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lorenzo-accaroli avatar image
lorenzo-accaroli asked

48V 775Ah battery... Bulk

I wish to try explaining the system and its behavior. Two strings (18 panels 9kW), two SS MPPTs 150\85 and 250/100, 48 V lead acid floaded 775Ah(C5), QUATTRO inverter, controller CCGX. Installed in November so bad weather and first weeks since it is installed during day time never reached absorbtion volt. Then inverter was switched off and MPPTs charges to float three or for days. Then inverter was switched on and the situation now is that during day only bulk and during evening batteries give power for a little bit time (20 min with 3kW loads)... Sorry for this fload of words but I need to know what is happening...

MPPT Controllers
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michelg answered ·

Hi Lorenzo, it seems that your batteries are not fully loaded, if you have the opportunity to run a charger either through a generator or a power line 230VAC. The batteries are probably sulfated and will need :

0) buy a refractometer in order to know what is the real state of each cell

1) charge the batteries till they get into fload mode

2) use the solar power to run an equalization up to get the batteries cells having the same SG

3) check every hour the density of each cell

4) have a journal (excel file) where you write every week / month the status of each cell

Currently, they are new AFAIK, so they need to go through a "break-in" process, but you don't have enough sun, so wait to have sunny days to make them work hard, and always try to get them reloaded on the same day.

Let me know how the things are going.

Michel.

PS: you have very good videos on YT done by ROLLS batteries, in order to understand how they perform, what issues can happen, etc.

Also, what kind of battery are using ? Model, manufacturer, etc. it will be easier to tell you.

This is a refractometer :

refractometre-antigel-concentration-uree-pour-glyc.jpg



refractometre-antigel-concentration-uree-pour-glyc.jpg (35.1 KiB)
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lorenzo-accaroli answered ·

Thank you michelg, i don't have opportunity to run an external charger but here in northern Italy this week is very sunny so yesterday I switched off QUATTRO and Victrob Connect today told me that batteries performs all three phases.

I have a TAB battery 5EPZS775 48V 775Ah(C5). They are not really new. They were ready one year ago but do to some delays in house building the stay under charge for few months, then in October they were send to perform a reconditioning and then were installed in November.

I'm going to watch YT videos you suggest thanks!

So it is a good thing to keep batteries only charging by sun this week and perform the equalization this weekend if it is sunny? What risks and waring I have to consider during the equalization? I bought the reflectimeter meanwhile...

Attached you can find the battery label20210126-173830.jpg




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michelg avatar image michelg commented ·

Hello Lorenzo, here is the link to understand the process of equalization (ROLLS, but more or less the same for every lead acid battery) :

https://youtu.be/J8DmZulWnus

Risks ? Basically they are going to make much more gas (Hydrogen), and you need to have a good ventilation. Also consider checking the SG every hour, till all cells have the same gravity (OPsZ are usually around 1,24, check your manual or ask the provider).

Have also a reserve of distilled water to refill the batteries, usually check the levels every month, when you check the SG (check them before adding the water).

Let me know if I can help on other subjects.

Michel

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lorenzo-accaroli answered ·

@MichelG


Ciao Michel, sorry for asking again. I have my reflectometer and I want to check SG of cells this weekend. Battery is still with inverter OFF. TAB datasheet tells that nominal SG @30°C and with fully charged batteries is 1.29 with corrector factor of -0.0007 /°C. So:


1) I have to wait evening when batteries are fully charged to perform measurement?

2) My battery are in external place. Do I need to correct the read data or I can put drops inside the refractometer and then enter in house, wait 1-2 minutes and read the SG?

3) If I will find that SG is OK, could I switch ON my inverter? (This would help with my power bill ;) )


Thanks again

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michelg avatar image michelg commented ·

Hi lorenzo ! You have to take the SG of your batteries at the same place, but need to calibrate first the refractometer, using distilled water, and putting the level at 0 using the screwdriver.

Then, you can check and note every SG cell and write it. At 30C you have 1,29, I presume around 10C you will get a 1.295 / 1.305 SG.

You can check the SG whenever you want, and will get a picture of the current status, then when "fully charged", you perform another reading so you will know if the batteries are sulfated (discharged) and which ones. So you can perform the equalization next day, after having the batteries fully loaded (according to the MPPT).

You can switch on the inverter, but when you perform and equalization, it is recommended to switch off everything to avoid false measurements by the MPPT.

A good video : https://youtu.be/Zfw64KKGs6M

Have fun ! Michel


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lorenzo-accaroli avatar image lorenzo-accaroli michelg commented ·

Ok, I performed SG readings. Here the results... They seems to be good, aren't they?

The video tells that a delta of 0.01-0.015 is normal. I have a maximum of 0.021 delta.

Now I want to switch ON inverter and perform EQ tomorrow or during the week, what do you think?


EDIT: I have two MPPTs, so how do I start equalization simoultaneously? I can start EQ entering in one MPPT then in the other...


Thanks as usual!sg-31-01-21.jpg

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michelg avatar image michelg lorenzo-accaroli commented ·

Hi Lorenzo ! I am just using one MPPT, but I believe that you shoud just switch only one of the MPPTs to equalize, as the other will detect that an equalization is performed and will probably stop doing it. Chose the one who has the most power during the afternoon. Probably 1-2h should be enough to correct the SGs.

Let us know how things go !

Michel


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lorenzo-accaroli avatar image lorenzo-accaroli michelg commented ·

Ok!! I think picture is not visible but this is my readings of this late morningScreenshot_20210131-153847_Office.jpg

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michelg avatar image michelg lorenzo-accaroli commented ·

Not sure what you mean about SG corrected. The correction is done by the refractometer, putting a drop of distilled water and setting it to zero (at least this how I proceed). In my opinion your batteries are around 75-80% charged, and you will need to proceed with the equalization after they are considered charged by the MPPT. Probably at least 3-4h to get them equalized, you'll have to check every hour : https://youtu.be/J8DmZulWnus

Michel

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lorenzo-accaroli avatar image lorenzo-accaroli michelg commented ·

I corrected the readings with temperature coefficient -.0007.. I set zero with distilled water before outside then every 4 readings check the zero again... (Always cleaning pipette and refractometer after every readings)... My concern is about the water level of cells before doing EQ but I don't have the filler system yet.. I know I'm a little boring about this, but I don't want to do some mess

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lorenzo-accaroli avatar image lorenzo-accaroli lorenzo-accaroli commented ·

Ok then, i finally bought a MK3-USB cable- Attached you can find the settings of quattro and assistant. Battery is now at 50v but still don't give power during night. tested SG, battery manufacturer tells it is ok. Please tell my why the behavoir isn't the one I expected SET.pdfImmagine 2021-02-07 182526.jpg

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set.pdf (240.6 KiB)
michelg avatar image michelg lorenzo-accaroli commented ·

Hi Lorenzo, regarding the Quattro, I am unable to help, as I don't use it and have no knowledge about it. Probably someone else will help you regarding the settings. May be you could open another subject regarding the Quattro, as the battery manufacturer said they are OK.

Michel.

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lorenzo-accaroli avatar image lorenzo-accaroli michelg commented ·

just did ;)

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