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MPPT not working properly after panel fault

My system was working earlier.. 4- 400w panels, Victron 150\85 controller, CERBO w\touch 50, BMV-712 smart, 4- 100Ah BB lithiums.

2 panels are on the roof and other 2 are leaning at same angle against side of the RV. All 4 have 15a fuse connected. So this system has never received much over 800w out of total 1600w. So I unplugged the 2 lower ones.. and used my multimeter to verify they were working. They both tested good. So I plugged them back in.. and verified on my phone they were working too. Climbed up top to test the other ones.. while reaching to unplug one of the panels, I noticed one of the connections shorted out and melted the plug. So I got some tools and cut it off and replaced the MC4. plugged it back in and climbed down. Came down and went inside.. Unplugged CERBO to reset it.. but the screen flicker about every 20 or 30 seconds.. and the controller has some flashing lights. Blue light comes on and then the yellow and green light rotate off and on.. I have disconnected the negative wires on the PV and Battery, waited about a minutes and reconnected them. No change. Then I disconnected the negative cable from the batteries for a minute also.. Hoping to restart the system.. No change.

System was getting about 50w of solar when I first unplugged them..


Since I posted.. I think it was an over voltage issue.

2022-08-07 180343.jpg 20220807_131129.jpg20220807_131853.jpg20220807_154812.mp4

brucesterj asked
brucesterj commented ·

2 Answers

How does the resistance of MC4 connectors compare with the resistance of 8AWG cable?

I am about to buy cables to connect solar panels to my RV. I'm using an MPPT 100/50. The panels are not mounted to my RV, so that I can move them around to where the sun is. Sometimes the sun is close (20 feet)... and sometimes it isn't (I plan on a max of 40 feet). At first, I was thinking of buying one pair of 40 foot cables with MC4 connectors on the end. Now I am wondering if it makes more sense to buy multiple pairs so that I can make the total length 20 foot or 40 foot, or even dedicate one pair of cables per solar panel (so that the cables are entirely in parallel). I am planning on using 8AWG copper (not CCA) cables. How does the resistance of the MC4 connectors compare with the resistance of the cable?

wandering-parakeet asked
klim8skeptic answered ·

1 Answer

Charge Controller Upgrade Renogy 200w Suitcase

Hello and Thanks from this newbie.

I recently purchased a 200w Renogy Eclipse Solar Suitcase. The Suitcase came wired in Parallel with a PWM Controller which I use to charge my two Interstate 12Volt 64Ah Batteries on my RV. Changing the panel over to Series wiring would be an overhaul as one panel is wired directly to the other panel via the junction boxes mounted on the panel.

I camp in Forested areas, so long periods of full sun is not always possible and would like to attain charging ability throughout the day. I also find my current lead acid battery setup bubbling over when charging.

Would upgrading the PWM charger to the Victron MPPT SmartSolar 75/15 benefit me? Would rewiring the panel to Series be a benefit on 200w as well?

bcborn asked
jalles345 answered ·

1 Answer

MPPT 100 | 20 Charge controller burnt fuse

The 25A fuse in my Victron MPPT charge controller was burnt—It was not blown. The connection point on the internal circuit board where the fuse plugs in was also burnt. A further point is that only one side of the fuse was burnt; It was the outermost connection, the one closest to the charge controllers casing. It is my understanding that this fuse is used for the “Load Output” feature (I have an older model). I do not use the load output feature and had disabled it through the app. A lot of current went through that leg of the fuse circuit.

I have recently been having problems fully charging my batteries. There has been failures with the charge controller where the PV voltage was 77+ volts, and zero amp. I disconnect the charge controller to reset it. After reconnecting I got normal PV reading of 63.74V and 2.5A. There has never been any error codes indicated in “History.” Also, the controller keep my batteries in bulk charge longer than usual and absorption time higher than I’ve ever seen. The amount of sun/clouds is the same on average as it has been the past 3 years.

Any thoughts as to the burnt fuse and/or recent behavior of the charge controller?

