Review Electrical Diagram - Van Conversion System

[paul deacon]

This is my first crack at electrical layout, I have a general power schematic and prettier Electrodacus/sense wire layout (discovered straight lines..) 

In case the pictures are not obvious the main system I have already purchased consist of

 8 x 280 aH EVE cells wired in 2p4S which will yield 560aH @ 12V

Electrodacus BMS

Electrodacus DSSR PV solar controller

3000W/12V Victron Multiplus Invertor

Lyxn Distributor (don’t need the flashy light but got a bundled deal) – will add additional bus bar to extend connections

2 x “smart” 12/12/30 amp DC-DC Orions in Parallel

350A/100mV shunts

I think I will buy the following solar panels as I like the idea of low profile nature and if I ever get the urge I can use the van as a patio

2x Alrska Flexible Solar Panel 100W 12V/24V Monocrystalline 

each panel 5.34A Imp, 18.7V Vmp

2 x Alrska 180 Watt Flexible Solar Panel, 12 Volt Monocrystalline

each panel 8.61A Imp, 20.9V Vmp

 So onto some questions I would really appreciate the input on.  I have a separate diagram for the BMS and control systems as the initial layout looks like I threw up on it. Once I get some feedback I will fix the lines but I found it was pretty helpful sketching this out in this rough format.  Some of this is not directly related to Electrodacus but just included for completness

Wire Lengths

• Which wires have to be equivalent length +/-v – I get main wires to and from bus bars but what about to DC DC Chargers and MPPT/DSSR20?

 Grounds

• I have small gauge “ground” cables from Battery Protect/ DSSR/& Lynx Distributor that I assume I will find a convenient chassis point to attach to. What should I do with the Green Cable highlighted at the Multiplus – tie that to chassis ground it seems like its expecting a larger gauge wire

 Battery

• Will be 2P4S,

 Bus Bar / Lxyn Distributer

• I have 3 additional “-ve/ground” connections that I was thinking I can extend the lynx with a dual bolt bus bar (for -ve need 2 from PV and one from BP which looks like a small “ground wire).  For positive I need to small sense wire +ve so hoping I can just connect on top of one of the existing connections – my rational on position is the highest loads/inputs should connect closest to the main battery lug

 Shunts

• Eletradacus use the +ve side for measurements, a main battery shunt first of battery and then a PV shunt
• I undersized the main battery shunt as I was originally going 24V – I think I will replace with what I have (350A/100mV)  with Victron Smart shunt 500A/50mV so that it can pull double duty talking to Victon and Electrodacus – I assume I can get the data from blue tooth wirelessly from the smart shunt but if I use a direct wire connection via VE direct do I have to do anything special ( some one mentioned it would need “fused sense wires” used on +ve line ..)   -  Worst case is I know I could add a third shunt on the negative side for just Cerbo but that introduces additional failure points and as its nice to have don’t wont do that

 DC DC Orion Fusing

• Is having a fuse at Lynx distributer then a breaker and a further fuse at the chassis battery connection overkill or appropriate?
• I got a deal on two isolated DC-DC – I don’t intend to use them isolated so is there anything special I need to think about or do, could not seem to find any info except remove jumper
• I am really fuzy on the triggering for DC – What I want to do is have them turn on with ignition (so H input) and then additionally have the ability to turn them off (Switch on the L side ) – The BMS also uses the L connection to turn off the Orions. 

 PV/Solar

• I have dual routes for PV charging though intend to always use both as i dont there is going to be excwss solar - hence I have not wired in a diversion circuit though i do have that version of DSSR. If there is an actual benefit from wiring either charge source parallel  vs series knowing I also plan to buy a conventional MPPT.  I plan to fit something like 600W on roof
• DSSR connections to panels don’t have a -ve connection – only a small ground wire,
• -ve return – As the way the electrodacus works they use a shunt on the positive side for battery and PV , So I need to provide -ve (ground though I appreciate that’s not what it is) – I can extend the negative bus bar from the Lynx distributer – obviously cable lengths are not going to be perfectly match
• Is switch the correct device on the Solar side of charger controllers as I planned to have breakers prior to these.
• As I only have two panels on each leg did not include fuses.
• I hope I can gang the sense/trigger wires for both the SSR and yet to be purchased MPPT – it seems that I have to use the VE direct if I pick Victron – I am assuming I can still collate Victron PV input via blue tooth

 Invertor

• I have read that getting 4/0 to fit on the Multiplus is a pain so figured I would run 2 x 2/0, for the short run post the switch was going to use a small length of 4/0
• I will plan to use trickle charging from Multiplus – I think the last I read I can wire +ve direct to EK1 (Maybe I can put a switch in line to disable this is I really need it ?
• I found a nice design for pre charge switch which I plan to use on the invertor switch – will be a dwell for a second at 1^st position then connect – credit goes to filter guy at DIY solar. 

 AC Distribution

• TBD probably panel from bluesea
• GFI – I read some issues with using MIDEA AC on GFI – Did I interpret Mark recommend some ferrules might mitigate this ?

