Victron (#TeamBlue) Advanced Systems + VRM - How We Done It -

Here is a situation to digest. Couple of days ago I get a low voltage VRM alert. I have the bmv set at 12,6v low voltage alert. The battery was 70% plus SOC, and no loads, apart from the propex gas heater set to frost protect 2deg. If that kicks in, it draws 30w no surge. It’s just a fan and a ignition for gas. When I went in the van, the voltage showing 13,2v, but, there is always a difference between vrm voltage and bmv actual voltage in the van. The bmv is 0,1-0,15v lower most of the time. What am I missing? After last alert, I have plugged the van on ehu, and charged to 100%SOC, you can see the amps climb to 75 ish. That’s the ehu charging. C954C497-6534-49B1-BCB5-D9D5C0065B9A.png45F7D760-B96C-4B65-9994-3DE3AB3F7A1A.png
 
It is interesting to note that the voltage dip occurred at the same time as the temp dropping below 2.5 deg. It seems too coincidental that the dip in voltage coincided with the temp change for this to be unrelated.
Where is your battery temp data coming from?
If you have temp monitoring on each battery, can you view the temp data from each battery within the bank?
I wonder what safety credentials are monitored by the ultramax bms to protect them from cold as it's as though a battery within the bank momentarily dropped out.
It is of course possible that a BMS had a wobble!
 
this would have been the trigger for the alarms. .

what caused this voltage dip with no effective current draw shown by the shunt??

can you zoom in any more?

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have you got a BM2 fitted to the battery? - to double check if the dip is real . . . or just a false reading?




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example BM2 24hr plot.

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Found this from your install:
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Where are the other batteries within the bank located? Is it somewhere that could be cooler?
 
these . . .?


looks like the BMS is basic.

Low voltage cut off.

High current cut off.

no temp control, dont charge below 0degc



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Found this from your install:
View attachment 142819

Where are the other batteries within the bank located? Is it somewhere that could be cooler?
That’s the battery with the ve bus temp sensor that reports to vrm via RPi. So the reading on vrm was supplied by battery 1 as in your post. The battery 2 is right behind the pictured one to the right, with blue tooth bat sense networked with the solar chargers. I’m aware it does not have low temp protection, and I set chargin* to stop bellow 4degC. I have taken a zoom in shot with both deeps, then zoomed on each one, no current deep enough to cause such a massive blip in voltage sag. 693EF15F-01F5-4FCF-936C-19D45B34697A.pngC9E53258-7951-42E5-936E-6A0A755F2C92.png449A929F-BC58-46B6-BF59-AB6D49E7A2A5.png
 
On the first deep, you can see current as well to 3,2A, witch confirms the propex started triggered by thermostat, and that rings true with about 30w draw.

Here is another anomaly picked up. It’s yesterday’s data. I had ehu plugged in briefly to bring it to 100% for overnight. The default 2day display zoom shows 7,5a up, and a deep in voltage to neg 15. But, when I zoom in manually, I see the true amps up 65a or so from ehu, and a deep in temp of neg 48 deg. It seems to me that the bolt onto batt terminal temp sensor, acts somewhat weird under batt receiving a charge. The actual temp in the van at the time was around 8degC as I was physically there when I did the ehu boost via touch screen. This correlates to the batt sensor before and after the deep. 360E9F5F-E883-4C2B-9136-AC67E5348654.png61559F79-16B1-4E7F-A3F4-39EDF6173D7A.png
 
That's defo a glitch .

Was thinking poor conection casting temp blip when current flowing from charger.... But that would be a POS temp reading with heat....

Your probe shows. Neg temp.

So a blip...

Might be worth putting your findings on the Victron tech forum to see if others have experience the same symptoms.?
 
Thank you I had a good read in there before. I ave come across various scenarios from diferent venus firmware. The one I run on RPi is 2,62 and don’t plan to upgrade. Lots of bugs on 2,7 up. Unless I have a cerbo with victron VE direct cables, I have to accept some blips. I suspect the home made cables with serial USB adapters are not perfect. Mine are diy cables, except one from mk3 converter on VE bus. For such a small system, I can’t justify the expense of a cerbo or GX colour control. Unless I implement more automations, the RPi stays in for the time being. I will look into changing the bmv700 to a 712. Mainly for the second battery monitoring. I still have a heat issue with the Orion on full chat for 2-3hrs. It gets mighty hot to touch, and I’m switching it of to cool, then back on if needed. I may have to run another one in parallel to reduce the load on one. But, as we come out of the winter, we don’t use B2B in the summer at all. The solar sometimes is more than I can use.
 
you had me thinking about my VRM install - RPI.

looks like v2.66

though i thought i had it on auto update


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You are ok, Even if is on auto update set, the RPi does not update automatically. You have to install the new release manually to the card. Only the genuine GX devices auto update if set to do so.
 
just been having a play about with the RPi & reloaded it.

also found some updated info regarding VRM + BMV712 installs and temp sensors.


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so i have the Blue temp sensor connected to the BMV712 - which means i cant measure the second battery voltage (the starter battery in a van) (which is a shame, but thats how it is)

this is the temp reading im seeing in VRM.

+++

and the BT BLACK Smart Battery Sense ( which i had at the start with the MPPT`s before getting the BMV)

i see it clearly says NOT visible in VRM. - but is to be used for BT VE-Smart Network




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Going out local to the devices and checking each ( local BT connection) i could see i had various VE Smart networks running. . .

looks like i had old VE network versions that were left running . . . which I've now deleted. .


and gone back to one main VE Smart network created on the BMV712.


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so looks like i can remove the "Smart Battery Sense", as the MPPT is how getting temp data from the VE Network.

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Just bagged myself a CERBO GX for £199 - :mexican wave:

happy days.

get yours here > Victron Energy Cerbo GX communications centre wifi bluetooth full system control 8719076048763 | eBay

or here > Amazon.co.uk : Victron Energy Cerbo GX


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I've already got three RPi VRM units setup to play with. . . . (one for van, one on solar shed, one spare for Lithium box or whatever)

but this is the Genuine real deal.

ill get it swapped out for the Solar Shed VRM install for review and testing.


this is my unit - its brand new :grin bounce:


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edit:

its in & fitted - just a rough lash up for testing..

basically the same as the RPI . . . just with more I/O.



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Last edited:
Victron Venus OS v2.80 + Ruuvi temp sensors.



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A few notes:

  • Victron is not stocking the Ruuvi sensors. They are available for purchase directly from ruuvi.com.
  • While the sensor itself also reports movement aka acceleration data, that information is not available within Venus OS.
  • As these require bluetooth, they are only officially supported on the Cerbo GX. However there are USB bluetooth adapters for CCGX and Venus GX that have been tested to work – more info in this post on Victron Community.
  • We’re working on a few last improvements: allow for multiple USB-connected Bluetooth adapters to improve the range, and warn when the coin cell battery is getting empty. Coming soon.



See the documentation for more details about this feature.



+++++++++++++++++++++++


i just order four temp sensor myself . . .






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heres the vid:





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The RUUVI tags are in . .


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there is a FW update out the box . . .



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the APP looks good . . .

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I've added one to the Solar Shed Victron install. . . .



there is an option to add it in on the CERBO GX.

to add I/O . . . under BT Sensors . . .


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this then brings up a new widget on VRM that replaces the standard weather/locations widget . .

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and you also get a new Tile in the advanced view showing temp, pressure, Humidity . .

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you also get to keep the BMV712 temp sensor data . . .



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