Completely confused with my solar system!!

[RVRoadramblers]

Hello all, I am completely bumfuggled over this new system we recently installed in our RV. Here are my system components for reference:
4 - 160W panels
4 - 100Ah Battleborn 12V LiFePo bats
Victron Multiples 12/3000/120 inver.
Victron Mppt 150/85
Victron Cerbo GX
BM 712 Smart monitor with shunt
Victron GX Touch 50 Display

We attempted to install this system ourselves and felt like we were doing it right but we've had issues on two occasions that we don't feel like we should.
We have woken up with the display showing low battery voltage when we are barely utilizing the system. We are very conservative when boondocking and keep all the lights off unless needed for brief moments etc.
The fridge is pulling a small amount for the 12v side (RV fridge on propane) our composting toilet has a small 12v fan and our WiBoost cel booster has a small 12v power supply and we do charge our cel phones at night but that's about it.
The thing that is throwing me ( other than the voltage dropping so quickly) is that this morning the display is reading 80% SOC but the voltage is showing 11.6V.
I don't feel like I understand the data that the touch display is showing me and I don't understand the states of charge on these batteries.
And is it possible that I have my battery monitor wired so that it is feeding false readings?
I'm sorry, I don't feel like I even know the right questions to be asking.

 

[MurphyGuy]

What does the victron app say is happening? It should show charge and discharge over time.

 

[RVRoadramblers]

What does the victron app say is happening? It should show charge and discharge over time.

Honestly ( and embarrassingly) I'm not sure I understand how to read all the data that the app has. I wish I could take a class on that. Here's a screenshot of the screen from the Mppt controller under the "history" tab.

 

[MurphyGuy]

I think there should be a line graph chart page that shows you near real time SOC states.. The next time your bats run low, check that line graph to see where the power is going.

I've only played with one victron system but I was impressed with the software.. really good software..

My guess (just a guess) is that you're underestimating the power draw of something.. probably that little refrigerator that most likely runs on a current sucking thermoelectric element. Maybe couple that with a cloudy day where the bats never get a good charge, and it can seem like something is wrong.

Check your software and figure out what's drawing current.. your little fridge probably has a guilty look about it right now.

This all assumes you have your charge voltages set correctly within the charge controller..

 

[RVRoadramblers]

I think there should be a line graph chart page that shows you near real time SOC states.. The next time your bats run low, check that line graph to see where the power is going.

I've only played with one victron system but I was impressed with the software.. really good software..

My guess (just a guess) is that you're underestimating the power draw of something.. probably that little refrigerator that most likely runs on a current sucking thermoelectric element. Maybe couple that with a cloudy day where the bats never get a good charge, and it can seem like something is wrong.

Check your software and figure out what's drawing current.. your little fridge probably has a guilty look about it right now.

This all assumes you have your charge voltages set correctly within the charge controller..

Thanks for the reply and suggestion. I don't suspect the fridge solely based on the fact that were used to having it on our older system with 2k Aimes inverter. But I have suspected settings within the components as you mentioned. So will mess with that to see what I can do.

 

[Uoavitar]

I have a large system in my 5th wheel that big enough to power multiple trailers. I have to tell them to be sure your fridge is on propane and don't use the AC as those 2 will drain my 18kw storage within hours. On our last trip we had one trailer plugged into me that had a large power drain when everything was off and his batteries where full. It took us a little bit to track down the draw but it turns out is was his waster heater that automatically went to AC when plugged in and there was no way to turn it off at his control center. The water heater itself had an AC power switch on it but nothing in the control center. Before we noticed it, it had a good sized draw of around 500w when heating. That size draw would drain your battleborns down.

 

[mikefitz]

Any inverter connected to the batteries will be drawing a standby current.
The BMV712 shunt should be connected so all current into and out of the battery flows through the shunt, its not too clear from the picture if this is the case. It looks like there are two shunts in the picture.
The 12v power and sense wire for the BMV712 has an in line fuse, check this and the 'quick connect' to the shunt.