 I appreciate I have not shared any details on loads – I sort of sized the major items knowing I will plan to have Midea U shape mini split AC working eventually, small air compressor,  will buy induction stove – better half will use a hair dryer and likely end up buying a ISO temp or may cheap out and use Bosch water heater . For DC the usual lights , Diesel heater, Lemans fan and  charging Ports….. I think I understand sizing of wires for the loads side (fusing for the wire not the load) but if there is some fundamental thing I need to be wary feel free to call me out – If I get motivated will probably do a separate diagram for those at it will help the layout but this is already a bit large and don’t want to lose the crowd…  

[Dacian Todea (electrodacus)]

Paul,

This is a long post with many questions. Hopefully I do not miss to much.

- I will suggest you look in to non flexible solar panels as those will not last long before cells will crack and panels will no longer perform.

Wire Lengths

The wires do not need to have equal lengths.

Grounds

Normally the DSSR will be close to battery so you can have a short wire to battery negative and not to some point on the vehicle chassis witch may be less reliable. The DSSR20 battery negative connection can be even a 18AWG wire.  It is the same thing for Victron battery protect.

Battery

Yes a 4s2p is not a problem Groups of two parallel cells are in no way different from a single larger capacity cell.

 

Shunts

The shunts need to be connected as in your drawing but need to be much closer to battery+ so a max of 30 to 40cm (about 1ft) wire between battery+ and battery shunt then PV shunt right next to battery shunt.

Not quite sure what was the comment about Victron smart shunt but that has nothing to do with SBMS0 as SBMS0 can not use it.  You can use a 500A 50mV shunt with SBMS0 but just the shunt (resistive element) and needs to be connected to battery+ and then to the shunt sense wires on the SBMS0.

DC DC Orion Fusing

The fuses or breakers are to protect the cables in case they get disconnected and shorted to negative.  Since current can flow both from battery and from charger you need to have fuses/breakers on both ends of the cables so it is not overkill.

Based on user manual page 5  https://www.victronenergy.com/upload/documents/Orion-Tr_Smart_DC-DC_Charger_-_Isolated/34439-Orion-Tr_Smart_DC-DC_Charger-pdf-en.pdf

It seems that remote port is relative to input battery so the simplest connection will be vehicle ignition switch to a 1kOhm resistor for protection then to EXT IO6+ and then the EXT IO6- connected to H pin on the orion remote port.

This way both ignition needs to be ON and the SBMS needs to allow charging and if you want you can add also an extra switch in series to be able to manually disable charging.

PV/Solar

The amount of solar you have will not require any dual PV array setup as your max solar charge rate is way under 0.2C

Breakers between panels and DSSR20 are not needed unless you want them for easy disconnect when you want to work on the system. A circuit breaker is likely less expensive than a switch.

 Invertor

This is the document you need to set the multiplus https://www.victronenergy.com/upload/documents/Manual-Connecting-other-lithium-battery-systems-to-Multis-and-Quattros-EN.pdf

All settings as that default example except last two where you need to select Disable charger.

[paul deacon]

Darcian

Thanks for the replies - might I infer from the comments that there was not to much wrong in how i configured the set up shown in the diagram on the Electrodacus side (EXT connection etc

Shunts

Yes I will have shunts basically as close as possible to battery - just made the length estimates as worse case for wire sizing 

i understand that the smart part of the shunt from victron can not be used by Eletrodacus system, but is there any way i can have sense wire across shunt from smart shunt to Victron and also to Electraduacus - if I could find out the specs of the Victron shunt in terms of resitance can it not be used or are you saying that the smarts in the Victron shunt will cause issues with accuracy ?

DC DC - this is an isoloated version and as I runing two in parralel - I think what I almost showing is what you describe, just that I dont need the parallel H remote wire between the two Orions - just  switch "power on" via the ignition switch

Panels

I will like to have an ability to disconnect panels - are you suggesting I can just use a only a breaker between DSSR and Panel and nothing else required form DSSR and Battery?

Do you think I have the remote trigger correctly joining the MPPT and DSSR and onto EXTIO4-.  I may use the DSSR for some additionall deployable panels and maybe have all 4 pannels run with the MPPT - any reason that would not work say these are not connected they would just show zero charge but wont stop the remaining  from working

[Dacian Todea (electrodacus)]

Shunt,

The Victron smart shunt is made out of two components. The actual current shunt (power resistor) and a blue box that contains the current shunt amplifier and a Bluetooth module that can read and transmit that value.

Since Smart shunt is designed to be installed on the negative side there is no way to use the same shunt for the SBMS0 witch require a shunt on the positive side.

You can use both the SBMS0 with his own stunts on the positive side and the smart shunt on the negative side but they will be independent.

Smart shunt only measures battery current shile SBMS0 measures both battery current and PV charge current thus it can also calculate the Load current as the difference between this two.

DC-DC

Not sure what you want to say.  Both the SBMS0 and the ignition need to be able to turn OFF the charging that means it will need to be installed the way I mentioned. Ignition will be +12V when engine is running that will go trough a protection resistor 1kOhm to EXT IO6+ and then the EXT IO6- will connect to the H of the DC-DC converter or converters.

The H will see zero volt so DC-DC be OFF if either ignition is OFF (engine not running) or the Lithium battery is full so the EXT IO6 is open circuit.

