Remote on/off - Victron SmartSolar MPPT 100/50, CERBOS GX and SBMS40

[Ross Aspinall]

I have a campervan with 1000w solar, self-built 1120ah 12v 4s4p lithium battery, external BMS Electrodacus SBMS40 with a remote on/off control.

I propose using 2 x Victron SmartSolar MPPT 100/50 on/off controlled by the SBMS40 BMS and connected to a Cerbos GX via basic VE direct cables. Reading the literature however, https://www.victronenergy.com/media/pg/Manual_SmartSolar_MPPT_100-30__100-50/en/features.html#UUID-20ac1af2-7925-4279-27cc-d14249d09217 one has to use a "VE.Direct non inverting remote on/off cable"  and "that when using this cable, it's not possible to use the VE.Direct port for any other purpose. Such as connecting to a GX device"

Is this true or in there a workaround?

[Dacian Todea (electrodacus)]

The slightly larger Victron SmartSolar 150/60 TR and up will have dedicated remote ON/OFF connector and thus you will not need to use the VE Port for that.

https://www.victronenergy.com/upload/documents/Datasheet-SmartSolar-charge-controller-MPPT-150-60-&-150-70-EN.pdf

But what will a Cerbo GX be useful for ? All that information will be provided by the SBMS40.

[Ross Aspinall]

I will look into those, thanks I wasn’t aware.  VE.direct is used to connect to the Cerbo GX for data collection  
Thanks for your feedback and support after all these years with the SBMS40.  It has been rock solid device and pivotal to having a DIY lithium battery foundation as an energy source, my experience is that often other devices cant integrate well into the sophistication feature set of the Electrodacus BMS’s  
My strategy to get off my 2 x Renogy DCC50S Chargers (no remote on/off and buggy featureless software).  I like Victron’s remote monitoring, accumulation, connectivity, and software and I wish to include tank and temp monitoring all in one place. SBMS40 shows in/out using a shunt whereas I want to see where the current in/out from all sources and loads i.e Solar MPPT, Alternator charging and shore power all in one place.  Yup i know what your going to say Dacian Solar is immensely cheaper than diesel vehicle alternator or grid power and I agree! However when you are on the move, remote locations, its winter, forced to be in the shade and sometimes here in Australia the days are not always sunny, one has no choice.
In saying all that the more I dig into Victron products the less engineering integration elegance it becomes, perhaps it is to sell you more products? My current full setup is as follows.

Campervan – Mercedes Sprinter LWB mobile office (heavy power user).  
Charging predominantly 1. Solar, 2. sometimes vehicle alternator, 3. while driving combination of 1 + 2 and very rarely 4. 240vac Shore power  
2 x Renogy DCC50S
Victron MultiPlus-II 12/3000/120-32 230V Inverter Charger
Victron Battery Monitor BMV-712 Smart BAM030712000
VE.Bus to USB cable
VE.Direct to USB cable
900w 20v of Renogy flexy tier 1 panels
100w 22v portable
CATL 280ah Lithium cells made into a 4s4p 1120ah battery.
Electodacus SBMS40

[Dacian Todea (electrodacus)]

How are those flexible panels installed ? are they still OK ? Usually they will not last long as cells will develop cracks due to vibrations.

Shore power will be preferable to vehicle alternator charging assuming you have the choice.

The energy from alternator (while driving) will cost you about 1 liter of fuel per kWh and depending on what you pay there for 1 liter that will be the cost likely at least $1 and that will be 50x more expensive than solar at probably at least 3 to 4x more expensive than shore/grid.

[Ross Aspinall]

900w of Flexy panels fine so far after 2 yrs they have a 5 and 25yr warranty, mounted with roofing screws.  https://au.renogy.com/175-watt-12-volt-flexible-monocrystalline-solar-panel/ .  I consider 900w of rigid solar panels mounted on the roof is too much weight with campervans so high up as mine is a high-top Sprinter.  It is important to keep weight (stability) and fuel costs down 😊  

Dacian agreed, shore power better but its all about where you are. In Aus there is loads of awesome free camping (off grid) so I don’t go to caravan parks, remote locations free camping where the best scenery is.  However one needs redundancy with Alternator/Shore power if you have forced shaded, cloudy or rain.   I hardly use the DC/DC alternator charging and rarely 240vac but its nice to know that they are there.   Here I am travelling in AU Northern Territory Diesel is around AU$2-2.30l. 

