Dual Battery Setup - Sanity Check

[escapen]

Yet another dual battery system thread!

Looking to get a sanity check on my diagram (apologies for how poorly it's put together), see what you all think and if I'm missing anything. I still have to calculate all of the wire gauges. All I know so far is that I'll be using 2/0 to from house battery to the SafetyHub in the rear. Any crossing of cables in the diagram don't mean they'll be connected in any way, I just suck at making diagrams. For the SB connectors, I used a black line outlined in red to represent both the negative and positive cables.

I'll be using the Shrockworks Dual Battery kit for the house battery. The RELiON RB75 house battery fits in the tray, except the length is 10.2" when Shrockworks lists the maximum length that works for their tray as 10.1". I'm hoping I can squeeze it in.

One thing I'm not sure of is where I'm going to fit all of the Victron stuff in the engine bay in my 2018 4Runner.

 

[rayra]

All those high-amp devices / loads on your house battery, but you think it's a good idea to block ~100A of available charging current to your house battery by putting a 30A DC-DC chokepoint on that engine-running power source? Let your smart solar take care of the 'topping off' of the fancy battery and put a simple inexpensive combiner solenoid in between your factory charging system and the house battery, instead of that DC-DC charger. Get the full available power flow from your Alternator / factory charging system while it is available. ****** good does a 'smart' DC-DC charger do when it is only passing 30A to your hungry house system and essentially blocking the potential full output of your alternator. Especially if you already have a 'smart' charger in the form of your solar controller?

I could figure out your diagram but it mgiht be easier to interpret if there was some sort of logical / physical arrangement of the elements that more cleanly shows the 'flow', left to right, top to bottom, whatever. Try to mimic their physical placement in the vehicle. Or at least group the elements by their principal battery or fuse panel source. Get the general payout working and then try to compress the elements into the visual space available, rather than plopping elements wherever and making a maze out of the wiring diagram.

 

[Chris Boyd]

Have another look at the ratings for the victron stuff. I’m not sure any of it is rating for The underhood heat loading you’d see in an engine bay. I’ve not looked specifically, but I wouldn’t put a victron MPPT there. I’d do some reading on lifePo4 batteries under hood too... many reports of that being a bad idea too.

You can greatly simply the solar aspect by using the redarc BCDC and its solar input which will also function as an isolator (they have a 50A now too). This is rated for under hood and used by many there. It has solar “green priority” and can charge lithium. (To raya’s point - this is why you’d need a dc-dc... or if the alternator is of the “smart” variety).

Given the heat loading on the lifePo4, you might see what large group 31 you could fit underhood. You don’t care about weight there I would think. Price would be much better too.

 

[Chris Boyd]

BTW, I just this past weekend got done swapping a 7 year old Luna Smart separator for a BlueSea ML-ACR which is rated for the environment and up to the task of >100A service. If you ditch the lifePo4, consider using that as the smart separator/isolator.

 

[Buddha.]

Personally I would ditch the lithium house battery and the DC—DC charger and run the biggest pair of regular lead acid batteries you can and a regular solenoid. Trying to put a lithium battery and it’s DC charger under the hood might be more trouble and money($800+?)than it’s worth.
How much solar do you plan on?
That solar controller seems a bit oversized. I run that same Victron 100/30 with 400w of solar and I could probably double my solar panels with that controller.

 

[Martinjmpr]

That whole setup looks hideously complicated and to my non-electrical-engineering eye, looks like there are a whole bunch of potential failure points that are going to be a nightmare to diagnose if something goes wrong.

I'm a recent adopter of the DC-DC charger but in this case I have to agree with Rayra. Why are you using one here instead of just putting in an isolator and charging the house battery off the alternator? Is it because your house battery is a Li-Ion and has a different charging profile?

And this is on a 4runner? Good grief, where are you going to put all that stuff? Is this for a vehicle that's going to be used or is it just a demo for an electronics shop?

IMO when it comes to electrical stuff, follow the KISS principle: Simpler is better. Imagine what a hassle it's going to be trying to diagnose a problem if even ONE of those connectors fails or a wire breaks.

I would echo what others have said above: Start with a SIMPLE dual battery system, charging off the alternator. Adding solar is easy - I have a 100w folding panel that plugs into the battery with an SAE connector. Is it the most efficient system possible? Nope, but it's SIMPLE and it WORKS.

Unless of course you have a Money Cannon:



In which case, knock yourself out.

 

[WOODY2]

Money Cannon, that's a good one!! Concur on KISS ?