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DC Solar Trailer - LBM questions (newbie)

B4nanasz

New Member
Joined
Jul 20, 2021
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9
Hello,

we are new to solar and SMA doesnt want to help bc we arent techs and the techs are too expensive and have came out twice and have not helped us with the problem.

we bought a DC solar trailer
It has the sunny island the master and slave
The midnight classic inverter
They look like the forklift batteries
And solar panels

the problem: it goes in to Low Battery Preservation mode every night at the same time and it goes in to a cycle of shutting down the loads every 10 minutes.

the batteries say they are full and it still goes into this LBM sometimes level 1 (most of the time) and sometimes level 2.

we do not have a generator connected to it. Is this why? Do I need one for completely off grid. Also I need it to run 100% of the time as that is our only source of energy, can I shut the LBM off or have the batteries release the energy without cutting the load or what do I do ?
Help?
Thanks in advance
 
I'm not familiar with your equipment, but maybe others will check in who are.

Do you have a DVM to use for troubleshooting?

It sounds like either your batteries are not able to carry the load. This could be because the batteries are failing .... or maybe they aren't getting fully charged.
It's also possible there is just a bad connection that is causing voltage drop.
Do you have any kind of battery monitor that tracks the voltage and current in and out of the battery?
 
I'm not familiar with your equipment, but maybe others will check in who are.

Do you have a DVM to use for troubleshooting?

It sounds like either your batteries are not able to carry the load. This could be because the batteries are failing .... or maybe they aren't getting fully charged.
It's also possible there is just a bad connection that is causing voltage drop.
Do you have any kind of battery monitor that tracks the voltage and current in and out of the battery?
Yes, I read the manual over and over. LBM should be getting triggered when the load isnt going to be used but what if it is being used 24hours ?!

also, I believe thats what the classic does , monitor and tracks the voltage and current in and out of the battery. The techs said that it looks good. They also checked the batteries and said those look good too.
 
I'm not familiar with your equipment, but maybe others will check in who are.

Do you have a DVM to use for troubleshooting?

It sounds like either your batteries are not able to carry the load. This could be because the batteries are failing .... or maybe they aren't getting fully charged.
It's also possible there is just a bad connection that is causing voltage drop.
Do you have any kind of battery monitor that tracks the voltage and current in and out of the battery?
Also, I must add it goes in to LBM even when there is no loads connected
 
Your issue is SMA's SOC (State Of Charge) the SI think the battery is at. SMA's SOC algorithms suck !
I would disable BatPro1 & 2 and set BatPro3Soc = 20% as a test.
The DC Solar Trailers are way, way under PV'd as far as Solar Power goes.
You will need to set the MASTER Sunny Island to STANDBY (Power will go OUT)
In Settings go to BATTERY PROTECTION:
#223-05 and set to 0%
#223-06 and set to 0%
#223-07 and set to 20%
I have not tried these on any of my Sunny Islands yet but will in the AM. I don't have anything being powered off them yet. I have one setup to test our new line of chargers selling to the grid only. I might switch some loads over to test.

This is assuming all the BATTERY CHARGE PARAMETERS are correct in #222
You might want to go through them and write them down and post so I can see what they are. They would be different for sealed batteries vs flooded (water needed), both types were used on those trailers.

If the settings above work then use up the old lead battery until it dies and switch to the new Lithium Iron batteries.
The Classic 250 on these trailers are only Solar Charge Controllers stripped down of a lot of functions and custom built for DC Solar and as such have no warranty. (I'm an engineer for Midnite Solar)
 
Your issue is SMA's SOC (State Of Charge) the SI think the battery is at. SMA's SOC algorithms suck !
I would disable BatPro1 & 2 and set BatPro3Soc = 20% as a test.
The DC Solar Trailers are way, way under PV'd as far as Solar Power goes.
You will need to set the MASTER Sunny Island to STANDBY (Power will go OUT)
In Settings go to BATTERY PROTECTION:
#223-05 and set to 0%
#223-06 and set to 0%
#223-07 and set to 20%
I have not tried these on any of my Sunny Islands yet but will in the AM. I don't have anything being powered off them yet. I have one setup to test our new line of chargers selling to the grid only. I might switch some loads over to test.

This is assuming all the BATTERY CHARGE PARAMETERS are correct in #222
You might want to go through them and write them down and post so I can see what they are. They would be different for sealed batteries vs flooded (water needed), both types were used on those trailers.

If the settings above work then use up the old lead battery until it dies and switch to the new Lithium Iron batteries.
The Classic 250 on these trailers are only Solar Charge Controllers stripped down of a lot of functions and custom built for DC Solar and as such have no warranty. (I'm an engineer for Midnite Solar)
Hi,
Thanks for your response !!
Okay so the reading for #222 is :
01# 240A
02# 90 min
03# 5.0 h
04# 10.0h
05# 14D
06# 180D
07# 2.55 V
08# 2.50 V
09# 2.50 V
10# 2.25 V
11# 4mv-degC
12# disable

flooded batteries


I should change it after you okay it ?
anyway, what is PV’d? Will this power a house ? An AC in a RV maybe ? I was told it could.
Thanks again
 
What are the specs on the trailer? How big is the panel array, battery(s), inverter. I think there a bunch of different model trailers in this line.
 