Looking now at your diagram it is incorrect because you need the H pin from remote port not the L.

Panels,

Both the DSSR20 and the Victron MPPT trough the remote ON/OFF cable require a signal that is about battery voltage in order for charging to be enabled. So it seems your diagram is correct as there is a 1kOhm from battery+ to EXT IO4+ and then EXT IO4- is connected to DSSR20 batt signal and the MPPT remote ON/OFF cable (yellow wire).

[Dacian Todea (electrodacus)]

Also looking at your modified diagram. You need breakers or fuses on the battery side of the MPPT and DSSR20 (those are mandatory) the one on the panel is optional at least for the DSSR20
That wire from DSSR20 battery+ connection to the positive bus bar needs to be protected so the breaker will need to be next to the buss bar to protect that wire.

[Richard S]

Thank you Paul. Your questions and Dacian's answers are of a great help to me. 

Dacian: thank you for all your works. And your patience at answering our questions.

[paul deacon]

So first the great news I finally got my power system installed in the van and have the Victron battery protect connected to a couple of loads (fan and diesel heater) seemingly working fine. I soon need to get these charged up so have some pretty pressing questions

1     I have yet to connect the charging sources and its showing 49% SOC, Cell Voltage 13.294 Cell delta 4mV ( I have a 12V system) will this be correct once I get the pack fully charged? 

2     I wanted to try out a quick charge source and went and purchased the 180W Alrska flex panels - spec is Pmax 180W, Imp 8.61 A, Vmp 20.9V, Voc 24.7V, Isc 9.13A all at 25deg C

I assume these will be ok to use? 

I will connect these to either  DSSR50/20 to charge but as they show V much higher than 12V what will happen on ideal solar days - in other words, will they damage batteries?

Thanks Darcian

[Dacian Todea (electrodacus)]

Paul,

1. The SBMS has no idea what the SOC is and so when initially connected it will show 49% no matter what the real battery SOC is in reality.

2. Yes the panels will work OK with your battery. They may not be the best quality and degrade fast over time based on reviews.

Do not worry about the panel voltage as that will drop at the battery voltage level when connected by DSSR20 / DSSR50

Looks like maybe they are 38 cell panels thus the bit higher max power point voltage compared to 36 cell panels or 32 - 33 cell panels.

In any case under full sun you should see about 10A so 130 to 140W going in to battery.

[paul deacon]

awesome thanks for the quick response - these were pretty cheap ($110 per panel) so I have low expectations but I got a three-year warranty - if they last that long I will be happy

[paul deacon]

The panels are working well so I guess I wired it correctly...

I have a couple more questions

1   - I cant seem to find where exactly and how I input my shunt values  (I am using a 500 amp 75mV ) 

2   I also am a bit confused about the operation of the XTC I installed,  I assume this is labeled EXT (even though I put it directly to the cells) - I am not so familiar with different bases - I would think I would set it up at 35F and 105F (wider range than you perhaps would recommend) that said does the SBMS by default take temperature controls form Internal (which is in the head unit ) or does it switch to Ext in which case I better get the values right?

 

thanks

Paul

[Dacian Todea (electrodacus)]

Paul,

1. If you only have the battery shunt then you go to Automation menu then ADC submenu and there you set the value of the Battery shunt as 75mV/500A = 0.1500mOhm

2. Not quite sure about this question. I guess you are referring to the external battery temperature sensor that connects to XT1+ and XT1- on the SBMS0 16pin green connector.

For that you need a NTC 10K  B3950 type of temperature sensor and that is where XT1+ and XT1- is connected defensively not to cell's.

As for setting the limits 35F is about +2C a bit to close to freezing normally I recommend +5C (41F) and to set the limit there it will be 3000b in binary

For a high limit 105F (+41C) is not much and in summer you may have that temperature even just from ambient thus maybe not a good idea. I will say at a minimum +50C (122F) and for that the binary will be 1180b

Temperature sensors have some tolerances thus if you want to be more precise you can just heat or cool water at the temperature you want to set and read the binary value for that in the Diagnostic menu then use that as the limit.

So say you heat water at 50C measure with an accurate temperature sensor then insert the NTC sensor in the water and check to see what value it reeds after temp sensor gets to water temperature than use that value in the settings.

But if you set limits and install a temperature sensor on the battery then if any of this two limits is exceeded all loads and all charge sources will be turned OFF.

If your battery is not inside a temperature controlled space best option is to have the battery in an insulated box and have a small 10 to 15W heater element with a thermostat set to keep you battery always above +15C (57F).

