and AS

[Steamy1]

I am hoping someone could help out with a question I have; I want to install the Renogy dc-to-dc 20 amp charger in our 19' Bambi to help charge the two (2) lithium batteries. I would like to use the 12 AWG positive and negative wires from the 7-pin harness, disconnect from the buss bar, connect on the input side, then use 12 AWG from the output side back to the buss bars.

First question:
is the 12 AWG sufficient for the 20 amp model?

I would like to mount the Renogy unit in the space where the wiring harness and buss bars are located, which also contains the fresh water tank. The space is under the street side dinette seat and there are no vents in the surround.
Second question:
does the Renogy unit generate significant heat such that I should bore holes in the seat base and install vents?

Any comments would be appreciated.

Thank you!

[nvestysly]

Originally Posted by Steamy1

I am hoping someone could help out with a question I have; I want to install the Renogy dc-to-dc 20 amp charger in our 19' Bambi to help charge the two (2) lithium batteries. I would like to use the 12 AWG positive and negative wires from the 7-pin harness, disconnect from the buss bar, connect on the input side, then use 12 AWG from the output side back to the buss bars.

First question:
is the 12 AWG sufficient for the 20 amp model?

I would like to mount the Renogy unit in the space where the wiring harness and buss bars are located, which also contains the fresh water tank. The space is under the street side dinette seat and there are no vents in the surround.
Second question:
does the Renogy unit generate significant heat such that I should bore holes in the seat base and install vents?

Any comments would be appreciated.

Thank you!

I'm sure somebody way smarter than me will reply but until then a few things come to mind...

If the positive and negative are disconnected from the buss bar it seems there could be a potential problem with running lights, turn signals, brakes, etc. if the Renogy unit fails.

Partly due to my uncertainty of electrical issues, I chose to route heavy gage wires from the tow vehicle to the Renogy unit. I wanted zero voltage drop from the tow vehicle to the trailer and maximum current available to the Renogy unit. I also used the DC to DC 50 amp Renogy unit because it includes some upgraded features. If you want to know more you can read about our installation HERE.

[SilverHouseDreams]

Originally Posted by Steamy1

disconnect from the buss bar, connect on the input side, then use 12 AWG from the output side back to the buss bars.



First question:

is the 12 AWG sufficient for the 20 amp model?

That is the right path to install, you move the 7 pin line from the positive bus bar to the DC-DC charger/converter and then connect that back to the bus bar.

As for the 12gauge wire, what is it fused at in your TV? 20amp in the TV will not be adequate, so if it is fused for 20amp then you would need a lesser DC-DC converter or to add a new dedicated charge circuit from the TV battery to the AS. The issue will be the voltage drop by the time the power reaches the DC-DC, to get the same power (watts) the amperage goes up...so it would be far greater than 20amp being carried on the wire.

As comparison, I have the 220W “18 amp” Victron DC-DC and if trips the 20amp fuse/breaker in the TV. I will likely just run a dedicated heavier charge circuit, but my battery is only 2’ in front of my bumper so that is easy...or I may go to a lesser DC-DC charger to reduce strain on my alternator.

[MsTara]

"That is the right path to install, you move the 7 pin line from the positive bus bar to the DC-DC charger/converter and then connect that back to the bus bar."

I am hoping someone won't think this is the stupidest question in the world.

What is the Bus Bar? Does someone have pictures to help me understand what that means?

I am looking to add in a second Battleborn to my 2018 Airstream Bambi and they are recommending a DC-DC convertor to help protect all three of the batteries and I am not quite "sure" where the DC-DC convertor goes and where to find the wires I would need. I am assuming they are under the dinette but what are the different wires to pull...

If someone has pictures that would be wonderful.

[1StreamDream]

Originally Posted by MsTara

I am hoping someone won't think this is the stupidest question in the world.

What is the Bus Bar? Does someone have pictures to help me understand what that means?

If someone has pictures that would be wonderful.

I don't have pictures from a bambi, but in my flying cloud, the bus bar appears to be an otherwise standard product. A bus bar is just a hunk of metal, the metal is an electrically good conductor (bronze, copper, etc) with screw lugs or screw terminals, to make connecting *many* wires to a common point much simpler, and better electrically (better electrical connection properties). Sometimes there is a variety of terminal/hole sizes, to accommodate a wider range of wire diameter.

