Solar MPPT stops charging if I current limit the Multiplus

Question

question

messy asked Aug 4, '22

Solar MPPT stops charging if I current limit the Multiplus

first - the equipment

Multiplus 24/3000/70-50 120V

SmartSolar MPPT 100/50

SmartShunt 500A

EG4 Lifepower4 24v battery

RaspberryPi running VenusOS

Sometimes we boondock or moochdock in our RV or i just don't want to pull so much amperage from our house shore for the RV and let the solar panels provide some energy, but if i current limit the Multiplus, my solar stops working and continues to not work even after restoring the Multiplus to 50A.

I've tried isolating the MPPT from the network so it's standalone, but then it reads about 2 volts higher on the battery than the smart shunt and my multimeter says and doesn't appear to charge because that elevated reading is at float levels.

I do not have a battery listed for compatibility with DVCC, so i have not attempted that to get what i am aiming for. it's my understanding that it's possible with appropriate communications to do this with DVCC but alas no battery compat.

When i set the current limit on the Multiplus - is it limiting the entire network's current? I can't quite tell from what i've read.

This seems like a pretty common scenario i would think so i'm wondering if i'm just doing something stupid.

I do have the SmartSolar's voltage set a bit higher than the Multiplus so that the Multiplus in theory would chill out earlier and let the solar contribute at least some at the end.

I've also recently been on the road with no shore at all and the solar still clamped down to 0A to the batteries. This scenario definitely used to work.

Any help debugging would be greatly appreciated

MPPT Controllers charge current limit

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Modifications Space

Node Red Space

Answer 1 · 2022-08-04T20:04:03Z

Mike Dorsett answered · Aug 04, 2022 at 08:04 PM

Try checking the Smart solar parameters with Victron connect app on your phone. In particular the battery charge current and also the voltages. Check also the wiring from the Smart Solar to the shunt - if the smart solar is reading battery voltage higher than the actual (terminal) voltage by 2V, this may indicate a blown internal fuse, or a disconnected wire.

1

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

messy commented · Aug 04, 2022 at 08:45 PM

interesting. will do when i can. it just starting raining here again and the access is in one of the exterior panels

0 ·

Answer 2 · 2022-08-05T17:30:13Z

messy answered · Aug 05, 2022 at 05:30 PM

I pulled out the 100/50, checked all connections. the connection to the solar disconnect wasn't as tight as i would have liked so i snugged it up.
i turned everything back on and for a brief time i was getting about what i expected, then it clamped back down to zero current.

so i swapped in a nearly unused 100/30 i had laying around and set it up with the same settings as the 100/50 after updating the firmware.

i also put the multiplus into a 15A current limit so that the RV would drain down the batteries by way of the A/C.

i'm somewhere between baffled and reaching for a hammer :/

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Answer 3 · 2022-08-05T18:00:42Z

messy answered · Aug 05, 2022 at 06:00 PM

i just noticed something i wasn't expecting. this new 100/30 when in standalone mode was also ready an elevated voltage (which went back down when i networked it - and would track with the shunt readings)

it looked awfully close to the float setting, no matter what float was set at. i started changing float in the app to different settings and the battery voltage reading from the standalone mppt would change to match the float when reporting battery voltage.

for me at least this is not expected behavior. i would think it would be reading the battery in order to adapt to the battery to correctly charge it.

i've also noticed in the app on the VE.Smart Networking screen where it displays what your device is receiving data from - i get "undefined" for values. things like :

Using external battery voltage sense from: SmartShunt ABC123 - undefined

Using external battery temperature sense from: VE.Bus Smart ABC123 - undefined

Using external battery current sense from: SmartShunt ABC123 - undefined

the "undefined" could be harmless, but in light of everything else it makes me wonder what's going on

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

question