Electrical Diagram Work in Progress!

[Rich Smith]

So i am in the thick of it and have a few questions. I haven't dug too deep into the EXTIO ports yet - as you will see they aren't labeled - but will be tackling in more detail over the next few days. 

1) Where should I located my shunt for the inverter? I left it off to the side in my diagram. 

2) because I am running 2 MPPT controllers, does it make sense (is it even possible) to have 2 VE Direct non inverting remote on/off cables as indicated in the diagram? 

3) I know the Victron Battery Monitor is redundant, but I purchased it 2 years ago and figure it might be useful to have; my "power display station" will be more than 12 ft away from my battery bank so my Electrodacus SBSO will have to be displayed somewhere closer to the battery bank out of sight. Not sure if that will be the final decision.. 

Any feedback would be greatly appreciated. 

[Rich Smith]

Here is a high res image link if the above image is hard to read: 

https://imgur.com/FJbDbkN

[Dacian Todea (electrodacus)]

1)  The battery shunt will be located immediately after battery+ terminal.

2) You will connect the two yellow wires together to EXT IO4- and connect the EXT IO4+ to battery+ through a 470ohm resistor.

3) You can install as many monitors as you want but it will be redundant.

I do not see a PV shunt as that will provide you with much more info than just having the battery shunt.

If you decide to use the PV shunt it will need to be installed in series with the battery shunt (as shown in the SBMS0 manual) and then you can connect the two MPPT's to that shunt so that SBMS0 can show the PV charge current but also be able to calculate Load current as the difference between the PV current and battery current.

You can even connect the Orion TR smart to PV shunt but I guess that will probably almost never be used so not that relevant.

That will need to be connected to say EXT IO5- (set as type 1) on the H pin of that remote port the L will remain non connected while the EXT IO5+ will be connected through a 1kOhm resistor to vehicle ignition so that way both the engine will need to be running and the SBMS0 to allow charging and if you want also add a small switch in series so that you can enable charging from alternator only if you need that as it is at least 20x more expensive than solar charging.

On point 1) I see you have a 100/30 and a 100/20 and for the 100/30 the remote cable will work by default but for the 100/20 you will need to configure that in the unit using the Victon software.

Battery seems extremely oversized for the amount of solar available. For a 10kWh battery I will expect about 2000W of solar PV 

[Rich Smith]

Thank you so much Dacian!

I made the changes that you suggested. 

Can you let me know if the shunt placement looks correct (particularly how the PV Shunt is connected to the Lynx distributor)? 

Also- for the Victron Multi - I only have the Aux 1 +/- connected- looks like im out of EXT IO ports to connect AUX 2 +/-. Is there a work around? 

HiRes link 

https://imgur.com/a/E0pFidg

Thanks again, mad respect. 

Rich

[Richard Bewza]

Rich

You will need to split your loads and charging sources into two separate busbars. I would use your existing blue victron busbar as your charge busbar and move the inverter and Battery protect. You can have up to 3 connections on one bolt per the yachting code book. After 3 connections you should definitely be using a busbar.

Your  100-amp shunts are too small. You will need a 200 amp shunt for charging and a 400 amp shunt for your loads.You do not want to put more than 66% load on any shunt continuously. This means the two hundred amp charging shunt should have no more than 130 amps continuously And the 400 amp load shunt should have no more than 260 amps continuous.

Rick 

[Dacian Todea (electrodacus)]

Rich,

Shunts seems to be connected correctly based on diagram (not sure how you connect those two 60A fuses on that separate charge buss but if is done as in your diagram then connection is correct).

As you will only have 50A max from PV the 100A shunt is fine but what Rick has mentioned is correct shunts can only be used up to 66% of the rating as continues current.

I see you have a multiplus inverter charger and if you intend to charge from grid you will also need an EXT IOx set as type 1 to control charging.

You can see this document for details https://www.victronenergy.com/upload/documents/Manual-Connecting-other-lithium-battery-systems-to-Multis-and-Quattros-EN.pdf

All settings as in that default example except for last two where you will set Disable charger.

[Rich Smith]

Well after a hiatus I am finally back at work on the van. I have got my battery all hooked up to my Inverter/Charger and have the Electrodacus all set up and everything works great. Will be zooming in on the communication aspect with SBMS0 and the components over the next week. 

I revised my diagram (attached) based on comments above and had a few questions that I was hoping you could help me with. 