[paul deacon]

1  I have both the Battery and PV shunt and found the setting for PV shunt and input corrected values - now the values I see from the Electrdacus and smart shunt are similar (not exact but not so concerned yet)

2  yes I have a NTC 10K  B3950 type of temperature sensor and it is connected to XT1+ and XT1and the SMBS unit is displaying a  value for this  EXT sensor. , I did a rough calibration with this connected to a known temp and voltmeter and it was reading correctly - what I am asking is what temperature is used for control for low or high temp disconnect

 either a) the so-labeled INT temp (which I assume is the sensor in the SMBS control  unit only when connected

or b) my added EXT temp sensor  

they are quite a physical distance apart - my temp sensor EXT is located inside my battery box which is surrounded by insulation (and also has a heating pad I separately control.  the battery obviously  has a pretty decent thermal mass and I think my EXT temp sensor is a better indication of battery temp than the control unit which will be mounted some distance away (and in a non-insulated box) 

A follow-up question say my EXT lead fails (as I did have to make it I am not exactly a skilled electrician)  will the system default back to INT

3  MaxPV Out - is that only related if I use the excess solar input as a diversion, or do i need to set it above 10 amps (i have a 560aH battery  so 0.3C is more like 168 A with the dual input DSSR50 PVa+PVB..

4  I cant recall if I asked this before but I assume for maximum efficiency the PVa and PVb need to be the same panel W/V? - currently, I have two parallel panels connected to PVa (2 x180W) panels - I have room on the roof for 1 more panel but i might need to size it down to 150W as the space available on my roof is limited.  So can i use 2x180W and 1x150W panel connected to the DSSR50 .  An alternative is I use the 180W panels as deployable and use those via my DSSR 20 (but will this be an issue for peak current ?,  and buy 3 x150W to use with DSSR as they will fit 

Paul

[Dacian Todea (electrodacus)]

2.  The limits will be relative to your EXT temperature sensor the 10K NTC B3950 you probably attach to battery.

If you set a low temperature limit say +5C (3000b) and the temperature sensor gets disconnected it will register as -45C and that means both your charge and discharge will be disabled.

3. That MaxPV limit is only valid for dual PV array setup and if you are not using a dual PV array setup that limit is irrelevant.

For example I have a 24V  560Ah (more like 520Ah real) battery and I connected 9kW of PV solar in dual PV array setup with array one controlled by EXT IO4 set as type 1 connected to two DSSR50 about 3kW of PV panels and the array two controlled by EXT IO5 setup as type 6 connected to 4x DSSR50 about 6kW of solar.

Then I set a limit of 80A as max PV output and when the PV array 1 outputs less than half this limit 40A the SBMS0 will check the PV array 2 that should be around 80A and so it will be using that unless that is also less than 53A in witch case it will connect both array 1 and array 2 to charging thus 3 total levels keeping the charge current around 80A allowing to exceed this limit by 20% if it is a slow increase thus I will not see more than 96A continues charge current unless that comes from the PV array 1 as that will be connected as long as it requires charging so I can see 105 to even 110A from that array 1 and it will not stop the charging but if array 2 is above 96A it will switch to array 1

4. You can connect any panels you want at PV A+ and PV B+ they do not need to be the same.  So yes you can have 2x 180W on PV A+ and 1x 150W on PV B+ 

You can just not exceed 30A on either PV A+ or PV B+ and can not exceed 50A as (PV A+) + (PV B+)

[paul deacon]

Ok new question if you are up for it , I want a safe but convenient way to disable my solar when its cold - I cant seem to find what I am looking for 

I am finding it a bit annoying to flip a breaker (which I have between the DSSR and the positive bus bar ) to disable my charging source (in this instance solar) - my breakers are all on din panel that will be somewhat buried in electrical cabinet which are a bit inconvenient.  

I am assuming a cost effective remote way to do this is to place a Victron battery protect between  the output to the DSSR and said breaker -and set up a charge source type 1 ( I will have to gang it through opto isolator)

Reason being I want to still have load source below 32 deg F (my battery pads and diesel heater) but not charge until I get over my charging target temp 45 deg F

is this the best most elegant way to do it - I can use a $50 BP as I don't think I will see anything close to 65amp total solar , or could I use something like an inkbird temp control relay set to cooling   

p.s I have been covering up my solar panels before flipping breaker but do I need to do this - will DSSR be unhappy if I disconnect under charge?

[paul deacon]

I have  insulated the batteries (they are wrapped with 3 inch of PET)  and have heating pads under the batteries triggered to turn on at 42 deg via an inkbird and they seem to be keeping them at temperature  - I have read a lot of your reasons to keep them above freezing vs turning off charge sources and I am warming to this idea :p) as the best way - But I still would like a remote switch to turn off the solar / DSSR

I think I have answered my questions and the BP is best way to go - but maybe I can make my trigger/EXT simpler and run all charging sources through the larger 220 version (Multiplus/SOlar and twin Orions) 

[Dacian Todea (electrodacus)]

Paul,

You can flip off the PV breaker anytime you want no need to cover the panels. The breaker should be capable to handle the small sparks during disconnection.

If your battery is properly insulated the battery temperature should never drop below your limit. 

Not sure how disabling solar charging will be helpful as you will want all PV energy available. Once the battery gets below freezing it will take a very long time (hours) with heating pad enabled to get back to the normal operating temperature and way to much PV solar may be wasted during that time.

You should not need any BP to disable the PV charging all you need is a digital thermostat with open and close circuit connected in series with the EXT IO4 (assuming you use EXT IO4 to control the DSSR).