Campervan has an office setup so heavy usage I’m using 2 laptops, 1 x monitor, Starlink, 100l fridge/freezer, 10l hot water, induction cooker etc I’d use 9-15% of 1120ah lithium a day sunny days in winter id reclaim that, however shaded, cloudy or wet locations will start eating into my remaining ah. 

[Dacian Todea (electrodacus)]

15% * 1120*12 = 2kWh/day

That is a low enough consumption that should in average be supplied by a 900W PV array alone (assuming the array is exposed to sun).

A sunny day should be able to cover almost two cloudy days I will expect at least 4 to 5kWh from that array.

I guess you may have added a photo of how panels are installed but I can not see it. All those flexible panels get damaged in this sort of applications due to vibrations (cells get cracks that reduce the output power).

[Ross Aspinall]

Yes your right, however individual short circuit amp tests reveal ok.  In saying that the set up is not optimised as all panels are wired in parallel back to the chargers and panels are slightly different power and voltages but same manufacturer.  e.g currently a cloudless Winter Day in Alice Springs NT I'd be pulling 45amps if i'm lucky.  

My strategy is to spread the solar across 4 different chargers including on a soon to be purchased Victron MPPT for the 4 x 175w in a series parallel config and the other panels on the 2 x Renogy DCC50S and the portable 100w panel on the SBMS40.  Unfortunately due to the the Maxair fan in the roof that's why all the different panels to fit around it.  The 2 x Renogy DCC50S are only 25v input see trailing info on panels and a photo attached.    

I have gone to Renogy support to ask the following on the remote switching for the 2 x Renogy DCC50S see what happens 

"I have another scenario I have 2 x Renogy DCC50S chargers is it possible to remotely switch on/off the charging with them?  I have a modern vehicle with a smart alternator using an external BMS - an (see attached) Electrodacus SBMS40 with many safety features to turn off/on charging

1. switch the IGN Signal Wire for Smart Alternator, but this could be an issue as the Renogy DCC50S doesn't use a a IGN wire for a standard Alternator? so if i switched it it may think i have a standard alternator?
     a. does the 2nd terminal next to the IGN (not used) has the ability to used somehow i.e short to ground? or a switched +12v
2.  using the "RS485 Communication port" somehow ?
3.  hack the Battery Temperature Sensor fooling it to think it is over/under temp by a dead short or suitable resistor? "

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4 x 175w Flexi panels = 700w
1 x 100w Flexi panel = 100w
2 x 50w Flexi panels = 100w
1 x 100w Foldable portable Solid panel = 100w
Total 1000w

4 x Renogy 175w Flexi panels
Maximum Power at STC* 175 W
Optimum Operating Voltage (Vmp) 19.5 V
Optimum Operating Current (Imp) 8.98 A
Open Circuit Voltage (Voc) 23.9 V
Short Circuit current (Isc) 9.50 A
Maximum Series Fuse Rating 15a

1 x Renogy 100w
Maximum Power at STC* 100 W
Optimum Operating Voltage (Vmp) 18.9 V
Optimum Operating Current (Imp) 5.29 A
Open Circuit Voltage (Voc) 22.5 V
Short Circuit Voltage (Isc) 5.75 A
Module Efficiency  15.0 % (Website says Cell Efficiency: 21.0%)
Maximum Series Fuse Rating 15 A


2 x Renogy 50w
Maximum Power at STC* 50 W
Optimum Operating Voltage (Vmp) 20.3 V
Optimum Operating Current (Imp) 2.47 A
Open Circuit Voltage (Voc) 24.3 V
Short Circuit Voltage (Isc) 2.75 A
Module Efficiency 14.4 % (Website doesn't say)
Maximum Series Fuse Rating 15 A

