MPPT 100/50s quit when AC out load over 1500w

Question

question

shawnshepherd asked Feb 9, '23

MPPT 100/50s quit when AC out load over 1500w

12v system.

under ac out load of 1500w+ one or both mppt 100/50s stop producing.

I wonder what could be causing the loss of power from the mppts during high loads?

update:

Changed a couple of things around, removed the MPPTs from the network (had them networked via bluetooth prior to adding cerbo) rebooted everything. still same issue. Did not have this issue prior to adding the cerbo and lynx distributors/shunt.

Also, see the red lights on the lynx on the right. There are no blown fuses in there and the lights go back to green when the MPPTs start sending power again.

update:

all connections secure, still the issue persists.

MPPT Controllers smart solar charging behaviour

d6044174-e26e-48e3-9b50-5fc58a64b2c2.jpeg (3.5 MiB)

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klim8skeptic ♦ commented · Feb 10, 2023 at 12:19 AM

I'm not seeing what you are describing in your photo.

Both mppt's are in bulk, and their combined output is 1160w.

More information is needed. Perhaps some VRM screenshots of the mppt when your fault is occurring?

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shawnshepherd klim8skeptic ♦ commented · Feb 10, 2023 at 12:40 AM

that's just an image of the setup, not during the issue.

one other thing, when the SCCs cut out the red lights on the lynx distributor they are attached to come on. no fuses are blown though.

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Alexandra ♦ shawnshepherd commented · Feb 10, 2023 at 04:08 AM

You might find that the battery voltage drops under the larger loads, then the mppts are forced to re track the mpp.

125A from 12V is a heavy load, you dont say what battery type they are but if they are lead/gels/agm it will be worse.

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shawnshepherd Alexandra ♦ commented · Feb 10, 2023 at 04:50 AM

LiFePO4 batteries (2) 540ah total. Battery voltage does drop under heavy loads. Think this might be causing the mppts to give up?

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shawnshepherd answered · Mar 24, 2023 at 03:26 AM

Still not able to pinpoint a cause but have eliminated the issue.

Removed both lynx distributors and the lynx shunt. Replaced the MPPTs and wired directly through the batteries. Everything is working as intended.

Lots of parts now collecting dust on the shelf but at least the system is functioning. Time for some post mortem investigations.

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Modifications Space

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Answer 1 · 2023-02-11T03:04:54Z

shawnshepherd answered · Feb 11, 2023 at 03:04 AM

Changed a couple of things around, removed the MPPTs from the network (had them networked via bluetooth prior to adding cerbo) rebooted everything. still same issue. Did not have this issue prior to adding the cerbo and lynx distributors/shunt.

Also, see the red lights on the lynx on the right. There are no blown fuses in there and the lights go back to green when the MPPTs start sending power again.

Thoughts, Victron?

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pwfarnell commented · Feb 11, 2023 at 09:31 AM

Voltage drop was mentioned above, the Lynx shunt in the photo above shows the battery holding the voltage. However, it would be a good idea to measure the voltage on the Lynx distributor bus bars or Multiplus in to double check the two connections between the shunt and the distributor in case one of those has not made well. Just clutching at straws but worth checking with the DMM.

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shawnshepherd pwfarnell commented · Feb 11, 2023 at 02:46 PM

will check the connections, bus bar and all others. probably also going to test removing the second (right) lynx distributor from the system.

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Answer 2 · 2023-02-16T03:34:48Z

shawnshepherd answered · Feb 16, 2023 at 03:34 AM

Not sure this victron juice is worth the squeeze

Incredibly frustrating to be pulling 100 amps/hour out of the battery during a bright sunny day just because the (victron) solar chargers don't want to work when the (victron) inverter is pulling amps.

Pulled all the new stuff out tonight, 4 steps backwards. Will test under load tomorrow. Spending tonight shopping for a different brand, maybe one with some decent (or any) customer support.

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klim8skeptic ♦ commented · Feb 16, 2023 at 06:35 AM

@ShawnShepherd Cant tell much from your photo. Or your posts.

Need more information.

