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llubi avatar image
llubi asked

Multiplus ("plastic" exterior) low amperage charging

Hi All!

My system is in a campervan, and it's:

1 x lifepo4 280Ah 12V

1 x Multiplus 12/1600/70

1 x BMW712, CerboGX, OrionSmart and MPPT 100/20

Wiring from battery to bus are 70mm2, wiring from multi to bus are as big as it fits, 50mm2. About 1,2m each cable.

Multi has been configured with Ve.config to lifepo battery, 52A max charging, and I think nothing more to comment.

Cerbo has DVCC engaged, with the option of limit charging disconnected.

2-3 times, I connected the van to shore, with the battery at around 50-60%, and the multi all the times make the same, start charging at +-50A, and 2-3 minutes later, go down to 30A and finishes charging at 15A. Battery stills at 50%, and temperature of the battery from 10 to 18 degrees Celsius.

What am I missing?

Thanks!

MultiPlus Quattro Inverter Chargercerbo gxmultiplus ve.bus
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3 Answers
Alexandra avatar image
Alexandra answered ·

@llubi

If this is a new install then you need to give it a bit of time and a cycle or two, to correctly calculate the SOC.

The BMV calibration maybe out.

https://www.victronenergy.com/blog/2017/04/13/instructional-video-how-to-optimise-the-bmv-700-series-sync-parameters/

https://www.youtube.com/watch?v=yMJ_vzB2avE

Of course your batteries will also have a BMS inside and they will be limiting the charge to the cells because it is doing its job.

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llubi avatar image llubi commented ·

It’s not a BMV problem, is the multiplus not charging using the configuration. Also not a new install, just the Multi is new.

I didn’t said before, but battery has no BMS, I configured 2 x battery protects to ensure battery won’t have problems

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seb71 avatar image
seb71 answered ·

What voltage does the battery reach when charging is finished?

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llubi avatar image llubi commented ·

14.20 to Absorption, 13.50 to float. But this is happening under 13 volts

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seb71 avatar image seb71 llubi commented ·

Your battery has a BMS?


Edit
I saw your other reply. So no BMS.


Did you measured each cell voltage?

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llubi avatar image llubi seb71 commented ·

Yes, all perfectly balanced at 1mv, but the “multimeter” has an error of 5mV, so they’re good :)

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seb71 avatar image seb71 llubi commented ·

It is normal for the current to drop as the battery gets closer to fully charged.

So the battery only reaches about 13V (3.25V cell voltage)?

Can you post a screenshot from VE Configure 3 "Charger" tab?

Also a screenshot from "Battery Voltage and Current" from BMV in VRM (during charging from the grid).

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llubi avatar image llubi seb71 commented ·

Yes, I know, but it’s to early to go 15A if battery is at 50%.
Battery goes up to 3,55V per cell, so if cells are at. I think that I understand you maybe the BMV is reading higher voltage than it really is, so multi is not using all the ampers?

In an hour I’ll update the picture, ASAP.
thanks for your help!

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seb71 avatar image seb71 llubi commented ·

If you get to 3.55V per cell, that is fully charged. Without a BMS, you might even want to stay slightly lower than that.


Your BMV is probably not correctly set so it does not reflect the actual SOC.

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llubi avatar image llubi seb71 commented ·

3,55 is the Max before going to absorption, according to battery manufacturer.
My problem is not with time or with SOC, is why the Multiplus does not charge as heavy as it is programmed to, 52A.
Sorry for bad picture...

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a3965857-d4f6-4d33-9816-beb8009a0353.jpeg (7.5 MiB)
seb71 avatar image seb71 llubi commented ·
My problem is not with time or with SOC, is why the Multiplus does not charge as heavy as it is programmed to, 52A

Because the battery does not accept 52A when fully charged.

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llubi avatar image llubi seb71 commented ·

Ok, but if battery is at 50% charge?

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klim8skeptic avatar image klim8skeptic ♦ llubi commented ·

You have not specified where the AC is sourced from? Grid or genset?

In the general tab, check your shore limit AC input current limit setting, should be above 4amp.

Also in the general tab, uncheck Enable battery monitor. Use the BMV for Soc, read up on DVCC.

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seb71 avatar image seb71 klim8skeptic ♦ commented ·

He said that initially it charges with about 50A for 2-3 minutes and then it drops to 30A.

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llubi avatar image llubi klim8skeptic ♦ commented ·

From grid, AC limit at 12A (default).

Will uncheck battery monitor, it’s checked.
Winston cells are 60Ah, picture is not of this installation, is just to share the “thing” controlling the cells

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llubi avatar image llubi klim8skeptic ♦ commented ·

Finally this made the change. Unchecked the battery monitor and updated firmware.

All night using the battery to go 50% SOC, connected to grid and charged at 52 - 53 amps until absorption, so 2,5 times faster than last week.

thank you so much!

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llubi avatar image llubi seb71 commented ·

3f73c819-e19f-4014-b704-be3a1b22ee86.jpeg..

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jwfrary avatar image
jwfrary answered ·

Have you checked the lithium battery option in ve.configure?

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llubi avatar image llubi commented ·

Yes. First by the new on-line VRM option. As It didn’t worked, bought the MK3 USB cable and made it again. No changes, if I reset the Multiplus it charges at “full” speed for 2-3 minutes, then it goes to 15A, reset and works again

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