new trodacus build journey and questions

[Peter Kuczynski]

Hi there, first time post here.

I finally charged all 8 3,2v 200ah cells to 3.65 and placed them in series.

I  then hooked up the SBMS0, and added a couple of wires to the 2 shunts temporarly. I eventually want to place this into a box, but right now its on my kitchen table.

I noted the sbms is reporting a constant battery drop. Meaning, I started at 3.65 per cell or 29.2 volts in total.

Currently, 2 days later,  I am at 26.977 and 3.378 per cell

It looks like I am discharging at -0.012 to -0.021 rate.

I have noting attached to the cellls.

Any thoughts ?

Thanks in advance!

Peter

[Peter Kuczynski]

Another screen shot of the electrodacus screen, the green battery icon ALWAYS shows 99%, why?

[Dacian Todea]

The battery is 99% as there was no significant load just the self consumption of the SBMS0 that is well below 1W.

The LiFePO4 will not stay at 3.65V and voltage is absolutely no indication of SOC see the graph below. The way SOC is calculated is based on energy in and out of the battery that is measured and calculated by the SBMS0.

So yes all looks normal and you have a fully charged battery.  Keep in mind that SBMS0 will need to control ON/OFF all charge sources and separately all loads and cells will not exceed 3.55V when the SBMS0 controls the charging.

[Chris]

Peter, the battery gauge still shows 99% as the SBMS0 has not measured any current being drawn from the battery. When it does, the battery SOC indicator (green icon) will start to drop.  This always shows the “mental picture” the SBMS0 maintains of the battery state of charge, it’s not simply a reflection of the battery or cell voltage.  

Don’t leave the battery fully charged with nothing connected to it for too long. It’s bad for it.

[Peter Kuczynski]

Thank you Dacian, thank you Chris.

I am a rookie, but, i purchased your sbms0 based on your support, which you now have done.

Much appreciated.

Ok, so, battery is OK. Now to Chris's point, I need to start using it. Its presently on my kitchen table waiting to be wired up on a carry case to my bus.

My first question, is regarding the battery temp, do I need to purchase a low temp cut off gauge? If  so which do you recommend?

https://amzn.to/3qgZDCh

I plan on leaving the battery in our bus during the spring thru the end of summer, we live in Illinois currently.

As I understand it, Lithium batteries are to be kept at near room temp, and not charged below 50 degrees F.

So I planned to install that batt temp sensor to cut off the battery should ambient temps fall below recommended charge/discharge recommendations.

Also, I plan to install heaters under the battery to counter excessively cold temps:

https://amzn.to/376RKaH

These would be controlled by a digital temp sensor.

Last, I need to add a inverter compatible with the Electrodacus. As my requirements are relatively low, I was thinking of this model.

https://amzn.to/3b5yQCk

All for now, and thank you for your guidance in advance.

Peter

[Dacian Todea]

Peter,

Yes you can use those temperature sensors you linked to.

If battery is in a cold environment then you will need to have the battery in an insulated box. If battery is not in an insulated box then the heater will just be useless as they will not manage to keep the battery above freezing and they will also use a lot of energy for nothing. If battery is in an proper insulated box then even a 10 to 15W heater element controlled by an electronic thermostat set at 50F will be more than enough. Those 65W heater elements are way to overkill for an insulated box and will do nothing if battery is not inside an insulated box.

If you will not be using the battery in winter then you can just disconnect everything including the SBMS0 and leave the battery there as there is no problem for the battery to be in below freezing temperatures as long as it is not charged it will be just fine.

[Peter Kuczynski]

Thank you Dacian, I appreciate your support.

I have a shunt question

I have purchased two of these shunts from amazon, but the difficulty is in mounting them.

https://amzn.to/2MXIEXg

I am instead looking at these shunts,https://bit.ly/37dnM55  can you comment on them?

Thanks!

[Oberon Robinson]

Peter, Dacian made a post about his shunt recommendations here: https://groups.google.com/g/electrodacus/c/ReL-z6vGFdw/m/vsmKm0grAQAJ

[Dacian Todea]

Peter,

Yes those shunts in first link are lower cost but they have no plastic support so they are harder to install the ones in second link may be easier to use.