1 x MEGAVOLT SOLAR SOLAR200-LMF 100Wp Monocrystalline Solar Module
Maximum Power (Pm) 100Wp
Open-Circuit Voltage (Voc) 22.1V
Short-Circuit Current (Isc) 5.88A
Maximum Power Voltage (Vmp) 18.3V
Maximum Power Current (Imp) 5.46A
Maximum System Voltage (Vmax) 1000 VDC
Temperature Cycling Range -40 °Cto+85°C
Weight 6.4KG
Dimensions  770x670x30MM
Tolerance +/-2%
All technical data at standard test condition (E=1000W/m² Tc=25°C AM=1.5)

[Dacian Todea (electrodacus)]

Adding MPPT to those 36 cell panels will not help you much maybe best case 10% extra energy and that will not change anything if you do not have enough energy the 10% will not change that.

The temperature sensor hack will not work with any such devices.

You just need a way to disconnect the chargers so maybe something like the Victron BP65 if the DCC50S can handle having the battery disconnected.

[Ross Aspinall]

Enabling remote on/off charging of two Renogy DCC50S Chargers via an external BMS (Electrodacus SBMS40 BMS) for a DIY 12v 1120ah 4s4p lithium battery.

The DCC50S manual states when using the external Temperature Sensor - "If the service battery type is set to lithium, the DCC50S will stop charging the service battery when its temperature is lower than 1℃ and recover to charge when it’s higher than 3℃."  In my own testing this is also the case when battery type is set to “user”.

All my safety/cell/control (incl. Temp) functions are controlled by the Electrodacus SBMS40 BMS making the DCC50S external temperature sensing redundant, however this hack will still allow Renogy DC Home app temperature monitoring in “charging mode”. 

When measured with a multimeter, the supplied temperature sensor is 33kohm at 0℃ and 11.53kohm at 22℃.  By switching in and out a 27kohm resistor via a Double-Pole Double-Throw Relay in series with the probe (27Kohm + 11.53kohm = 38.53kohm) is the right value to fool the charger to think it is under 1℃ and stop charging.   

[Dacian Todea (electrodacus)]

Some chargers will ignore the temperature sensor if it is not present at power up. You will want to test that if when you connect the DCC50S to battery without having a temperature sensor connected it will still stop charging else I do not think it will be safe to thrust this method.

Also why not use a 33Ohm resistor to make sure that if battery temperature is very high so low sensor resistance you are still above 33Ohms.

You should be able to use small SSR (optorelay) as it will use much less energy even than a small signal relay. There is a short period that all temperature sensors are disconnected in your setup. You can have the fixed resistor in series with the temperature senor and have the normally open side of the relay or optorelay in parallel with the resistor (shorting that reistor) then when relay is not supplied the contact will open and resistance will add up.

[Ross Aspinall]

Cheers for the follow up Dacian!.  Under testing fortunately, you can switch in/out 33kohm at any time and it will stop/start charging.  If you remove the probe altogether it will default to 25c.  
As for the Optocoupler do you mean one oif these and in my case 2 x these for each circuit https://temperosystems.com.au/products/pc817-optocoupler-isolation-3-3v-5v-12v-24v/ ?  
As for the 33Ohm resistor do you mean like this diagram circled in red?

[Dacian Todea (electrodacus)]

Something like the TLP172GM will be better as it is mosfet based so there will be no voltage drop across and so not influence the temperature measurement.

The 33KOhm will be in parallel with the TLP172GM output so in your diagram the top side of the 33kOhm resistor is connected in the right place but the bottom should be connect to the other side of the closed switch.

That way at 22C the resistance will be 12kOhm while switch is close circuit and 12kOhm + 33kOhm = 45kOhm when switch is open.

