DC Solar trailer questions.

[Fullblast]

I have recently purchased a DC solar trailer, which came with 2) 510 ah@6 hour forklift batteries, a Kubota 11kw generator and 2600 watts of panel wired at 48v.

It also has the tower lights. I left the front tower light on 12 hours a few nights ago, and left one on again last night and it died in the middle of the night after about 5 hours.

I don't know if if the batteries were completely dead or not, but neither light would come on. I do not know if there is a switch that won't let the system run at a certain battery level or not.

So I've had the generator running for 5 hours already. I just stopped it to let the panels do the work.

Does it normally take this long to charge the batteries up if they get completely drained?

How can I tell if the batteries are fully charged?

I checked the water levels in 48 cells and they are all full.

Any help would be greatly appreciated.

[Fullblast]

I found the battery Soc on the inverter. Going to run tests once it's 100% to see how much juice the lights are drawing.

Does it usually take 6-8 hours to do an equalizing charge?

Is there a way to test if any of the cells are bad? I'm just curious and trying to see the percentage capacity % the batteris are really at.

They are Gnb industrial forklift batteries made in 2015. I'm assuming they should be 70-80% of their original capacity. Is it possible to get 10 or so more years out of them?

[Mike90250]

When you run FLA batteries flat, you take a lot of cycles out of them. You are going to have to be more careful and see how long they last. Who knows how they were treated before you got them.

[peakbagger]

I purchased a later version of your trailer, I have the American Tower version (white trailer) It was quite new as it never had the DC Solar logos applied and various components are dated 2019. I assume you are checking specific gravity of each cell after equalizing? I did not buy mine direct but the individual who bought 6 at the NH auction had one with a bad cell in the battery.If you have a bad cell its going to kill the rest of the battery quickly. He found a new cell and installed it but its not pretty. I added a desulphinator to the batteries. I have the so called operating and technical manual on my unit but it really is not that technical. I have seen descriptions that some were in warehouses while some were sitting in fields. My guess is the ones in warehouses would have been dead flat while the ones in the field might have been charging but expect the diesels did not run so its likely the batteries were not equalized. My guess is the memory card on the inverters has history on the operation but the card is only active with the inverter on line so you may just see how often the trailer was actually used or tested.

Note the inverter battery state of charge does not agree with the Midnight Solar charge controller. My charge controller has auto EQ disabled, so I enabled it and ran an equalizing charge until it was satisfied, the inverter after the EQ charge initially reported a 60% state of charge and then when I checked later if had gone up to 96%. Outback literature indicates that the inverter actively tests the charge state to assure that the battery is being maximized and adjusts state of charge

At some point I need to do a point to point check on the wiring can come up with schematics then figure out how the inverter and charge controller work with each other. Mine is going to get tied into my house and I will enable the inverter to draw power to equalize instead of the diesel plus I can export but too many projects right now. In the meantime I force and equalization via the charge controller every month or so with the diesel.

[Fullblast]

I just got the trailer a few days ago, so I'm still trying to figure it out and I can't find a downloadable manual online.

This trailer is a 2015 model.

The Kubota diesel has 500 hours on it.

It took over 8 hours with the generator to go from flat to 97% yesterday.

I then ran 1 light tower last night which is 480 watts total.

It took 8 hours for the 480 watt lights
to drain the batteries down to 25% as indicated on the sunny island inverter Soc.



For 2) 510 ah forklift batteries to run down 73% in 8 hours from running 480 watts,I'm assuming something has to be definitely wrong with the batteries.

* I just tested each cell with a multimeter and each one cell is 2.0 to 2.1 volts at 60% Soc.

I'm charging with the generator now to get to 100% capacity then will test each cell again.

*Now one of the cells in the middle of the battery is smoking really bad, so I shut the generator off. The batteries are at 60% Soc on the sunny island inverter. Also 2 more are smoking but nearly as bad as the first.

Do I need to get a hydrometer to see if these cells are messed up?

Does it sound like these batteries are shot or is there a possibility of finding the bad cells and replacing them? Maybe try using a desulfator?

[peakbagger]

I am not a battery expert but I think you need a hydrometer. You should have equal specific gravity readings on all cells after equalizing. Assuming you are keeping the batteries full of distilled water during the charge, its sounds like you have dead cells. The seller of my unit had one other array with a bad cell. He had to cut the bus bars off and replace one cell ( I do not know where he got one) He then had to drill and tap the posts and install copper bus bars to tie in the new cell.

[Fullblast]

Thanks, I am going to pick up a hydrometer today and learn how to test the cells. I'm trying to learn how to do an equalization charge and learn the system in general.

I have my suspicions that the batteries were topped off with water before I bought it because they were all full to the top and the owner told me he had only checked the batteries once before. I have no idea if they used distilled water or not. This is only speculation though. I highly doubt he ever did an equalization charge either.

Is there a way to find out if distilled water is in my batteries?

