Lack of PV power to batteries


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Rasmusm88

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Mar 2, 2022
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39
Hi all

I have a question regarding some in my opinion strange charging behavior. Not sure whats wrong.

My setup is 400ah 14s200p batteries ~20kwh
Victron multiplus 2, 48v / 5000va
Victron 250/100 mppt
Cerbo GX
Batrium watchmon core with k9 via canbus to GX unit.
20 panels of 310w / 6.2kwp

Here is a small video, I'll try to explain what I think is weird
System is off grid for now, due to everyone here in EU wanting solar, the approvement time is upwards of 12 weeks now... At least I can charge my car now.

See PV power is around 800w going into the battery in the video. Target in batrium is set to 50a using ramped target. I figured that was quite low power coming in, so I tried with a heat gun turning to max heat, you will see the AC load increasing of course, but also the PV input increasing a lot at the same time, like something is compensating for the extra load. As soon as I turn off the heatgun the PV power goes down, so something in the system is limiting the incoming power? Same thing if I turn off the inverter, so only mppt charging.
I was hoping to see a full charge this weekend but not gonna happen with this going on..

I kinda wanted it to do as batrium says, target set at 50a give more power to the batteries (SOC% might be wrong, have not had the system running for more than a day)

In the charging tab, limited power cell volt im not sure what that is ? and what Im suppose to set it at

(Headphone warning, from heatgun)
View: https://youtu.be/Z2UW2XZulUI


I hope some of you guys can point me in the right direction :) I doubt its mppt setting, but could be wrong

Have a great sunday,
From Rasmus
 

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OffGridInTheCity

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I have Batrium but don't use the ramped target feature - my charging is 'wide open'.

However, I agree it looks like something is limiting charge current to the battery. I'd suggest experimenting to confirm charging behavior. Let the battery run down enough to allow full-charge per your settings, pick a time of day when you have enough PV, turn the loads off, and then see what happens - e.g. does it charge per your settings/expectations?.
 

Korishan

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How are your settings in the Victron for load balancing??

When you have no load, there is 13A going into the battery. When you create a load this is cut in half.
No load PV output is 760W, when loaded 2300. So the panel utilization went up by 3x. AC load went up 3x as well.

So from what I am seeing is that the Victron is slowing the charging of the battery down just enough to compensate to be able to provide full power to the AC load w/o pulling any battery power

You can't dump full power into the batteries while also trying to pull an AC load. If your Controller is set to start slowing down on the charge current as your SoC gets full, it'll back off on the current loading.

So check the Victron settings to see what the values for Float, Full, etc settings are.
 

Rasmusm88

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Mar 2, 2022
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I did notice earlier today when charging at lower soc, it would charge at full 3500w available, but like when soc increase it seems to limit it for some strange reason 🤔 I could try like you say to swap out the ramped target to wide open hm.

Korishan, yea seems like it. My thoughts was instead of holding back, why not put it into the batteries if theres available pv for it, instead of limiting it.
Ill check with the victron VE configure 3 software later if theres something I've missed, wont surprise me hehe
 

Rasmusm88

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Mar 2, 2022
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Its set to 56.7v in batrium, and inverter setting also 56.7v as with mppt, float 0.1v below
Heres some pics from the configure, not using any assistants at the moment.
I hope you can see where I screwed up hehe

Just noticed there is a setting within the mppt In the Usage and output menu set to battery life atm. Can set to user specified and always on and always off, and some other, will have to check up on that one
 

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Korishan

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Its set to 56.7v in batrium, and inverter setting also 56.7v as with mppt, float 0.1v below
Ok, so you are 2V within end of charge. So basically the charger is ramping down. This is partially done so that the charger doesn't overshoot the charge voltage. This is especially true for chargers that are lithium smart as the current needs to drop down as the top voltage is reached. This is called CCCV, Constant Current, Constant Voltage.

