Charging issues

Donald Tyson · Joined: 24 Jul 2023 Posts: 584 Photos: Thistle

Alain, both house batteries are 12.08V. The starboard starting battery is 6.1 and is hooked parallel to the port side which is 12.8....13.3-13.4 with the solar on and the Stbd battery turned off.

Donald Tyson · Joined: 24 Jul 2023 Posts: 584 Photos: Thistle

I'm a bigger sort of guy and I can't see any switches on the charger or the inverter. I've used my camera to peer in to the back sides. Nothing. In the Starboard battery box there are fuses to starting battery charger and also a breaker to the house batteries. There is also a switch to turn on the DC Inverter. The little screen on the Inverter reads 11.9. not enough.

Tomorrow I replace the starting batteries and will re evaluate.
I'll also be getting a new 50 amp adapter to connect my house power to the boat.

I'm about at the end of what I can tolerate. Time for a technician.

alainP · Posted: Sat Jul 12, 2025 11:35 am Post subject:

Don, if your inverter is connected to the house batteries (as it should be) and those batteries read 12.08 V the 11.9 V at the inverter makes sense, the slight voltage difference is the loss in the wiring connecting batteries and inverter.
I agree that hiring someone to sort things out is the right move. Make sure to get a diagram when everything is said and done,

Tom Hruby · Posted: Sat Jul 12, 2025 4:26 pm Post subject:

First of all: if your battery is fully charged and only reading 12.08 V you need to replace the batteries. A fully charged Lead Acid battery (AGM or Flooded) should be reading 12.6-12.8 V when fully charged, and with no load on it.
Also, if the voltage at your inverter (battery end) is reading less than the battery when it is not in use, the voltage drop is not a result of the wires, but rather a poor connection (most likely corrosion).

Donald Tyson · Joined: 24 Jul 2023 Posts: 584 Photos: Thistle

While I agree 12.1 or 12.08 is not a proper level. So I assume that those batteries are shot just like the surveyor said that they soon would be (2017)
Yes, this time I'll hire someone, I believe I know the right fellow and that he will let me watch or even help to learn. Thanks Alain.

Donald Tyson · Joined: 24 Jul 2023 Posts: 584 Photos: Thistle

Thanks Tom, I agree, Yes, I want to replace them all. They're all from 2017. Then if he wants to diagnose further he will know that it's not the batteries. Now that I have seen this I bet it was the batteries all along because everything was fine at Hontoon. 6-7 months can make a diff. As John Highsmith mentioned the fridge...Just to be sure... I'll have the tech run me through the sequence for using the fridge without draining the starting batteries. Replacing the Batteries should also assure that the connections are all good as well.

thataway · Posted: Sat Jul 12, 2025 7:18 pm Post subject:

Tom Hruby · Posted: Sun Jul 13, 2025 4:11 pm Post subject:

Also, always use "marine" rated wires. That is tin coated copper. Never use aluminum, copper coated aluminum, or just plain copper. After 29 years of going electric I know from experience that any of the latter will eventually corrode (even plain copper). In my first electric boat I tried to save money by using 6 gauge pure copper jumper cables and later 2 gauge welding wire, but all of these ended corroding inside the plastic jackets. The wires were corroded over the entire 15 ft of their length.

So, in addition to checking all the connections as suggested by Bob, you will need to make sure the proper wire was used.

Donald Tyson · Joined: 24 Jul 2023 Posts: 584 Photos: Thistle

Yes, One by one we will check. Thanks for mentioning the need for caution.

So, in addition to checking all the connections as suggested by Bob, you will need to make sure the proper wire was used.[/quote]

Donald Tyson · Joined: 24 Jul 2023 Posts: 584 Photos: Thistle

Sometimes I trap myself by making assumptions and not following them up with questions , huh, imagine that, me not asking questions!. When I bought this boat, I merely assumed that the solar panel worked to keep all batteries topped off. As it turns out, I now have learned that it is only hooked up to the port starting battery.
I drop this boat off at a local dealer today and he's going to look for a way to have the solar panel top off all batteries and keep everything fresh. Maybe way too expensive I don't know. He first has to find out what the potential is for the solar panel. It may only be good for one or two banks.
He will start by replacing all the batteries and then tracing and checking all the wiring. One of the things that he commented on was that all of my accessories are hooked to the starting batteries and not the house batteries. He may make some changes on that...

Tom Hruby · Posted: Mon Jul 14, 2025 3:50 pm Post subject:

Check the wattage of the solar panel. If you can't get at the label assume the maximum is about 20 watts/square foot. If the panel is flat, and not facing the sun at 90 degrees and your boat is moving in different compass directions, the actual value is much lower. Here in the Pacific Northwest I have found that on bright sunny days my average between 10 and 4 is 65% of the rated capacity. So a 100 watt panel will produce only 65 watts x 6 hrs = 0.39 kWh/day.

On my 22 ft cruiser I was only able to put on only 12 square feet of panels (together they are rated at 260 watts), and I had to search far and wide to find some that filled almost the entire cabin top. At most I get only about 1kWhr of energy per day. This will not even recharge my house battery to account for the drain of the fridge.

So if you want to be able to shunt power from the panels to either the house battery or starting battery I suggest a simple switch. It does not make sense to try and charge both batteries at the same time from solar.