New to solar...advice wanted please on absorb float etc

Started by jay, April 18, 2017, 09:12:27 AM

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jay

Please go easy lol...newish to solar as way to expensive to bring grid to farm & wow what a way of life! My question might be super simple but im trying to understand the float of batteries. So batteries are gel 24 x 2v 500amp hr set at 48v. 2 x classic 250 one being fed by 10 x 200watt panels (2 strings of 5) the other 10 x 250watt panels (2 strings of 5). Gel batteries so eq & absorb set to 55.6 55.6 & float set to 54.0v they are set in followme & the master is reading 53.6v the slave 53.4v on the status batt (right hand side) both sitting on float. The master clicks to resting back to float often & the code is 38. The slave sits on float while the master clicks between. I ran the dishwasher in the hope of seeing them click to absorb or bulk however the batt (right hand side in status screen) got down to 50.3v for master 50.1v for salve & both didnt move off float. Once dishwasher finished they jumped back up to 53.7 & 53.6v resting for master float for slave. Firmware updated including MNGP updates 3 nights ago to current & reset etc all done as purchased a screen display for lite so we could sit & watch as recently had panels burn out & didnt notice with the screen blank. So my question i guess is once the batteries hit float how come if i was to do 7 loads of washing & run the dishwasher etc wont it jump back to bulk or absorb...why only once in the day will they bulk absorb etc. Isnt that the point of the chargers to recognise they need topping up so they are full come sundown or am i looking at it all wrong?

mike90045

I have a couple questions for you.

1) are you batteries GEL or AGM   In the world of batteries, GEL means jelly electrolyte, most often used for emergency standby use and cannot be quickly recharged.  AGM means liquid electrolyte and dense fiber glass mat (wick) that cannot leak/spill. (Absorbent Glass Mat) AGM is often used in solar.

2) When you did your washing test, was there Full Sunlight at that time?  If there was enough sun, you should have stayed at the float voltage.  If your voltage dips low enough, that will trigger a new Bulk - Absorb cycle.  ( I can't recall what Midnight calls that setting - Re-Bulk? )

3) with your large arrays, do you use a combiner box for the PV strings ?  You don't appear to violate the "More than 2 strings needs combiner fusing", but yet you had a panel burn.
http://tinyurl.com/LMR-Solar

Classic 200| 2Kw PV, 160Voc | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph )| Listeroid 6/1, st5 gen head | XW6048 inverter/chgr | midnight ePanel & 4 SPDs | 48V, 800A NiFe battery bank | MS-TS-MPPT60 w/3Kw PV

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Quote from: jay on April 18, 2017, 09:12:27 AM
Please go easy lol...newish to solar as way to expensive to bring grid to farm & wow what a way of life! My question might be super simple but im trying to understand the float of batteries. So batteries are gel 24 x 2v 500amp hr set at 48v. 2 x classic 250 one being fed by 10 x 200watt panels (2 strings of 5) the other 10 x 250watt panels (2 strings of 5). Gel batteries so eq & absorb set to 55.6 55.6 & float set to 54.0v they are set in followme & the master is reading 53.6v the slave 53.4v on the status batt (right hand side) both sitting on float. The master clicks to resting back to float often & the code is 38. The slave sits on float while the master clicks between. I ran the dishwasher in the hope of seeing them click to absorb or bulk however the batt (right hand side in status screen) got down to 50.3v for master 50.1v for salve & both didnt move off float. Once dishwasher finished they jumped back up to 53.7 & 53.6v resting for master float for slave. Firmware updated including MNGP updates 3 nights ago to current & reset etc all done as purchased a screen display for lite so we could sit & watch as recently had panels burn out & didnt notice with the screen blank. So my question i guess is once the batteries hit float how come if i was to do 7 loads of washing & run the dishwasher etc wont it jump back to bulk or absorb...why only once in the day will they bulk absorb etc. Isnt that the point of the chargers to recognise they need topping up so they are full come sundown or am i looking at it all wrong?

There is a re-bulk setting. By default it is around 8V for a 12V system IIRC. So you would have to go below whatever you have Re-Bulk set at. If you go back to Bulk it will cycle through Absorb again and you don't really want to do that. If in Float and the voltage drops below the Float set point it will go to Float MMPT and try to get back to the Float set point voltage.

Assume you have a breaker in each string. Not sure what you issue was with panels.
John

10 x Kyocera KC140, Classic 150 w/WBJr, Link10 Battery Monitor, 850 AH @ 12v Solar One 2v cells, Xantrex PROwatt SW2000
Off Grid on Houseboat Lake Don Pedro, CA