[paul deacon]

Hi Dacian

I was more concerned with the DSSR as currently the set up i have 

2x180W panels - DSSR - Din rail 50 amp BREAKER - din rail 30 amp fuse (will need to increase it though i do appreciate this is redundant it was free and fit in my din rail box) ) - PV shunt  - Lynx Distributer 

Not shown is the solar connections into the breaker on the left

yeah i ran it today heating batteries and running solar  after heating over night- and I was able to get a net gain in charge today  so  I am gaining confidence this will work well  - I prefer it it's way as once I get my panels permantly installed I want them starting to add charge as soon as they can vs me manually turning them on 

I might experiment with a inkbird between the IOXTas you suggest - its another layer of protection I can consider though I do think it will be redundant - the only  reason I am considering it is if the heating pads fail (they were quite cheap and i don't know great a quality they were) I might want a way to warm up things below set point - granted this will take a long time 

I assume I can also just insert a manual switch on EXT in series also instead - just to give me a remote switch to turn on / off solar - 

[Dacian Todea (electrodacus)]

Yes you can add a switch in series with EXT IOx for manually turning off solar charging.

As redundancy you can have a low temperature limit set at +5C in the SBMS that will turn OFF both charge and discharge and you set the battery temperature thermostat to more say +10 or +15C so as long as the heater works there are no issues and if it fails the temperature will drop below +5C and SBMS will disconnect everything.

But 2x 180W is not much solar so you can get as little as just 100Wh in a very cloudy/overcast day thus your battery box should be designed so that heat loss is less than 4W or you need more panels.

[paul deacon]

Yes I have the set up now like that with cut of lower than my batteries and it’s working well 

I will add 2 more panels for sure that will be on top of roof on the dssr20 permanently  then perhaps an additional two more for the DDS50 (total 4x 180w) as the deployable panels for high solar needs in summer and for helping with ac loading 

I assume 180w panels 36 cell are about largest I can use with my 12v system 

[Dacian Todea (electrodacus)]

Yes 180W is about the largest PV panel for 12V maybe there are some 200W with 33 cells a bit less standard.

[Chris Sailor]

Paul,

a bit late but some points:

1) ground: you need to connect the whole installation to ONE ground point otherwise you get ground loops. if not possible then 2 points, one in front and one back.

the wire size must be according to the max load, so with the inverter a 90sqmm cable will do.

2) solar: on an RV with very limited solar space Darcian's 12V DPPT solar approach is unsuitable as you get much more effective panels with the same surface that are higher voltage (which is also favourable as the voltage drop in the cables cost a lot Watts). So its favourable to use MPPT that by the way also report via VE-Direct to Cerbo the solar output. you just wanna harvest max from the small surface you are given on top of an RV. like this just get best panels that fit and as high voltage output as possible. Panels always connected in parallel on an rv due to shading issue.

Also here i advice to google for experience with the specific semi flexible panel you chose as what they advertise to what you really get is often very different for semi flexible panels, also how they hold up. expect them working as long as warranty is. expect the output of the panels max 50% what they rate. all very different to fixed panels. Additional the MPPT you can simply switch off which its remote. just all so much easier then the dppt approach with matching panels.

Dacian's dppt approch is great for a house where you can get a lot of panels even for free, used or a siginficant discount because standard is now 48V and you don't care much about of space as you have it anyhow and adapt its mounting.

3) shunts: as you figure the Electrodacus shunts go on the positive side while victron the smart shunt must be connected to neative side of the battery. nevertheless good to have it as you cannot connect Electrodacus to cerbo, so the smart shunt must do. I highly advice instead of the smart shunt use the battery monitor BMV712.

Reason is the BMV712 also contains a relay (which smart shunt has not) you can program and this is your last resort method in case BMS fails as it disconnects the battery in case of under or overvoltage and the BMS fails. That is also required by installation law and in case your RV burns down and you don't have that insurance can bail out and pay nothing as this requirement is not met. the BMV712 also connects via ve-direct to Cerbo. Additionally you can use the 2nd input of the BMV 712 (which the smar shunt has not):

a) connect it to the middle of the bank, so it measures the difference between Pack 1+2 and pack 3+4. so the BMV 712 can actually dedect also imbalances additionally to BMS and you can also program the relay to disconnect if thats getting too big. i advise to to do that.

b) alternative connect it to your starter battery and you can see that in the cerbo too.

4) PV-shunt lug stacking: i can already see from your foto that the 2 lugs stacked on top of the PV-shunt don't connect properly and you will get heat up issues as their surface is not even. You need to use special stacking lugs as the standard lugs don't have an even and big enough surface to get stacked (some by random do but min. 90 degrees angle between lugs, better 180degrees, you can try that). alternative just connect a small busbar to the shunt and connect the lugs there.

5) DC2DC chargers: advisable to install them above and not below like you have as they get very hot and heat all thats above. also ventilation from bottom is too small like you have it now.

[paul deacon]

1 I have a single ground from lynx distributer to a floor attachment to the body which I prepared by removing to bare metal - I also grounded the multiplus frame to same point

2  I will see how solar goes and have protected space for an MPPT - I have been using some of these flex panels as deployable panels as I will use these as supplements to what ever I mount on roof - so far I seem to getting 12 amps or so from the combined panels 180*2 = 360W but this is in winter with not so much sun - I got a  3 year warranty on these so at $119  per panel each I will think of them as disposable.. 

