Multiplus ("plastic" exterior) low amperage charging

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question

llubi asked Mar 20, '21

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 Charger cerbo gx multiplus ve.bus

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Modifications Space

Node Red Space

Answer 1 · 2021-03-20T18:20:45Z

Alexandra answered · Mar 20, 2021 at 06:20 PM

@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 commented · Mar 20, 2021 at 07:04 PM

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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Answer 2 · 2021-03-20T18:29:04Z

seb71 answered · Mar 20, 2021 at 06:29 PM

What voltage does the battery reach when charging is finished?

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llubi commented · Mar 20, 2021 at 07:02 PM

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

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seb71 llubi commented · Mar 20, 2021 at 07:08 PM

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 seb71 commented · Mar 20, 2021 at 07:27 PM

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

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seb71 llubi commented · Mar 20, 2021 at 07:37 PM

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 seb71 commented · Mar 20, 2021 at 07:41 PM

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 llubi commented · Mar 20, 2021 at 07:49 PM

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 seb71 commented · Mar 20, 2021 at 09:39 PM

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 llubi commented · Mar 20, 2021 at 09:56 PM

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 seb71 commented · Mar 21, 2021 at 07:55 AM

Ok, but if battery is at 50% charge?

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klim8skeptic ♦ llubi commented · Mar 21, 2021 at 12:59 AM

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 klim8skeptic ♦ commented · Mar 21, 2021 at 06:43 AM

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

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klim8skeptic ♦ seb71 commented · Mar 21, 2021 at 07:26 AM

I see 3 devices measuring Soc.

Do Winston make a 70Ah cell?

Just need clarification.

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llubi klim8skeptic ♦ commented · Mar 21, 2021 at 07:57 AM

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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seb71 llubi commented · Mar 21, 2021 at 08:02 AM

You said you do not have a BMS. That "thing" looks like a BMS.

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klim8skeptic ♦ seb71 commented · Mar 21, 2021 at 09:01 AM

Thing is an ISDT BG-8S.

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llubi klim8skeptic ♦ commented · Mar 21, 2021 at 08:50 PM

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 seb71 commented · Mar 20, 2021 at 09:40 PM

..

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3f73c819-e19f-4014-b704-be3a1b22ee86.jpeg (90.8 KiB)

Answer 3 · 2021-03-20T18:53:46Z

jwfrary answered · Mar 20, 2021 at 06:53 PM

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

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llubi commented · Mar 20, 2021 at 07:01 PM

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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