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cleanlivin avatar image
cleanlivin asked

MPII, charging LiFePO4 parallel of 3, wild fluctuation of charge voltage

All equipment is brand new.
All appears to work perfectly in the DC circuit and AC systems until I go to charge the batteries with the MPII. It works fine in Inverter mode but not in Charge.

However, MPII does not charge at a consistant current at any time.
Show the same problem on the 712 shunt display and in the VConnect on my MacPC.

Here is my own schematic. Either I have received from V. dealer a flawed unit but far more likely I have something wrong.

I have a video of the shunt control display clearly showing the rapid jumping betweens voltages, but site will not accept a .mov file even though they say they do. I can email if you send me a note.

Need help as I have checked over and over again every cable and connection.
Thought it might be a grounding problem but not sure and can't seem to define for sure either way. ALL else works except charing.

Batteries are the Redodo Mini 100Ah SMART batteries and I am wondering could they be the issue with their new BMS.

Guidance and jb-16x-electrical-schematic-master-dc-9-22-2023-3.jpg


Help is sincerely appreciated. Also here are my MPII settings - Opps! Can't get them to take the list of MPII settings either, not as a jpg, png,

I'm going to post this much and see if I can just copy the MPII settings in a new post.

Thanks,
Jack


battery charging
jb-16x-electrical-schematic-master-dc-9-22-2023-3.jpg (2.9 MiB)
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6 Answers
cleanlivin avatar image
cleanlivin answered ·

Here are my MPII settings:Screen Shot 2023-09-23 at 12.42.11 PM.png


screen-shot-2023-09-23-at-124211-pm.png (294.0 KiB)
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janieronen avatar image
janieronen answered ·

Are these three batteries very close to each other or coupled with long cables? Are you able to see battery internal BMS information via bluetooth in example? Deviation in amperage could be caused if current is not equally shared between batteries. That can happen if not top-balanced and or in example if long interconnection cables. Also different temperature batteries have different internal resistance.


If cannot see BMS data then you could add voltage sense cable to your Multiplus to get accurate battery voltage.



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cleanlivin avatar image
cleanlivin answered ·

Battery cables are really short, all 3 batteries are laid on their side, as you can see from the image I will try to add now.

The batteries are: #1 on "floor" in right view of photo.
#2 is on bottom of back/right part of photo.
#3 is on top of #2 in back/right part of photo
The three batteries (I actually purchase and have 4 but no way to get the 4th in there) are what Redodo calls "SMART" but that does not match my idea of smart, no blue tooth that I have found.
Before install the 3 batteries, all three were within .05 of each other.

I wish I could post the video I have on my iPhone and now MacStudio here. Video is a .mov file but just no way to get this site to define why it rejects. Guess is file is 25.4MB. If size is the issue, I can shoot a shorter video and post.

Right now I have all components shut down untile I can get input. Too much money here to mess up.

img-5738-2.jpg img-5739.jpg


img-5738-2.jpg (2.6 MiB)
img-5739.jpg (2.5 MiB)
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cleanlivin avatar image
cleanlivin answered ·

This is in my 2022 Airstream Basecamp 16X. The tiny compartment under the front galley sink. Taking out a large shelf was required and the cavity opening is 13" wide by 20" high.

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klim8skeptic avatar image klim8skeptic ♦ commented ·

@CleanLivin Where is the multiplus voltage compensation wiring connected?

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cleanlivin avatar image cleanlivin klim8skeptic ♦ commented ·
I don't know of such a cable. From the name you used it sounds important.

Please advise and I will look into. Jack

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cleanlivin answered ·

My best friend pointed out that my batteries are not connect in the same manner as show a Victron schematic. Tomorrow I will change to match having cables from the batteries connect to the ends of the left + lynx bus and the - connect to the far right bus at the ends of each bus.

Question - In the Victron schematic they have the Lynx mounted vertical like I do BUT there show the Lynx ground to the frame coming off a terminal on the top of the Lynx negative bus??? Or are they attaching to just a screw that holds the cover on?


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cleanlivin avatar image
cleanlivin answered ·

My Lynx does not have a terminal where it is shown on Victron's schematic.

Could that just be a screw that holds the cover on, which I am not using due to space issues?

screen-shot-2023-09-23-at-91728-pm.png

screen-shot-2023-09-23-at-91728-pm.png (491.7 KiB)
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klim8skeptic avatar image klim8skeptic ♦ commented ·
It does have a bolt for the lug though.

Keep an eye on those water hoses, being ss clad will conduct electricity.


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cleanlivin avatar image cleanlivin klim8skeptic ♦ commented ·
I have been wondering about that and have been thinking of wrapping them completely in foam or some none conductive media.

Any suggestions?

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cleanlivin avatar image cleanlivin klim8skeptic ♦ commented ·

Would you be referencing the bolt in my setup on the far right bus at the top of this image?

I thought it was just to hold the bus bar in place, but I can attach the trailer frame 2/0 cable to that for thee full system ground, and then the MPII goes to the solo bolt in the center of the (-) bus bar?

img-5491.jpg

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img-5491.jpg (2.3 MiB)
cleanlivin avatar image cleanlivin cleanlivin commented ·
The 5/16" bolt, top right bus.


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