USB outlet addition

[steilkurve]

Hello. I’m adding a Blue Sea 4.8A dual outlet to my AS 2020 Bambi 22FB. Two questions:

1) What gauge does Airstream use for 12V circuits, 12 gauge?
2) Should I add an inline fuse between the outlet and the existing wire I connect it to?

Thanks!

[GMFL]

12 gauge is correct. And “that” wire would be fused at the panel so there is no need for an inline unless you are connecting straight to the batteries.

[steilkurve]

Originally Posted by GMFL

12 gauge is correct. And “that” wire would be fused at the panel so there is no need for an inline unless you are connecting straight to the batteries.

Thanks GFML. That’s helpful. And is it ok to connect that wire to one feeding a nearby LED light fixture? Was thinking of making the connection with wire nuts and then further securing with electrical tape.

[mcc272]

Generally wire nuts are a bad idea on RV’s and boats. The vibration causes them to loosen. Crimped connectors are what is generally recommended. They are widely available and cheap as are the crimp tool.

[rowiebowie]

Originally Posted by steilkurve

Thanks GFML. That’s helpful. And is it ok to connect that wire to one feeding a nearby LED light fixture? Was thinking of making the connection with wire nuts and then further securing with electrical tape.

Someone in the distant past mentioned a problem tapping into lighting wiring. Do as GMFL suggests and wire back to a fused connection at the main power box.

[steilkurve]

Originally Posted by rowiebowie

Someone in the distant past mentioned a problem tapping into lighting wiring. Do as GMFL suggests and wire back to a fused connection at the main power box.

Thanks for all the input. I will wire back to the 12V fuse box. Now, never done it before in my Airstream. How easy is that to do. Can I plug in fairly easily or do I have to pull out the box.

[jeffmc306]

Originally Posted by steilkurve

Thanks for all the input. I will wire back to the 12V fuse box. Now, never done it before in my Airstream. How easy is that to do. Can I plug in fairly easily or do I have to pull out the box.

You should be able to find a 12V circuit to tap into on the low voltage side of the fuse box (right side of the photo below). Check to see if there’s an unused connection on the fuse block.

[steilkurve]

Originally Posted by jeffmc306

You should be able to find a 12V circuit to tap into on the low voltage side of the fuse box (right side of the photo below). Check to see if there’s an unused connection on the fuse block.

Thanks. I do have unused connections. 2 to be precise so I’m good there. I’m clear on where to plug the positive. What about the negative? Is there a ground bus on the fuse box? Also, is putting the battery disconnect to off enough or should I physically unplug the negative and positive at the batteries before doing the work?

[jeffmc306]

Originally Posted by steilkurve

Thanks. I do have unused connections. 2 to be precise so I’m good there. I’m clear on where to plug the positive. What about the negative? Is there a ground bus on the fuse box? Also, is putting the battery disconnect to off enough or should I physically unplug the negative and positive at the batteries before doing the work?

Great questions! I wasn’t sure about the power so I grabbed my meter to test it.

With the switch in “Store”, the power to the 12V fused circuits is disconnected. That said, it’s always best to disconnect the batteries to remove all the potential. Lots of amps in those batteries!

With the switch in “Use” I read battery voltage across the red and white wires at the buss. Next, I checked on the right side of the fused circuits to one tap and also read battery voltage.

Regarding your question about running a wire to the negative buss, you could or you can look for the 12V “rats nest” where Airstream has a junction box. I’ll put a photo of mine that says “Caution 12V DC Panel”. I found mine next to the Inverter under the curb side twin bed. I didn’t pull the cover to see if there’s a negative buss but you could check if you want to only run one wire back to the fuse panel.

Hope that helps! Let us know what you end up doing.
Best,
Jeff

[steilkurve]

Originally Posted by jeffmc306

Great questions! I wasn’t sure about the power so I grabbed my meter to test it.

With the switch in “Store”, the power to the 12V fused circuits is disconnected. That said, it’s always best to disconnect the batteries to remove all the potential. Lots of amps in those batteries!

With the switch in “Use” I read battery voltage across the red and white wires at the buss. Next, I checked on the right side of the fused circuits to one tap and also read battery voltage.

Regarding your question about running a wire to the negative buss, you could or you can look for the 12V “rats nest” where Airstream has a junction box. I’ll put a photo of mine that says “Caution 12V DC Panel”. I found mine next to the Inverter under the curb side twin bed. I didn’t pull the cover to see if there’s a negative buss but you could check if you want to only run one wire back to the fuse panel.

Hope that helps! Let us know what you end up doing.
Best,
Jeff

Thanks for checking all that for me Jeff. I appreciate it. I’ll play it safe and unplug at the batteries. On the connection, after some more reading I understand the rats nest on my AS should be right behind the converter. I was able to take this bad photo from the access in the closet. Can you make something out? Definitely lots of wires coming there though can’t spot negative cables. Again, I’ll know more when I pull it out.

