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voltage

Understanding: Series Vs Parallel for 2 x150W panels with SmartSolar 75/15

Wow... I've read a LOT of great info on this site. But there are a lot of numbers and my pea-sized brain still has a couple of questions. Here's what I know: (Please correct anything I've misunderstood!)

* Panels in SERIES Voltages add, and current remains the same, while for panels in PARALLEL their Amps add together and voltages remain the same.

* Battery charging begins once the panel Voltage is more than 5V above the voltage of the battery.

* SmartSolar controllers can handle more amps from the panel(s) than indicated by their model numbers - they just don't push more than that charge into the battery above the limit (eg my SmartSolar 75/15 will limit Amps into the battery to 15A

* Voltage indicated by the model number (eg 75V for my SmartSolar75/15) is a hard limit that will damage the controller if exceeded by the total open circuit voltage stated on the panel(s).


I already have a SmartSolar 75/15 and one 12V 150W panel with these specs:

VOC 22.3V and Vmp 17.9V with max current 8.73A

I currently have a 21V 150Ah AGM battery but plan on replacing it with a 200Ah LiFePO4


I have a second panel the same that is not connected, and the possibility of a separate 310W panel also. Here are the questions:

Assuming I don't want to buy another Charge Controller - 1. If I connect the second 150W panel in Series will I start charging earlier in the day or if its cloudy or partially shaded because the voltages are added and therefore higher earlier in the day than if they were in Parallel?

2. In series voltages add. So 2 panels at Voc 22.3 x 2 = 44.6V This is under the 75Vlimit... any problem with this aspect?

3. In Series the current is the same - since the panels put out 8.73A my 15 A controller wont be close to the max it can push to the battery. Is this a waste of the potential of the panels?

3b. Would It be smarter to put the same 2 panels in parallel, accept that they wont start charging as early in the day or as often in partial shade or cloud but get more amps (which might on rare occasions when everything is perfect exceed 15A since 2 x 8.73A = 17.46A, and therefor be limited to 15 A by the controller)?

4. If i were to replace the 150W panel with a singe 310W 12V ( Voc 40.5V, Imp 9.4A) panel would I get similar results to the total 300W of a 2-panel in parallel setup?


I know there is fair bit here. I hope your answers can not only educate me but also help clarify for future readers who, like me, spent a long time trying to understand this stuff by amalgamating knowledge from previous posts...




Stephen asked
Stephen commented ·

1 Answer

MultiPlus-II sudden low battery alarm while battery is full (BSL stubby)

Update 25/11

The battery once again gave a low voltage alarm while about 80% SoC, causing the inverter to restart. There is clearly something wrong. My best guess (based on many informed opinions) is a serious BMS firmware bug or design flaw. It could also be severely unbalanced cells, or a faulty cell. BSL is apparently working on improving the firmware (they're aware something is wrong).

I'm working with the installer to have the battery exchanged for something that actually works reliably. I would not recommend buying a BSL stubby for the time being, at least not until they sort the BMS issues out.

---

Hi,

Hardware details:

Setup details:

  • Grid connected to AC-IN
    • Grid feed-in is disabled.
  • AC-OUT-1 is feeding essential loads (no more than 2000W, average about 300W-700W)
  • AC-OUT-2 is feeding geyser (on timer 10:00-15:00) and stove.
  • ESS mode: Optimised (with BatteryLife)
  • The system is less than a week old and has been running perfectly up until a few hours ago.

Issue description:

The inverter suddenly shut down and started up on its own after a minute or two. The battery was about 99% SOC when this happened.

The following alarms occurred:

[image]

On VRM I can also see there was a "High DC ripple" warning at the same time.

The system ran fine after that for a while after which the same thing occurred again, but this time it coincided with a grid failure (load shedding). The same alarms occurred:

[image]


During both occurrences, the load on the inverter was at most 500W (nothing was switched on additionally when it happened).

Does anyone have an idea what the cause could be? I'd appreciate any input.


VRM images (please let me know if other log data could be useful):

[image]

[image]

[image]

[image]

I did also notice on the MPPT daily history, the minimum voltage for the battery today was 44.72V, which seems very wrong:

[image]

Usually it discharges to about 45% throughout the evening, and then the minimum voltage hasn't fallen below 51V before today:

[image]


anrich asked
Alexis Kalogerakis answered ·

4 Answers

Question about accuracy of the Voltage meters in Victron MPPT's and Smart Battery Sense?

