27 replies to this topic

[ramblinChet]

delete

Edited by ramblinChet, 06 February 2024 - 10:00 AM.

[ri-f]

I installed a Blue Seas 60 amp thermal circuit breaker (similar to the one you show) under the hood, next to the lead-acid battery on the driver side. I have a second one near my DC-to-DC charger in the camper, which is next to my LiFePo4 battery. I use both of them as switches to turn on/off the DC-to-DC charger, which I only use on occassion if the solar isn't enough - pretty rare. I also use Blue Seas thermal circuit breakers (different amperage) as on/off switches for my solar, as well as for an auxiliary fuse panel. These Blue Seas breakers are very convenient and well made, as all of their component parts.

 

Rich

[Wallowa]

Just had an 80 amp breaker like the one in your photo mounted on firewall driver's side about 2 feet from Tundra battery as part of the new BB battery [in Hawk] and Victron Orion Tr DC/DC install....second breaker in the DC/D-BB Battery circuit is 2 feet from charger/battery on the shelf where the removed BlueSea 7611 was previously mounted on passenger's side shelf under lid for battery box...this on a side dinette '16 Hawk.  4awg wire used.

 

I just figured out that I can easily use the breaker on the firewall to disconnect the DC/DC charger....will do this when Tundra  AGM battery is on Battery Tender to prevent/stop float charge on BB battery in Hawk and will also disconnect on really hot days when battery temp is an issue and when solar is abundant since charger is in battery box and would add to heat.

 

Phil

 

Ps...Chet, I am uncertain...is that a Li battery under the hood and insulated?  Are you using DC/DC charger on it or on a battery in a camper?  Or does this have nothing to do with a DC/DC charger?

Edited by Wallowa, 23 June 2021 - 06:09 PM.

[Outnabout]

Just had an 80 amp breaker like the one in your photo mounted on firewall driver's side about 2 feet from Tundra battery as part of the new BB battery [in Hawk] and Victron Orion Tr DC/DC install....second breaker in the DC/D-BB Battery circuit is 2 feet from charger/battery on the shelf where the removed BlueSea 7611 was previously mounted on passenger's side shelf under lid for battery box...this on a side dinette '16 Hawk. 4awg wire used.

I just figured out that I can easily use the breaker on the firewall to disconnect the DC/DC charger....will do this when Tundra AGM battery is on Battery Tender to prevent/stop float charge on BB battery in Hawk and will also disconnect on really hot days when battery temp is an issue and when solar is abundant since charger is in battery box and would add to heat.

Phil

Ps...Chet, I am uncertain...is that a Li battery under the hood and insulated? Are you using DC/DC charger on it or on a battery in a camper? Or does this have nothing to do with a DC/DC charger?

Phil-
When you installed the DC/DC charger what gauge wire did you go with? Also, did you make a new camper to truck connection in the bed of your truck? Did you do away with the Blue Sea ACR?

I keep tossing this idea around but the more I think about it just keeping the camper separate from my truck and relying on solar to charge doesn’t seem like a bad idea. I’ve lived through many power outages, not life and death. I like to keep things simple. Less stuff, less problems is my thought.

-Tom

[ri-f]

.. the more I think about it just keeping the camper separate from my truck and relying on solar to charge doesn’t seem like a bad idea.  I like to keep things simple. Less stuff, less problems is my thought. -Tom

Keep it simple, with some redundant backup. Solar can handle most of your energy loads. If you find yourself under a heavy tree canopy for a few days and don't want to move, or in low-light, short winter days, a B2B charger can top your battery off in a few hours, on your way to the next camp. It's a nice option in the Pacific NW and higher latitudes, but not everyone needs it. If you do install a B2B, a 30 amp charger will work very well and won't stress out your alternator. Lot of people use Victron Orion because they have other Victron equipment and want to keep all their Victron components happy.. I prefer the Sterling Power Model 1230 B2B charger over the Victron, even though most of my other stuff is Victron. There are no heat buildup issues with the Sterling, that many people with Victron B2B complain about. As far as wire goes, I use 4AWG from under the hood and back to an Anderson connector mounted to the Flatbed headache rack, then 4 AWG into the camper to a bus bar where I switch to 6AWG to fit the B2B connectors. If you go with a 30 amp B2B then you could use 6 AWG all the way (even 8 AWG would work, but you'll limit your potential for full current a bit over a long run with anything less than 6 AWG. I like 4 AWG for the B2B because it won't limit your current through wire losses and, if you use a marine-grade 4 AWG cable it's flexible enough to route easily and isn't significantly thicker than 6 AWG. As far as the Blue Seas that comes stock with the camper, just bypass it. If you are using a LiFePo4 camper battery, the ACR 7611 is not recommended by Blue Seas. It's okay with an AGM, but not really compatible with Lithium. Anyway, the B2B will be much more efficient.

 

Rich
 

[JaSAn]

I have a 1/2 inch thick piece of plywood resting on the side of my battery that I attached a B.S. circuit breaker to (the truck battery cables holds it in place).  I can take a picture of it tomorrow if interested.