[uncle_bob]

Originally Posted by MsTara

"That is the right path to install, you move the 7 pin line from the positive bus bar to the DC-DC charger/converter and then connect that back to the bus bar."

I am hoping someone won't think this is the stupidest question in the world.

What is the Bus Bar? Does someone have pictures to help me understand what that means?

I am looking to add in a second Battleborn to my 2018 Airstream Bambi and they are recommending a DC-DC convertor to help protect all three of the batteries and I am not quite "sure" where the DC-DC convertor goes and where to find the wires I would need. I am assuming they are under the dinette but what are the different wires to pull...

If someone has pictures that would be wonderful.

Hi

The cable from your 7 pin connector comes into the trailer somewhere. It eventually winds up in a big tangle of wires somewhere near the front of the trailer. Deep under that pile of wires (and possibly under a cover that has a hazard label on it) is a set of breakers tied to a copper bar. The breakers look like bolts from the side you are looking at them. The copper bar is the main DC distribution for the trailer.

Since this is Airstream, it's very much a "go and see" sort of thing to find the beast. On our Classic, you disassemble the sofa to get to it ....

Bob

[Steamy1]

Attached is a rough schematic of how I installed the Renogy 20 amp dc-to-dc charger in our 2015 23FB. I can send a picture of the installation if interested.

I went with the 20amp as I wanted to use the existing 10AWG wires from the 7-pin pigtail. Probably won't give me a lot of charging power but it will help maintain the batteries while driving.

[bonediggy]

I plan on installing 2 1000 watt Battle born batteries in our stock 2021 Caravel 22FB. I also purchased a Renogy 60 amp DC to DC Battery charger. After reading through a couple of these forums, I have alot of questions.

First off, it sounds from this post that I need to replace the current WFCO converter with a wfco 8950l2 MBA in order to properly charge the new LiPo batteries.

After looking at the specs on the wfco 8950l2 MBA it looks like it is 50amps. Is my 60 amp Renogy Dc to Dc converter way too much? If so, would you recommend getting a 20 or 40 amp version or is it possible to throttle down the amps somehow?

I plan on running 4awg wire to anderson connectors similiar to this

video

However, it doesn't look like his D+ wire is ran correctly. What is the best way to setup the D+ wire? Could you splice it from one of the 7 pin wires? I saw alot of mentions about taking the hot 7 pin connector and running it to the renogy. Could you run that to the D+ port or is that a bad idea?

Any assistance would be greatly appreciated. As you can probably tell, I am a total newbie when it comes to this stuff.

[Hans627]

Originally Posted by bonediggy

I plan on installing 2 1000 watt Battle born batteries in our stock 2021 Caravel 22FB. I also purchased a Renogy 60 amp DC to DC Battery charger. After reading through a couple of these forums, I have alot of questions.

First off, it sounds from this post that I need to replace the current WFCO converter with a wfco 8950l2 MBA in order to properly charge the new LiPo batteries.

After looking at the specs on the wfco 8950l2 MBA it looks like it is 50amps. Is my 60 amp Renogy Dc to Dc converter way too much? If so, would you recommend getting a 20 or 40 amp version or is it possible to throttle down the amps somehow?

I plan on running 4awg wire to anderson connectors similiar to this

However, it doesn't look like his D+ wire is ran correctly. What is the best way to setup the D+ wire? Could you splice it from one of the 7 pin wires? I saw alot of mentions about taking the hot 7 pin connector and running it to the renogy. Could you run that to the D+ port or is that a bad idea?

Any assistance would be greatly appreciated. As you can probably tell, I am a total newbie when it comes to this stuff.

Regarding the converter I would call these guys and they should be able to help select the correct convertor. They are very helpful and may be able to provide suggestions. https://www.bestconverter.com/

[richard5933]

Originally Posted by bonediggy

I plan on installing 2 1000 watt Battle born batteries in our stock 2021 Caravel 22FB. I also purchased a Renogy 60 amp DC to DC Battery charger. After reading through a couple of these forums, I have alot of questions.