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shawnshepherd klim8skeptic ♦ commented · Feb 16, 2023 at 02:48 PM

ok, thanks

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kevgermany ♦♦ commented · Feb 16, 2023 at 06:42 AM

Here we are mostly volunteers, unpaid, with occasional input from Victron staff. Your dealer is primary support.

It would help if we had more details. Like screen shots of what the MPPT readout is when shut down. Which equipment is in the system. Is there AC input.

First guess is that you're drawing such a heavy load from an undersized system that the MPPT sees the output as a short circuit.

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shawnshepherd kevgermany ♦♦ commented · Feb 16, 2023 at 03:17 PM

That was no shot at the community here, it's been a great resource. It is unfortunate that victron is using it as a substitute for customer support. If victron does not want to provide direct support maybe they find a way to stop this junk from being sold on Amazon by a 1,000 different "dealers".

I will look at the short circuit angle. 2500+- VA with a MultiPlus-II 2x120V 12/3000/120-50 (Cont. output power at 25°C 3000 VA (Non-linear load, crest factor 3:1)) Based on the numbers, system seems to be properly sized.

Also, the MPPTs worked as expected prior to installing the Cerbo GX, Lynx Distributors, and Lynx Shunt.

Also, also, would the MPPTs not throw an error if there was a short circuit trip? Get errors for every other over limit issue.

Hope you're having a great day Kev.

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Answer 3 · 2023-02-17T14:46:54Z

Daniël Boekel (Victron Energy Staff) answered · Feb 17, 2023 at 02:46 PM

Hi @ShawnShepherd

is the system online? is it ok if a developer logs in to it to try and find out what is happening?

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shawnshepherd commented · Feb 17, 2023 at 03:12 PM

Thanks for reaching out. The system will be offline for about a week. When I get back to it I'd be happy to have a developer log in and see what they can see. If you are able to glean any information from the data already uploaded to the VRM you are welcome to look at it.

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Daniël Boekel (Victron Energy Staff) ♦♦ shawnshepherd commented · Feb 17, 2023 at 06:26 PM

Hi @ShawnShepherd

I've looked at the history, and when the MPPT's stop working, they don't see any PV voltage, PV voltage goes down to zero.

Can you measure the actual PV voltage at the terminals of the MPPT's when this happens?

I've never seen this before, maybe there is an EMC problem causing measurements to be incorrect (if PV voltage is present when this happens)

First try than would be to do some cable management and route the PV cables away from battery cables (and AC cables)

Please make an @-mention to me when replying, as you'll be away for a week I understand. so I'll get a notification of your reply.

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shawnshepherd Daniël Boekel (Victron Energy Staff) ♦♦ commented · Feb 18, 2023 at 03:22 AM

Just want to make sure we are looking at the same thing (screenshot below). The MPPTs continue to see and report PV voltage during events. The screenshot shows the report from Thursday 216/2023. It's the last time we had the system online (on the internet). I did one test after we had good, consistent sun (turned on the coffee and the microwave at the same time) you can clearly see the drop before we shut the internet down. During the drop the PV voltage remains reasonably consistent.

Also, It might be worth noting that both of the MPPTs do NOT tend to go out simultaneously or instantly. They also seem to be "struggling" to come back to producing power, teetering up and down.

There are also no warnings or notifications triggered/reported during the events OTHER THAN the red lights on the Lynx Distributors (when the Lynx Shunt was included). Regarding the fuses in the Lynx Distributors, they have been changed multiple times, connections checked and rechecked, none have ever "blown".

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mppt-output.png (133.2 KiB)

shawnshepherd Daniël Boekel (Victron Energy Staff) ♦♦ commented · Feb 25, 2023 at 10:43 PM

Hi @Daniël Boekel (Victron Energy Staff)

We have the system online again. Let me know if there is anything I need to do to grant access.

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Answer 4 · 2023-02-17T15:18:04Z

shawnshepherd answered · Feb 17, 2023 at 03:18 PM

Still working backwards, removed on of the Lynx Distributors and the Lynx Shunt. Put the old SmartShunt back on the system.

Still seeing the MPPTs stop sending power under load.

Next will be removing the Cerbo gx from the system.

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