Answering these questions should help other Victron users who notice voltage variances on their Victron equipment gauge whether there could be an issue, or whether what they're seeing is considered normal.


1) What is the Volatge metering accuracy of both the internal MPPT and Smart Battery Sense Voltage meters?


2) What is the voltage meter model/part number and manufacturer?


3) How can one be sure they're accurate if they aren't calibrated/checked every year like digital multimerers need to be, especially after 1 year?


4) Testing of equipment is a waste of time if you're not using a guaranteed in spec digital multimeter, Correct?


5) What is the minimum accuracy of a digital multimeter for a reading to be considered "correct" and/or accurate?

not-a-hard-question-to-answer asked
not-a-hard-question-to-answer commented ·

1 Answer

Lets try a second time. Whats the Voltage accuracy of Victron products?

Disclaimer:

It seems questions often arise on this forum about the Voltage accuracy of Victron units and variances between voltages measured vs what's displayed on the app.

SINCE there is zero information about the accuracy of the Voltage meters in Victron products, it makes sense that some questions be answered on this community page, which is there to help Victron users!


Elvis, Kevgermany - You didn't like my replies to you and those who commented on my previous question, before you got offended and blocked my account - Maybe go back and read the "so called assistance" that was provided and understand I'm not some completely useless person "like you all suggested" and as a result I gave blunt responses in return showing my appreciation for the RUDE/little assistance and belittlement I received for you.

I fielt my replies were warranted, considering the attitude and belittlement I got from a number of you. All because I don't have access to a "very expensive" FLUKE DMM!


• My questions of how to confirm accuracy of a DMM, fell on deaf ears.

• My questions of the products number/model number of the voltage meters in Victron products, so I could answer the above question, fell on deaf ears.

• My question about how you can all guarantee the accuracy of Victron voltage meters when you all told me that unless a DMM is calibrated every year its not guarantee accurate, so I clearly asked how and why the Victron units can/are still considered accurate when they aren't calibrated every year? This fell on deaf ears.

• How can Victron products be guaranteed to have accurate Voltage if they're not regularly calibrated?

• Exactly what accuracy percentage does a Digital Multimeter need to have to be considered accurate enought to perform testing?


^^^These are SIMPLE QUESTIONS that will help MANY future Victron users and save them from having to create posts/questions when it's already been answered (the whole point of this community according to community guidelines)...


Let's watch you delete my account again for trying a second time to ask BASIC questions all because you assume I'll abuse you - The difference is that if you actually provide clear answers and don't provide VAGUE information, or try to waste my time asking for irrelevant information and/or imply I'm useless, then my replies will be respectful.

If you waste my time again, be rude or vague you will get blunt/rude replies in return - Not sure why you're surprised by this.


* I've been told I'm blunt due to my Autism, but that won't change the sour people who have been offended at my responses to them after they wasted my time, or implied I am useless (which in itself) is very insulting to me!

^^^ You offended me and/or wasted my time first before I gave it in return...

not-a-hard-question-to-answer asked
not-a-hard-question-to-answer edited ·

2 Answers

multiplus 12/3000 voltage reading to low

Hello,

the multi is always reading voltage about 100mV to low also in no load conditions.

After disconnecting the multi for a few minutes the voltage reading is ok, but it’s getting worse after some time.

BMV 712 and BMS and multimeter is measuring the same voltage, only the multi is reads wrong voltage.

The absorption and float voltage is getting also about 100mV higher as programmed voltage.

lars78 asked
lars78 edited ·

0 Answers

Victron MPPT 100/30 and Smart Battery Sense reading 0.2-3V higher than battery

Hi there,

I have searched this fforum looking for answers or other users who have had a similar issue and have found some reports but no answers.


I have a 100/30 MPPT with a Smart Battery Sense connected to my AGM battery bank and I've noticed the MPPT na smart battery sense seem to be reading 0.2-0.3V higher than my battery bank according to two different multimeters.


I specifically noticed this last night when the Victron unit specified my battery voltage with a small load applied was sitting at 12.61V, yet when checking with my multimeter my battery bank was sitting on 12.32V.


I purchased the Smart Battery Sense due to noticing an error in the voltage between batteries and the MPPT, the Smart Battery Sense helped get it closer, but it was never exact.


After living off the grid ina caravan for a bit over a year with this setup, I am noticing my batteries don't seem to be holding charge as good as they first did and I suspect this is due to me having accidentally run them to low as a result of the variance from the Smart Battery Sense and the MPPT.