Check the link Oberon provided.

[Peter Kuczynski]

Thank you both.

I stil clearly dont know what im doing.

I have both shunts connected, its a 200A 75mV shunts.

I am going to work on a mount, perhaps a wooden board.

The current issue is I am seeing a discharge. .021 A. I have no loads connected other then the sbms itself.

I read the earlier shunt postings you kindly provided, and one other person also noted the same thing. Your advice was:

"

Please test that all loads are turned OFF when you go to SBMS EXT IOx menu and set EXT IO3 as type 0 and same for all charge sources the charging should stop when EXT IO4 is set as type 0"

I have done that, and se no difference, the batterys [8 200 Ah in series] are contining to discharge. If I remove the shunt this does not happen, its just whe the shunt is connected to the sbms0.

Please note the setup in the pictues is only temporary, i am still working on mounting everything in the DeWalt roller tool box.

[Peter Kuczynski]

The other weird thing ive observed with the sbms0, is when I power cycle it, removing the ribbon cable, the SOC, green battery icon, sits at 49%. Ive had to turn on a external power source, a battery charger, only then does it pop into a 99% reading.

[Dacian Todea]

Yes the 0.021A is normal calculated self discharge of the SBMS0

So yes all seems correct and that small 0.021A x 27V = 0.6W is about the SBMS0 self discharge (that is calculated and added to the SBMS0 not measured).

Not sure if the current shunt sense wires are connected with correct polarity as I do not see the SBMS0 side of the wires.  On the current shunt it seems you used solid brown on the battery+ side of the battery shunt that should be ADC1p but on the PV shunt you connected the orange wire on the side between the two shunts and that should be PVn

Yes it is normal that at initial connection you get 49% SOC as SBMS0 has no idea what the battery SOC is when initially connected and can only know after a first full charge.

[Peter Kuczynski]

Great, I understood that amount of discharge is normal. Great.

Here is my wiring for the shunts and the sbms

RE: "On the current shunt it seems you used solid brown on the battery+ side of the battery shunt that should be ADC1p" <<<  Yes I did.

RE: "but on the PV shunt you connected the orange wire on the side between the two shunts and that should be PVn" <<< In the pictue, the Orange is on the right most shunt, left screp, the White/Orange, is the right most screw.

First the SBMS:

12 Pin slot
1 PVn to Solar array shunt1,5, white/orange
2 PVp to Solar array shunt1,5, orange
3 ADC1n to Battery shunt, white/brown
4 DC1p  to Battery shunt - Pin 4 (ADC1p) is connected to the battery side of the shunt. Brown

The shunts, in the pictures , shunt closes to the battery[current] is first followed by the PV shunt.

Current shunt: Brown WhiteBrown/Brown - left shunt

PV shunt: Orange White/Orange - right shunt. Farthest away from the battery.

Linking both shunts are two bus bars.

Peter

[Peter Kuczynski]

RE: es it is normal that at initial connection you get 49% SOC a

So is charging the battery, either from a external short power source or PV source, the only way to get the battery indicator to read 100%? Meaning, to move past the 49% charge indication.

Because when I apply shore power, it immediately moves to 99%.

Peter

[Dacian Todea]

As I suspected the PVp and PVn are connected the other way around so you need to switch the PVn / PVp wires on the shunt with PVp (orange) connected on the side where you connect the PV panels.

Your battery is full thus as soon as you connect any charger it will get to 100% probably in a few seconds.

Yes charging is the only way to set the SOC correctly initially. You normally never remove the SBMS0 from the battery so once the SOC is set to 100% the SOC will be correct as it will be calculated based on the energy in and out of the battery.  

[Peter Kuczynski]

I reversed the two wires at the shunt, [not at the sbms0] and connected by external charger to the pv shunt, looks like were good!

One issue down. Once I finalize the mounting of the shunts, ill tackle the battery temp probe. Then the DSSR20's.

Thanks Dacian and Chris !

Peter

[Dacian Todea]

Peter,

Looks like you have 200A 75mV current shunts and you did not set them properly in the ADC menu.

