question

Rob Beckers avatar image

MultiPlus 3000 exceeding absorb Voltage

One of our customers has an RV with a MultiPlus 12/3000 installed, and 4x Battle Born 100Ah 12V lithium-ion batteries in parallel. The only charging source at this time is shore-power.

She reports strange behavior when the MultiPlus goes into absorb; the lights flicker, fans beep due to under-Voltage and such. I had her measure the Voltage while charging and it was in the high-15V range, touching on 16V at times!

The DIP-switches on the MultiPlus are all set to "off" which would mean the absorb Voltage is 14.1 Volt, and there is no temp-sensor attached (so not temperature compensation, as it should be for lithium-ion batteries). Very likely the BMS in the batteries is switching off due to over-Voltage, and that's causing the effects she's seeing with the appliances.

The question is: What could cause the MultiPlus to exceed its set absorb Voltage of 14.1 Volt??

Pictures of the install are attached (and no, there are no solar panels installed yet, despite the SmartSolar in the picture, so that charge controller is doing nothing).


Thank you for your help!

-Rob-

Solacity Inc.

20211117-102152-1.jpg20211124-092550.jpg20211124-092609.jpg


MultiPlus Quattro Inverter Charger
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8 Answers
Alexandra avatar image
Alexandra answered ·

@Rob Beckers

Have you verified with a meter?

If it is exceeding absorption voltage it is very likely the batteries are shutting down to protect themselves.

Also using dip switches is a black art. Their current positions does not indicate how it is programmed in any way.

It is best to have a gx device in the system and an mk3 to usb adaptor used with ve config or victron connect, to make sure things are set right in software and are functioning correctly.

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Rob Beckers avatar image
Rob Beckers answered ·

Thank your for your reply Alexandra!

The absorb/battery Voltage was verified by the customer using a multimeter. Unfortunately they are 4000km away from our shop (clear across the country), and they don't have a MK3-USB. So I cannot personally verify what the internal settings are. The MultiPlus is a brand-new unit just out of the box, so we can be pretty certain nothing was set in memory besides the defaults, which best I understand means it should honour the DIP-switch settings.

-Rob-

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Rob Beckers avatar image
Rob Beckers answered ·

Alexandra, just read through your link about programming by using the DIP-switches; it's a little different from how I thought this was working and very informative! I'll give the customer a call and see if we can talk her through setting some explicit charge settings using those switches, and storing them.

Will report back with the result.

Thanks again!

-Rob-

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Rob Beckers avatar image
Rob Beckers answered ·

The customer and I sent over setting the charge parameters, following the instructions. While I cannot verify what is set, I am confident she did everything correctly, and we should have the unit at 14.1 Volt for bulk/absorb.

Despite that, charging via the still runs the Voltage up to 16+ Volt (and to a point where I'm pretty sure the BMS switches off the batteries). Screenshot from the BMV-712 attached.

-Rob-

screenshot-20211125-083850-1.jpg


2 comments
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@Rob Beckers

it is possible it is set for lead acid and it is trying to equalize. So battery tpe is incorrect possibly

the mppts can be changed.

Alexandra, not that I know.

What I'm going to suggest is that the customer gets an MK3-USB, and hooks the inverter up to a computer. That way we can actually verify and positively set the Voltages. That will likely also update the firmware to the latest, who knows, maybe that's part of the problem.\

-Rob-

kevgermany avatar image
kevgermany answered ·

The multi looks to be in float.

There's a 12:12 Orion in there. Is that wired to charge the house batteries? Did the customer set/check that?

And interestingly the starter battery is shown close to zero volts. Is that not wired in, or incorrectly wired?

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Rob Beckers avatar image
Rob Beckers answered ·

The orion is a DC-to-DC charger for when the engine is running (charge from alternator). The screenshot is when the engine is not running, as were the earlier measurements. Solar is not hooked up, the only charging source is the MultiPlus.

Noticed the zero Volt starter battery as well. I've not asked but assume it's just not hooked up.

-Rob-

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amgrumpy avatar image
amgrumpy answered ·

Hi,the owner didn't run the batteries down to low voltage disconnect by any chance before charging on mains?

Cause this happened to me with lifepo4 in an easy solar unit everything was sweet for months until i decided to test battery capacity.I ran them down until disconnect,im not sure whether it was easy solar or batts that shut off first as im on a learning curve :-) i then plugged into 240v and at absorption the voltage went nuts until bms disconnected.

I took to victron installer/rv mechanic,they just did a firmware update,set parameters again,monitored unit and it came good,so i dont have a specific reason only that a reset/update of unit fixed it.

Cheers.


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Nope, batteries are switched on (the BMS that is). When not charging a stable Voltage is present. What is IMO happening is that the BMS in all of the batteries is switching off based on over-Voltage, and at that point the MultiPlus spikes at 16+ Volt (the BMS in these batteries kicks out around 15 Volt).

Of course, the real question is why the MultiPlus runs the Voltage up THIS high to get to the point of causing the BMS to disconnect...

-Rob-

Paul B avatar image
Paul B answered ·

From the picture you dont seem to have a voltage Vsense connected

check the Multiplus Reference voltage connections are on the correct battery bank, and are connected on the NON battery side of any shutoff relay and that its getting the correct voltage reading

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At a Min connect these to the Multis Pos and Neg terminals - In preference they should be connected to the battery if there is no rely cuttoff anyware.that is

1637999926970.png

1637999926970.png (15.2 MiB)

Installing battery sense wires won't make any difference in this case. Yes, it gets the inverter a more accurate measurement of the actual battery Voltage, but if all worked as advertised, and even if there's a relevant Voltage drop over the inverter wires, the inverter would/should still not exceed 14.1V at the inverter side of the wiring (and that it's a little lower at the batteries doesn't matter, once the current tapers to zero during absorb the Voltages will be equal). This ain't the problem...

-Rob-