Battery Isolator For TT. Yes or No?

[Blue_Hill]

Sorry for a stupid question if this has been done to death, but I've been thinking that I should install a battery isolator to keep my truck battery and trailer battery separate. When I started doing a little research, I found two camps on the issue. Some said absolute must and others said not necessary for a TT.
What do you folks think?

[Blue_Hill]

vermilye wrote:
If you install an isolation relay, be sure it is rated for continuous use. There are many that are designed for intermittent use & the coils overheat & fail...

Thinking about this one which has been recommended.

Link

I just have to find one in Canada for a reasonable price. Amazon in Canada is out to lunch on this one.

[vermilye]

If you install an isolation relay, be sure it is rated for continuous use. There are many that are designed for intermittent use & the coils overheat & fail...

[subcamper]

An isolating solenoid will work fine.

A diode isolator will drop about 0.7VDC, which could be a problem.

I installed a solid-state CMOS isolator with very little voltage drop from:

Battery Isolator/Combiner

I did this in conjunction with a dual battery in our Suburban (bought a second battery tray from GM used for diesel trucks that bolted right in), which acts as a backup starting battery. It isolates the second underhood battery and also the camper battery, but keeps them fully charged.

Steve

[MEXICOWANDERER]

One weekend I camped between Mammoth Lakes and June Lake at a NFS boondock campground. Saturday morning I found myself jump starting three tow vehicles whose owners arrived late Friday and forgot to disconnect. Temps were chilly so I guess they tried operating their heaters.

Theory, good intentions, and reality sometimes do not get along. An isolation system is not like a gigantic investment in time, trouble or money. A smart solenoid is about as easy to install as it gets. I HATE ignition control and toggle switch disconnects with a purple passion. The ESSEX type tower solenoids are ten times as reliable as any can type solenoid.

[Blue_Hill]

YC 1 wrote:
I think you must first prove they are isolated or not.

With thing connected start the truck. Measure the voltage on the TT batteries and the truck batteries. They will be a bit different so write them down. Shut the truck off and take the measurement again. Then go inside and turn every light on you can find, even turn the heater on if possible so you have a large DC load.

Now measure the voltages on each battery bank. Write it down. You will see your TT battery voltage sink and if your truck is not already isolated with the ignition off you should see that battery voltage going down a bit too. If it holds steady you have isolation.

That said, I too just unplugged my truck at night when I had a TT. Worked great. For a bit of a quicker picker upper I would face the truck to the TT and use automotive jumper cables to give the TT batteries a bit of a charge before retiring. This would warm the batteries too helping them in cold weather.

I'm pretty sure they aren't isolated, because the terminal on the 7 pin connector is hot regardless of whether the key is on or off.

[YC_1]

I think you must first prove they are isolated or not.

With thing connected start the truck. Measure the voltage on the TT batteries and the truck batteries. They will be a bit different so write them down. Shut the truck off and take the measurement again. Then go inside and turn every light on you can find, even turn the heater on if possible so you have a large DC load.

Now measure the voltages on each battery bank. Write it down. You will see your TT battery voltage sink and if your truck is not already isolated with the ignition off you should see that battery voltage going down a bit too. If it holds steady you have isolation.

That said, I too just unplugged my truck at night when I had a TT. Worked great. For a bit of a quicker picker upper I would face the truck to the TT and use automotive jumper cables to give the TT batteries a bit of a charge before retiring. This would warm the batteries too helping them in cold weather.

[scrubjaysnest]

Blue Hill wrote:
Sorry for a stupid question if this has been done to death, but I've been thinking that I should install a battery isolator to keep my truck battery and trailer battery separate. When I started doing a little research, I found two camps on the issue. Some said absolute must and others said not necessary for a TT.
What do you folks think?

Check your owners manual, most newer chevy and ford products with the factory tow package come with relay isolation.
Dodge/Jeep or at least our 2005 jeep and 2008 dodge don't.

[N-Trouble]

Trying to understand a scenario where you would run down your TV batteries and can't think of one. I always disconnect when I camp. I never rely on my TV batts to dry camp. Big no-no... If your trailer batteries aren't up to the task look at upgrading your battery bank and/or adding solar or use a genny.

[time2roll]

You have an isolator. Just pull the 7-pin connector.

[ScottG]

I installed one in my last truck. I prefer the way it is now, hard wired.
In the rare event that I don't want the truck and trailer batteries connected, I will unplug the truck.
More often I want them connected. When we dry camp I leave the truck connected until we go to bed. So we draw from it for several hours and then just rely on the TT batts. This gives us a little extra capacity. It's also nice to be able to drive around during the day then come back and let the trucks batteries give the TT's batts a little extra charge simply by equalizing.
So we've had it both ways and much prefer the hard wired method.

[MEXICOWANDERER]

I think if you leave the truck connected and run down all the batteries you are not going to be a happy camper.