The solar readings you have indicated that 3 days ago you charged to full, 2 days ago the batteries were charged to full again and needed 1.46kWh, suggesting that this is your daily power use. One day ago the solar input was 520 watts but did not get the battery to full, suggesting a shortfall of around 1kWh. But the batteries have a capacity of over 5.2 kWh, so a fall to 11.5 volts does not fit as the capacity remaining should be around 80%, 4.2kWh. This matches the BMV reading you have.
Not 100% sure but I think the system uses the voltage reading from the MBV shunt so I would confirm there is no fault in the cable /fuse run to the shunt. I also suggest checking all connections in all the positive and negative paths in the installation.
Measuring the battery voltage with an independent meter would be useful.

A daily use of 1.4kWh is a lot for conservative use of a few lights, phone chargers and fans so there is power use elsewhere.

Mike

 

[RandR]

I am learning about RV solar myself, so NOT any kind of expert, but our systems are somewhat similar. So maybe we can both learn something! First, how are your solar panels wired? 2nd, I maybe wrong but it appears you have more than one connection from your batteries to anything else? I mean not from battery to battery, but from batteries to shunt, or to the inverter. I used a Victron Lynx power in as a distribution point for my batteries, so I have 1 positive from batteries out, and 1 negative to shunt out. Easy to control, easy to monitor. Also doesn’t your victron battery monitor have a Bluetooth out put? I use my victron 500A shunt Bluetooth monitor for battery status. Hope this helps!

 

[RVRoadramblers]

Yeah, we know not to run the fridge on 120 or the AC. In fact we removed those plugs from the solar side of our circuit panel. And our water heater gets turned off while in travel mode and has to be turned on either to gas or electric with separate switches and we only use the propane for that. Again, all things we are used to from the previous system. These issues we're having now seem to have come since the upgrade.
Which has me concerned and suspecting that I have either connected something incorrectly or have neglected to set some parameter settings withing a component such as the Mppt controller? I don't know, I'm really scratching my head.

 

[RVRoadramblers]

Hey, sorry R

I am learning about RV solar myself, so NOT any kind of expert, but our systems are somewhat similar. So maybe we can both learn something! First, how are your solar panels wired? 2nd, I maybe wrong but it appears you have more than one connection from your batteries to anything else? I mean not from battery to battery, but from batteries to shunt, or to the inverter. I used a Victron Lynx power in as a distribution point for my batteries, so I have 1 positive from batteries out, and 1 negative to shunt out. Easy to control, easy to monitor. Also doesn’t your victron battery monitor have a Bluetooth out put? I use my victron 500A shunt Bluetooth monitor for battery status. Hope this helps!

Hey! Thanks for the response. Sorry for the late reply. I'm currently traveling hard and in mostly remote areas without service ATM. I will be at my destination in a couple more days and will be able to be more attentive.
But, to try and answer a few of your questions. My panels are 12v wired in parallel so it's a 12v system coming down to the Mppt.
I'm not sure I understand the more than one connection question but I do have a positive lead running from the batts to a positive bus bar and from there through the shunt before connecting to the inverter. There is also a positive lead from the same battery post that is the positive side of the solar coming down through the Mppt and then through a fuse before connecting to the bat. The only other connections directly to the battery is one lead on a positive post with a slow-blow fuse to the smart shunt and another (black & red) from a negative post to the inverter which I forget right off what it's connected to on the inverter board. When I get a chance, I'll pull that cover off and look to see what it is. And yes, I do have a Bluetooth on the display monitor and use that to check the batts from the app.
I am suspecting that I may have a setting wrong somewhere or may have something wired incorrectly. I just watched a Victron video talking about a common mistake is wiring some DC loads before the shunt.
This is difficult to diagnose while in travel mode so looking forward to getting planted where I can dig in better.

 

[Rocketman]

Here are a few items…
First check that all the batteries are being charged and discharged at the same rate. To do this get your DMM (digital multimeter) and check the voltage of each battery- check it only on the battery stud for each battery. You want to do this when the batteries are lower charged (first thing in the morning) and when they are full. My guess… because it looks like you have good connections you will find all the battery voltages the same in both tests. But you want to rule out a bad connection.

