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Old 12-09-2023, 11:26 AM   #1
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23 Volts??

Is there an explanation for this?

My NOBO has a factory Go Power solar controller / 200 watt panel, a Victron smart shunt, and 4-100AH Chins batteries. It's been a few weeks since finishing the installation and charging up with the solar and shore power via factory converter. Yesterday the sun was intense for a few hours here in central Ohio, so thought I'd switch on the battery bank, then the solar to see what the shunt would show.

Well, the shunt showed 23.24v and zeroes for current, power, and consumed. I checked the solar controller which showed 14.7v and battery status of 'full' (first time I've seen this since switching to LiFePo4 batteries and selecting that mode on the solar controller.

I shut the solar panels off and connected to shore power to activate the converter and switched on the trailer. The shunt then showed 14.15v with current at -.44v and power at -6 watt.

Since the system is new to me. I'm not sure what these numbers are indicative of. Is that 23v shown within normal operation range or is the shunt trying to tell me something isn't right ?
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Old 12-09-2023, 12:56 PM   #2
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Something is odd there as the shunt should only show the battery voltage.
Are you using the Bluetooth app for the shunt? Or do you have the display?
My guess is the 23 volts is the panel voltage from the solar.
Either something is wired wrong or your mixing up what your reading.
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Old 12-09-2023, 01:26 PM   #3
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I'm fairly sure the panel is a GP-PV190M. If so, they spec open circuit voltage @24.09 and 20.4v with 9.45A at max rated output. I would say all is well with the panel. That also fits well with the input rating of the Go Power controller.
Your controller output does seem a bit high (s/b 14.4) at bat terminals. That assuming the LiFePO4 profile. But reasonable and explainable.
As kcmusa mentions clarification needed as to how the shunts wired. Took a quick peek at the Victron guide and it makes sense is you have the Aux terminal monitoring the panels and VBatt+ to the batteries.
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Old 12-09-2023, 02:26 PM   #4
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Quote:
Originally Posted by kcmusa View Post
Something is odd there as the shunt should only show the battery voltage.
.
Shunt shows net in and out of battery since all neg flow goes thru it, yes?
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Old 12-09-2023, 02:35 PM   #5
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Took a quick peek at the Victron guide and it makes sense is you have the Aux terminal monitoring the panels and VBatt+ to the batteries.
Aux monitoring not used, only the positive is connected to the positive bus. The shunt sits in between the battery neg bus and the trailer negative bus so it conducts all negative.
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Old 12-09-2023, 05:33 PM   #6
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can you post a picture of your readings

the solar controller may be showing you what voltage the panels are producing

if you have a separate shunt it will only show voltage at the battery
max 14.4v

If you have a multi meter measure the battery voltage at the battery terminals while the solar is connected
If it reads above charging voltage 14.4 ......... turn OFF the solar and have it serviced.
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Old 12-09-2023, 05:56 PM   #7
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Quote:
Originally Posted by Aussieguy View Post
can you post a picture of your readings

the solar controller may be showing you what voltage the panels are producing

if you have a separate shunt it will only show voltage at the battery
max 14.4v

If you have a multi meter measure the battery voltage at the battery terminals while the solar is connected
If it reads above charging voltage 14.4 ......... turn OFF the solar and have it serviced.

I have a pic of the shunt but not the controller. Pretty sure the controller was reading 14.7 and for sure the battery status stated 'full'. I like your suggestion, next sunny day I will repeat and take pics of shunt and controller, and if the shunt shows a wild reading will put the multi meter across battery buses.


My scientific wild a** guess is that when the battery reads 'full' the controller passes along the panel voltage instead or something weird. Have to research that.



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Old 12-09-2023, 07:43 PM   #8
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Might be beneficial to do some tracing and create a schematic of the 12v charging system (solar in particular). Both your work and Forest Rivers. Pays off ten fold doing the troubleshooting now or down the road.
Double check where VBatt+ is connected to. At that point check against a multimeters reading just to verify what the Victron is reporting. The Victron shunt is a quality unit and doubt there's a issue with it but stranger things have happened.
What I would expect is that the GoPower controller display would be flashing. That's the normal action if its seeing battery voltage > 15.5v.
Regardless, as Aussieguy states if it is anything greater than 14.4v disconnect the solar.
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Old 12-10-2023, 08:46 AM   #9
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check settings in the shunt
good thing is it cant hurt anything if wrong setting ... will just give wrong calculations results
-------------------------------------------------------------------------------
disconnect solar

check each battery is wired correct in parallel (all positives connected together) check each battery voltage at the terminals

then go to busbar Positive and negative take reading for combined batteries

------------------------------------------------------------------------------
if you got a test battery ... use it instead of your new Chins
connect solar to the test battery

what controller is there?
check for any any settings for selecting 12/24 v output

connect to test battery and measure voltage at battery terminals as it is actively charging .... drain some power from test battery
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Old 12-10-2023, 08:47 AM   #10
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As others have said, it is either a physical setup issue or an issue with the setup of the Victron Shunt software. I have a Victron charger that uses the same Bluetooth software. I know that there is a setup section for user defined items.

