One of the house bank batteries died (it started sulphurating and then wouldn’t hold charge) while on our shore power charger. This forced us to think about the batteries.
We have left the starter battery as it is as this seemed pretty good. For the house bank we now have 4 x Trojan T-105 6V 220Ahr batteries. So we now have 440Ahr capacity (double what we did have). We have built a new battery box to house the extra 2 batteries.
We also solved the problem of how to connect everything to them.
6mm x 25mm copper bar (made from of copper tape lightning conductor) drilled and tapped with M8 brass bolts for terminals.
We need these because we have the following directly connected to our batteries:
One 1 both 2 switch (that feeds everything on the switch panel)
A split charge relay & sensing cables
A shore power charger & sensing cables
Two solar panels MPPT controllers & sensing cables
The alternator & sensing cables for smart regulator
The battery monitor sensing cables
Nothing we think shouldn’t be there but too much to fit onto a single short M8 stud.
These should maximise our output from the panels and having 2 will give us some redundancy. It was also cheaper to buy two of the smaller controllers than one that was big enough for all 4 panels.
The panels are wired as 2 sets of panels. Each set wired in parallel to two charge controllers. Wiring in parallel although theoretically slightly less efficient should minimise any effects of shading on a single panel.
All the connections have been done with MC4 waterproof connectors. These were easy to use and means that it is straight forward if we need to change the way the panels are connected.
Each panel has 4mm2 cable running from it. Each pair of panels has 6mm2 to the MPPT controllers and connected directly to our house battery bank.