Blue Sea Systems Disconnect Switch Installation

[Avenger61]

It's exactly like the picture Dan-Nickie posted

[dan-nickie]

Hold on a minute and I'll do a simple drawing.

[dan-nickie]

I think what may have been confusing to most is the fact that it is a marine switch and you want to control each battery independently.
I put a similar switch on a boat a few years ago.
You may need another short cable or two.
See if this helps.

[Avenger61]

That's perfect!! The only difference is right now I have a ground going to one battery and a jumper to the send battery ground. basically I have the positive and negative from the camper going to the first battery with jumpers to the second battery. From what I see in your diagram though that shouldn't matter. I can simply run battery positives to switch 1 and 2 (as in the diagram) and camper positive to switch common (as in the diagram and leave the negative side alone. Thanks everyone for all the help. This was a huge hit to my mod ego, but a picture and help from you guys can even get a dummy through the tough spots.

[dan-nickie]

I think you have it.

Yes, you can leave the negative side as is.

Yes, remove the jumper between the two positive leads and use it to connect either 1 or 2 on your switch.

[dan-nickie]

One thing you may want to think about or maybe someone will comment is the battery charging process.

On my boat, I would use one battery running the radio or trolling motor all day and when it ran down I would switch to the other battery. By the end of a day, I might need to switch to 'both' to crank my big motor. But I was always back home by the end of the day and the charger was put on the batteries until next time.

How will you handle keeping both batteries charged while on multi day camping?

[Avenger61]

That's a good point. I usually don't dry camp for more than a weekend at a time so I think I'll be fine if I watch what I use. I only had one battery in my last pup and never had a problem. I seldom use much power during the day but this camper does have more electrical items to consider. I'll probably have to do the ole trial and error thing in the driveway a few times to test it all out before talking a dry camping run. I read somewhere on this forum that you should only us a charger one battery at a time too - I'll have to watch that.

[pgandw]

This probably more complex than you want - but knowledge is power (or in this case, battery life).

I have a similar setup for my A122 - two size 24 12V batteries so that I can camp in Fall and Spring weather in the Colorado Rockies for a long weekend.

First, use both batteries in parallel (BOTH) if you are expecting to use any significant battery capacity. The number of recharges a lead-acid battery can undergo without serious loss of capacity depends on its construction AND how deeply it is discharged. The rule of thumb is to never discharge a lead-acid battery below 50% if you can help it - and less is better for battery life. If you have the 2 batteries in parallel, you have twice the amp-hours before you reach 50%. Or if you have fixed amount of amp-hours drawn, you halve the amount of discharge in each battery - instead of one battery being taken down to 40%, the two batteries go down to 70% each - much better for your battery life.

The paralleling assumes well-matched batteries. If they are not well-matched, one battery will carry much more of the load than the other, causing both to have shorter lives. Where batteries are not matched, you should use one at a time and try to switch before reaching the 50% discharge point.

In an ideal world, the matching includes equal wire lengths from the load to each battery. That's why the camper wire ares on the (-) post of one battery and on the (+) post of the other battery. With the switch in the circuit, you ideally want equal wire lengths to each battery from the switch. On the minus side, ideally you again want to end the camper wire at a separate post, and run an equal length wire to each battery (-) post. The heavier the current through the wires, the more important equal lengths become. If you only have parasitic loads (2-3 amps) and 10 gauge or better wire, it's not such a big deal. OTOH, if you are running 10-12 amps, having equal length wires helps balance the batteries.

For charging, if the batteries are matched, charge them together. If they are not matched, charge them one at a time.

hope this helps
Fred W

[Avenger61]

I installed the disconnect switch today, just as shown in Dan-Nickie's post above, and it seems to work like a champ (nothing blew up!). However, I've been monitoring the batteries for the last three or four hours and noticed that they have gone from 13 volts to reading 13.5 volts. I never noticed anything over 13 volts before I put in the disconnect switch. I am connected to shore power and both batteries are selected on the disconnect switch selector (to keep them charged). I used the same size wire on all connections and neither the wires or batteries are warm to the touch. Everything seems to work just fine, should I be worried?

[dan-nickie]

I just looked at mine. My monitor is showing 13.5 float charging plugged into campground power.

[camaraderie]

If you are plugged into power...you should never see less than 13.2-13.4 or so. AFTER boondocking...when you plug back in...you should see at LEAST 14.4...which will gradually ramp down to around 13.8 after 2-3 hours... and then in the low 13's after 4-6 hours. It generally takes 4-6 hours on a decent charger to get your batts back to 100%. The ONLY time you should see anything below 13 is when you are boondocking.

[Avenger61]

Thanks! That helps ease my mind a lot. I was afraid I missed something in Dan-Nickie's diagram and everyone's tutoring efforts. Batteries are much more complicated than I ever imagined!! Thanks everyone!!!

[mikehaynes]

I am new to this forum and rving, I have a 2013 Concord 225Le and do not understand what this switch does. The switch is a single circuit 6006. Could someone explain the use. Thanks

[pgandw]

The switch was likely installed by a former owner, not the factory.

The purpose is to cut off the battery when the trailer is not in use. There are some "parasitic" draws on the battery that will run it down in a week or two if the battery is not isolated or "cut off" from the camper. Not needed if your RV remains plugged in all the time.

You could remove ALL the cables from one terminal of the battery, and accomplish the same thing, but the switch is more convenient.

hope this answers the question
Fred W
2019 Flagstaff T21TBHW A-frame
2008 Hyundai Entourage minivan
camping Colorado and adjacent states one weekend at a time

[mikehaynes]

Thank you for your response.