1. I took Richard Bewza's advice above and split my charging sources onto another busbar. Does that look right what I have done? I have kept all the negative runs on the Lynx Distributor as I didn't think I needed a separate busbar, but let me know if I do need one and will add. 

2.  Is the large 400amp T-Class fuse installed in the right place? I put it after the large shunt which I think is the right place. 

3. I discovered that both the EXT IO3 and EXT IO4 are used for the inverter so the SBMS0 can shut off inverter charging/loads based on the high and low voltage parameters I have set (I am using the default parameters). In my diagram, I only used the EXT IO3 for this function. Because I don't have any more pins available, will I have to remove something else? Is there any way to add pins to the SBMS0? 

Thanks again for all your help!

Rich

[Dacian Todea (electrodacus)]

1. All looks to be OK in the diagram.

2. Yes the 400A fuse is placed correctly.

3. Will you ever use the Inverter/charge as a charger ? If it is only used as an inverter then you do not need anything other than EXT IO3.

I will have a device called DEXT that will allow you to multiply the number of devices you can control. Hope to have that available in about two months.

[Rich Smith]

Thanks Dacian!

I appreciate the input. 

I have another issue now that I am dumbfounded by. I was trying to update the settings on the Multiplus II using the VE Configure software and the MK3- USB-C dongle. After running Parallels and windows on my Mac, I was finally able to get it working. I changed the battery type to Lifepo, added the two signal BMS support assistant, changed the settings that you indicated. Everything seemed alright. I then clicked the “Send Settings” button to update the Multiplus- it asked me if I wanted to send motified setting or all settings, I clicked the former and it appeared to update everything and then indicated that it was restarting the unit. Now it won’t turn on. I unplugged the dongle, and turned the unit off. It appears to be bricked.  Ever experienced this before? I tried to reconnect both VIctronConnect and VE Configure and neither shows the unit connected. 

Any ideas?

Thanks,
Rich

[Dacian Todea (electrodacus)]

Hi Rich,

The unit should be OFF unless it is connected correctly to EXT IO3 and IO4 on the SBMS.

The unit will be turned ON by the SBMS assuming SBMS has no errors like low battery cell.

Not sure if you set the AUX 1 or AUX 2 to control the inverter ON/OFF.

Say you set the AUX1 to control inverter ON/OFF then for inverter to power ON the AUX1 terminals will need to be shorted and that is what the EXT IO3 on the SBMS will do assuming battery is OK to allow discharge.

[Rich Smith]

Here are some images of the wiring/settings. Everything look correct? 

[Rich Smith]

[Dacian Todea (electrodacus)]

You connected to AUX1 and AUX2 but you set the AUX1 and Temperature sense input.

Also you set AUX1 to control charging so it should be connected to EXT IO4 not EXT IO3 as you did.

So I will say move both connections to the right so connect the blue wires (EXT IO3) to T-sense connector as that is what you set in the Assistant.

And move the green wires (EXT IO4) to AUX1 as that is what you set to control charge sources.

[Rich Smith]

It worked!!  Thanks so much, that was pretty obvious I guess, lol. Now that it has powered on, I should be able to open VE Config again- in order for it to be wired correctly, I would just change the setting from "Temperature Sense Input", to "Aux Input 2" and then switch the wires from the T-Sense connectors to the Aux 2 connectors on the Multiplus II? 

you are the best, 

Thanks

Rich

[Dacian Todea (electrodacus)]

Yes you can just switch T-sense to Aux2.

[Rich Smith]

Thanks D. 

So I have assembled all of my components and tested. I am getting a few weird results which leads me to believe I have wired something wrong. 

image 9461 is what I see when I hooked up a little led strip as a DC load. 

Image 9462 is when I hooked up a power supply to my mppt charger and ran 30v/5amps into it simulating a solar panel. 

When I plug in my multiplus II, the electrodacus shows that 90amps are being pumped into my cells. If I have a load going while the charger is charging, the load goes to 0 on the screen. 

I am almost there, I can taste it!

Thanks,

Rich

[Dacian Todea (electrodacus)]

Rich,

Have you set the current shunt resistance in the ADC menu ?

For PV shunt you need to set 50mV/200A = 0.2500mOhm

For battery shunt you need to set 50mV/500A = 0.1000mOhm

30A at 5A = 150W  and 150W / 13V = 11.5A so likely the battery shunt is setup correctly but not the PV shunt witch should show the same value.

