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Victron Multiplus 24/3000 Low voltage disconnect: I don't understand some simple detail, I'm sure

interestingfellow

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Aug 5, 2020
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My multiplus went into low voltage disconnect at 25.8v but I have it set to 23v.

I have a Multiplust 24/300 in my camper on 560ah 2p8s eve280's
I also have a BVM712 and a RPi running Venus. The venus and VRM sees all my equipment and works as it should
I used the USBMK3 and Vconnect to make the settings changes in my Multiplus as well as genuine ve.direct cable my BVM712

Multiplust Settins
23v DC Low voltage disconnect
26.2 DC Low Voltage Restart
25v DC Low Voltage Warning
I *had* battery monitor enabled in the multiplus, but don't think I was supposed to, since I have a smart shunt and Venus

BVM712
I had low SOC alarm turned off (now set to %10 and %11 reset)
and I did have Low voltage alarm set for 24v with reset at 24.1


Why did my multiplus shut down inverting while my batter was at %15/25.8v?

And then, when I plugged it into shore power to charge, it wouldn't turn "on" inverting or charge. I waited 60 seconds and then turned it "off" at the switch on the front, and then back to invert/charge "on".Now it's operating properly.multiplus lvd shutdown.JPG
 
Voltage drops under load.

It will then rebound when the load is removed.

You can minimize this drop with lithium batteries and good clean connections with properly sized wires but you can never eliminate it.
 
If you were running the microwave (or other heavy loads), the power sag could have dropped it down. Also, if you were running the microwave and then added another 120v item (toaster, hairdryer, etc), you may have overloaded the inverter. ( we do that occasionally).
 
I just dont think that was the case. The only loads were my 12v converter (35w at the time) and my absorbtion fridge <300w
At 24v that's < 20amps, mybattery is 560a, and it's 8ft of 1/0 wire.

I had my rooftop ac (1400w) and microwave (1400w) on for 2 minutes the other day as a test, no problem.
 
20a can cause a voltage drop even on 4/0 if the connections are poor somewhere.

That said, how sure are you that the battery is actually charged? False readings are possible even with a shunt if things get weird with the system.
 
Please don't mistake my brevity for being rude: I was on my phone earlier with sausage fingers and a tiny keyboard.

This is a new setup that has only been charge cycled twice. I've been watching everything very closely I'm competent enough to attempt this, but it's still new to me and I lack experience.

All the readings from all my equipment line up as one might expect so I don't think there is a bad connection. I'm going to load the system after it charges fully and feel the connectors. Everything is actually close and there aren't too many connections. I used hydraulic crimpers and copper lugs; everything seemed really decent, but I might just not know.

But ALSO
Yesterday I installed the sinowealth serial driver package so I can attempt to have Venus read and control my Daly BMS. I have not built the cable for the daly, yet, but do have a gps/ch340 plugged into venuspi usb. I'm almost certain that when I unplugged the ve.direct cable for the shunt from venus that the venus mistook the gps usb serial output as voltage and temperature alarms from my shunt because it threw all kinds of high and low voltage and temperature alarms. It may have been a fluke software glitch, I dunno.

I appreciate your assistance!
 
Having the same problem and a complete newby. Did you resolve this??

Thanks,

Michael
 
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