I am only speculating, but if the system is physically set up properly, and your multimeter indicates that the lifepo4 battery is operating properly voltage wise, then possibly there is a problem with your setup on the Victron software.
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Old 12-10-2023, 09:10 PM   #11
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check settings in the shunt
good thing is it cant hurt anything if wrong setting ... will just give wrong calculations results
Maybe that's it, something caused the shunt or software to generate a stupid number. What, I don't know yet.

For those that don't have a Victron shunt, they are simple to set up especially if your system is all organized on buses. If they're wired backwards they'll show a negative when should show a positive :lol:

I double checked the install and put a multi meter on the battery bank - No issues there. I did take the time to research the shunt settings for LiFePo4 and updated accordingly. I can't imagine any of those default values would affect voltage display.

Still hoping to repeat on the next sunny day.
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Old 12-11-2023, 10:08 AM   #12
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Voltage and current readings on the shunt should be accurate and not a function of settings (maybe a tweak for calibration). Where is the shunt positive connected. Measure from that point to the shunt negative and compare the voltmeter reading with the shunt reading. They should be the same.

When you load your circuits with a somewhat known load is the shunt reading the current correctly. My lights will draw 1.5A when on and I know things are good looking at my shunt display. Inverter or other heavy load should increase the current reading.

In my wild guess there is a bad connection somewhere that ends up making a series circuit (mentally drawing how that could even happen).
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Old 12-11-2023, 10:34 AM   #13
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Where is the shunt positive connected. Measure from that point to the shunt negative and compare the voltmeter reading with the shunt reading. They should be the same.

When you load your circuits with a somewhat known load is the shunt reading the current correctly. My lights will draw 1.5A when on and I know things are good looking at my shunt display. Inverter or other heavy load should increase the current reading.
"Shunt Battery Minus" is from negative battery bus. This bus connects the negatives from 4 100AH batteries. "Shunt Load Minus" is to trailer negative bus, all the trailer's loads come back thru the bus.

So you're suggesting measuring from the Shunt's 12v source to the shunt battery minus - validating the shunt's display. Good idea.

When I turn the trailer lights on, I see the display's current value go further negative, as I'd expect. I haven't turned on the inverter yet but will, and expect to see much more current flow.
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Old 12-11-2023, 11:26 AM   #14
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Battery voltage is pretty stable. When I plug my 70A 14.4V charger on my battery, I get a little bump up from the 13.? but the meter sure doesn't show 14.4 until the battery gets charged (hours later).

If say your SCC failed and the panel voltage was connected to the battery, it won't raise the voltage to the panel voltage but will continue to show the battery voltage. Won't be good in the future to keep the high voltage applied but the point is that a higher voltage applied to the battery won't show up right away.

I've seen some factory SCC that have a common positive connection and am working on how a mis-wire job could show 23V. Gotta love a mystery.
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Old 12-11-2023, 11:57 AM   #15
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Quote:
Originally Posted by DES-1 View Post
*****
Yesterday the sun was intense for a few hours here in central Ohio, so thought I'd switch on the battery bank, then the solar to see what the shunt would show.

Well, the shunt showed 23.24v and zeroes for current, power, and consumed. I checked the solar controller which showed 14.7v and battery status of 'full' (first time I've seen this since switching to LiFePo4 batteries and selecting that mode on the solar controller.******

Have been thinking this part over for a while. Were the solar panels turned on or off when you switched on the battery bank. It's usually recommended/required by most solar controller mfr's that the batteries be connected first. Would it make a difference in your case? Don't know but when you turned off the solar panels and turned on the converter/charger it all seemed to be normal. Just wondering.

As for the zero current, the 23 volts, and 14.7 volt readings, I can't speak for Chin batteries but a Battleborn battery BMS considers 14.7v as "overvoltage" and can shut off which can lead to zero current readings on a monitor. With a solar controller active yet disconnected effectively disconnected by the BMS it's possible that there was an effective doubling of voltage (or close to it).

Voltage doubling in DC circuits occurs when a combination of diodes and capacitors are connected in a specific circuit.

(example)


Loose or corroded connections can become points of rectification, acting like diodes. Capacitance can occur pretty much anywhere wires are close as well as within devices.

The cure is often just checking all connections so there is "shiny metal to shiny metal" contact and switching on on batteries and solar panels in proper sequence.

I would also see if the solar controller provides a way to set the Bulk/Absorption voltage, often in a custom or user select option. If you're using a LiFePo4 default it may be too high for the BMS. If you can set the voltage yourself I'd strongly recommend using 14.4v so any peak in output doesn't risk turning off the BMS in the battery.

Just some thoughts.
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Old 12-12-2023, 10:18 AM   #16
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Were the solar panels turned on or off when you switched on the battery bank. It's usually recommended/required by most solar controller mfr's that the batteries be connected first. Would it make a difference in your case? Don't know but when you turned off the solar panels and turned on the converter/charger it all seemed to be normal. Just wondering.

