Single battery v. Dual battery (Off grid side by side)

I'm in the process of building out the back of my Taco for camping. I plan to have a behind the bumper light bar, some rear-facing camp lights. I ordered the 3 cig 12V DC power block from Leer and plan to use it to run a fan in the summer and some sort of

$40 Car Cozy 2 - 12-Volt Heated Travel Blanket with Patented Safety Timer by Trillium Worldwide (Navy, 58" x 42")

heated travel blanket in the winter and probably charge some phones overnight. I will more than likely driving during the day to charge up, but might stay stationary for 2 nights.

Will a single battery setup suffice? I was thinking the X2 31M battery + a larger battery cage.

Do I need to go dual batteries? If I go dual, I have a few more questions:

1. I was thinking about going with the Off Grid Engineering Side by side kit.
   1. If I do, will the extra
      $290 OPTIMA Batteries OPT8040-218 D35 YellowTop Dual Purpose Battery
      Yellow Top provide enough juice to power my stuff (in conjunction with my current battery or a matching Yellow Top)?
2. Would a
   $330 OPTIMA Batteries OPT8016-103 D34M BlueTop Starting and Deep Cycle Marine Battery
   Blue Top get the job done, using my current stock battery as a starter?
   1. I know the recommendation is two get two of the same style battery, about the same age, but I'm not too thrilled about replacing my stock battery that is not even a month old.
3. Would the Blue Top even fit side by side with my stock battery?

My local off-road shop said they can make a dual battery setup work, all I have to do is bring in the deep cycle I want to use, and they will do the rest. I like this idea because I can still use my current starter battery, but I'm worried they might not be the experts in this area. Also, where else could I even mount a second battery if not in the Off Grid Side by Side system? I don't have a TRD Off Road, so the Split System is a no-go.

 

If you are going to be camping out of the back for more than just a couple of nights, I would definitely look at getting a dual battery setup. You don't want to be left stranded somewhere because your starting battery is dead. I'm building out a dual battery system in my '17 right now. I'm using the off grid engineering Auxilliary battery tray with an old Group 27 deep cycle battery. Right now its hooked up to a solar panel in the bed of the truck that keeps it topped off, but eventually I will be connecting it to the main starting battery using an Automatic Charging Relay from Blue Sea. I've only had the OGE tray for a couple of days but it is very well built and it fits very nicely in the space behind the air box (if you have the Off Road).



I'm not sure about the heated blanket but the yellow top should be more than capable of charging a couple of cell phones many times between charges. You'll need to know how many amps the accessories you have draw and for how long you want to run them. These lead-acid batteries love to be charged, so try to leave as much room in the budget as possible so it doesn't get run down too much. I found this following website to be useful in determining (roughly) whether my battery is capable of running the accessories I wanted.

 

Looks like the heated blanket is 48 watts and 4 amps. If there are any experts here that can tell me how long it would take for that to drain the Yellow Top.

 

The yellow top comes with two ratings: 66Ah or 75Ah
You should never discharge the battery below 20% of its capacity so we'll take 80% of the total rated Ah for our calculations:
66*0.8 = 52.8
75*0.8 = 60

To figure out how many amps the blanket will pull:
48Watts / 12V = 4A

To find out how long you can run the blanket continuously on the battery between charges:
52.8Ah / 4A = 13.2 hrs
60.0Ah / 4A = 15 hrs

This is theoretical, and there is going to be some efficiency loss in the system from the cables, any inverters, heat, etc.

 

Awesome, Thank you!