[jeffmc306]

Originally Posted by steilkurve

Thanks for checking all that for me Jeff. I appreciate it. I’ll play it safe and unplug at the batteries. On the connection, after some more reading I understand the rats nest on my AS should be right behind the converter. I was able to take this bad photo from the access in the closet. Can you make something out? Definitely lots of wires coming there though can’t spot negative cables. Again, I’ll know more when I pull it out.

You may have “another” rats nest besides the back of the distribution panel. I pulled up the manual for your trailer and found the wiring diagram on page 8-16. While it doesn’t show the location of components, it did show a DC busbar.

Here’s the manual: https://www.airstream.com/wp-content...ers-Manual.pdf

If you’re up to tracking it down, you could terminate the negative to the busbar or to the negative on the converter (or any negative you come across).

Good luck!
Jeff

[steilkurve]

Originally Posted by jeffmc306

You may have “another” rats nest besides the back of the distribution panel. I pulled up the manual for your trailer and found the wiring diagram on page 8-16. While it doesn’t show the location of components, it did show a DC busbar.

Here’s the manual: https://www.airstream.com/wp-content...ers-Manual.pdf

If you’re up to tracking it down, you could terminate the negative to the busbar or to the negative on the converter (or any negative you come across).

Good luck!
Jeff

Thanks again Jeff for your trouble. It’s very helpful. I definitely know where the ‘formal’ DC bus bar is. It’s at the other end of the trailer under the bed. I’d just like to avoid fishing the wire all the way there. I’ll see if I can find a connection box or other behind the converter or use a negative connection on the converter itself as you suggest. Alternatively, could I use the negative of a light fixture next to where I’d like to put the outlet but still wire the positive directly on the distribution panel? Nic

[jeffmc306]

Originally Posted by steilkurve

Thanks again Jeff for your trouble. It’s very helpful. I definitely know where the ‘formal’ DC bus bar is. It’s at the other end of the trailer under the bed. I’d just like to avoid fishing the wire all the way there. I’ll see if I can find a connection box or other behind the converter or use a negative connection on the converter itself as you suggest. Alternatively, could I use the negative of a light fixture next to where I’d like to put the outlet but still wire the positive directly on the distribution panel? Nic

Nic, yep - you can use any negative close to your USB charger. It’s such a light load you could tag into any positive that’s live if you didn’t want to run it all the way back to the fuse panel.

[jeffmc306]

Hey, I pulled the cover off the DC box under the curb-side bed, just under the inverter. Inside the box are both positive and negative busbars. You could connect directly to the positive buss and use an inline fuse (like the one in the photo for my solar controller).

Hope that helps!
Jeff

[steilkurve]

Originally Posted by jeffmc306

Hey, I pulled the cover off the DC box under the curb-side bed, just under the inverter. Inside the box are both positive and negative busbars. You could connect directly to the positive buss and use an inline fuse (like the one in the photo for my solar controller).

Hope that helps!
Jeff

Once more, thank you Jeff! I had some time this morning so I went to where my AS is stored and was able to get the job done. Here's how it all went down!

I pulled out the electrical panel (after disconnecting the battery cables). No rats nest there with a bus or connection box. The only bus is really at the other end of the trailer under the bed. See first attachment.

Therefore, as I was putting the USB outlet in the closet that's right next door to the panel on my Bambi, I simply decided to bring both the negative and positive from the outlet to the panel directly.

I had an open slot for the positive as stated in previous posts. As for the negative, I wasn't sure but took your advice. Given there was no bus in close proximity, I simply connected it to one of the two big negative terminals at the top of the panel (and where what I assume is the cable from the battery disconnect switch ends). See attached photos again. The wire I plugged in is the black one (didn't have white). That is ok I assume, right?

I then cut the hole in the closet wall and used an access panel to connect the wires to the outlet and secure it in place. Looks and works great. See last couple of photos.

Question, do I need to add a fuse? My positive is connected to the 9th terminal and there was already a fuse in that slot. Fuse slots 10 and 11 are empty

[jeffmc306]

Awesome job, congratulations!

You don't need another fuse; it's probably a 15 A. You could reduce it down to a 10 A if that's the only thing on the circuit. The fuse will protect from a dead short. Did you try it out yet?

Now that you've completed that project, what's next?

Cheers!
Jeff

[steilkurve]

Originally Posted by jeffmc306

Awesome job, congratulations!

You don't need another fuse; it's probably a 15 A. You could reduce it down to a 10 A if that's the only thing on the circuit. The fuse will protect from a dead short. Did you try it out yet?

Now that you've completed that project, what's next?

Cheers!
Jeff

Well, many! Next one on the list is installing a Simarine Pico battery monitor. It’s all planned out, am just waiting for delivery of a crimp tool for battery cable lugs. And I have a push out latch I want to install on the closer door to prevent it from swinging open as we’re on the road. After that, I have a WiFi Ranger Converge to install. Debating if I’ll do that myself as it’ll require drilling the roof (electric fridge only so no vent to fish cables through). May just leave to my AS dealer if they indeed reopen in the next couple of weeks as planned. No shortage of projects...