Solar panel charging question

[dennis41]

This is about a 2016 C30CB...I noticed the other day while in the bowels of my boat that the wires connected to #2 on the solar panel controller go to the Thruster battery. How do amps from the panel get to the Start battery? Or do they get there at all? And the reading on the Remote Meter for #2 must be for the Thruster battery, right?.....not the Start battery, as was stated in my long ago new boat orientation.
Should those wires be connected to the Start battery instead?
So currently, the only source of Start battery voltage info is #2 on the analog gauge on the electrical panel. The way this is set up now, it seems the only way the Start battery gets charged is via shore power or engine alternator.
Just trying to understand the whole charging thing.
Thanks,
-Dennis

 

[Shano]

The way it is supposed to be set up is 90% house and 10% start battery. On our boat at first I thought that the solar panel was connect to our thruster battery but on closer inspection (not totally sure yet) it seems that our start battery is In the thruster battery’s place. That is, our thruster battery is on the outside to starboard and the start battery is on the inside. I haven’t had the time to trace the cables to the buses etc or from the starter to the bus or battery whichever it is and it is not easy to trace because of the space limitations etc. I do now have a good clamp tester so I will get testing and figure it out. If I am wrong then our thruster battery is getting the 10% charge. I do need to figure it out because I am going to replace the start battery and obviously I want to replace the correct battery and not have to redo the job! I did do some testing with my new Ancell 200 tester and I tested both batteries before using the thruster and after - both batteries had a big drop in voltage after using the high draw thruster so which makes no sense to me yet. I am learning tho....slowly. My last few boats were much easier to figure out.

 

[dennis41]

Well, Shano, this sounds like another question for Andrew. It never really occurred to me that the batteries might not be positioned as shown in the owners manual. I,too, am replacing my start battery - with a Northstar group 31AGM. As you know, it's a job for a contortionist to remove & replace a battery in this boat, so I want to do it right the first time.
Andrew, perhaps you can straighten us out on this & my questions in my previous post as well.
Thanks,
-Dennis

 

[Shano]

I did some more testing, this time using the voltmeter at the panel and the remote thruster controller. Initially, both bank 2 and 3 had a large voltage drop when activating the thrusters however after the first test only bank 3 had a large voltage drop when using the thrusters. I can’t explain why the initial voltage drop on both bank 2 and 3 happens but it is clear that bank 3 is the thruster battery. So I went in the lazerette and tested the voltage drops with my Ancell tester and my batteries are set up as they should be however the solar feed was going into the thruster battery. I changed this so now the start battery is getting the 10% solar charge. Progress!

 

[dennis41]

Thanks Shano for doing that testing. It confirms the layout as shown on pg.20 of the owners manual,which also shows controller output #2 going to the engine battery. I will also redirect those wires to the engine battery. This finding is especially good since my new battery just arrived & now I'm confident I will be replacing the right one 🙂 .
Andrew, you might want to tell Dave, John or your lead electrical Q.A. guy about this. It just might be a chronic wiring error.
Thanks again, Shano.
-Dennis

 

[Shano]

Hey Dennis, I’m happy to share whatever insight I have! I am very interested in seeing how easy it is to swap your new Northstar in with the existing cabling, I am thinking of buying the same battery and maybe later the NSB 27m for the thruster battery. I am not that concerned about the thruster battery if it fails or somehow gets below 10.8 volts while we are out. It might make docking a lot harder under certain conditions but not being able to start the engine - that is obviously another situation all together!