question

i-jaghoori avatar image
i-jaghoori asked

24/3000/70 Multiplus not switching to inverter mode fast enough

I have a 24/3000/70 Inverter/Charger that is connected to 3 strings of 24-Volt battery bank consisting of 9 SPRE 12 225 Trojan batteries. It charges the batteries with city power and goes into inverting mode when there is a city power outage. When the city power is on, it supplies power to the loads from city power only, and only when the city power is out, it goes into inverting mode. Where I am located, the city power does go out at least once every 24-hours for a few hours. The device works fine most of the times, but every now and then, it acts strangely. Lets say that the city power has been on all night long and the batteries have been fully charged with almost zero load on them. In the morning, the inverter lights indicate that it is float charging. However, when the city power goes out, the low battery indicator comes on and the inverter doesn't output any power from the batteries as it should. It stays like that for a while (minutes and sometimes a few hours), and then suddenly, while the city power is still out, goes into inverting mode and starts outputting power. Like I said, it doesn't happen consistently, only sometimes. My batteries are fairly new. They were installed about two months ago.

Thanks for your feedback in advance.

MultiPlus Quattro Inverter Charger
2 |3000

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

3 Answers
pmikep avatar image
pmikep answered ·

I have not seen that behavior with my 24/3000. Did you put a voltmeter on your batteries? Maybe they really are low? I'm not familiar with your batteries - could they be in a BMS shut down mode? Last, assuming that there's nothing wrong with your Multiplus, is the city power really off? (Brown out? Someone has an improper grid tie feeding power to you?) Try physically removing the AC Line 1 wire the next time the city power goes off. (Or try removing the wire now to see if the Multiplus kicks in immediately.) Does changing the UPS mode on the Multiplus make a difference?

2 |3000

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

i-jaghoori avatar image
i-jaghoori answered ·

It acted again like that this morning, except it took a lot longer this time to switch to inverting mode. I checked on here after the fact, but I will try those things you suggested. When I say the city power is out, I’m talking about a brown out. I’m located in Afghanistan. There is no feeding in to the grid here.

1 comment
2 |3000

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

pmikep avatar image pmikep commented ·

Ah... I'm going to guess that Brown Out conditions are confusing the Multiplus then.

You might need to think of your Line voltage more like a bad Generator. There are some settings in the Multiplus for that.

Do you have Power Assist enabled?

0 Likes 0 ·
Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @i jaghoori

I'm guessing brown-out too, grid voltage lowers slowly, invert tries to match it and when grid is disconnected it cannot bring it up again.

try raising the AC input disconnect values, like also needed when using a generator:

https://www.victronenergy.com/live/multiplus_faq

2 |3000

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