Victron 100/50 only charging 40 watts

DIY
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1

Victron 100/50 only charging 40 watts in full sun.

21 volts from solar panels and 9 amps from each of 2 panels on Winnebago RV.

21 volts at SmartSolar charge controller at the PV terminals.

Max charging on Victron app is 40 watts, what’s wrong?

Thanks.

2

Welcome aboard - lots of helpful folks here may have some suggestions.

There’s lots of possibilities. Starting with the easiest:

  • Check all your wiring connections are tight and fuses are properly seated.
  • Use a voltmeter to check the actual voltage at the terminals, and make sure it matches. Could be a bad/loose connection.
  • Use a DC clamp ammeter to check the actual current.

Tell us a bit more about the setup:

  • What kind of battery? If LiFePO4, then if it has an internal battery management system, it could be shutting down.
  • What else is in the system? eg a Cerbo GX/Ekrano GX, Multiplus inverter, any loads on?
  • What exact panels do you have, and what do the labels say (eg 21 V might be the VoC open circuit voltage with no load)
  • How are the panels wired? eg in parallel?

Pictures or a schematic also help.

Good luck!

3

I’m a newbie to RV’s and solar.

I have checked all of the fuses and connections that I can think of.

I have checked the solar panel voltage at each of the disconnected solar panel terminals. It varies between 21.9 and 22.1 volts. I have the same voltage at the PV terminals on the solar controller. I have 9 amps from the solar panels also. My meter only goes up to 10 amps for testing.

the 2 batteries are Lithionics, LiFePO4 with internal BMS.

It has a Cerbo GX and Xantrex Freedom XC Pro inverter/charger.

They are Zamp Panels - 190 watts. Open circuit voltage is 24.16, max power is 20.00 volts. Short circuit current is 9.70 amps, max power is 9.50 amps. They are wired in parallel.

Hope this helps, and I appreciate any help that that anyone can give me!

4

Ok, that’s helpful.

It sounds like the panels are probably ok.

  • The panel voltage when connected and under load will be less than when you tested them disconnected (which can be up to VoC max)
  • 22V at the solar charger terminals is reasonable, especially under full sun on a perfect day, for parallel batteries.

Some questions:

  1. Is this a DIY project, or did a professional install the setup for you?
  2. How do you know it is only charging 40 Watts? what’s telling you that?
  3. Is the charger a SmartSolar or Blue Solar 100/50 ?
  4. If it’s SmartSolar, have you connected your phone to it via Bluetooth to see what it is doing?
  5. Does the Cerbo “talk” to the Lithionics BMS, and report the internal information, like battery voltage and charge current limit and temperature?

I don’t know Lithionics, but…

  • Many batteries have a CAN BUS BMS cable to the Cerbo, and so the Cerbo can see how the batteries are doing.
  • If your Lithionics is bluetooth only, then there is no way the Cerbo can do anything with them.
  • If the internal BMS is talking to the Cerbo, it could throttle back the charging.
  • If the BMS is determining the batteries can’t take any more, they may cut off charging by disconnecting power inbound.
  1. Are both panels facing the same direction, and/or are they shaded or obsured by anything? That can cause a drop in power if different directions or shaded. The weaker panel may drag down the power.

I’m sure a few other folks may have helpful tips.

I use a Klein Tools CL390 meter - it has a clamp that goes over a wire for measuring amps, and it means you don’t have to break the circuit to check.

5

This was a professional install, but the installer said I have to bring the rig to them to check out. And they’re 2,200 miles away from me.

There’s a Victron display monitor that shows the solar charging watts, the battery SOC, and charging/discharging staus.

It’s a SmartSolar charge controller and it’s connected to my phone through the app so I can see data. I can see the each of the batteries temp, volts, last full charge, etc. on the Lithionics app.

Thanks.

6

Ok, 2200 miles is a long drive!

Does the Cerbo GX Touch display match what the phone tells you from the SmartSolar, and does that match the Lithionics ?

In other words, if you turn off all the loads, so that the power is just going to the battery and running the devices, the currents/watts should be in pretty close agreement.

Did you also check the VE.Direct or CAN BUS BMS data cables? Might be communication issue.

Any errors / notifications?

Wildfire smoke?

I’m out of ideas.

7

My other problem is the local Winnebago dealer had it for 12 days and said they don’t know what’s wrong with it and can’t fix it because it’s not stock since we had the Victron upgrade installed.

The Cerbo touch display matches the SmartSolar battery voltage at13.72. The Cerbo touch screen shows 34 watts and the SmartSolar app battery current at 2.30 amps. Everything is off in the coach.

The Lithionics app shows 13.56 volts, 0 amps.

No errors or notifications.

I will look up where to locate the data cables so I can check them.

I may have to schedule an appointment at the Winnebago factory to fix this, they are evidently very good and accomodating there.

Thanks so much for you help!

8

Maybe the batteries are full. 12.8V is nominal (3.2v per cell), and 13.56 is fairly full up.

9

How are you concluding the amps?

If you have 21V and 18A, that’s 378Watts - where should that energy go, if not into the battery? If the mppt does only report 40W, then there can’t be 9A and 21V on the PV In-Side, technically.

There’s a Victron display monitor that shows the solar charging watts, the battery SOC, and charging/discharging staus.

What’s the SOC when that happens? Does it also show the battery voltage?

10

Yes, they are at 99 & 100% right now. I just charged the batteries up a few days ago. It showed the same 34 to 40 watts solar charging even when the batteries SOC was 30%. The system has never shown more than 40 watts.

11

How about a picture of the panels and the Victron equipment? Maybe a keen eye will spot something.

12

I disconnected each of the terminals from the solar panels to the combiner box. I then checked the voltage from each of the panels with my multi meter and then switched the meter to amps to read the amps coming from the solar panels. At the SmartSolar controller, I can only read the voltage. It was the same 21 volts. My multi meter only reads up to 10 amps, so I can’t read the amps there.

13

Attached are the requested pictures. Let me know what you think.

Thanks

Solar pictures.zip (680.4 KB)

14

Is your Cerbo connected to the internet? If so, connect to VRM and allow one of us access to the system.

15

It is but I’m not at home right now.

16

I tried to find 190W panels on the Zamp Solar (and Dometic their new owner) web page, but no luck.

Thanks for posting the photos. Something doesn’t add up. There’s 3 panels in IMG_2492, not 2, and they look smaller than 190W.