Seems current shunt shows about double the value meaning you maybe set to 0.5000mOhm instead of correct 0.2500mOhm

[Rich Smith]

Hi Dacian, 

Everything is working great. I redrew up the diagram to show the EXTIO ports with the added 817 Octocoupler. Think I am on the right track but would you mind verifying? 

Thanks!

RIch

[Dacian Todea (electrodacus)]

All looks OK just make sure you remove the red jumpers from the 817 optocoupler board.

[Rich Smith]

I have completed everything but have run into 2 issues that I can't seem to figure out. 

1.) My mppt controllers don't seem to be activating with the remote/ve. direct cables. Because I have two mppt controllers, I combined the VE. direct cables and wired to the EXTIO4 (-) port and wired the EXTIO4 (+) port to my positive bus bar with a 470 ohm resistor.  the port is set to Type 1 for charging. When I unplug the ve. direct cables, the PV shunt shows the solar panels are working and charging as they should. The settings on the SBMS0 are below. I fully charged the battery bank and then let the batteries drain to less than 96% and nothing happens. I did change the RX port of the 100/20 victron mppt to "remote on/off". I tested the wire that I attached the resistor to, and it was reading 250-300 ohms which is low, could this be the issue? 

2.) this isn't a huge deal but wondering why this is happening: The master switch for my PV shunt was working fine before I connect the EXTIO ports to the victron components. When I would turn it off while the master switch was on, my loads would stay on as expected. But now when I shut off the PV switch (both mppts, and DC to DC charger are on this shunt/run) the loads turn off. If I unplug the remote pins and replace with the jumpers, this doesn't happen- the loads remain on. Any ideas? 

Everything else is working like a dream! Thank you!

[Dacian Todea (electrodacus)]

1) From your photo I can see that battery is fully charged thus charging is disabled. So nothing abnormal. The charging will start when battery will discharge enough for charging to be re-enabled that means all cells need to drop below 3.4V

But you can not connect the EXT IO4 directly to MPPT VE port you need the Victron remote ON/OFF cables.  In your diagram you show VE.direct non inverting remote ON/OFF adapters.

2) Not quite sure what do you mean by "master switch for the PV shunt". If is the switch you installed after the PV shunt in your diagram then that has nothing to do with the Load's.

[Dacian Todea (electrodacus)]

2) Just checked your diagram and your positive buss bar is disconnected from battery by that PV switch so you should not connect your EXT IO3 resistor there if you do not want for your loads to turn OFF.

[Rich Smith]

I am confused regarding the cables. If these aren't the right cables, can you show me the right ones? The ones I bought seem like the only viable option. 

Thanks, 

Rich

[Rich Smith]

ah gotcha! I will connect it directly to the battery. Thanks!

[Dacian Todea (electrodacus)]

They are the correct cables and the yellow wires will need to be connected to the EXT IO4-

The charging will stop when battery is fully charged and that will be normal operation.

In your photo of the SBMS0 the charging was disabled as battery was full. Is easy to see at the bottom of the SBMS0 screen that PV1 is not highlighted meaning the battery is fully charged.

It also showed a 11.7A discharge current so Loads where enabled.

[Rich Smith]

Hi Dacian,

My SOC jumped to 100% last night for some reason. I don't have shore power hooked up, nor are my solar panels exposed to the sun. I have not started the car so the DC to DC charging is off. I was at around 50% last night before I went to bed and this is what it is showing this morning. The cell values have remained unchanged. Any idea why this would be and what I should do to resolve? 

Rich

[Dacian Todea (electrodacus)]

Rich,

Your battery seems to be somewhere below 10% SOC so you should charge.

There can be two reasons why SOC got to 100%

One will be a bad connection to one of the cell sense wires. If any cell shows 3.55V for a few seconds the SOC will be reset to 100% as it will think battery is fully charged.

The other possibility is that one of your shunt sense wires got disconnected and thus it showed a large charge current thus SOC incremented to 100% over many minutes to hours.

[Rich Smith]

Hi Dacian, 

I charged my battery bank back up and everything was working. I then had to properly secure my batteries in place which I ended up having to unhook the ribbon cables from the terminals in order to do so. Once my batteries were secure, I wired everything up and discovered there was no power to the SBMS0. After closer inspection i realized I wired the ribbon cables backwards from the main negative terminal to the positive terminal. I rewired and double checked that I had the wiring correct- still no power. I decided to remove all of the shunt wires, the EXTIO ports and the thermistor wires to troubleshoot. I unplugged the ribbon cable terminal from the unit and plugged back in with still no luck. Checked the voltage on my battery cells and they are all above 3.2v. Is there a fuse or something inside the SBMS0 unit that i could have blown? Anything else stick out to you that I could have done wrong? 

