Two batteries wired parallel question

[Treatcg]

I plan to buy an additional deep cycle battery to go along with factory one. I will hook it up to the stock battery with 8 gauge wire. Is it safe to charge the batteries in this configuration while plugged in to a generator?

[Mustang65]

Originally Posted by Treatcg

I plan to buy an additional deep cycle battery to go along with factory one. I will hook it up to the stock battery with 8 gauge wire. Is it safe to charge the batteries in this configuration while plugged in to a generator?

As long as you purchase the 2nd battery with the same Mfr/Make/Model you should have no issues. Example: most TT's come with a 12 volt Interstate RV/Marine hybrid batteries (thicker plates than a car battery but thinner plates than a true deep cycle battery) and are a size 24, I believe 85Ah. As long as the second battery is identical to the existing one, there will be no issues.

Yes, the TT's battery charge controller only sees 12VDC source connected to it. Most of the newer TT's have charge controllers capable of pushing out 40 amps (not that I have ever see it), but that is what they are rated for and they go through 3 modes to properly charge them. I would make sure that both batteries are at full charge before connecting them together.

The only suggestion I would make, is use 4 or 2 gauge wire connecting the 2 batteries together.

Below is the proper way to wire (2) 12 volt batteries in parallel.

just my thoughts,

Don

[Treatcg]

Thanks for the help

[Scoutr2]

You can go to your local Auto Zone, O'Reilly's Auto Parts, etc and purchase battery cables in whatever lengths you need. That would ensure you have the correct wire sizing and good lugs for connections.

And if it were me, I'd install a battery disconnect switch at the same time. Your propane leak detector and a couple other things in your trailer will provide a steady draw on your battery unless you disconnect it each time. A switch is much handier.

The disconnect should be used on the ground (negative) side, for safety (no arcing). That said, I use a sealed disconnect switch (from the heavy equipment industry) and have mine on the positive (hot) side. I do this because I can disconnect the electric tongue jack, which is grounded through its connection to the trailer frame. Disconnecting the battery ground wire still allows the tongue jack to be operated while the trailer sits in storage.

[Treatcg]

I went with two group 29 deep cycles and 4 gauge wire to hook them up. Put the battery that came with the TT in the duck boat. Thanks for the help.

[RoyBraddy]

Be sure to hook them up exactly as MUSTANG65 Diagram shows.. This allows equal DC currents for both batteries. I use 4AWG cables for all of my battery connections and make all like connections the same lengths.

The idea is to present equal charge paths for the batteries in your bank.

Roy Ken

[Seann45]

Personally I would go with 1 ga.. I have felt too many warm wires over the years to use anything less..