3 Can you tell me more about how you use the BMV712 relay as a fail safe 

4 I will look at lugs on shunts so far they are running cool but will extend one of the cables to ensure 180 deg 

5 I have 4 small fans on each DC cooling the Orions - I wanted them low to draw cold air - I will also have a push and pull fans in the enclosure to pull heat in on cold days from top and more often cold air in from other end  - will see how that goes

[paul deacon]

Can someone explain how I can determine if I set up the two signal BMS on Victron Multiplus correctly? 

Electrodacus is normally open so set up as follows
Battery full Aux 1 is OPEN (EXT5 for multiplus Charge)
Battery empty when Aux 2 is OPEN (EXT via Octocoupler via Battery Protect for AC out)
set to disable charger and do not adapt SOC

Victron Multiplus Settings 
Absorb 13.9v (default was 14)
Float 13.5

How can I determine if the shut down / stop charging is working correctly for Multiplus 

Furthermore what if I have the DSSR solar charging instead - which does not seem to have any specific "bulk"/Absorb/ float settings to configure 

[Dacian Todea (electrodacus)]

I'm guessing you have

Battery full Aux 1 is Open (EXT IO5 set as type 1)

Battery empty Aux 2 is Open (EXT IO3 set as type 2 can be trough some optoisolator board if you need to control multiple loads).

Yes set to disable charger.

Absorb can be left to default 14 to 14.4V irrelevant as it will never get there since SBMS0 will stop charging using Aux 1 when any cell gets to 3.55V

Float is irrelevant as it will never get to that point.

You just go in to SBMS0 EXT IOx menu and set the EXT IOx controlling the charger (maybe EXT IO5) from type 1 to type 0 and push OK to confirm then charger should stop. Then set back to type 1 and charger should be enabled.

You can test the same way the DSSR just set the EXT IO4 (assuming that is what you use) to type 0 and solar charging should stop.   SBMS0 will do the same automatically when any cell gets to full charge 3.55V

[paul deacon]

So I have just experienced a new issue but maybe its normal behavior

I finally used solar / dssr to charge batteries to full (all times before been using victron multiplus charger) - the pack got to maximum of 13.82 as far as i can tell (i do have one cell that is typically higher so maybe it got to 3.55?) - the default OVP is set at 3.55 = 14.2v  - I am reading from victron cerbo shunt and not electrodacus 

when I took a look at the DSSR its off  (i am hoping / assuming this is the logic trigger) 

and i used a clamp meter and I am getting 0A from panels

I sort of assume panels would be still showing current into DSSR 

If this is normal when would i expect the DSSR to come back on ?

where and how can i get to logging data from electrodacus

[Dacian Todea (electrodacus)]

Paul,

Yes when any cell gets up to 3.55V the battery is fully charged so charging will stop and only start again once all cells are below 3.4V

[paul deacon]

so cells are below 3.4 now and DSSR has not recovered - its not showing the power light even when there is voltage at the input terminals - whats a safe way to disconnect and reconnect the DSSR50?

[Dacian Todea (electrodacus)]

Paul,

Check that Max SOC is set at 99% in the DMPPT Settings menu.

A photo of the SBMS main monitoring screen page 1 will be useful to diagnose the problem.

Also not sure what your location is but if it is night time the DSSR50 light will not be ON as it is supplied by the solar panel.

Disconnecting and reconnecting DSSR50 will not change anything and there is no restriction on how to disconnect or reconnect.

[paul deacon]

Dacian,

DMPPT screen, I didn't think these were relevant if I didn't set SOC type 

Look like I set this at 90 - which is odd as I know the SOC got to 99%, also 10 amp limit I am not sure is set as I was getting 19 amp, I mean there might be a chance I have never taken it to 100% charge on the Electrodacus 

Yes I understand the light only comes on when there is solar input - 

Paul

[paul deacon]

Dacian - message two after sitting overnight 

Solar panels now working and showing on DSSR with no setting changed from the above

I can change the 90% SOC something higher but I am still unclear on what just happened 

Thanks

[Dacian Todea (electrodacus)]

Paul,

The SBMS0 worked correctly.   Due to Max SOC setting at 90% the SBMS0 will only charge once to 100% SOC and then will re-enable charging only if battery SOC is below 90% so at 87% and then will only charge to 90% until the next day when it will again do a full charge to 100%.

If you change the Max SOC to 99% this limitation will be disabled and charging will be done to full multiple times a day so charging will start as you expected when all cells are below 3.4V.

So with current settings the SOC will get to 100% SOC once in 24hour period then for the remainder of the day it will only start charging at 87% and stop at 90% keeping the battery around 90% for the rest of the day.

[paul deacon]

Ok - are  you saying regardless of DMPPT setting (in my case 90%)  it will always charge to 100% once per day ?

So mine is working that way as i am charging currently at 92% which is above the setting 90 but today is classed as a new day

is there a record somewhere that I can tell its reached 100%

Paul 

[Dacian Todea (electrodacus)]

Paul,

Yes it will charge to 100% only once every 24h.