The lowest I had taken my batteries down to was 12.24v (according to the Victron app) which would mean the actual Battery Voltage would have been close to 11.9V or 12V - Much lower that I have ever planned to discharge the batteries.


According to both MPPT and Smart Battery Sense both units are running up to date/latest firmware.


As a half assed workaround, would changing the MPPT's charging parameters to be 0.25V higher allow the batteries to reach full charge (I assume it will) but don't want to cook the batteries at the same time?


Any advice as to what the cause and fix could be.


I am running 6 gauge wire about 800mm from MPPT to batteries so voltage drop should be fairly minimal and the Smart Battery Sense should be providing an accurate reading anyway.


Thanks,

Glenn.

Closed

Hates Spam asked
Hates Spam edited ·

8 Answers

Batteries 92% absorption stage, battery voltage less than set absorption voltage

Hi,

I have set my Quattro II with 48V lead acid (4x12V) absorption voltage setting in VE.Configure to 57,60V.

System is now:

Charger on, absorption stage.

Battery voltage 52,36V

Current 0,00A

Shouldn't the battery voltage be the same as in settings 57,60? Or is this the voltage between absorption cycles during float?

VRM/GX says that Quattro is in Absorption stage, so I would assume that those cycles (spikes in repeated absorption) happen when it reaches float stage, which it has never done yet.

My main concern is that it won't charge it to 100% level, not sure where / how it calculates the charging level. But with 0,00A current it surely wont ever get there.


Br,

Juha

Juha Tuomala asked
kevgermany commented ·

3 Answers

Voltage Sense Wire Size

I'm on the final hookup of my multiplus 3000 on my boat and have a simple question. The manual calls for a 20awg wire to connect the voltage sense. Will an 18awg work? I'm in Alaska and tinned wire can be hard to find here. I have tinned wire from 4/0 cables to 18awg but nothing finer.


Thanks, Tator

tator asked
ako answered ·

2 Answers

BMV-712 Main Voltage Showing 0.02V

I have a BMV-712 connect to 2xVictron Super Cycle batteries, today my monitor started reporting an incorrect battery voltage of 0.02 or 0.03V. This is on both the device itself and the android app (via bluetooth), nothing has changed in my system except for taking a firmware update on the app.

I've checked the voltage with a meter and its reading 13.08 from the shunt to my fuse where the power supply for the BMV is located. I also unscrewed the inline fuse and looks to be intact, just to be sure i checked the voltage from the end of the fuse to the shunt and again was 13.08V so seems to definitely be a software / device issue? I've done a number of factory resets without any joy always just displays the .02V after the reset.

Kind of out of ideas here and would welcome suggestions.

https://photos.app.goo.gl/S9rs1kK25tYuyg4u6

https://photos.app.goo.gl/ZKKrMFAFbc4heScA6

Thanks,
Ian

ian-doyle asked
kevgermany commented ·

3 Answers

Output voltage of the LOAD Output on 75|10 controller

Hello,

I read that the output voltage of the LOAD Output on a VictronEnergy MPPT Bluesolar 75|10 controller was the same as the output voltage of the battery. I plan a 12V Battery to the controller.

My question is : is the LOAD voltage output always 12V (as long as the battery is charged enough) or is it the same as the battery (which can vary between approximately 11V and 14V, depending on the mode) ?

Thank you for you answers !

agarreau asked

0 Answers

Battery voltage drop when high load is connected

Hello,

I have installed the following off-grid system, which has been working pretty good for one year.

  • 4 300W solar panels
  • MULTIPLUS-II GX 48V
  • SMARTSOLAR MPPT 150/35 48V
  • 8 Acid Lead batteries of 6V each (Deka GC15)

However I'm wondering if the behavior I see when I plug a 1200W water heater during the central hours of the day is expected.

As you can see from following graphs the battery voltage drops when load is active and jumps back to an higher value afterwards.

Reading other posts on this subject I've got this is expected indeed, but my question is: do I have to worry about this voltage drop? In other words: should I power on the AC generator if the battery voltage goes down to 46V like in the picture below?

Thanks a lot,

Matteo


[image]

[image]

the-salmon asked
nickdb commented ·

3 Answers

Voltage Error (Please Help)

Hi there,

I currently stay in my van full time.