[Ross Aspinall]

Thanks Dacian.  Ok understand if and appreciate if one has PCB boards, and mounting terminals etc. I am best suited to a pre made Module, I cant find any modules with a TLP172GM in it I have found this using the TLP187 though.  Will this do?  
Help me to understand why the extra resistor……I am using the SBMS40 as the over/under/monitoring/control I don’t really need the Temp monitoring via the Renogy DCC50S.  Given when open circuit momentarily it defaults to 25c does it really matter?
Also your first post you said “33Ohm resistor” last post you saying “33kOhm resistor” which one?

[Dacian Todea (electrodacus)]

That board is based on Sharp PC817 not the Toshiba TLP187 but neither will work as they have a default voltage drop so if you are interested in the temperature measurement that will not be correct.

Sorry it is 33kOhm. If you are not interested in the temperature measurement the PC817 boards should work you just need to test to make sure. 

[Ross Aspinall]

Thanks Dacian,

No, all temp monitoring and safetey will be done though the multiplus 2 and SBMS40 temp sensors.  I am assuming the following will work?  See link I have purchased the exact same board 817 Optocoupler 4-Way Board.  Will i need the 1kohm resistors on the 12v side? my system is 12v

https://diysolarforum.com/resources/electrodacus-sbms0-i-o-summary-chart.112/version/234/download

[Dacian Todea (electrodacus)]

You will need at least a 300 Ohm resistor on the EXT IOx+ input in order to protect both the wires and the optoisolator inside the SBMS40 in case EXT IOx- is shorted to ground.

[Chris R8]

I had the same problem with 3x MPPT 50/100 and VE-Direct with cerbo. Another problem the remote cable of 30 and 50/100 MPPT switches on low (really Victron, very safe....irony off) means if that flimsy ve direct connector gets loose due to vibration the MPPT stays on and Electrodacus cannot shut it off in end of charge, HVC or desaster shutoff. Confronted Victron with this issue and they told me I should put all 3xMPPT and the 2xDC2DC charger on a charge bus and switch the whole charge bus with a victron battery protect via Electrodacus. Victron has the same issue with Victron smart BMS and cerbo, this solution Victron suggests to their installers. This way you have the ve-direct for cerbo and in case remote cable of BP220 gets disconnected the BP220 switches off as it switches on high.

3 remote cable costs the same as a BP220. I would get the smart BP220 so you manually via Victron BT app can switch charging on/off manually, also easier to program.

[Chris R8]

Would not put the multi 3000 on that charge bus, I have a separate combo bus with 2xmulti and switched on 

/OFF VIA sBMS. This is needed as multi is load and charge and the battery protect works only in one way and due to manual the inrush current of inverter will destroy the battery protect.

[Chris R8]

I would also recommend to plan in an active balancer. 4p with 280AH cells means that 0,1V devation at 3,55V is about 4x2Ah hours=8AH and the 150mA passive one will need a month to balance that. You have quite small solar and the flexible will deliver maybe a 1/3 of their rating so I expect you have same situation then I have that bank is hardly in the full and in balancing area.

Means you simply need more balancing current so bank gets quickly back to balance.

[Ross Aspinall]

UPDATE: Just a reminder of the Hack I am doing - Turn the Renogy DCC50S Chargers off/on by tricking with resistors an over/under temperature state of the external temperature probe circuit. This will be triggered by the Electrodacus SBMS40 at a Cell overvoltage 3.3v fault state via an optocoupler board 817 module, see diagram.
Issue upon testing the system - when the SBMS40 is in normal state it powers the 817 Module and turns the Renogy DCC50S Chargers off, however I want to turn on the 817 module when in fault state thus turning the chargers off, I have tried all the relevant function types for the EXTIO on the SBMS40. Any ideas on a solution? 

[Dacian Todea (electrodacus)]

When is the DCC50s turning OFF ?

Is it when there is no temperature sensor attached or when the temperature sensor has 43kOhm (I assume the sensor is 10kohm at room temperature).

There is also another 3Kohm in series with the output of those modules so it will be 46kohm.

Also have you removed the red jumpers ?