[Jon R]

I have a crew cab long bed hd truck, and a Grandby with the battery at the rear, so it’s a longer wire run than most trucks. It’s a 2021 so it has a smart alternator. I have a Victron Orion 12/12-30. I used 6awg Ancor marine type IIi cable.

When the dc to dc converter is bulk charging the battery delivering 30 amps, the converter input voltage (coming from the truck at the battery compartment) is above 14 volts. Based on this, I think the 6awg wire is adequate. It also is convenient in that the Victron input connections will take up to 6awg.

Edited by Jon R, 24 June 2021 - 05:56 AM.

[Wallowa]

Phil-
When you installed the DC/DC charger what gauge wire did you go with? Also, did you make a new camper to truck connection in the bed of your truck? Did you do away with the Blue Sea ACR?

I keep tossing this idea around but the more I think about it just keeping the camper separate from my truck and relying on solar to charge doesn’t seem like a bad idea. I’ve lived through many power outages, not life and death. I like to keep things simple. Less stuff, less problems is my thought.

-Tom

 

Tom,

 

Wires are 4awg and new connection plug is an Anderson mounted to bed wall....no isolator hence Blue Sea 7611 was removed...as stated above the Victron Tr Orion DC/DC is a 30amp model...with Bluetooth to my phone...agree that when lacking solar or 110v power the DC/DC will quickly reinstate the SOC used....redundancy.

 

Phil

Edited by Wallowa, 24 June 2021 - 02:40 PM.

[ri-f]

OP - Blue Seas 50 amp thermal CB is mounted to the fuse box under the hood on a 2nd gen Ram 2500. The fuse box lid can still be removed with the circuit breaker attached. Secure and as close to the battery as it gets. May not be the same set up on a new Ram,

 

 

Jon- as for using 4 AWG marine cable with a 30 amp DC-to-DC charger, I add in a few extra feet on my run for ease of install and some flexibility in running the wire. With a run of 25 feet (including some slack) 6 AWG is okay, but on the borderline of 4 AWG. So I went 4 AWG assuming a 3% critical loss. It's really not significantly different in terms of size and expense to use 4 AWG, so why not?

 

Also, 4 AWG can handle a larger DC-to-DC charger if you decided later to scale up, assuming you had a large, high-power alternator or a dedicated second alternator or weren't concerned with stressing out your stock HD alternator. 4 AWG would be at its limit for a 60amp charger on a 20 foot run.

 

One last thing about limiting wire size on a long run: you can use a smaller guage wire (e.g. 4 AWG instead of 2 AWG) that is still safe, but has a less critical loss of efficiency, about a 10%, to actually limit the current if you wanted, say, 45 amps of current instead of the full 60 amps. In other words, if you wanted more than the 30 amp charger could provide, but didn't want the load and stress of a 60 amp charger on a stock alternator. There are plenty of options and more than one way to install a safe and effective DC-to-DC charger, and it all depends on your priorities, existing equipment under the hood, and mods you're willing to do.

 

Rich

[rando]

 

One last thing about limiting wire size on a long run: you can use a smaller guage wire (e.g. 4 AWG instead of 2 AWG) that is still safe, but has a less critical loss of efficiency, about a 10%, to actually limit the current if you wanted, say, 45 amps of current instead of the full 60 amps. In other words, if you wanted more than the 30 amp charger could provide, but didn't want the load and stress of a 60 amp charger on a stock alternator. There are plenty of options and more than one way to install a safe and effective DC-to-DC charger, and it all depends on your priorities, existing equipment under the hood, and mods you're willing to do.

 

Rich

 

It doesn't quite work that way.     Using smaller diameter wire between the truck alternator/battery and the DC-DC charger will actually slightly increase the current draw on the alternator/battery, not decrease it.  

 

It is a little bit counter intuitive, but one of the main reasons to install a DC-DC charger is to overcome wire losses that limit charging to the battery.   As long as the input voltage is within the specified range (typically something like 8 - 16V) the DC-DC charger will take the input voltage and boost  (or buck) it to the specified output voltage at the specified output current.   As a result, a lower input voltage (ie if there is more loss on the wires) will result in a higher input current in order to provide the same output voltage/current.  

 

As an example, say you have a 30A DC-DC charger and are charging your battery at 14V - the output power is 420W.   Now assume the DC-DC is the typical 90% efficiency, then the input power is about 460W.    Lets say your alternator is putting out 13.5V and you have super fat wires to the DC-DC (~no voltage drop), then the current draw on the alternator is 460/13.5 = 34A. 

 

Now assume skinnier wires and a 10% voltage drop.  The DC-DC will still be drawing 460W, but now the voltage at the DC-DC is 12.2V, so the current is 460/12.2 = 38A.    Not a big increase, but certainly not a decrease. 

 

In general a DC-DC charger lets you run smaller wires to the camper and still get good charging to the battery.   Technically the wires only need to have sufficient ampacity to support the DC-DC without worrying about voltage drop, but in practice it takes careful configuration of the 'engine running detection' algorithm if you are going to use smaller wires with higher voltage drop.