First off, it sounds from this post that I need to replace the current WFCO converter with a wfco 8950l2 MBA in order to properly charge the new LiPo batteries.



After looking at the specs on the wfco 8950l2 MBA it looks like it is 50amps. Is my 60 amp Renogy Dc to Dc converter way too much? If so, would you recommend getting a 20 or 40 amp version or is it possible to throttle down the amps somehow?



I plan on running 4awg wire to anderson connectors similiar to this

However, it doesn't look like his D+ wire is ran correctly. What is the best way to setup the D+ wire? Could you splice it from one of the 7 pin wires? I saw alot of mentions about taking the hot 7 pin connector and running it to the renogy. Could you run that to the D+ port or is that a bad idea?



Any assistance would be greatly appreciated. As you can probably tell, I am a total newbie when it comes to this stuff.

A big part of the answer to the question about the size your DC to DC charger will be the available current from your tow vehicle. For example, if that circuit has a 30-amp output max, there's no point in installing a charger which can use more.

[uncle_bob]

Originally Posted by bonediggy

I plan on installing 2 1000 watt Battle born batteries in our stock 2021 Caravel 22FB. I also purchased a Renogy 60 amp DC to DC Battery charger. After reading through a couple of these forums, I have alot of questions.

First off, it sounds from this post that I need to replace the current WFCO converter with a wfco 8950l2 MBA in order to properly charge the new LiPo batteries.

After looking at the specs on the wfco 8950l2 MBA it looks like it is 50amps. Is my 60 amp Renogy Dc to Dc converter way too much? If so, would you recommend getting a 20 or 40 amp version or is it possible to throttle down the amps somehow?

I plan on running 4awg wire to anderson connectors similiar to this

However, it doesn't look like his D+ wire is ran correctly. What is the best way to setup the D+ wire? Could you splice it from one of the 7 pin wires? I saw alot of mentions about taking the hot 7 pin connector and running it to the renogy. Could you run that to the D+ port or is that a bad idea?

Any assistance would be greatly appreciated. As you can probably tell, I am a total newbie when it comes to this stuff.

Hi

I assume we are talking about two 100AH BB's ....

If you intend to add a second alternator to your tow vehicle and run custom cabling back to the trailer ( along with a custom connector) the 50A DC/DC should do fine. Something like 4AWG from the front of the truck back to the DC/DC in the trailer would be typical.

If you are running through the 7 pin connector, there are a number of limits.

First up is the DC/DC being rated for *output* rather than input current. If your battery is at 14.2V and the input to the DC/DC is at 10V after line drops, you could easily be up over 80A into the DC/DC.

Next up, the 7 pin is basically a 20A sort of device. It's fused at 30A in most setups, but the typical setup is only going to get you 20A through all the wire and multiple connectors.

Typically you put in a DC/DC that has an output rating of < 15A for the 7 pin, or you get one that can be programmed to limit the current.

Making this even more fun, most DC/DC's will shut down if they can't get what they are looking for. You can put it in. There's no smoke. There's also not much charging going on .... Simply verifying that "all is well" is not as easy as one might think.

I'm not a big fan of the WFCO converters, but they are easy to swap out ....

Bob

[ryanc55]

Originally Posted by richard5933

A big part of the answer to the question about the size your DC to DC charger will be the available current from your tow vehicle. For example, if that circuit has a 30-amp output max, there's no point in installing a charger which can use more.

To add to Bob's correct info:

Assuming you're making new runs to both batteries, make sure you're fusing both sides to the converter's specs, which should be well under the 100A continuous the 100Ah BB battery can take.

From a quick look at the Renogy manual I don't see that it has a settable input voltage turn on point, so you would want to connect the D+ wire so that you don't drain your TV batteries. The 7 pin AUX line *may* suffice, but it depends on your vehicle. Some have AUX on only while running, some when on accessory, and some all the time. You might have to run a separate ignition circuit line, or use a battery separator.