Make sure all (and that means every single wire) that connects to the negative side of the battery is on the load side of the shunt (BMV712).

You may get a little more solar power if you connect your panels in a 2s2p array, instead of the the 4p you have now. It might bring in more power in a day- or it might not- testing is the only way to find out.

Make sure the settings on the BMV712 are exactly what Battleborn wants. Does the “time since last full charge” match the mppt’s when they go into float?

Finally, you may just be using more power than your solar can generate. The day before the 11.50v problem you only got about half the solar power other days were receiving. When living off grid, if the batteries are lower at night, you need to either add power(run the generator), or cut power, some ways are; turn off the inverter during the night. Use less power in the evening (turn off lights, etc). No microwave, etc.

The BMV712 and the touch display can help you learn exactly how much power each item in your rig uses. In the evening/night (so you don’t have solar variations) you can see the total watts being used both 120v watts and 12v watts. Watch them as you turn each item on and off. You may have an energy hog. At night, when you go to bed, what is the normal draw on your system (dc 12v watts).

Every night I check the Victron software on my phone and look at my SmartShunt(same as your BMV712). I look at the “Time Remaining” field to make sure I will not get woke up by a low voltage alarm. Better to take action at 10pm than try to figure out the problem at 4am.

 

[RVRoadramblers]

All good points and suggestions. I will check each of them and see what comes up. Thank you!

 

[Rocketman]

Also, your BMV712 was lying to you - your batteries cannot be 80% full and your voltage be at 11.5v (assuming there were no heavy loads running). At 11.5v your batteries are at Zero%. If no heavy loads you need to make adjustments in the BMV712 settings.

However, if you were running the inverter with a heavy load - you could have had a power sag that drops your volts way down. Were you running the microwave at the time of the alarm?(or other large wattage 120v items)?

On my rig (500ah of lithium and Multiplus 12/3000), in the morning (with 80% batteries) I can run the microwave, however, if another 120v items runs (hairdryer, electric heater, toaster,etc.) my inverter will cut off and I will get the low voltage alarm. It’s just trying to do too much. So every time that occurs (my wife says “oops- sorry”, 30 seconds later the Multiplus will restart - we turn off the second load item - restart the microwave and when it gets done- run the second load item.

This power sag, will happen even if the batteries are 100% full and I am in great sun. Because it is caused by overloading the Multiplus. The 12/3000 can only produce 2200w. (Less if it is hot - summer or ran for a long time at full power - see the spec sheet).

Good luck -

 

[RVRoadramblers]

Also, your BMV712 was lying to you - your batteries cannot be 80% full and your voltage be at 11.5v (assuming there were no heavy loads running). At 11.5v your batteries are at Zero%. If no heavy loads you need to make adjustments in the BMV712 settings.

However, if you were running the inverter with a heavy load - you could have had a power sag that drops your volts way down. Were you running the microwave at the time of the alarm?(or other large wattage 120v items)?

On my rig (500ah of lithium and Multiplus 12/3000), in the morning (with 80% batteries) I can run the microwave, however, if another 120v items runs (hairdryer, electric heater, toaster,etc.) my inverter will cut off and I will get the low voltage alarm. It’s just trying to do too much. So every time that occurs (my wife says “oops- sorry”, 30 seconds later the Multiplus will restart - we turn off the second load item - restart the microwave and when it gets done- run the second load item.

This power sag, will happen even if the batteries are 100% full and I am in great sun. Because it is caused by overloading the Multiplus. The 12/3000 can only produce 2200w. (Less if it is hot - summer or ran for a long time at full power - see the spec sheet).