Thank you for researching! I do have a solar panel on/off switch installed. I always disconnect the panel before shutting off the battery bank, and likewise always switch on the battery bank first before turning on the solar panel. I have the basic factory solar controller, the go power GP-PWM-30-SQ. I'll take another read of the manual.


Looks like the Absorption charging voltage is set to 14.4v when LiFEPo4 is selected.


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Old 12-13-2023, 04:16 PM   #17
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Resolved (?)

I've managed to duplicate the 23v readings. My conclusion, based on observation, is that when the solar controller tops off the battery bank, as witnessed by it reporting 'full' and 100% charged, the shunt reports a 23+ volt charge with no draw. When I turn the trailer on and turn on lights for good measure, the shunt reports about 13.2 v and correctly shows an outflow of .7 amps or 9 watts. Afterwards, I shut the trailer off and the voltage read 13.85v.

So, I guess I'll chalk it up to a reporting anomaly between the solar controller and the shunt. I documented this test with 7 or 8 pics. While this is not what I had hoped for I can't imagine that any harm is being done.

I did manage to collect some operational information along the way. It seems the factory wired converter is supplying 38 charging amps, and the solar panel is supplying a paltry 3.6 amps (low winter sun). The solar is abysmal, but am OK for now with the converter but it's 12-15 amps below it's rating.
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Old 12-13-2023, 04:44 PM   #18
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Somethings still wrong and needs correcting. Shouldn't be seeing 23v on the 12v battery bus regardless of the state of that solar controller.
At the point in time you see ~23v collaborate that reading with one from a multimeter. That will better determine if its a reporting issue.
I have a GP-PWM-30-UL that i had replaced earlier. Not the same as yours but similar. Ill go out to the shop and see if I can replicate what you see.
Results:
On a full charged Pb battery:
@23v in 14.5 out. Constant at 14.5 up to 35v (max rated input)
@13.9 in 13.8 out.
No transients or anything else close to weird.
Totally believable that the unit failed closed and that may explain the 23v. Initial N-channel failures can be like that.
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Old 12-13-2023, 06:04 PM   #19
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Originally Posted by DES-1 View Post
I've managed to duplicate the 23v readings. My conclusion, based on observation, is that when the solar controller tops off the battery bank, as witnessed by it reporting 'full' and 100% charged, the shunt reports a 23+ volt charge with no draw. When I turn the trailer on and turn on lights for good measure, the shunt reports about 13.2 v and correctly shows an outflow of .7 amps or 9 watts. Afterwards, I shut the trailer off and the voltage read 13.85v.

So, I guess I'll chalk it up to a reporting anomaly between the solar controller and the shunt. I documented this test with 7 or 8 pics. While this is not what I had hoped for I can't imagine that any harm is being done.

I did manage to collect some operational information along the way. It seems the factory wired converter is supplying 38 charging amps, and the solar panel is supplying a paltry 3.6 amps (low winter sun). The solar is abysmal, but am OK for now with the converter but it's 12-15 amps below it's rating.
How are you "turning the trailer on" and "turning the trailer off"??

Battery disconnect?

Shore Power main breaker/unplugging??
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Old 12-13-2023, 06:18 PM   #20
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Umm...

Quote:
Originally Posted by TitanMike View Post
Have been thinking this part over for a while. Were the solar panels turned on or off when you switched on the battery bank. It's usually recommended/required by most solar controller mfr's that the batteries be connected first. Would it make a difference in your case? Don't know but when you turned off the solar panels and turned on the converter/charger it all seemed to be normal. Just wondering.

As for the zero current, the 23 volts, and 14.7 volt readings, I can't speak for Chin batteries but a Battleborn battery BMS considers 14.7v as "overvoltage" and can shut off which can lead to zero current readings on a monitor. With a solar controller active yet disconnected effectively disconnected by the BMS it's possible that there was an effective doubling of voltage (or close to it).

Voltage doubling in DC circuits occurs when a combination of diodes and capacitors are connected in a specific circuit.

(example)


Loose or corroded connections can become points of rectification, acting like diodes. Capacitance can occur pretty much anywhere wires are close as well as within devices.

The cure is often just checking all connections so there is "shiny metal to shiny metal" contact and switching on on batteries and solar panels in proper sequence.

I would also see if the solar controller provides a way to set the Bulk/Absorption voltage, often in a custom or user select option. If you're using a LiFePo4 default it may be too high for the BMS. If you can set the voltage yourself I'd strongly recommend using 14.4v so any peak in output doesn't risk turning off the BMS in the battery.

Just some thoughts.
Umm, Mike, that's the Greinacher circuit. It needs AC in to produce DC with twice the amplitude. Essentially on positive peaks one diode charges its capacitor to the peak voltage. On negative peaks the other diode charges its capacitor to the negative peak. The two capacitors are connected in series, so their stored voltages add.

It's an AC-to-DC+ripple circuit, not DC to DC. Well, really it could operate with DC that had a lot of ripple. I don't see where you would get that in an RV. See this link.

Back in 1968, when I was in college, I had to work with a Cockroft-Walton generator which is a cascade of these circuits to produce a very high voltage. It was used in a Cyclotron particle accelerator. My main job was to operate the Cyclotron.
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