Charge Controller Firmware: v1.59

Charge Controller Interface - Firmware: v2.41; Bootloader: v1.16

brian-kent asked
Mike Dorsett answered ·

1 Answer

MPPT different voltage to BMV712

Hi, I have setup a new system. 100ah lithium battery, SmartSolar MPPT, BMV712, Multiplus 12/1200 and Cerbo GX.

All settings as per the advice on here and the videos.

All seems good except the MPPT is reading a higher voltage than the BMV by .1v, so instead of charging to 14.4v/13.8v, it is charging to 14.3v/13.7v.

Here is the VRM screenshot:


They are very close to each other on short cables.

The battery is at 13.7v, so it is the MPPT that is reading incorrectly.

Is this normal? Should I increase the absorption and float voltages on the MPPT to get it to the correct level?



deangi asked
Mike Dorsett answered ·

2 Answers

MPPT Ralay Steuerung wie anschließen?

Hallo, ich habe an einer Anlage 2 MPPT Victron Laderegler mit schaltbaren Ralay (3 polig)

mit einem Ralay möchte ich bei hohen Temperaturen einen Lüfter an und aus steuern. Ich stehe da etwas auf dem schlau und finde auch keinen anschlssplan im internet, kann wer helfen...

wie klemme ich dort den lüfter an das relay? welche spannung brauche ich?

danke für hilfen

micha854 asked
Stefanie answered ·

1 Answer

MPPT 75/15 not charging but MPPT 100/20 is

So, I have 2x45W cells connected to an MPPT 100/20 and 1x55W cell connected to an MPPT 75/15, which in turn are charging a LiFePO battery bank. Up until approx. two months ago they were charging just fine, but somewhere around there after a F/W upgrade the 75/15 hardly charges anything. The thing is that when the the cell has a clear los of the sun, the voltage is usually around 19-21V but still it won't charge. The other cells connected to the 100/20 could go as low as 15V but still is charging albeit very little. The 75/15 just sits in "off" mode the whole time.

I've checked all fuses, measured voltages on the cell, after the fuse, on the terminals and it all checks out. Both MPPT's have the same configuration, power reset it, reset to factory defaults and what not.

Does anyone have an idea what causes this situation?

magnus-fredholm asked
magnus-fredholm commented ·

0 Answers

8 Panels (east / west)


I have 8 panels (200W, VoC 20,25V, Vmp 18V,Isc 12,68A). 4 Panels are facing south, 4 Panels west.

What is the correct way of "plugging" them together?

  1. All 8 in a row, with one MPPT 250/60 (or would i loose Ampere during morning times, as 4 panels are in shadow)?
  2. 4x2 (4 in a row) with one MPPT 150/30 connected via Y cable (or is the MPPT not able to find the maximum / best MPPT point for those two strings?)
  3. 4x2 (4 in a row) with two MPPT 150/30

As option (2) is of course the cheapest option, I would of course prefer that one..

Thanks a lot!

timo-1 asked
tom4x answered ·

2 Answers

Is it okay to disable/enable charging on an MPPT?

When I do so via the VictronConnect app, it displays a message that this should only be done for maintenance. This makes me wonder if it's damaging somehow? Some I've spoken to suggest it shouldn't be done during the day when there's a solar charge going in. Can anyone confirm either way if it's okay to disable charging ... this is more for testing purposes, rather than 'maintenance'. Not something I'll do on a regular basis though.

Any advice would be appreciated...

sv-far-out asked
Alexandra commented ·

1 Answer

[SOLVED]SmartSolar 100/20 Load Output not disconnecting on Low Voltage!!

Hi Folks,

I have a SmartSolar 100/20 with 300w of panels and a 24v battery bank.

I have been experimenting with the Load Output function and (as others have reported) cannot seem to make it work properly.

VE.Direct = Jumper removed

RXPort = Load Output Configuration

TXPort = Normal communication

Load Output = User def algorithm1 off < 24.5v on > 25v

Firmware = 1.59 (Latest).

The load has been < 24.5v for more than 20 mins and is still connected.

I notice other folk have had this issue but I did not see any successful resolution.

I find it hard to believe its a hardware fault as the load output succesfully turns back on once the voltage > 25v + 2 minutes.

