Voltage measuring of Smart Solar MPPT 150/100 incorrect

Q&A and troubleshooting
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1

HI

We have an installation where the Smart Solar MPPT 150/100 is measuring the voltage 2V above the real voltage from the Pylontech batteries. This resultss in solar charge being stopped when the batteries are only 75% full. We measured at the “Battery” connectors on the Solar Charger and it gave the same reading as the CCGX i.e. the
Solar Charger is measuring 2 volts above the actual voltage.

What could be causing this issue- is there a solution?

Thanks
Lazza

2

Hi Lazza,
I do not have a solution but I have exactly the same situation.
(I think this could be a direct Victron ask of …HELP…)

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My Max SOC has been dropping day by day at 1% and is now sitting at 71%
I have a BlueSolar Charger MPPT 150/70 that is currently reading 1.4v too high.

The MPPT reads 52.4v yet the terminals of the MPPT the multimeter reads 51.0v, At the bus bar the reading is 51.0 and the batteries are reading…51.0.
Now this system has been installed for two years with no problems.

Anyone any ideas?

3

Hi.

Doesn’t look like we’re going to get a solution for this. What I’ve done is kick up the charge voltage manually and will get the client to disconnect the VE direct cable from the CCGX to the MPPT on a day when it’s sunny to see if I can trick the solar charger to charge to the correct voltage, taking a lot of care not to go over the limits.

I think it must be one or two diodes (diodes normally have around 0.7V voltage drop, so 2x0.7=1.4V would make some sense) that have failed within the battery voltage measurement circuit … but who knows?

Let me know if you find anything out!
Lazza

4

Hi
I have tried disconnecting and even leaving for 24hrs to see what happens and if there is a “reset”. Nothing changed.

The last week or so I had more time to look at this problem and realized not only was the voltage different at the MPPT and the ve bus but this difference was also not fixed, it was increasing day by day.

This started in July when the difference was reading +/- 0.2v to today when the difference is 1.4v. I have tried to attach a png.
image

If you have the same issue then :
Plotting ve bus v, batt mon v and mppt v in VRM over the time and you can see the voltage drift.

I suspect a hardware failure.
As such I have raised it with the distributor whom are helping.
I will keep you informed.

5

Just thought last night that my last post might not be clear.
And since the image attached fine :+1: this may be clearer ?

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May 19th
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Aug 02nd
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Sept 02nd
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Oct 02nd
Hope this helps.

6

@Trev
Have a look at Pre RMA bench test instructions - specifically section 6: “Pre-RMA test form - MPPT solar charger” point 7 “Functionality” :-

Measure the voltage on the solar charger PV terminals. Compare this to
the solar voltage as indicated in the VictronConnect app.
Are they both the same? A small deviation is allowed due to
measurement inaccuracies

Hope this helps

7

Hi
Thanks and I will check but since the next point on the list is

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I guess the result speaks for itself.
The link for the Pre-RMA bench test is fantastic. I had not found that!!
Maybe if it was in the support section of the warranty and repairs then I would not be still chasing this issue.
Thanks

8

Lazza

Update for you.
The issue is within the MPPT, Victron are replacing it as its under warranty.
I asked for help from the distributor who were very helpful.

Trev

9

Thanks for the update Trev. Unfortunately our MPPT controller is out of warranty, it’s over 5 years old now. Well done at your end though