Connecting a Zig marque 1 panel

Starter +ive to lower blade of source selection rocker switch LHS (panel front).
Leisure battery +ive to upper blade of same switch.
Fuses as close to the battery terminals as possible on both. 100mA FB will do or just go with the cable rating. [Edit:] 30A fuse if you're keeping the bus bar setup and 2.5mm² cable.
Meter ground (white wire) to good chassis ground or battery -ive.
This will enable the next to useless voltmeter.

Try not to use existing circuits for meters as then they will only measure the circuit load voltage not the battery terminal voltage.
[Edit:] Ah, I see the numpties at Zig have already catered to put a 30A load on the meter conductors by using it as a bus bar.

Load +ives to their respective fuse holder blades for the rest.

It's based on a common ground wired system with chassis returns.

The point of connecting the starter battery is to monitor it's health, charging and discharging. It looks like you can run your pump, lights and aux. from either battery depending on the selector switch in emergencies.
If you want a proper job meter get a SmartGauge or a Trimetric.
At the very least get a digital panel mount with 0.3% accuracy, three digit display.
At the very very least an ebay job with an adjustable trimpot because nothing you buy on ebay will be calibrated.

I'd put the main battery monitor in the living area by the way. That's where you'll reference it most.

There's huge problems with alternator charging. It's as rare as hen's teeth to see it done right.
The alternator by design is not a charger it's a generator it supplies power to electrical loads by observing the state of duress a battery is under. The battery leeches charge from the system that is not to say it charges. When it is heavily discharged it appears and behaves as a larger system load.

It's as intelligent as a box of hammers but it can work like an elephant.

To make an alternator a charger it needs vast quantities of copper.

The problem being; it's regulated (cable) meters from the battery on cable, terminations, connections, switches, fuse holders, fuses that is effectively a resistor, it reads only the voltage of the tips of the wires attached to it's internal regulator. The best way to allow it to see the battery end of things is to use short direct runs with big cables that have effectively no resistance (<0.3% voltage drop at full load) so it can see the battery(s).

The next problem with split charging is that the alternator will never see the true voltage of your leisure battery; only the voltage of the sum of your starter battery plus your leisure over 2 (or worse if you use diodes...really don't they're garbage for this purpose). So it's already producing half (ahem...half-ish..relative bank size, discharge level etc..) of what it ought in terms of charge current.

There's a few ways around this.

The best is two alternators with a redundancy switch, with big cables on the leisure side.

The next is give it a (super-expensive) brain like a Sterling Battery to Battery charger they pop up here cheap every now and again.




The Sterling will still require a cable upgrade so best tackle that first, eh?

The most prevalent is a relay switched by the dash charge indicator light but it's not unidirectional so the starter cannot be charged by other charging sources like PV or mains without further intervention.

I use me noggin' and a switch that fires a 200A latching relay. When I abandon the vehicle I use a SmartBank because it's super intelligent and not limited to current as it has an external relay. All the kaboodle I pick up from this seller for buttons. He's on holliers but I know he has a few more in stock along with 200A previously loved state of the art relays...also for buttons.

You can reroute your alternator B+ to be closer your leisure battery, but only start from your starter, with the auto-electric loads still on the starter side. This is finicky but worthwhile.

The issue with your "heavy duty" VSR is it's not big enough for purpose in ampacity or mechanical strength to hold the cables you require for an alternator charger. It'll work as a generator and develop a feeble amount of charge and be safe if protected with two 30A fuses on the existing cables at each battery positive but you've lost most of your charge before you started.
It takes at least 12 hours to charge a deep cycled battery, your alternator, usually does no more than 2 hours. You want it to work hard and fast. Expecting it to get cycled batteries over 85% is usually asking too much of it.

My Mk-2 alternator charge circuit used to produce 7A max at the leisure battery. I'm on Mk-9 now and I've increased my harvest almost tenfold with just direct cabling on heavy conductors (and a bigger, faster, more better alternator). I reckon I could squeeze her to fifteenfold with enough dosh and desire.

Alternators are only good at bulk charging they're fast and powerful but for the last 10% you need lots and lots and lots of time with diminishing current which is where a PV module rules the roost.

Honourable mention.

No idea P. the bumblebee has been on mains float the last two weeks. I've a 110W panel angled 15° on the house that harvested roughly 10Wh today.
I had 75Wp coming in on the solstice.
I've been running on the alternator charge mostly since November, 600W is the most I've seen outta that but I can only check the Trimetric while the engine is idle (low RPM) because it's in the living compartment. Belt is still slipping a tad on startup...methinks I need to replace the pulley for the original...Summer Job.

I can pull the log file but the alternator will probably have contaminated the data. Although I usually don't bother running the alternator through the charge controller these days unless I want extra oomph. The 200A relay does a much better job. They regulate about the same in absorption but the relay kicks bottom in bulk. [Edit: Relay wired on 35mm² cable, solar controller wired on 16mm² with a 40A breaker]

Lowest the batteries have seen was 70% SOC because I fell asleep with the fridge running off the inverter. They're mostly sitting between 80% and 92% SOC.
I'm taking her outtov port for a week tomorrow I'll let you know later.

Mwa! I've just thought of a redundancy / dirty start assist for a 12V / 24V setup;

Centre tap the 24V battery to a relay and parallel to the starter battery.

10m is standard length. You might get welding cable cut per metre.
30m for two core and 100m for mains flex. Smaller lengths will be astronomical prices.

You can mount AGM sideways. I will refabricate the battery tray to shoe-horn in a battery if needs be.

$400 is what they cost. Hence I did the kWh lifetime calc because you won't find better outside of forklift cells.

The flooded TMX is probably the best battery you can get. Its more expensive than golf carts though and doesn't perform as well.