[Ross Aspinall]

When is the DCC50s turning OFF ?  when the 817 module is energised 
Is it when there is no temperature sensor attached or when the temperature sensor has 43kOhm (I assume the sensor is 10kohm at room temperature).  Both with external 33Kohm in circuit or not, I haven't tried removing the temp probe.  Anything above 33kohm will switch it off.   I don't need the temp probes they are redundant as I am measuring temperature via SBMS40 as well as the Multiplus 2.  I could easily do away with them and the 817 module   
There is also another 3Kohm in series with the output of those modules so it will be 46kohm.  You mean 33Kohm? As above tried either way
Also have you removed the red jumpers ?  yes 

Its like I need a NC output from the SBMS40 not a NO.  Or a 2 way relay with NO/NC   

[Dacian Todea (electrodacus)]

The EXT IOx is close circuit when charging is allowed and open circuit when is not allowed. This the the safe way as if the EXT IOx wires get broken / disconnected for any reason the charging will be OFF.

It will be fairly simple to fix the problem by just connecting the 33kOhm resistor in parallel with the 817 output.

So the wire from the temperature sensor connects to V1 and the 33Kohm resistor connects between V1 and G

This way when 817 is energized (close circuit) it will short the 33kOhm allowing charging and when 817 is open circuit there will be the 33KOhm in series with temperature sensor so charging will turn OFF.

[Ross Aspinall]

Thanks Dacian, 

Just so I get this accurate,  The manual States; 

"The EXTIO3 and EXTIO4 are the output of mini SSR (solid state relays) in this case CPC1002N with 700mA 60V capability more than sufficient for any inverter remote ON / OFF port"  suggesting a NC when charging 

You sent an email to me (rossaspinall@hotmail Dot.com) Sat 24/06/2023 2:04 AM AU time - stating The EXT IO4 as a NO.......  

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"The EXT IO4 (same as all other EXT IOx) is just a NO relay (it is not a relay but an optoisolator so it can handle max 50mA)

It is the Toshiba TLP187 you can read more about here https://groups.google.com/g/electrodacus/c/9VmM3frdW2w/m/a1_myI_WAQAJ

The + and - signs for EXT IO4 are due to the parasitic diode so it can open the circuit only in one direction.

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is the Elecrodacus SBMS40 NO or NC when in (Normal) charging state? 

Could i do away with the the 817 Module and go direct to EXT IO4 for Both of the DCC50S Temperature circuits?  And use your solution?  I did notice 3v on these temp circuits when powered on however will dual voltages affect the outcome?  I.e EXT IO3 - For my Victron Multiplus 2 and EXT IO4 for Both Temp circuits. 

Or just do as the diagram 

[Dacian Todea (electrodacus)]

EXT IOx is capable of max 50mA. Most inverters will only have 1 to 2mA trough the switch so it should be enough.

NC or NO have specific meaning and the EXT IOx all use an normal open solid state relays or optoisolators and that just means that if the SBMS is not powered and you measure EXT IOx you will measure Open circuit.

But when charging is enabled the EXT IO4 set a type 1 will be close circuit.

This is the only safe way as if the EXT IO4 wires become broken the charging will stop as circuit becomes open circuit.

You can not use a single EXT IOx to control both DCC50s as they may get damaged or interfere with one another if temp sensor is paralleled. Is best to have an optoisolaTtor for each individual device.

The diagram is correct just do not forget to remove the 33kOhm that was in the old schematic only have the two drawn with red.

[Ross Aspinall]

Thanks for your help on this one Dacian,  

For the groups benefit as follows 

Problem Statement - The Renogy DCC50S controller charging is not able to be switched by a Electrodacus SBMS40 as there is no remote off/on circuit.

Solution - Hack the Renogy DCC50S charge controller temperature circuit by switching in/out a 33kohm resistor with an 4 way 817 optocoupler module switched by the the Electrodacus SBMS40 EXT IO4.  This will fool it to think it is -3c (below zero Centigrade) causing it to shut off and on charging 

works well with 3 weeks of testing, Final working diagram as follows 

[Dacian Todea (electrodacus)]

Thanks for the feedback on how it works.