That sounds like a ton of fun replacing some bad cells, but it's better than paying several grand for new forklift batteries. I found a pair of 540 Gnb batteries on eBay for a great price, but I want to know whats wrong with my batteries first.

On another note, I ran a 535 watt window unit ac for 10 hours last night and it only drained the batteries 11% or so.

The tower lights are supposed to be 480 watts, but they drain the batteries very fast, like 65-75% over an 8 hour period.

*Do you have the tower lights and if so, how long can one of the lights stay on before it significantly drain your batteries?

[Mike90250]

Is there a way to find out if distilled water is in my batteries?

No. tap or well or creek water has impurities that slowly degrade the battery performance. The nastier the water, the faster the degradation.

[peakbagger]

I did have two light towers, one of them has since been removed as it is in the way. I have to alter the panel arrangement so that snow sliding off one row does not bury the batteries and generator. I have tried the lights once or twice but did not run them long, I dont plan to use them long term except rarely. Until the trailer get tied into the house I am charging my Rav 4 hybrid for now direct off the trailer. My guess is the damage is done to the battery once the "dirty water" has been added and gone through a few charge cycles. The nasties will have plated out on the cells and the damage is done. I went through several gallons of Walmart distilled water topping mine up when I got mine. None of the plates were uncovered but they do hold quite bit of reserve. One of my "Blinkies" does not work but in my climate the only time the level drops is during equalization. I do not think DC Solar programmed the trailers to equalize but that option is available in the Midnight Solar Menu. I think that if they did equalize them they did so at wherever they stored them between rentals off line voltage. Of course most of the them were rarely if ever rented and sat for year or two so they all need equalizing. FYI when I equalize with the Midnight Solar, the diesel does not turn off automatically when the Midnight Solar indicates that the battery is equalized, I have to kill it with the fuel stop lever.

Ultimately the trailer will be used to build a house and then it will get stripped and reconfigured for a permanent installation. By that time I expect I will reprogram the equipment to suit my use.

[Fullblast]

I was thinking I would have to fill them up some with water also, and was surprised they were topped off. I just hope he used distilled water. Anyhow, I ordered a Deka hydrometer and am going to try and equalize the batteries once that gets in.

I ran a 535 watt window unit ac for 10 hours last night and the battery only went down 7% according to the Sma inverter Soc.

Do those sma 6048 inverters draw much juice just by being turned on? They are 6kw each and it seems like they are drawing a lot of power just to stay on.

What is the point in having a master and a slave inverter? Can I turn one of them off for better efficiency?

I would like to add about 4-6kw worth of 435 watt solar panels to the system and mount them on a frame on the ground.

I'm assuming going with a a few midnite solar 250s will be best since it already has the midnite 250 and the midnite combiner box.

[peakbagger]

My guess is that they set the units up for 240VAC output which requires two inverters? My guess is with some reprogramming one SMA could run 120 VAC but my guess is it would also need to deal with the 240VAC input from the diesel. I think the Midnight Solar has additional input capacity but you would need to rework the combiner.

[Fullblast]

I'm fine with 240 volt. I'm going to remove those California twist receptacles and put a 50 amp RV outlet and another 50 on the side of the box.

I can't get my batteries to charge past 82% as indicated on the Sma inverters Soc. I've tried it 2 days in a row running the generator and it just sticks at 82%. Is this a common thing or could the inverter Soc be wrong?

My panels charged the battery to 82% today then I ran the generator for another hour and it stayed at 82.

I got the batteries to 97% the other day.

Could the batteries not be allowing a 100% charge or is it the inverter chargers fault?

I believe its rated for a 100 amp charger, but only puts out 85 amps.

[Fullblast]

Could you tell me what you mean by using a desulphinator? Is that a chemical additive, or is it something like a Battery life saver unit?

Does the battery life saver work to help de-sulphate the batteries? Can a de-sulphator mess with the inverters any?

I have my hydrometer now. I'm going to do an equalizing charge, then wait a night and check the specific gravity the next morning. Is that the proper way to do it?

[Mike90250]

desulfating pulse machines don't mess with the inverter, but their voltage pulses can confuse the chargers, trial and error. Maybe just disconnect the desulphinator while chargeing

[peakbagger]

FYI , I in process of modifying my trailer so it will survive a winter with snow. It means relocating one set of panels, so that all panels face the same direction. While removing the panels I discovered that someone used THHN wire which is not rated for solar use. My trailer is one of the white American Tower versions that appear to be late in the production. The panels cables are okay, its the home run wiring from the beginning and end of the string that plugs into the electronics box.. Mine are wrapped up in spiral wire wrap.The plastic coating on the wires I removed was flaking off along with the specs for the wire. The wires are two small for the MC4 connectors which means that connectors end seals are not effective.

I do not know what code applies to a mobile trailer but a FYI, that these wires at some point could cause a mysterious fault to ground. Its not that difficult to change out if you have the correct MC4 connectors and USE2 PV wire (check on fleabay).