Good luck -

Yeah I'm familiar with that happening from the previous 2k system but this is something else. It's leaning more and more to the settings like you suggested.
The morning we awoke with the low voltage we hadn't run anything yet and overnight we had just been running two maxair fans, fridge on LP, a Wi-Boost, composting toilet vent fan, two cel-phones on wall charger and of course the inverter itself. I believe the LP sniffer might draw a trickle as well, but we should have been able to sustain that without dropping it that low.
We don't use the microwave or any of that when we're out booning so I had those plugs moved over to a separate sub-panel along with the 120 side of the fridge l, the AC and the washer/dryer so that they're only hot when we're hooked up to shore. So it's not any of that.
I'm gonna get the settings of the Battleborn site and check my BMV settings. I never went into that after I put it in. I did go through the inverter with a BB tech and got those set but didn't think about the BMV needing the same.

 

[Supervstech]

How big were the batteries in the old system?

 

[Supervstech]

Hey, sorry R

Hey! Thanks for the response. Sorry for the late reply. I'm currently traveling hard and in mostly remote areas without service ATM. I will be at my destination in a couple more days and will be able to be more attentive.
But, to try and answer a few of your questions. My panels are 12v wired in parallel so it's a 12v system coming down to the Mppt.
I'm not sure I understand the more than one connection question but I do have a positive lead running from the batts to a positive bus bar and from there through the shunt before connecting to the inverter. There is also a positive lead from the same battery post that is the positive side of the solar coming down through the Mppt and then through a fuse before connecting to the bat. The only other connections directly to the battery is one lead on a positive post with a slow-blow fuse to the smart shunt and another (black & red) from a negative post to the inverter which I forget right off what it's connected to on the inverter board. When I get a chance, I'll pull that cover off and look to see what it is. And yes, I do have a Bluetooth on the display monitor and use that to check the batts from the app.
I am suspecting that I may have a setting wrong somewhere or may have something wired incorrectly. I just watched a Victron video talking about a common mistake is wiring some DC loads before the shunt.
This is difficult to diagnose while in travel mode so looking forward to getting planted where I can dig in better.

Ok, the second shunt needs to go away.
The output of the charge controller needs to connect to the main bussbar.

 

[RVRoadramblers]

How big were the batteries in the old system?

The old system was running four 225Ah 6V AGM Bats. S/P

 

[RVRoadramblers]

Ok, the second shunt needs to go away.
The output of the charge controller needs to connect to the main bussbar.

Ok, so by second shunt are you referring to the one on the far right hand side right of the hydraulic lines?
All that's on that is the ground wire from the inverter through the shunt and to the trailer. I repeated that connection based on the previous install. Should I ground the inverter directly to the trailer or does that also need to be included on the negative busbar?
And for the the controller, are you saying (controller-breaker-busbar) and it will feed the bats from the lower cable running to the positive post? Just trying to affirm that I understand your suggestions.

 

[Rocketman]

I just saw the second shunt - what info does it give you? Is it a large enough capacity to run every through it (including the Multiplus?)

Your picture doesn’t quite show everything- so it’s hard to understand.

You want the negative on the batteries connected to the battery side of the BMV712, (then if you want to keep the second shunt the bmv712 load side will go to the second shunt battery side).Then the load side of the shunt has the inverter negative and the negative going to the black bus bar. The black bus bar has the solar controller, the negative wire for the rig, and everything else.

Until you get the wiring for the shunt so all negative power goes through the shunt the battery percentage is completely wrong - Because it is not counting all the loads. If you are getting low voltage alarms - your batteries are out of power.

 

[Supervstech]

Ok, so by second shunt are you referring to the one on the far right hand side right of the hydraulic lines?
All that's on that is the ground wire from the inverter through the shunt and to the trailer. I repeated that connection based on the previous install. Should I ground the inverter directly to the trailer or does that also need to be included on the negative busbar?
And for the the controller, are you saying (controller-breaker-busbar) and it will feed the bats from the lower cable running to the positive post? Just trying to affirm that I understand your suggestions.

ALL power needs to go through the victron shunt ONLY. If you ground the inverter, it needs to be fed from the victron shunt.

The battery negative NEEDS to be ONLY fed through the victron shunt. Then the negative bussbar, then the frame.
I would connect the inverter directly to the bussbar.