Running OEM Electronics off Aux Battery and SBI vs Marine Switch? (1 Viewer)

[82SC]

So I was wondering if I wanted to let me kids watch a movie on the rear entertainment system without the engine running how long until you'd drain the main battery?
Or could I find a way to be able to run the OEM electronics off the AUX battery

I am in the midst of planning and installing a dual battery system. Redarc has been very helpful and the tech forwarded me this diagram as his "ultimate dual battery setup"
I posed the question to him and waiting a response but want to ask you guys too.

If I added a 1/2/1+2 Martine switch could this solve my question and could potentially get rid of the SBI?
This would be in conjunction with the BCDC.

If I connected the Main Starter Battery to 1 and Aux Battery to 2, and then output was the OEM wiring harness.

I could run the car most of the time in the 1 position.

If I am in the car waiting and want to turn a movie on for the kids without running the engine, I could pop the hood, flip the marine switch to 2 and then run down the Aux battery playing the radio or the rear entertainment system. Also would allow all the OEM USB and cigarette lighters to continue to charge of the AUX battery while engine is off.
Then switch to 1 and startup and leave.

And potentially switch to 1+2 in the rare case I need to jump start myself.
Not as fancy as the SBI but essentially an analog version of an SBI with the added benefit of being able to run the OEM electronics

Plus the off switch could also prevent any parasitic draining or forgotten interior lights from draining the batteries to 0


OR

If I ran it the way it is diagramed. Parked the car and turned it to the on position and ran all the electronics
Would the BCDC and SBI sense that the Main battery was dropping voltage and top it off from the AUX battery?

 

[TeCKis300]

Therein lies the problem with most dual battery setups. It's primarily two banks to run different things, yet everything still only generally has access to a single battery. In a car, unless majorly rewiring a bunch of things and consciously trying to decide or switch what runs on what bank, it's far easier to manage and use as a single bank.

Forgive me if I'm a bit cynical about most dual battery configurations. Including Redarc's "ultimate dual battery setup", complexity for it's own sake, which may just be to sell the maximum amount of Redarc gear. IMO, the ultimate upgrade shouldn't require a bunch of fussing or managing of anything electrical. It should just work.

I camp. A lot. Including letting my kids sit in the car and watch movies. I prefer the KISS approach - have a healthy and strong single battery. Keep a lithium jump starter with you as the uber mitigation. Too much additional complexity in the electrical system, besides being a PITA to install, manage, and troubleshoot, may just be a liability in itself.

A single upgraded group 31 may be all you need if you consider yourself a power user over stock, which is plenty healthy.
Group 27 - 90Ah (stock)
Group 31 - 115Ah (27% more capacity)
2x Grp 27 - 180Ah (100% more capacity)
2x Grp 31 - 230Ah (255% more capacity)

For a single upgraded battery

Homebrew Single Group 31 Battery Install

Took a cue from this thread and ordered a high quality Deka 1131PMF battery. It's a flooded lead acid which has the advantage of full compatibility with the stock smart alternator charging profile (and longest life prospects). With often sought features of AGM including: - Spill proof - Heavy...

forum.ih8mud.com

If you're a true power user (rare), then here's a super simple strategy for duals. Real expanded capacity for everything on the car

KISS Dual Battery Upgrade

There’s been a lot of discussion on batteries and battery systems. Here’s my attempt to offer an easy button. The task of a battery first and foremost is to offer power and reserve capacity. There’s many battery setups and systems talked about. But perhaps some of those are solving a problem...

forum.ih8mud.com

 

[CharlieS]

The BCDC doesn't charge the starting battery, it only manages charging of the auxiliary (house) battery.

It manages charging for batteries with different battery chemistry that need different charging profiles, and allows for/manages solar charging input.

You don't need a BCDC if you're running a pair of flooded lead acid batteries.

I found the smart battery isolator to be waste of money in my setup. I neutered it to make it into a self jump solenoid by removing the "smart" portion (red box).

 

[Bunga]

A counterpoint: There are two (M6 L bracket I think) factory cables on the starter battery. It looks like one is from the alt and the other is for the fuse main. Is that correct?

If so, it looks like I can run the battery to the alt like stock, and take the second line off the battery and attach my Victron smart low voltage cutoff (between the starter battery and the stock bracket) for the fuse side. Then I can protect the starter battery down to a precise voltage, and split that to run a single pole double throw (spdt) switch to my second battery and use it like a true house battery.

Thoughts?

​

 

[82SC]

That’s what I am thinking.

Check out this video.


Around the 11:30 mark.

I reached out to PDP and redarc
And sounds like they using 2 5 pin relays to achieve this. I’m working on getting a detailed wiring diagram.

This is exactly what I was looking to do.

I was thinking actually of the cable that comes off the main wiring loom into the fuse box as the possible point of wiring.

 

[Bunga]

I wish there was a clear description of the loom. I'm going to see how far I can strip down and trace those two and see if my guess can be tested.

 

[82SC]

I was gonna just hook up my jump pack to different areas and see what runs and what doesn’t.

 

[Bunga]

Looks like one of the lines is from alt and the other to starter, so isolating that would do nothing.