Reset for a new day is done at midnight assuming the SBMS time is set correctly.

You can check the PV current graph to see if charging has stopped and if it did it means it got to 100% SOC.

[paul deacon]

New question

I am happy with the way the DSSR 50 SBMS is perfroming but I have questions  on getting more perfromance out of my set up 

I am finalizing my solar with a fixed installation on the roof  - I am using  2 x 180W fixed panels for input A on DSSR and 2 x100w flex panels into input B (these are really bonus as I am using them as seating surfaces.. 

Info on 180W panels on roof 

Currently I am only seeing 6.3 to 7 amps @ 13.4V  per panel yielding ~94W  - current wire legth is <10ft) its 80 deg clear day, 

 

specs on panels  

Imp 8.61 

Vmp is 20.9V

Voc 24.7

Isc 9.13

Previously I had experimented with the same fixed 180W panels on floor  - I could get a little bit more out of them with some orientation -I have seen absolute maximum for one panel of 7.5 amps (using a clamp  meter and verfying on SMBS)

I plan  on using same 10 AWG guage wire I used when experimenting in deployed mode on the floor  On the roof the maximum wire length will be 21 ft to the furthest front panels with connection in rear of van through roof, I sort of think as I have an excess of V I am not not going to gain much by upsizing this and i dont particilarly wnat to use something other MC4 connectors which i am not sure 8 AWG will fit.

Are my panels just mismatched to the DSSR - would I see more using a MPPT that would take more advatage of the higher voltage ? I really dont wsntt to use a different controller and it will be clumsy on controlling these but it does seem like I am leaving a lot of power untapped with my current set up 

[Dacian Todea (electrodacus)]

What is the dimensions maybe a link to spec on those panels ?

Vmp seems a bit to high for typical 36 cell panel and it may be that specs are not correct.

There are a lot of fake specks on the smaller panels.

If the spec where real and panel oriented directly at the sun you should see at least 8.5 to 9A peak.

Maybe you have some shade on the panels but based on spec I think those are not 180W panels. Seeing a photo of the panel's and the dimensions I could be more sure if that is the case.

[paul deacon]

https://alrska.com/products/alrska-180-watts-mono-solar-panel-12-volts-monocrystalline-solar-cell-charger-high-efficiency-module-for-rv-marine-boat-off-grid

27.7 x 48 inches

[paul deacon]

Also I measure them around 19V 

[Dacian Todea (electrodacus)]

So they are flexible type ? In that case cracked cells are very possible and that will significantly degrade the output.

But it is unclear as they show both flexible and glass type panels. The spec is for the glass and aluminum frame one based on weight so not sure witch one you have.

I was able to count the number of cells and they are not 36 as mentioned in the spec but 38 so that is already a lie not just in the spec but also in the model number AK-180-36MFE

Each cut cell is about 6" * 1.2" meaning they cut each 6x6" cell in to 5 pcs and since they have a total of 38 * 4 cut cells = 152 cut cells that is about 30 cells full size.

Depending on the efficiency of this cells I will expect a rating of 160 to 170W for this panel so not that far off 180W claimed. But it is much more likely that cells are nothing special and panel is 140 to 150W

But that junction box will most likely shade the cells just under and that could drastically reduce the panel output .

If you fully shade a single cut cell out of 152 cells the panel output current decreases by 25%

[paul deacon]

No these are fixed panels they used the wrong (flex panel)  picture.  I found out how fragile these flex panels were in some tetsing i did and hence why I swapped them out - 

[paul deacon]

Any idea why my SOC seems so out of wack with that reported by Cerbo - they were tracking within 5% and I don't really do any control with this value but it is a bit odd - The only thing I can think is accuracy is not great under small loads - what is different is I disconnected my primary load source  (the fridge which consumes maybe 2 amp/hour) and have been just running with the fan and SBMS so a load of less than 0.9 amps/hr

Currently, my 12V system is at 13.44 with electrodacus reporting 53% and Cerbo 92% I would believe closer to 90% is correct

FYI - I let the system get to full charge a couple of weeks ago at 100% (3.55V individual shutt off) and both there synch at 100% 

[Dacian Todea (electrodacus)]

So was the last full charge a few weeks ago ?

Was there no charge in the mean time ? or did you used some sort of method to not get to full charge ?

You may have sources that do not pass trough SBMS current shunts.

The SBMS will correct the SOC every time you have a full charge witch normally happens every day or almost everyday with solar.

 From that point SOC is calculated based on battery shunt current measurement so if that measure all battery current accurately then SOC will also be accurate.

13.44V seems very high but I do not know if this voltage is measured while you have a charge current so I can not say anything about the real SOC based on voltage alone.

[paul deacon]

yes the last full charge was about 10 days ago

yes I have only been partially charging (I have been working on permant install of the solar panels so some days no charge at all - some days just one panel )

Everything I think passes through the shunts  - the only piece that's outside the shunts is SBMS itself as that is directly connected 

13.44 reading was when it was being supplied with ~ 10 amps of solar charging 

[Dacian Todea (electrodacus)]

I have no idea what the real SOC is in this case. Voltage will say nothing if you where charging with about 10A

If this was the voltage while there was no charge or load current then I could have guessed that SOC was above 95%.

