Charging house when motor running shows no change on Victron.

bmcminn

bmcminn

Active member
Joined
Apr 8, 2025
Messages
25
Fluid Motion Model
C-248 C
Vessel Name
Umi Nami
Hey folks. I can get more details if you need them but right now I'm away from my boat, a 2026 C-248. It's new (24 hours running), so in theory everything should be working fine.

Everything electrical seems to be working great except, I can't get the battery to charge when the motor is running. It charges great when plugged into shore power, but otherwise nothing obvious.

I have tried this with the switch on the main panel set to shore power, the center position, and the inverter. With the battery charger switch off and on. With the house battery off and on. Maybe there is a combo I haven't tried but I think I've got them all.

When I look at the Victron app I see no major change in voltage or amp draw. I can see a draw-down change in the app by turning things on and off, even small stuff like my laptop and a display. But I never see it go up unless it's hooked to shore power.

Does this seem right to you all? I can ask my dealer about this, but I have a list of things and want some back-up from the community. Even in theory.

Thanks for any insight.
 
If the battery’s are down even to 90 percent you should see positive current (amps) coming in when running your engine. The engine battery needs to be fully charge before the DC DC converter charges the house bank. My boat has twin engines. So you will see at the most half of mine so around 30 amps. The voltage is not a good indicator.
IMG_5817.png
 
Have a 2025 Solara 250c, which is basicly the same boat. Same issue with mine, but luckily it was identified by the FM rep while running the boat during the factory delivery training and was fixed before it was shipped to my dealer. Not sure if its a common problem, but it was a defect from the factory on my boat prior to final delivery.
 
fred237 said:
Have a 2025 Solara 250c, which is basicly the same boat. Same issue with mine, but luckily it was identified by the FM rep while running the boat during the factory delivery training and was fixed before it was shipped to my dealer. Not sure if its a common problem, but it was a defect from the factory on my boat prior to final delivery.
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What was the fix?
 
I saw this problem on a newer Cutwater, in that case the problem was that the house and start battery negatives were not connected together, so the DC to DC charger wasn't sensing voltage properly. Make sure there is a battery cable connecting the two bank's negatives. Otherwise you'll need an electrician with a multimeter to look it over.
 
The good thing is that you have a new boat that the factory is still responsible for. And you are asking questions and identifying issues early. Keep asking questions and reading posts.
 
This is a slightly different problem. It's been on shore power, plugged into my house for over 48 hours. The batteries were at around 21%. They got to 83% about 12 hours later and haven't changed since. The switch is set to shore power. Is there a reason it would be this way given that my usage has been really light?

Thank you all for the help. At this rate I should have these kinks worked out by spring.

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bmcminn said:
This is a slightly different problem. It's been on shore power, plugged into my house for over 48 hours. The batteries were at around 21%. They got to 83% about 12 hours later and haven't changed since. The switch is set to shore power. Is there a reason it would be this way given that my usage has been really light?

Thank you all for the help. At this rate I should have these kinks worked out by spring.

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View attachment 26517
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Is it possible your battery monitor may not be programmed correctly? What are the settings you have for battery capacity, charge voltage, etc.?
 
JMarshallR25 said:
Is it possible your battery monitor may not be programmed correctly? What are the settings you have for battery capacity, charge voltage, etc.?
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It has shown 90-100% as recently as last week. The app shows the same charge as the Victron monitor on the helm station...

Thank you, that's a great idea. I'll take a closer look at it tonight, but I don't think it's what is going on with my situation.
 
Another thought.
Our 2026 Solara has Epoch batteries. You can get the app for epoch batteries and pair with each battery. Then you can see the true state of charge of each battery. Not relying on the victron monitor.
I tried loading a screen shot but not working right now.
 
Also on the screen of the dc-dc it should show how many amps the engine is charging to the house.
 
Mike and Sarah said:
Another thought.
Our 2026 Solara has Epoch batteries. You can get the app for epoch batteries and pair with each battery. Then you can see the true state of charge of each battery. Not relying on the victron monitor.
I tried loading a screen shot but not working right now.
Click to expand...

This is important because your EPOCH batteries also have a thermal blanket that comes on around 40 degrees so they can be used during cold temperatures. The Lithionics battery I have is the same, and offers Bluetooth to the BMS so I can see the real SOC. When I run extended periods of time without plugging into shorepower, my Victron BMV will "drift" away... Victron may read 58% while Lithionics will show 64%. I go into the Victron app and set it manually to match that of the Lithionics. They drift apart slowly, as I usually only notice this after I spend many weeks disconnected from shorepower, and don't get back to 100% SOC via solar for many weeks.

Battery temp is 42 degrees, BMS outside temp is 31 degrees. Thermal blanket is on, allowing me to charge my LFP battery down to -20 degree. The thermal blanket bypasses the Victron shunt, thus in this case, I would expect my battery SOC to be lower than Victron would report.

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I agree with Martin, your Victron is showing 83% charge, but the voltage is that of a full charged battery and there is no current going in, which suggests it's really at 100% but the Victron is off.
 
Like Martin says
If the battery is truly charged full you can do sync on the victron app. Which will change the percent to 100 like a reset.
 
Thank you everyone. That was the issue. Synced now and at 100%!
 
Martin, the Victron shunt should have reset to fully charged on its own according to their literature. Here is the quote. I have AGM not lithium so I can't provide the settings. Do you know of any reason that this function should not work on lithium also?

7.2.2
The battery voltage must be above this voltage level to consider the battery as fully charged. As soon as the battery monitor detects that the voltage of the battery has reached this “charged voltage” parameter and the current has dropped below the “tail current” parameter for a certain amount of time, the battery monitor will set the state of charge to 100%.
 
SKing said:
Martin, the Victron shunt should have reset to fully charged on its own according to their literature. Here is the quote. I have AGM not lithium so I can't provide the settings. Do you know of any reason that this function should not work on lithium also?

7.2.2
The battery voltage must be above this voltage level to consider the battery as fully charged. As soon as the battery monitor detects that the voltage of the battery has reached this “charged voltage” parameter and the current has dropped below the “tail current” parameter for a certain amount of time, the battery monitor will set the state of charge to 100%.
Click to expand...
On our 2026 Solara we found the victron not resetting (sync) on its own even after the batteries were fully charged. Victron was off 7 percent when compared to the Epoch app which shows each battery independent from the victron. Epoch app showed full charge but victron was constantly 7 percent lower over the first week of ownership. Since sync victron both apps have matched the last 6 months.
 
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