What performance difference can I see with a DC to DC converter?

[richard5933]

Originally Posted by IrisnGerald

Perhaps a silly question …

How does it effect fuel mileage?

The trucking industry looked into more efficient alternators to reduce fuel costs. Seems like adding a load to the alternator would be the inverse.

Link … https://www.ttnews.com/articles/effi...ts-experts-say

The amount of charge that most of our battery banks will accept is going to have only a negligible affect on fuel economy.

But since there is no free lunch here, you've got to get those electrons into the batteries somehow. Other than running solar when driving to charge your batteries, charging them from the tow vehicle is the only viable option. If you leave a campsite with depleted batteries and hope to have them charged upon arrival, then you pay the price to get them charge and take the ever-so-slight hit on MPG.

[swat2]

Originally Posted by Kawboy01

As others have replied the 7 pin will only provide a minimal amount of charge current for the lithium batteries you have. On our 21GT27FBQ with solar the 180 watts solar, we installed 2 SOK 206 lithium and the 7 way just didnt cut it. I ran 4 gage weld cable from TV battery thru a 40amp breaker to the rear where I connected a Renogy 20amp DC2DC charger mounted in the front compartment of the AS with an Anderson connector and more 4 gage cable. I pulled the fuse that provided the power to the 7way so we dont need to pull the plug when overnighting. We could have gone bigger on the DC2DC but with the solar and the way we travel the 2 SOK's get plenty of charge. I would definitly recommend a DC2DC charger.

I'm in the middle of installing a Renogy 20 amp DC-DC charger in my 27' Globetrotter. I've finished the 6 gauge welding wire run from TV battery to the rear bumper, including a 30 amp Blue Sea circuit breaker on the positive cable and ending with an Anderson connector. Any tips on bringing the cable from the DC-DC on the trailer side through the floor? There doesn't appear to be any space left where the existing 7-way and other wires come up through the floor. The hole appears to be plugged with a black rubber compound (dry, not tacky). I'd rather not have to make a new hole in the floor if possible.

[richard5933]

Originally Posted by swat2

I'm in the middle of installing a Renogy 20 amp DC-DC charger in my 27' Globetrotter. I've finished the 6 gauge welding wire run from TV battery to the rear bumper, including a 30 amp Blue Sea circuit breaker on the positive cable and ending with an Anderson connector. Any tips on bringing the cable from the DC-DC on the trailer side through the floor? There doesn't appear to be any space left where the existing 7-way and other wires come up through the floor. The hole appears to be plugged with a black rubber compound (dry, not tacky). I'd rather not have to make a new hole in the floor if possible.

I ended up having to make a new hole near the existing one. There was just no way to install the extra pair of wires without risk of chaffing against the edges. Since the area where my original hole was located stayed dry, I wasn't too worried. I used a rubber grommet on the sheet metal, and then packed the hole with electricians putty from both the inside and outside. It's likely the stuff you're seeing in the existing hole. Electrician's putty will prevent water from getting through the hole, but it can be removed at a later time if needed to run additional wires. I'd advise against using something like caulking to fill the hole, as you will eventually need to run additional wires through the new hole for something and will want a removal barrier in there. Plan for future expansion now and drill the hole larger than you need.

[10Smiles]

I too drilled a new hole next to the existing one. Not too difficult and now I have lots of room to expand in the future. Mine was for adding a portable solar connection on the tongue.

[swat2]

Richard and 10Smiles - thanks for the replies. What size holes did you both make? I'll check the forum to see if there are any posts on drilling/cutting a hole in the Airstream floor.

[richard5933]

Originally Posted by swat2

Richard and 10Smiles - thanks for the replies. What size holes did you both make? I'll check the forum to see if there are any posts on drilling/cutting a hole in the Airstream floor.

Can't remember the exact size, but it was chosen according to the grommet sizes that were available for me. I seem to remember about 1-1/4".

The hole I drilled was near the original one, in the very front of the trailer which puts it a few inches behind the very from cross member and forward of the spare tire. I carefully checked below and cross-referenced to above before drilling to make sure that I hit nothing, and I drilled using a standard-issue hole cutting bit with a centering lead bit. After the saw teeth of the bit were about halfway through the material, I went underneath and continued cutting from below to make sure that I didn't have a blow out on the bottom of the hole.

This area of the trailer has no belly pan, just a layer of sheet metal underneath the sub flooring.

[swat2]

Originally Posted by richard5933

Can't remember the exact size, but it was chosen according to the grommet sizes that were available for me. I seem to remember about 1-1/4".

The hole I drilled was near the original one, in the very front of the trailer which puts it a few inches behind the very from cross member and forward of the spare tire. I carefully checked below and cross-referenced to above before drilling to make sure that I hit nothing, and I drilled using a standard-issue hole cutting bit with a centering lead bit. After the saw teeth of the bit were about halfway through the material, I went underneath and continued cutting from below to make sure that I didn't have a blow out on the bottom of the hole.

This area of the trailer has no belly pan, just a layer of sheet metal underneath the sub flooring.

Thanks, that's very helpful info!