[bonediggy]

Thanks for the info. I think I figured it out. I was able to tap the D+ into the 7 pin green wire which is for the running lights. I replaced the Wago 2 port connector that connected the green wires with a Wago 3 port and now I am able to essentially turn on the dc to dc converter when I turn on the running lights of the car (which is also used for the airstream camera so I always have them on while towing). According to my Victron BMV 712 smart shunt, I am getting about 46 amps. Granted I ran pretty long wires because I want to be able to charge the camper when my tow vehicle is about 6 feet from the camper. I ran 4 gauge wire with Anderson connectors. The starter battery has a 100 ANL fuse and the Renogy Dc to DC goes to a Lynx distributer with a 100 Mega fuse.

[uncle_bob]

Originally Posted by bonediggy

Thanks for the info. I think I figured it out. I was able to tap the D+ into the 7 pin green wire which is for the running lights. I replaced the Wago 2 port connector that connected the green wires with a Wago 3 port and now I am able to essentially turn on the dc to dc converter when I turn on the running lights of the car (which is also used for the airstream camera so I always have them on while towing). According to my Victron BMV 712 smart shunt, I am getting about 46 amps. Granted I ran pretty long wires because I want to be able to charge the camper when my tow vehicle is about 6 feet from the camper. I ran 4 gauge wire with Anderson connectors. The starter battery has a 100 ANL fuse and the Renogy Dc to DC goes to a Lynx distributer with a 100 Mega fuse.

Hi

At least on my truck, the running lights can be on under all sorts of conditions. If you are pulling 48A, you can flatten the truck battery mighty fast.It's not a deep cycle battery so the "you get 50% of the AH rating" stuff is very optimistic when looking at it ... Even with 4AWG wire, you may well be putting 70 or 80A into the DC/DC when you are getting 48A out. That's a lot of current from a truck battery.

Bob

[BigAl]

Does the current really pass through the battery or from the alternator to the battery terminals then to the dc_dc charger. I thought electricity always followed the easiest path.
Al

[uncle_bob]

Originally Posted by BigAl

Does the current really pass through the battery or from the alternator to the battery terminals then to the dc_dc charger. I thought electricity always followed the easiest path.
Al

Hi

Electrical current can flow from any connected source to any connected load. How much comes from which source and goes to with load depends on some wonderful math you learn in first year EE class.

Given that the alternator is the only real source in the TV and that the battery can flatten pretty quick, it's going to come from the alternator in fairly short order.

Bob

[NeahBay]

I'm installing a Victron Orion-Tr Smart 12|12-18amp isolated DC/DC charger in my 2021 Caravel 16RB. Trying to fire it up yesterday, I got nothing. So today, I've been trying to find a good diagram to show me the error(s) of my ways. I found this thread (again), helpful ideas but alas, still not enough to answer my questions to my satisfaction. Victron's website is next to useless, trying to decipher the engineer speak. Why is installing THIS device so poorly documented?

I finally thought to check AMSolar.com (duh, but of course!), and quickly found a wonderful diagram showing the proper installation. The space in the 16RB under the dinette is pretty full, and I will probably have to cut a hole to allow for proper ventilation. It'll be a couple days before I get this completed (lack of parts, again).

https://amsolar.com/rv-battery-acces...ltchgs60-ww7de


I hope this helps someone else, besides me.
Bob

[dog_and_cat]

Bob, I'll be installing this as well in my '21 GT this summer. Curious what you learned from the diagram that was different from your original install.

Thanks

Chris

[MIFC]

I’ve been thinking about this install as well as my TV is next to worthless charging the batteries on the road. I’ve been intimidated a bit by the wiring concepts, but this diagram is very helpful.

Thanks for posting!!

[Ephraim]

We upgraded to lithium last year and I installed an Orion TR 12-30 DC-DC to charge while traveling. I was concerned about the voltage mismatch between lithium and lead acid mostly, but took it as an opportunity to get some real charging in during travel. I have to admit that when boondocking, and between the 800W of solar and the Orion it is really nice to be able to leave a site with discharged batteries and arrive at a new site fully charged.

I added a panel next to the TV battery that has a 50 breaker/disconnect and battery isolator. Then I ran 6ga all the way back to the bumper and used a 50A Anderson mounted right next to the 7-way. The Orion is mounted under the front couch and wired into the DC distribution box. I did disconnect the 7-way DC feed in the distribution Box as well.