As you have a 560Ah battery that means each 1% SOC corresponds to 5.6Ah *13V = 73Wh

SBMS uses maybe 0.7W assuming WiFi is enabled so 0.7W * 24h = 16.8Wh/day * 10 days = 168Wh

That means that if the only discrepancy between what SBMS measures and what Cerbo measures was just the SBMS self consumption the discrepancy will not have been higher than about 3%

Best guess is that either one of the current shunts measures incorrectly either SBMS or Cerbo and it is a large error close to 1A or more likely Cerbo at some time during this 10 days reset the SOC to 100% while the SBMS did not as no cell got to 3.55V for that to happen.

So if the shunt is setup correctly on SBMS so it is able to measure current accurately then real SOC is likely much closer to  50 or 60% than SBMS shows.

[paul deacon]

Voltage was 13.31 overnight with no charging voltage and that was 91% on cerbo around 51% electrodacus

I am going to ensure I get the cells 3.5v / 14V battery as I know SBMS will reset to 100% then 

[Dacian Todea (electrodacus)]

In order for SBMSto get down to 51% SOC over 10 day period you will need to have a very large measurement error.

So please check that SBMS battery current shunt resistance is set correctly in the ADC menu and also check that with all loads and all charge sources disconnected the battery shunt current is around -0.05A and not significantly more.

[paul deacon]

Good Morning Darcian - so hopefully you can ally my fears a bit as what just happened concerned me

So I let solar charge to what I thought was shut off and I am getting concerned as BMS did not shut down - i saw over 3.53 for two cells but BMS did not seem to shut off DSSR50

I know shut off works as I have charged to full previously 

it got to 14.06 (individual cells were 3.6, 3.53, 3.51 and 3.4X didn't catch last one as i busy flipping said Solar  switch to prevent over voltage ) 

My individual cells normally show an average of 3-5mV - there are 3 cells with 0-1mV and a stray cell that is larger 

i manually flipped the solar disconnect at time SBMS showed 72% SOC - then it quickly changed to 99%

I am now going to connect a few loads to get SOC to draw down and charge again to see if DSSR50 will shut down..

My shunts i think are input correctly

Main battery Shunt EXT BattShunt(500A/50mV) Value SMBS is 0.1000 mOhm

PV Shunt (is a 350A/100mV)  Value shown in  BMS is 0.2857 mOhm

The SOC in past has tracked somewhat closely between electrodacus and Victron  so to me something has changed 

I have no idea if this is a factor but its  stupid hot here and I have no active cooling beside a maxair fan and I have seen battery temperature close to 105 deg F as shown by thermocouple direct on a cell  - I think i have over temp set at 45 deg (its in your weird units but is set atOvertemp  1182b

[Dacian Todea (electrodacus)]

Paul,

With default settings SBMS will stop charging when any cell exceeds 3.55V for consecutive 6 seconds.

Voltages you may have seen may be due to cell balancing and not real cell voltages and cell balancing by default will be ON for just 3 seconds thus measured voltage may exceed 3.55V for 3 seconds while cell balancing is enabled but that voltage is not the real cell voltage and can be higher or lower and thus the reason cell balancing is turned off so SBMS can see the real cell voltage without the addition or subtraction of voltage drop on cell sense wires.

 

I do not know what the starting point was yesterday you mentioned 51% so I can only asumme SOC got even lower than that before you got at 72% and then jump to 99%

Let me asumme it only dropped another 2% from yesterday so you started charging from 49% and you did so up to 72% when it jumped to full charge 100%. That means the real SOC was 72-49 = 23 and 100 - 23 = 77% meaning both the SBMS and the Cebo where wrong about the real SOC.

So yesterday the real SOC was 79% but SBMS indicated 51% and Cebo 91%

The battery shunt is a bit low resistance to make accurate measurements at very low load or charge currents. The input of the SBMS0 ADC is plus minus 90mV that means with this current shunt the measurement range of the SBMS0 is plus minus 900A

Since ADC resolution is 16bit (plus minus 15bit) that means 900A/32768 = 0.028A is the measurement step. Still this will still not result is such a large measurement error.

Based on the fact that real SOC was around 79% and SBMS measurement was 51% means your current measurement is off by probably 10% to 20% and that accumulated over 10 days to over 100% error as you did just partial charge cycles so not possible to correct the SOC error over the 10 days thus it accumulated.

So say your load current is 0.800A (real) but the SBMS0 measures 0.900A  (about 12% error) then that over 10 days of partial charge and discharge could have accumulated to the type of error you experienced.

As you see you do not need a very large measurement error to result in a very significant SOC error over 10 days with no full charge.

You can try to calibrate so you have better measurement accuracy and allow a full charge everyday as that will correct the SOC thus SOC error will not be able to accumulate as it was the case now.

[paul deacon]

Ok so I think I am tracking your explanation - I will let it charge Tomorow to 100% 

Your explanation makes sense as the error seems to have got much larger since I turned off all the loads and charge sources and with 16 bit precision and the small delta