0.075V / 200A = 0.3750mOhm and that is what you need to set for both PV shunt and Battery shunt in the ADC menu then go to Device Settings and push the Save device settings button so that the shunt values are permanently stored (even after a power cycle).

Then both battery and PV shunt current will indicate the current current of around 5A.

[Dacian Todea]

"I have wired up my DC step down converter  from 24 to 12.

IS my battery protected from too much dc power draw by the Sbms0, or should I wire in my Victron Smartshunt 12/24 / 100 ?

I am not sure if the Sbms0 supports the Smart Batteryprotect, if I need it, ow how to connect it to the Sbms0.

Pictured is a 40a 24 to 12 converter, fused by a 50A breaker which goes into the small DC panel.

My intent to power dc appliances such as a small fridge and 2 diesel heaters for now.

"

Peter,

Not sure why your question was not posted here.

Of course the SBMS0 can not protect your battery. The DC-DC converter you have has no remote ON/OFF so you will want a Victron Battery protect the BP65 should be good enough and you do not need the smart version just the regular one as there is no advantage in paying extra for the smart version. And if the DC-DC converter is 40A on the 12V output it will only require a bit over 20A on the 24V input.

[Peter Kuczynski]

Good morning!

Looks like I need a little troubleshooting assistance with my single test PV panel is NOT charging.

I finally hooked up both my DSSR20's as per the manual, 10g wire. I am using only one panel to test, so as expected, the RED light is lit on only one DSSR20.

However, I am not getting anything from the 100W PV panel . When I disconnect the pv panel, the read light does go off on the DSSR20, Ive tested this on both DSSR20's, they behave same way.

Its possible the battery's are fully charged, m not sure how to test that theory. Soc is set to 85%, and ive tried setting it to 99%, no change. SBMS0 has been restarted. It keeps loosing its time/date settings each time, not a problem for now.

I have a 1000 ohm resistor soldered on each DSSR20, the resistor is on the Bus Bar end POS, so I am not jumpering them, both are connected to the PV bus bar directly using their own wire.

In the picture, I am holding the cat-6 wire with the soldered resistors connected to the PV bus bar, which is powered on ON its on a 150A breaker..  I am reading over 26.6 volts at the PV bus bar.

I

[Dacian Todea]

Peter,

It looks to me that you connected the Batt remote directly to Battery+ through resistors. Please remove that as you will damage your battery.

After resistors you need to go to EXT IO4+ set as type 1 and then the EXT IO4- is what is connected to DSSR20 Batt

 

[Peter Kuczynski]

Oh jeez, disconnected.

[Dacian Todea]

What happens is that DSSR20 is forced to ON always in your setup so SBMS0 has no control and can not stop the charging. Also because of that during power up the SBMS0 since it was not able to stop the DSSR20 was considering the 100W panel current as zero Amps as SBMS0 will do a zero offset calibration on power up but it assumes it has remote ON/OFF over all charge sources and over all loads so it can turn them all OFF during power up sequence and thus it can do a correct zero offset calibration.

When you connect the DSSR20 correctly through the EXT IO4 you will also see the 100W panel current.

[Peter Kuczynski]

Hi Dacian, Ok, check me out.

The DSSR20's light up w the RED led as expected, I tested both w the single panel, but there no charging taking place, possibly because its late in the day, the panel is indoors in a window, but the panel still should give me a single watt.

The W/Blue is POS w the resistor and goes to extio4 +, slot 12 on dssr20.

The Blue comes out of the dssr20 port 11 extio4 NEG and goes to the DSSR20's jumpered Batt.

[Dacian Todea]

No you will likely not get even a few mW from a panel in a window with no direct sun.  You need the panel outside in direct sun and no shadow on the panel.

[Peter Kuczynski]

Ok, the issue is Im building this in a apartment, which has no access to place a panel outside other then in a window, so even a single mW to show everything is working and wired correctly before I drag it out outside would help.

Right now Im not seeing even a single mW. If I wire up my Renogy mppt, I'll guarantee you I'll get a few out of that.

But if you think this looks wired correctly now ,Ill take it outside.

