If you are looking to get the most power out of your 3 batteries for your fridge you need to look at how the dealer hooks up your 3 batteries. The most common way that dealers hook up batteries (more than one) is to connect them in parallel and connect the load cables to the battery that is closest to the existing TT cables. it is the most inexpensive and easiest way. They will tell you that there is no benefit to any other methods (the attached link will prove them wrong). The issue with wiring them this way is that the battery that has the load cable on it gets most of the Amp draw and the others need to slowly push their power into the first battery. Same logic holds true for charging. In other words the first battery is doing most of the heavy duty work.
You have 2 additional choices of hooking up your 3 batteries. The 2nd choice (much better that the above method) is to hook the 3 batteries in parallel, and connect the TT's Positive cable to the positive terminal of battery #1 and the Negative cable to battery #3. This makes the current draw/charge go through all 3 batteries, but of course it is not the BEST method. This method is the best for hooking up (2) 12 Volt batteries.
The last and BEST method for hooking up your 3 batteries (or more) is to take short battery cables of equal length from each battery terminal (3 positive cables and 3 negative cables), connect the 3 Positive cables to the Positive TT's Positive cable, then connect the 3 Negative battery cables to the TT's Negative cable that is connected to the TT's frame. This charges and drains each battery almost equally.
So now that you are totally confused here is a link to some diagrams an the TEST results of using these methods over the common way of hooking up your batteries.
SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank
Also, here is a link to our RVing with SOLAR social group here on the forum. There is a lot of SOLAR and BATTERY information here.
2013 Jayco Eagle 284BHS
250Watt Grape Solar Panel, MorningStar MPPT 60 Charge Controller
1500 Watt Ramsond PSI, 2 Trojan T145 Batteries (260Ah)
2 - AirSight Wireless IP Cameras (used as rear view cameras)
EnGenius WI-FI extender, D-Link wireless (n) modem
MagicJack Internet Phone
2012 Ford F150XLT, EcoBoost w/3.73
157" Wheel base, HD Towing Package
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