If you really wanna test the chargers capability, drop the battery voltage another 2V and do the test again. You'll see the amps jump even higher during charging.
 

Rasmusm88

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Thank you, I bet you are right about that. But that does not clear up why its not behaving as expected pr batrium settings, right :unsure: ? Will see later today but expecting rain the next couple of days. Battery voltage is down to 53.5 right now
 

Korishan

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that does not clear up why its not behaving as expected pr batrium settings,
No, that pretty much aligns with what Batrium is configured for. It's a Lithium based BMS.

55.0V (Current Battery Voltage) / 56.7V (Bulk Charge Max Voltage) = 97%
Well, 97% is bigger than 95%. So "Bulk" charging is done. Now it's slow charging to bring to 100%.
1664188512047.png



1664188612180.png

If I'm reading this graph correctly, this is the charge profile that is selected and this is what Batrium will tell Victron to follow. Too bad it doesn't have numbers on the graph. But I'm guessing that the battery is towards the bottom of the Blue line near where it flattens. Then there will be pulses, aka absorbtion charging, every 7 days for 15 mins (this is if the battery isn't used below 95%).

I don't have a Batrium or Victron, so kinda guessing on that last part. Maybe someone else can confirm/clarify on that graph.
 

Rasmusm88

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Mar 2, 2022
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That does make sense yea thank you, your guess is beter rhan mine :) So if I wanted batrium to control it more, I should maybe change the settings to 58.8v/4.2v batrium will stop the charging at 4v anyways hmm, could try that
 

OffGridInTheCity

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Interesting info...

I relay on CC/CV built into my Midnite Classic charge controllers and go with the seemingly straight-forward top voltage settings approach. My Batrium Charge Target feature is not used.

Is the graph (above) / discussion the Victron charge controller CC/CV function control? But why use both Victron CC/CV and Batrium Ramped Target?

---- Side issue -----
Looking at my newer Batriums I see that if I were to edit this page,
1664205132389.png

I would have to give values as there's no 'disable' option in the drop down. Is this why you're setting Ramped Targets?
1664205265162.png
t


My older Batrium has this - no options for Charge Target but again I never 'activated' it.
1664205433066.png
 
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Rasmusm88

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Mar 2, 2022
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Unsure, I'm pretty new to all of this trying to piece all the information together. Yes the graph is from the victron software :unsure:
 

Rasmusm88

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Yea, I'm not sure on how to disable it at the moment. So using the ramped target, i figured that was ok to use :)
 

Rasmusm88

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Mar 2, 2022
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So to update you all, I'm still trying to figure this out. I figured the inverter settings is ofcause irrelevant since it's not charging from grid.

So my mppt is doing the work.
I found this in the victron touch screen(see picture) that explains why its only charging to 55.0v.
I have tried every thing now to try and change that to 56v, I have not succeeded yet...

Can you see any settings from my batrium screen shots that would indicate a charge voltage to 55v? I could have missed something, but went over it all many times now.
The settings from my victron phone app is irrelevant, and says "external control" which indicates its bms controlled right now.
Not sure what to do from here hm. Tried factory resetting the mppt with no luck.

Next thing would be resetting batrium, I wonder if I should send them an email and ask batrium about this issue
 

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OffGridInTheCity

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I don't see anything in Batrium shots that would restrict charging to 55v.
I agree - I'd focus on understanding/learning to set the Victron settings you show and agree the 55.0v settings looks suspiciously like it could be an issue. But I'm not a victron person.

I'd want to understand exactly what "Mode setting", "BMS Controlled",, etc mean / are doing.
 
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Rasmusm88

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Mar 2, 2022
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I finally figured it out.
For anyone with victron, and same problem as me.
Go into your touch screen -> settings and DVCC menu, there is a charge voltage set point, change that to what you want.

Go into your BMS menu and press redetect battery, should clear up the problem

Here's some more info I found

Thank you all for helping out !
 
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