question

vanandthewoods avatar image
vanandthewoods asked

Multiplus 12/3000 low battery warning then shutoff under high AC load.

I have a victron multiplus 12/3000 inverter with 2x 150ah lithium batteries from Ohmmu wired in parallel. The batteries and inverter are wired with 4/0 cable.

When I try to run a high draw appliance (in this case an espresso machine), the low battery light comes on, and the inverter shuts off.

What might be causing this issue? Everything I have found on other forum posts here is related to wire gauge, but I don't think that is my issue. Is there anything else that might be causing it?

multiple inverterslow battery warning
2 |3000

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4 Answers
Ulrich avatar image
Ulrich answered ·

Hello,

an espresso machine often needs 2000 watts to heat up. 2000 watts correspond to 2400 VA (incl. Reactive component). Then at least 182A flow at 13.2V. The length of the cable is also decisive. At 2m, the cable cross-section must be 25qmm, then 12.68V arrive at the inverter.

The inverter settings must be made accordingly. (VEConfig)

25qmm corresponds to AWG 4 (https://en.wikipedia.org/wiki/American_wire_gauge)

The cables between the battery and the bus bar must be of the same length so that the load is evenly distributed across both batteries. The inverter must also be connected to the bus bar.

I hope I could give you the right hint?

greetings

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vanandthewoods avatar image vanandthewoods commented ·

Thank you for the response.

So the length of cables between my batteries is the same. The length for busbar to battery, and busbar to inverter is similar, but not exactly the same length, maybe 6-8 inches different. There is less than 6ft of cable between the batteries and inverter. Could such small differences in cable length be causing my issues?


Thank you.

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

Hi @vanandthewoods

Check the maximum discharge current of your batteries, 2x 100Ah is usually not enough to provide enough current to a 12V 3000 VA inverter.

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vanandthewoods avatar image vanandthewoods commented ·

Ohmmu lists the discharge rate as 200A per battery. Since my batteries are wired in parallel am I correct in thinking that I have 400A maximum discharge rate? How much current would be sufficient in this case?

Thank you

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Ulrich avatar image Ulrich vanandthewoods commented ·

2m cable length
25sqmm

3000VA
13.2V battery - 4.92% = 12.49V
12.5V battery - 5.38% = 11.79V

2500VA
13.2V battery - 4.09% = 12.66V
12.5V battery - 4.56% = 11.93V


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chriscross avatar image
chriscross answered ·

I have the exact same issue but I cannot reset SOC on my Lynx Shunt or on Multiplus II and it is not charging the LiPo on AC power. So currently balancing the batteries individually and try to get them back to 100 % then put them in parallel again and reconnect to Lynx and Multiplus


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kajimike avatar image
kajimike answered ·

I had this same issue. The problem is that the voltage the Multiplus was seeing was lower than the BMV 712 was reading, or my battery bluetooth was reading. Once I attached a MK3 USB dongle to the Multiplus and watched this occur I could not see the actual low voltage value. Once doing that I reset the low voltage cutoff values to be lower than the value causing the fault. Works fine now.

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