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Rainbow Solar avatar image
Rainbow Solar asked

Multiplus on firmware 433 and 459 goes to float too early.

I have been running my Multiplus compact 24V 1600VA on firmware 159 for ages with no issues. I recently updated to firmware 459, restored the previous settings, activated the battery monitor option and input my battery capacity.

The first time after the update, the batteries charged fully and got to 100% capacity on the attached BMV. Subsequently, the batteries do not get fully charged before switching to float. The batteries charge to about 70-75% and then switch to float. The batteries keep getting about 9A charging current whilst on float showing that they are not fully charged.

Absorption was set at 29.4V and float at 26.04V.

I switched to firmware 433 but had the same issue. So, I am back on my original 159 firmware.

What may be the problem and how do I resolve it? Thanks in advance.

MultiPlus Quattro Inverter Chargerbattery chargingfloat
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boekel avatar image boekel ♦ commented ·

can you show all settings you had in the one or the other? screenshots / or the configuration files would also work.

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Paul B avatar image
Paul B answered ·

I presume you are talking abou the BMV reading

In the BMV under setting there is a option that says charged voltage this maybe set to high

Based on you absorption setting it should be set at around 29.3 to 29.4 then set the tail current to a figure that causes it to flip to 100% when you want them to be full


I hope I have got the right meaning here as I am prsuming that you are using the BMV as the main soc CONTROL

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Stefanie (Victron Energy Staff) avatar image
Stefanie (Victron Energy Staff) answered ·

I think you're having the same problem I have with my Compact and 433/459. Mine either goes straight to absorption forever or straight into float after switching the Multi on and independent of SoC. Looks like the Compact does not play well with firmware 433 and 459. Let's hope a Victron official jumps in and comments.

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Rainbow Solar avatar image Rainbow Solar commented ·

After using it for a few weeks, I noticed that my Multiplus compact on 433/459 immediately jumped to float when connected to our massive diesel genny. However, it functioned normally when connected to the grid.

I also noticed the excessive absorption immediately after updating the firmware. I assumed that it was probably calibrating theMultiplus’s battery monitor.

So, I had to downgrade to the 159 firmware and my problem was solved. My guess is that the issue is related to the battery monitor option in the 433/459 firmwares.

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funkaddict avatar image
funkaddict answered ·

Hi @Rainbow Solar ,

I had the same issue with my Multiplus. They way I fixed it was using the MK2 usb adapter along with the VE Config utility and set Bulk to stop at 98% battery charge and set the charge efficiency as per MPPT specs. Now my battery no longer stops at 85% as it was set by default. I also set my MPPT absorption and float around 0.3V higher with the bluetooth dongle so that the Multi will trigger itself when it's reached the abs/float voltage. Please let me know if this helps.

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Rainbow Solar avatar image Rainbow Solar commented ·

Thanks. Your solution is a workaround to the bug. I hope the Victron development team can identify this bug and correct it in subsequent updates.

I am afraid that implementing your solution will shorten the absorption time of my system since I have no solar input on it. So, I am stuck on the 159 firmware until the development team can sort it out.

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