Another Multiplus Generator Question

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dbuchner asked Jul 11, '23

Another Multiplus Generator Question

Hi all,

I am having issues with charging my batteries with a 3300W generator during times when we aren't producing enough solar power. No bueno.

The setup:

Victron Multiplus 48/5000/70 Inverter (Firmware: 430 VEBus: 2624430)
Victron SmartSolar MPPT 250/100-Tr VE.Can Bluetooth Solar Controller (v1.61)
Victron Venus GX
2x BYD-B-Box-Pro-13.8kWh LIFPO4 Batteries
1x 3300W petrol generator
20x panels on the roof (obv.)

Connecting a generator to the AC input of my multiplus results in a few minutes of bulk and then turns off the system. Meaning the power turns off for 30s, the multiplus turns off, resets and then comes back on. No errors or faults in any logs and the generator remains on at all times with no overload lights or warning on the genny.

My configuration in VEconfig is as follows:

General
Dynamic Load: On/Off no difference.
AC Current limit: 12A (matched with charger current limit)

Charger
Weak AC Input: On or Off makes no difference
Charge Current: Limited to 12A (genny is 12.5A max, have lowered as low as 11A same behavior)
Bat Type: LiFEPo4

Inverter
PowerAssist: Off (IF turned ON it turns into to a circular nightmare of switching back and forth between AC and Battery)

Hertz: 50 (wide Hertz set) When monitoring this I never see the generator outside of ±49.5 to 51.

I have read and tried most of what's described here: https://www.victronenergy.com/live/multiplus_faq

To prove that it does in fact work here are the VEconfig and VRM screenshots when it works but as I said it only works for a few minutes at a time, shuts the inverter down, restarts and then repeats the same process. After a few tries it typically just ends up in bypass mode and powers the site from the generator but doesn't bulk/charge the batteries.

I've read quite a few of the posts which mentioned that generators are somewhat of a hit and miss situation but this seems different.

Feels like I am missing something obvious (is this where the assistants come in???)

Cheers

Dan

charger Generator multiplus ve.bus

screenshot-2023-07-11-at-51325-pm.png (700.2 KiB)

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Answer 1 · 2023-07-11T08:36:32Z

JohnC answered · Jul 11, 2023 at 08:36 AM

Hi @dbuchner

The genset is getting the blame, but I don't think that's the cause.

You have BYD batts, presumably fully integrated given External Control is indicated. The 430 firmware is out of place, and this link suggests that 469 is the minimum supported.. https://www.victronenergy.com/live/battery_compatibility:byd_b-box

I use the exact same 2624 Multi and have tested it with numerous gensets (to the limits), but never seen the Multi shut down. To do that it's something deeper than genset rejection.

Bring your system up to scratch with a fw update on the Multi in particular. The latest is into the 5xx range. Then work from there.

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dbuchner commented · Jul 11, 2023 at 10:17 PM

Hi @JohnC, I was afraid that would be one of the answers. ;) I am not looking forward to upgrading everything. I had not seen the BYD compatibility piece and honestly I mostly discounted the bats as being the issue as the inverter does the switching. I'll have to wait until the weekend for the upgrades and report back. Thanks

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Answer 2 · 2023-07-11T09:13:13Z

Michelle Konzack answered · Jul 11, 2023 at 09:13 AM

If your Generator can deliver 12,5A max continuous, set the MultiPlus to 8-9A and do not forget, to set the input to "Generator"

Do not use "weak AC input" if you set the input Amos to 2/3 of the rated power.

With this settings my generators did not produce any errors anymore and my MultiPlus-II was working rock solid.

Good luck.

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dbuchner commented · Jul 11, 2023 at 10:43 PM

I'll give it a shot once I've upgraded all the software.

So you're saying:
AC Input set to 8-9A.
Disable Weak AC.
Charge Amps 40A.

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Answer 3 · 2023-07-11T11:45:56Z

klim8skeptic answered · Jul 11, 2023 at 11:45 AM

@dbuchner you might want to increase your charge current to load your genset up to about 2/3 of its rated output.

Something between 40-50a, what ever the genset is comfortable delivering.

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dbuchner commented · Jul 11, 2023 at 10:40 PM

@klim8skeptic So this is an interesting one. The original charge current was set to 40A.

The AC input max is set to 12A as to not overload the genset.
At 23VAC and 12A the genset has theoretical max of about 63A.
With the charger set to 40A the genset would run up higher and higher and eventually the victron switched from bulk to passthrough, which is why I lowered the charge A (first 30, then 20 then matched to the 12A of the max AC input A, even though I understand this is different).

At 80%, which is what the Victron Genset guide mentions, it should be 50A and at 2/3 it's 42A.

Do you know why or what would be causing a stop to bulk mode if the charging amps are too low? In particular if it works for a short period of time?

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Answer 4 · 2023-07-11T16:26:37Z

derrick thomas answered · Jul 11, 2023 at 04:26 PM

I see ESS on your screenshots. Have you tried disabling LOM detection for testing purposes?

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dbuchner commented · Jul 11, 2023 at 10:13 PM

yes, LOM detection is disabled.

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