Peter

[Dacian Todea]

Peter,

Is the window larger than the panel ? Is there any shadow on the panel ? is there direct sunlight heating the entire panel ?

The amount of current produced by the panel is directly proportional with the amount of light and inside the amount of light will be typically very low.

So if your window is not facing the sun there will just not be anything to see as current will be to low maybe just enough for the DSSR20 self consumption and that is just a few mA it will have no chance to power an MPPT.

As the red LED from DSSR20 is ON the panel is working it is just likely not producing much more than to power that LED and maybe some mA that is just in the noise of what the SBMS0 can measure depending on what current shunt you use.

[Peter Kuczynski]

Hi Dacian,

Ive been troubleshooting this to no avail,  So in my eyes everything is working. Except we are not charging.

I have a good panel, good cabling from the panel to the DSSR20's, and power at the Dssr20's.

Let me answer your questions first.

re: Is the window larger than the panel ?

     slightly taller, same width, see picture. Sunlight hits it direct at 90 DEG in the morning during testing.

Is there any shadow on the panel ?

    Panel is behind the glass of the window, but nothing else, so sunlight hits it dead on. No trees or anything else.

is there direct sunlight heating the entire panel ?

    YES

re "So if your window is not facing the sun..."

   Window is facing directly into the sun in the early morning, no trees, just glass of the window.

Im attaching some pictures.  I re-seated all the wires into the Dssr20's, as well as the 1000 ohm wires to Batt on the dssr20's. I observed the red light go off then on , when I replaced the wires back into their slots.

I appear to be getting good power at  the switched PV bus bar over 26 volts, and from the panel, 17 volts and 20 amps ?

Picture of the panel at the window w a slight tilt, so be as close as possible to 90 degrees.

Picture of the SBMS0, the White/Blue wire is on port 12, and is connected to the PV bus bar and has a soldered resistor.

   The Blue wire comes FROM port 11 on the Sbms0 and goes to the Dssr20's, Batt, and is jumpered from the first one to the second one.

Picture of the PV bus bar, with 26.63  volts of power, and the W/Bl wire connected. The two RED wires go to the Dssr20's.

Picture of the Dssr20s, show, both Red wires from the PV bus bar, both Ground wires from the ground bus bar. 2 Red wires from the panels Pos. and Blue wire from the Sbms0 port 11.

Picture of the Sbms0 face place, showing NO pv amps coming in.

Picture volt meter reading 26.63 at the PV bus bar.

Picture Voltage reading 17.69 at the panel wire, testing the entire wire to the panel.

Picture reading the same wire and panel Amps.

Finally, picture of the panel specs.

Is it a setting on the Sbms0 I can check?

Peter

[Dacian Todea]

Peter,

Thanks for the photos as it makes thing a bit more clear.   In the photo the panel seems to have the last row of cells maybe last two shaded and if a single cell is shaded the panel will just produce as much current as the worst shaded cell.

The red LED indicates that there is some voltage on the panel else you will not see that light up 

Im attaching some pictures.  I re-seated all the wires into the Dssr20's, as well as the 1000 ohm wires to Batt on the dssr20's. I observed the red light go off then on , when I replaced the wires back into their slots.

I appear to be getting good power at  the switched PV bus bar over 26 volts, and from the panel, 17 volts and 20 amps ?

The above comment you made is very confusing to me. What is the spec of your panel ? 

I look at the earlier discussion and it looks like you have an 8s 24V battery and you try to charge using a 32 cell panel so of course that there will be no charge current. You need a 60 cell PV panel or two of those 32 cell panels in series to get any charge current.

So problem solved. You need at least a 60 cell PV panel the one you have is just 32 cells so you need two of them in series if you want to charge a 24V battery.

[Peter Kuczynski]

>>it looks like you have an 8s 24V battery and you try to charge using a 32 cell panel so of course that there will be no charge current. You need a 60 cell PV panel or two of those 32 cell panels in series

That is correct.

Oh boy, sorry for taking your time up w this, of course, that makes sense.

I'll order a 60 cell panel. Eventually I will have 4, i was just looking to test for now.

Thanks again Dacian,

Peter