Issues at first set up of PV lifepo battery system controlled by electrodacus

[Philipp K]

Hello

Today i powered up my system for the first time: PV solar (2x400 watt), 304Ah lifepo battary, SMBS0 with newest firmware, DSSR50.

I have some strange loading/charging values and the capacity value seems to be incorect. It startet at 50% and decreased to 0% within 30 minutes.

DSSR50 is open, input voltage 33V, output voltage 26V, however no current is mesurable from solar panels. All loads are disconnected.

What could be the problem? Seems to be something with the shunts?

Thanks for your assistance in advance...

Philipp

[Dacian Todea (electrodacus)]

Philipp,

Can you provide a photo of the current shunts and their connections ?

It looks as if you have 150A 75mV shunts or 200A 100mV shunts for both PV and battery and both shunts have one of the sense wires disconnected but could be one of many other combinations.

[Dacian Todea (electrodacus)]

I seen the photo you sent with the shunts trough email. if you replay to email it will not be posted here.

Have you updated the SBMS0 firmware to version 6 ?

If so then issue is not hardware but software configuration.

In the EXT ADC set the factory calibration to zero that way it will use the zero offset from the last power up.

When I sell the SBMS0 with the new version 6 I do a factory calibration but since you likely updated the firmware yourself there is no factory calibration value thus the reason you always read full current.

To set a factory calibration you can go to Diagnostic then Raw ADC values menu wait for at least 2 minutes after you powered the SBMS0 then push the UP key 5 times until a read message appears and then push the OK key to copy the last power up calibration in to factory calibration an then if you want you can set the Factory calibration to 1 to use that instead of 0 to use the last power up calibration.

[Philipp K]

Yes, i flashed the new firmware by myself and i did not set a factory calibration. I will do this tomorow and post the result here.

Thank you Dacian!

[Philipp K]

It worked! :-)

However, the DSSR50 does not to work, no current passes it.  I connected GND to battery negativ, RC+ to EXTIO4+ and RC- to EXTIO4-, set type 1 as default. I first mixed up the polarity, which should not be a problem, as there is not current, wright?

And can i put the victron mp charger in parallel to the EXTIO4 together with the DSSR50?

[Dacian Todea (electrodacus)]

In the last photos of the SBMS0 it looked like there where no errors so if you set the EXTIO4 as type 1 the DSSR50 should start charging.

Of course the PV+ will need to be connected to a PV array and be daytime to see the DSSR50 LED turn ON and start charging.

There is no real polarity for this version of SBMS0 so it was not important it will still have worked.

The RC+ will output a positive voltage close to PV array voltage that is current limited and trough EXTIO4 will be connected to RC- enabling charging.  The Victron is similar but I think it has a fixed 5V so you can not parallel with DSSR50 as the Victron could be damaged.

If you provide the exact Victron model we can find a solution to parallel the two but you need to add an extra component or two.

A photo of the EXT Ox page where all EXT Ox are displayed will be helpful to see if the EXT IO4 has no errors and thus is not ON because of that (like maybe you set some temperature limits or some other conditions).

Also a photo of the connections to DSSR50 could be helpful if the EXT IO4 is enabled and problem could be with the connections to DSSR50.

The setup is very simple the EXT IO4 will be open circuit when charging is disabled and close circuit when charging is enabled. So you can test that DSSR50 is working by just shorting the RC+ to RC- and the orange LED should illuminate the Electrodacus logo.  Maybe is as simple as you forgot to turn ON the PV breaker.

[Philipp K]

I've found the problem: it was the parallel wiring with the victron multiplus. As soon as i deconnected the mulitplus, the PV started loading the battery. However PV input is lower than battery input, which is impossible. I guess this is a different offset of the shunts.

My set up: PV, lifepo battery, Victron multiplus II compact 24/3000 and Victron battery protect (BP) 65. I will install the two signa BMS assistant on the Multiplus

My intention was parallel wiring for Victron charger / DSSR50 (EXTIO4, Type 1) and BP 65/ MP inverter (EXTIO3, Type 2). So as far as i understand: sharing a EXTIO needs identical voltage and should not exeed the 50mA limit. Unfortunaly the beginners guid does not cover a set up with trigger current below 50mA but different voltage.

[Dacian Todea (electrodacus)]

Likely when you powered up the SBMS0 last time there was current trough at least one of the shunts and thus the zero offset current was done incorrectly.

If you turn OFF all loads and all charge sources your current's should read zero. If not you will need to power the SBMS0 again to get the correct zero offset making sure no current flows trough the shunts.

If difference is very large check your current shunt resistance as maybe you did not set that correctly or you reset that by doing a factory reset at some point or power cycling before saving the device settings.

Both current shunts should be set to 0.5000mOhm in your case. As you updated the firmware the settings have changed so you need to check the EXT ADC menu see that all is correct there 0mA offset and 0.5000mOhm

[sailingharry]

Philipp,

I'm not entirely following your configuration.  However, I see you are trying to control a BP 65 and an MP on a single EXTIO.  I struggled with this (I use a BP to control several chargers -- a Victron Centaur, 4 MPPT, and a towed generator on a sailboat), and eventually worked out having a single IO control both the BP and the MP.

My post on this is here:  https://groups.google.com/g/electrodacus/c/ZrgZgWp-oB0/m/KFYphTWrAgAJ

It  might help.

Harry

[Philipp K]

The difference is very small, about 15mA. The picture below is taken with disconnected loads and charging disabled. I will power up the SMBS0 again and then i will see.

[Dacian Todea (electrodacus)]

That looks good. What is the difference between PV and Battery current when there is no load just charging ?

Take also a photo of the Diagnostic / Raw ADC values. while charging.

[Philipp K]

Thank you Harry

This is a completely new approach to me. None of the victrons documents shows this solution. For the two signals BMS assistant the only way to activate charging/inverter is descibed by shorting the two pins of the repective ports (Aux1/Aux2/Temp Sense).

However, i am not shure, if your suggested solution works with my set up with a non Smart BP 65 and the 24/3000 MP compact II. Victron warns of sharing the remote wires,as the voltage differs signiffacntly: 5V for the MP and battery voltage (>24V) for the BP, wich controlls the loads in my system. Im not familiar with your setup, but i guess its a 12V system.

My favorit solution would be a two channel optocupler PC817: The two positiv input connectors were shortened and connecto to EXTIO+ and the ground pins to EXTIO-. The other two pairs connector were connected to the remote pins oft the BP and to the Aux1/2 of the MP. As far as i understand, this principle can used either to controll the DSSR50 and MP charger over the Aux2.

@Dacian: could you confirm that this might be a possible solution?

[Dacian Todea (electrodacus)]

Philipp,

Yes Victron has multiple standard for remote ON/OFF so you can not parallel them directly due to different voltages that they operate at. The BP65 is fairly flexible and allows all sorts of configurations but the MP will not accept battery voltage or ground to any of the two remote ON/OFF pins.

Using separate optoisolators is the best option so either the PC817 or the ElectroDacus DEXT.