What are the specs on the trailer? How big is the panel array, battery(s), inverter. I think there a bunch of different model trailers in this line.
2650 watts of 10 panels
Midnite Classic attached pic
2 forklift batteries on it. They are 24 cell, 48v, 540Ah rated, and 1900 pounds each
 

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2650 watts of 10 panels
Midnite Classic attached pic
2 forklift batteries on it. They are 24 cell, 48v, 540Ah rated, and 1900 pounds each

Question #1 (pretty much always) is how much power are you planning on using for the house?

You have 2650 watts worth of panels which means on a awesome day when the sun is maximum, there is no bird poop on your panels, no shading, perfect conditions, you are looking at maybe 13kwh of power. I would figure 10kwh would be more likely on a good day. So if you plan on using more than 10kwh per day, it doesn't matter how big your battery is, you will eventually run out of power.

48v x 540ah = ~26kwh. Because the batteries are lead acid and you don't want to go below 50% state of charge, you have 13kwh to play with (which seems to match the panel configuration). So I would figure to be safe you have 10kwh to play with. If you can deploy more panels that number would go up.

I am pretty sure that is what Wizbandit was talking about when he said these trailers are under PV'd (under paneled).
 
You have 2650 watts worth of panels which means on a awesome day when the sun is maximum, there is no bird poop on your panels, no shading, perfect conditions, you are looking at maybe 13kwh of power. I would figure 10kwh would be more likely on a good day. So if you plan on using more than 10kwh per day, it doesn't matter how big your battery is, you will eventually run out of power.
And this is assuming you live in a 5 hour of sun location...
 
Question #1 (pretty much always) is how much power are you planning on using for the house?

You have 2650 watts worth of panels which means on a awesome day when the sun is maximum, there is no bird poop on your panels, no shading, perfect conditions, you are looking at maybe 13kwh of power. I would figure 10kwh would be more likely on a good day. So if you plan on using more than 10kwh per day, it doesn't matter how big your battery is, you will eventually run out of power.

48v x 540ah = ~26kwh. Because the batteries are lead acid and you don't want to go below 50% state of charge, you have 13kwh to play with (which seems to match the panel configuration). So I would figure to be safe you have 10kwh to play with. If you can deploy more panels that number would go up.

I am pretty sure that is what Wizbandit was talking about when he said these trailers are under PV'd (under paneled).
Thank you for being the first to tell me that , everyone I have asked hasn’t. Also, yes ! In the middle of Arizona ? went off grid but as you can see struggling ! Lol thanks for all your help again, I have to find out how many more panels I need and if I need to add anything else.
 
No worries, I hope you figure it out. If you give us more details we can make suggestions (which are free and you don't have to follow them). If you have land I would panel the crap out of it with used panels (especially if you are off grid completely). You can get 250watt panels locally (in AZ anyway) from Santan Solar for $50 each (maybe less if they are on sale). You can ground mount them, or put them on the roof. You will still be limited by the battery size, but if you have enough panels and a big enough inverter you can power all the big stuff while the sun is up. Unlike the grid, you want to run all your big ticket items during the sunniest part of the day (dishwasher, laundry, AC, water pump(s), etc. ), and then when the sun starts to set you go to bare minimum (AC and lights maybe). With 13kwh of battery (assuming the batteries are good), you should be able to get through the night with a mini split AC feeding one room.
 
No worries, I hope you figure it out. If you give us more details we can make suggestions (which are free and you don't have to follow them). If you have land I would panel the crap out of it with used panels (especially if you are off grid completely). You can get 250watt panels locally (in AZ anyway) from Santan Solar for $50 each (maybe less if they are on sale). You can ground mount them, or put them on the roof. You will still be limited by the battery size, but if you have enough panels and a big enough inverter you can power all the big stuff while the sun is up. Unlike the grid, you want to run all your big ticket items during the sunniest part of the day (dishwasher, laundry, AC, water pump(s), etc. ), and then when the sun starts to set you go to bare minimum (AC and lights maybe). With 13kwh of battery (assuming the batteries are good), you should be able to get through the night with a mini split AC feeding one room.
Great, we do have a lot of land to fill. 5 acres.
nice , thanks for the lead on the panels! They have lots of selection.
we have this .... do we need another one for 10 more panels of 240w?
 

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Based off the link above (shown below) you could run two more panels on your current setup if you rewired the panels (Edit Based off your combiner box picture is looks like 2 Series, 5 Parallel right now). I might even risk running 3S5P if you could face each string in a different direction (South East, South, South West). That way you would a longer solar day, but not all the panels would be producing at the same time to keep you under the 2880w limit.