I really dont want the hassle of returning the item, so please can someone help me resolve this. I hope I am missing something obvious.

regards (see screenshots below).






vonny232 asked
vonny232 answered ·

1 Answer

MPPT Charge controller LOAD output stopped working

Hello Everybody,

I have a problem with a bluesolar charge controller mppt 75/15 in a 24V system. I have a 24V solar array and two batteries. So far everything worked fine.

The charge controller has a 20A fuse that shows no damage. Batteries are fully charged and controller in Float.

So far I had an alarmclock and a water pump on the LOAD Output of the controller. The alarmclock has very little power requirement and the pump draws maximum 5 Amps (it is fused at 7,5A).

Since yesteday the charge controller refuses to power both devices. I also tried them separately.

With nothing connected to the load output I have the following voltage :

BATT : 27.4 V

PV : 44.3 V

LOAD : 21,7 V

It is already suspect to me that I don't read the same voltage on the BATT and LOAD outputs but maybe it is normal ?

If i connect any device to the LOAD output, the voltage drops to 2,5 V on the LOAD terminal and nothing is powered. The two other outputs keep their readings. The jumper is in the middle position.

Is my controller fried ?

Many thanks,


raven asked
raven commented ·

1 Answer

MPPT not charging during Multiplus absorption (DVCC)

Should DVCC allow the MPPT to charge when sun is available, even when the Multiplus starts a charge due to low SOC early on a sunny day?

I've found the Multi will still be in absorption and the MPPT will go to float, but decides not to bother with any output, even though it could.

If i turn the MPPT charge off and on (in Victron Connect) it will try to charge for a few seconds but quickly cycle through Bulk-Absorption to float and give no output.. Only when the Multi goes to float does the MPPT start charging.

I'm using DVCC, + Ignore AC, both MPPT absorption and float voltages are higher than the Multi's

Could it be overheating? Today was hot and the batteries showed a peak of 37 Deg C, or maybe an incorrect setting, I.e. reduce the Ignore AC charge to end after bulk, but that's not ideal until we have more solar?

Or a symptom of the MPPT adaptive charge, either way i thought DVCC should tell them both what to do, as the Multi decided to use the AC In mains to charge when there was enough sun to cover the end of the absorption phase :( ..?


VRM link:


Al asked
ludo edited ·

5 Answers

[SOLVED] complex solar panel setup...

I'm reading (here) as much as I can to be able to choose the components I need but it's a steep learning curve and I am not confident I can make the right choice...

Solar panels: JA Solar 405Wp

(Parameters at Standard Test Conditions)
-Open Circuit Voltage (Voc) [V]: 37.23
-Max Power Voltage (Vmp) [A]: 31.21
-Short Circuit Current (Isc) [A]: 13.87
-Max. Power Current (Imp) [A]: 12.98

I have 2 solar panel locations:
- 6 panels will fit on a high roof facing south, 51 degree angle
---> PROBLEM: 1 panel partly in the shadow until 1 PM

- 4 panels will fit on a garage roof facing South, flat roof (E-W placement)
---> PROBLEM: all panels in the shadow until 1PM


- Victron Multiplus II 48/3000 ??
- battery: Victron 48V LiFePo ??

But my main problem is choosing the MMPT's !

how to group the solar panels, for example: the one on the roof which has shadow, is is better to connect it to a seperate MMPT?

Many thanks to anybody willing to help me out!

alwaysinthelight asked
alwaysinthelight edited ·

3 Answers

What are the Smart Solar MPPT 150/100 VE.CAN limitations in regard to output current?

Is there a possibility of damaging the unit if say PV voltage is kept below 150 volts at all times but the array size is such that it could output very much more than 100 amps without the limitation? I currently have a 24 volt setup with 2.4 kw panels. The output current can reach 75 amps. If I were to install a second 2.4 kw of PV in parallel, PV voltage is the same but potential output is 150 amps. Does the 150/100 reduce output to 100 amps irrespectice of overreach without damage. The second set of PV is to cover low solar input in winter but in Summer would not be needed. I have not found an answer to other questions which is directly related to this question.

howard-r-jones asked
Stefanie commented ·

1 Answer

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