Thanks,

Rich

[Dacian Todea (electrodacus)]

Rich,

Yes there is a PCB fuse (trace) that has blown when you connected all the cell sense wires with reverse polarity.

Look between the micro controller and the cell balancing resistor and you will see a small PCB trace that was designed to melt in case of reverse polarity. If you have a soldering iron just repair that PCB trace with a piece of wire.

From that trace there is also a 33V TVS diode that helped the fuse blow so please check that is OK and not shorted by using a multimeter on diode test and you should see a voltage drop of 0.7V in one direction and open circuit in the other direction if the diode is OK if diode is damaged you will see 0V in both directions and in that case just remove that diode. There is a group of diodes there but you are only interested on the one with the markings "CM".

[Rich Smith]

I had a go at it! Don't think i will be winning any electrical engineering awards but it did the job. The diode read .8v and was performing similarly to the ones above so think it is alright. 

Once I connected it to the ribbon cable and reconnected all of the EXTIO ports, shunts, and thermister, i realized that my Victron Inverter/charger wasn't working. Zero power so none of the AC outlets or DC loads are working. I turned on the van to see if my DC to DC charger worked but it to was not charging. The blue "bulk" light is flashing on both Mppt's and DC to DC. I checked that there is 13.15v reading at the +/- terminal on the inverter. cells are reading 3.28v. 

Any idea? 

Thank,

Rich

[Dacian Todea (electrodacus)]

Rich,

A photo of the page 1 of the SBMS monitoring screen will be useful to know if there are any error preventing the inverter and charger to turn ON.

[Rich Smith]

[Dacian Todea (electrodacus)]

You setup an external temperature limit in advanced parameter settings but did not install the temperature sensor thus the SBMS has disabled charge and discharge.

So either install a temperature sensor or remove the limits you set and power cycle so that they take effect.

[Rich Smith]

Hi Dacian, 

I was on a hiatus until about a month ago. My battery system is working but have some issues that I am trying to trouble shoot. I realized that both my solar chargers and my alternator charger aren't charging. When I connected to the victron app, it was saying they were off because of the remote on/off with the SBMS. Could it have something to do with the temperature sensor? I changed the advanced parameters settings of the temperature sensor to what it recommended on the unit showing in the pictures below. There was also some weird bug that showed my load was 360A which was obviously a glitch as I wasn't running anything. After unplugging the ribbon cable everything appeared to be normal, not sure what that was about. 

any help would be appreciated. 

Rich

[Dacian Todea (electrodacus)]

Rich,

The 360A on the PV means that your PVn shunt sense wire is disconnected (open circuit) so check that connection. If you restarted and powered ON while that wire was disconnected it will set the current shunt offset calibration wrong and even if you fix the wire it will no longer read any value. So fix the wire then power cycle.

Maybe check also the EXT wires controlling the charging as maybe they are also disconnected or broken as the PVn wire.

Please send a photo of the Diagnostic screen also if you still have problems.

The temperature limits seem to be set correctly (assuming you want your battery in the in the +5C to +60C range) and your battery temperature sensor seems to be connected and temperature is at +24C. Also I asumme that you power cycled the SBMS0 after you set those temperature limits.

[Rich Smith]

So I did check the PVn shunt sense wire and it appears to be solid. I did however, see that my EXTIO4- was disconnected which is my mppt remote on/off for both my controllers. I reconnected and then restarted the SBMS and noticed that when the inverter was clicking on, it would immediately click off. I then saw that there is a UVLK error. I have attached the diagnostics screen and the advanced parameters screen showing my UV settings. 

[Dacian Todea (electrodacus)]

It all looks good with the current shunts in diagnostic screen.

I asumme the under voltage lock is set at default 2.5V (cant see in your photo as it is about to lines below that).

If it is set correctly at 2.5V it just means that due to the load of your inverter turning ON one of the cells drops below 2.5V so check the connections between cells as you may have a bad high resistance connection due to oxidation or just no sufficient torque or you have long cables connecting the cells and that will not work as those will act as inductors.  