My battery voltage in my van recently dropped to about 9.5 and I then started the van as solar wasn’t great and charged it back up for 30 mins, it now jumps up and down and the voltage reading is constantly flashing at me and giving me the warning triangle? Does anyone know as to why this is?

joshsmithz asked
kevgermany answered ·

2 Answers

Multiplus voltage differences

Hello,

I'm reading in this community for a while now and get many help/hints to setup my storage system. But now I have a questions and didn't find this kind of topic in this community before.

I have just changed my installation from a Multiplus II 3000 GX to a Multiplus II 5000 GX. It is an grid connected ESS System with 5* Pylontech US3000C. Everything works well so far.

But there is one issue that bothers me a bit. The Multiplus have a voltage difference of 0,30 V between the Multiplus itself and monitored in VRM Portal "VE.Bus DC Voltage And Current" and the real voltage. The BMS from Pylontec and all the other voltages monitored and shown by the GX device shows 0,3 higher voltages. I also messured everything with a multimeter and the higher voltages are correct. If I messure also directly with my multimeter on the DC terminal of the Multiplus directly (without calble and inverter/charger are off) the voltage ist 0,3 Volt higher than monitored by the Multiplus.

As the Multiplus uses this messured voltage to steer everything, the real voltage is everytime higher. For example I need to set charge voltage limit to 50,0 Volt to get 50,3 Volt in reality. Also if I don't limit the charge voltage, the real charge limit will be not 52,4, but 52,7.

It may be that these deviations are normal and are the usual variations of measurements. In this case it is ok. But as I still have the possibility to return the Multiplus and to get a new one, I want to be sure. My former Multiplus II 3000 had a deviation of 0,1V.

What are you experiences and values? Are your messured DC voltage by Multiplus the same like messured from BMS/Multimeter/reality or do you have also these kind of deviations?

Many thanks in advance.

Bye Dirk


dirk-s asked
JohnC answered ·

2 Answers

Low voltage with 100% reading on the batteries


So, first off I’m not completely familiar with how the victron system totally operates. We purchased our rv used with a 3k inverter 24v inverter and 4 Battle Born 1200a/hr batts. The previous owner had ran the generator to charge the batteries, but we decided to add a MPPT and array. There is now a 250/100 MPPT connected to two REC 355 panels with a third 320 Panasonic panel we had given to us. All three worked together amazingly (859w max) when we came off shore power to move spots, and hook back up. The next day when I went to move the RV to travel I had a “low voltage” reading from my jack system. The problem continued when I reached my destination, “low voltage” when trying to auto level. When I hooked back into shore power, everything worked. I took the RV’s lead acid battery (hooked up with a 100w panel and separate 100/15 MPPT) in for testing and it had a dead cell, replaced it, but the problem has continued.


It being hot out we ran our three ACs on shore power and then suddenly the system dropped, “low voltage” alarms on the GX constantly. I have isolated the AC issue down to the mid AC unit that only works on the fan setting (blower), but the wife and I were talking on this latest travel day and came up with the idea that something screwy is going on with the Battle Borns. Looking at the history I can see that the day we moved spots we were getting good max and min voltage, but the day we departed the min voltage has been super low.


Looking for suggestions on where to go from here.

[image]



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[image]

gator6 asked
macca61 answered ·

3 Answers

Why does V Sense power MultiPlus-II and other loads?

Why does the V Sense connection on my MultiPlus-II 2x 120 V inverter charger power my inverter charger and other items connected to my Lynx Distributor?

Setup:

I Just installed my MultiPlus-II 2x 120V. I’ve attached the AC lines (in and out 1), but not connected to shore power. The chassis ground of the MultiPlus is attached to the chassis ground through the negative busbar of the Lynx Distributor. The negative busbar of the Lynx Distributor is also connected to my battery bank via a SmartShunt. The positive busbar of the Lynx Distributor is isolated from the batteries by an uninstalled class T fuse and the battery disconnect switch being in the off position. The positive and negative DC connections of the MultiPlus are connected to the positive and negative busbars of the Lynx Distributor.

Issue:

When I attached a pair of wires directly from the batteries to the V Sense input of the MultiPlus-II the MultiPlus-II, which was inadvertently on, began to operate and energized the Lynx busbars. The busbars remained energized even after the MultiPlus was turned off. This results in battery draw even with the disconnect switch in the off position. Any ideas or insights would be welcome.


kelflanagan asked
sjung commented ·

1 Answer

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