Otherwise, yes you would need another controller to use 10 more panels.

1626895001508.png
 
The setup of these trailers is 5 panels in series x 2 strings in parallel.
Most of the batteries on those trailers are toast. Mine has less than 20% capacity left in them. I fully charged them, discharged them at low rate (1440 watt) till just above low-bat cutoff. charged them again with 48 volt forklift charger. did that a couple of cycles. did not gain any capacity.
My 2 batteries are toast. Other thing I found is that the load of the 2 islands just generating 2x120 volt is a considerable draw on the batteries overnight as well. I added another 2500 watt of ground mount solar panels with 2 MPPT controllers to it. I am thinking about converting everything to li-ion. Should save a lot of weight on the trailer. My trailer has talesun 235 watt panels on it. It's specs are 13.45 watt/sq ft with optimal conditions. While more modern panels can get up to 19 watts/sq ft. That would mean change of mppt controller(s) etc etc.
I am not really optimistic about the concept of this trailer. imo one lead acid battery would have been a better sized battery for the amount of installed solar. I hope B4nanasz got a good deal on it.
 
The setup of these trailers is 5 panels in series x 2 strings in parallel.
Most of the batteries on those trailers are toast. Mine has less than 20% capacity left in them. I fully charged them, discharged them at low rate (1440 watt) till just above low-bat cutoff. charged them again with 48 volt forklift charger. did that a couple of cycles. did not gain any capacity.
My 2 batteries are toast. Other thing I found is that the load of the 2 islands just generating 2x120 volt is a considerable draw on the batteries overnight as well. I added another 2500 watt of ground mount solar panels with 2 MPPT controllers to it. I am thinking about converting everything to li-ion. Should save a lot of weight on the trailer. My trailer has talesun 235 watt panels on it. It's specs are 13.45 watt/sq ft with optimal conditions. While more modern panels can get up to 19 watts/sq ft. That would mean change of mppt controller(s) etc etc.
I am not really optimistic about the concept of this trailer. imo one lead acid battery would have been a better sized battery for the amount of installed solar. I hope B4nanasz got a good deal on it.
I tried messing with the LBM settings as the first guy suggested but it didn’t work. It actually shuts down completely now. My next step was to add panels like @iamrich suggested but you are saying that you added panels and it didn’t make it better? I am thinking the batteries might be a problem but everyone who has came to check them say they are good ... how do you know yours is toast? Idk is 10k a good deal? I am starting to feel like it wasnt worth it. Had it working for two days and now I am wasting so much money on gas for a generator bc the solars arent working.
 
I tried messing with the LBM settings as the first guy suggested but it didn’t work. It actually shuts down completely now. My next step was to add panels like @iamrich suggested but you are saying that you added panels and it didn’t make it better? I am thinking the batteries might be a problem but everyone who has came to check them say they are good ... how do you know yours is toast? Idk is 10k a good deal? I am starting to feel like it wasnt worth it. Had it working for two days and now I am wasting so much money on gas for a generator bc the solars arent working.
You should give some readings from the display of the charge controller.
Please give some feedback about the actual voltages you see: beginning of the day, around 1pm and at end of the day.
In the morning it should say "bulk" meaning it is pumping all the energy it can get from the PV panels into the battery.
at some point it should go in to "constant" mode (i forgot how that is mentioned on the MPPT charge controller) and eventually it should get in to "Float mode" That is the mode to "top off" the batteries. My batteries eventually go into float mode at 52-54 volt if I remember correctly,

Just measuring voltages of the batteries are not enough.
I don't know how the people you contacted tested the batteries.
I measured the individual cells on the pack (open the metal lids on top of the batteries) , both when completely charged and when discharged to low bat situation.
This is screenshot of my battery measurements:
Screenshot from 2021-07-24 20-17-51.png

Each cell is supposed to be 2 volt, but after discharging the lowest was 1.03 volt and the highest 2.07
Good indication the cells with lowest voltage are toast.
Then I bought one of these
bat_hydrometer.png
You stick it in each cell and get some of the acid from the cell in the unit. the meter will show the state of the cell.
caution: wear gloves and goggles when doing things with battery acid.
I tested all the cells (last line in the screenshot) and my cells are really shot.
One of the cells had black particles floating in the acid.
It is a lot of work to test all that, but that is imo the only way to find out the real status of your batteries.
I paid about the same amount and if you have to buy all the individual items it was a good deal.
But when the things are broken (like in my case the most expensive part: the batteries) this deal suddenly is not so good.

Let me know if you have more questions.
 
I have a dc solar trailer the batteries are the problem, after refilling with water, and charging with around 10,000 watts, then discharging as quick as possible, the batteries have improved, supposedly repeating that cycle will make them stronger
 
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