A photo of the battery could be helpful.

[Rich Smith]

I did have a positive and negative cable that were taped off and attached to my battery for my power supply- I disconnected those and that fixed the UV error. Thank you. I then was double checking my connections and the PVn wire looks sound. I did realize that my EXTIO6+ wasn't properly connected which I fixed. My chargers still seem to be offline from checking the victron app. Do I need to recalibrate my shunts or something and then do a restart? 

On Friday, August 8, 2025 at 11:38:07 AM UTC-7 electr...@gmail.com wrote:

[Dacian Todea (electrodacus)]

When are the chargers disconnected ? Is there any flag error like before it was an UV error. 

Also what is the SOC when the charger is disconnected. If battery is full the charger will of course disconnect.

Do you have any setting to maybe limit the charge SOC to some level say 80% as that can also disconnect the charger if you decide to limit the SOC so battery is only charged to full 100% once a day and for the remainder of the day it only maintains 80% if you set this in the SBMS0 DMPPT setting.

Is your battery capable of handling multiple chargers all at the same time ?  Maybe you try to charge at to high of a charge rate and you get an OVLK error due to one of the cells exceeding 3.75V for a fraction of a second when charge current peaks to high.

There will always be a reason for charge source being disconnected and I will need tome details of what happens when it is disconnected. Battery temperature if you installed an external temperature sensor and set limits can also be a reason for disconnecting charge sources (but loads will also be disconnected in that case not just the charge sources).

Just looked at your older diagram and I see that you have a 4S2P EVE pack. In the diagram it looks like maybe the pack was split in two parts 2S2P and 2S2P in series. Are this packs physically at a distance from each other ?

[Rich Smith]

I just realized I messaged you privately with the below message so added to the public thread. 

Thanks for the response- alright, so its not the sensor:). I have attached the electrical diagram that shows the octocoupler and why I used it. It worked up until recently and I figured it was the SBMS0 that was not turning it on. I will do some more trouble shooting and bypass the octocoupler to see if that could be the problem.  

Thanks D

Hi Rich,

"Screen 5 of the Monitor section shows my IT/ET at -40/-45."

That is not related to SBMS but to DMPPT450 that you do not have installed. So there is nothing valuable for you in page 5 of the monitoring screen.

The IT and ET temperature's you can see on screen 1 and are +13C internal temperature and +10C external temperature so in normal range at the moment you took the photo.

The reason why Load is not enabled has nothing to do with the SBMS0.

Not sure how you connected the EXT IO3 to the optocoupler. A photo of those may be useful to diagnose the problem.

EXT IO3 is already an optocoupler so it can controll the BP65 directly but maybe you want to controll some other things other than BP65 thus you added some extra optocouplers controlled by the EXT IO3. 

Best regards,

Dacian.

Good morning!

I had to disconnect the 12 pin ribbon cable for my build and after plugging back in and charging to 100%, my DC loads are not working. After trouble shooting, I realized that it is the BP-65 that is not turning on with my remote sense wires in my EXT I03 ports (through my Octocoupler). The voltage was 13.4 on the terminal going into the BP-65 and only 1.5v on the upstream terminal of the BP-65. The red light on the octocoupler is not on either. I presume this has something to do with my temperature sensor which I would be happy to remove completely. The only reason I installed the temperature sensor is because my battery bank and victron components are installed in my bench seat of the van and my power monitoring setup (electrodacus, guages) are located in my upper cabinets. Here are the screens that make me think it is the temperature sensor that is the culprit. Screen 5 of the Monitor section shows my IT/ET at -40/-45. Is my presumption correct? If so, should I verify by removing the sensor and power cycle? I did change the temperature range in advanced parameters to min 3000b and max 1040b. Would I have to reset these values if I were to remove temperature sensor? 

[Dacian Todea (electrodacus)]

Have you removed the red jumpers from your optoisolator board ?

You mentioned that red LED is not ON on the optoboard.  You will need to check your EXT IO3 connections. Make sure the 1kOhm resistor is properly connected to the Battery+

As it was with temperature being in range you will have had current flow trough that 1kOhm resistor to EXT IO3 that will have been close circuit (assuming i set as type 2 in the SBMS0 menu and ET was above +5C when you made the test).  Then once that all works the red LED will be ON and then assuming you removed the RED (may be other color on your real board) jumpers the BP65 should allow current to Load.