XW+ 6848, 48v bat bank, use grid as backup

Xeyrruken · January 2019

Hello there, i have my XW+ installed, everything is working great, Since I have the grid line connected to the inverter, I want to set up the Grid Support, no selling, only to allow the batteries to charge if during the night they get to 50%, could anyone please explain a bit how to do this, I have read the Owners Manual but I don't quite get the instructions there.

mike95490 · January 2019

Your dealer ought to be able to help with reading the manual. Before you go adjusting things, you really need a good grasp on electrical terms and calculations.
Many of the settings interact with others, setting the battery size/amp hours is one that is critical

WaterWheel · January 2019

As Mike said there are a lot of interlinked variables but here are a few settings to play with.
Grid Support enabled
under Advanced options
Grid support V try 48.4
sell disabled

I prefer to leave the charger disabled. A hard load that dips the battery voltage for more than a few seconds can activate the charger when the batteries are still a bit above your desired 50%. But if you want to leave the charger enabled I'd start with Battery recharge V at 48.2v and go from there.

Do not totally rely on your SCP or Combox battery meter. If you've got LA batteries use the SG readings regularly. good video If you run LA batteries https://www.bing.com/videos/search?q=rolls+schneider+battery+video&view=detail&mid=AF89235D2A45973D0423AF89235D2A45973D0423&FORM=VIRE

Xeyrruken · January 2019

I have already set up battery Battery type = AGM and Battery bank amp which is 440ah, the LBCO = 43.4 For this number I contacted the batteries manufacturer and they stated that a bank of 48v, 50% DOD is 43.44VDC, everything is set, I have grid support enable, when I get home I will look at the rest of the options I will not turn on AC breaker until I have a better config parameters.

WaterWheel · January 2019

43.4v for 48v bank sounds like a lot lower than 50% SOC.    My chart shows that to be a dead battery.

With your LBCO set at roughly 50% SOC and a desire for grid charging to enable at roughly the same point I'd make sure your LBCO delay is fairly long, like the 300 second max.

I set my LBCO at 47.2, about 30% SOC.    Long power outages are common here, often we don't notice that the grid has been down for over a day.    If the neighbors don't have power we often don't notice because the neighbors are too far away to hear a generator and nobody panics because power outages are common.    The well pump may run dipping battery voltage so I went with the long 300 second delay.

May I suggest that instead of having the charger automatically cutting on you instead enable grid support.    The inverter will pull about 80 watts constantly but with grid support voltage set at about 49.4v your inverter will automatically increase the use of grid voltage to supplement the battery power until it goes almost totally to grid power with very little drain on the battery when the battery gets below the set voltage.    49.4v works out to about a 70% SOC battery before the grid fully steps in and handles 98% of the load.

The roughly 100 watts is about 2.5 kwhs/day so about 25 cents a day worth of grid power used each day that the batteries stay above the set voltage.

By enabling the charger manually if you know the next day will be sunny you don't need to charge the batteries. It won't really hurt your batteries to let them sit a day at 70% waiting for the next sunny day.    Your grid support will keep the house powered.

Xeyrruken · January 2019

WaterWheel said:

43.4v for 48v bank sounds like a lot lower than 50% SOC.    My chart shows that to be a dead battery.

With your LBCO set at roughly 50% SOC and a desire for grid charging to enable at roughly the same point I'd make sure your LBCO delay is fairly long, like the 300 second max.

I set my LBCO at 47.2, about 30% SOC.    Long power outages are common here, often we don't notice that the grid has been down for over a day.    If the neighbors don't have power we often don't notice because the neighbors are too far away to hear a generator and nobody panics because power outages are common.    The well pump may run dipping battery voltage so I went with the long 300 second delay.

May I suggest that instead of having the charger automatically cutting on you instead enable grid support.    The inverter will pull about 80 watts constantly but with grid support voltage set at about 49.4v your inverter will automatically increase the use of grid voltage to supplement the battery power until it goes almost totally to grid power with very little drain on the battery when the battery gets below the set voltage.    49.4v works out to about a 70% SOC battery before the grid fully steps in and handles 98% of the load.

The roughly 100 watts is about 2.5 kwhs/day so about 25 cents a day worth of grid power used each day that the batteries stay above the set voltage.

By enabling the charger manually if you know the next day will be sunny you don't need to charge the batteries. It won't really hurt your batteries to let them sit a day at 70% waiting for the next sunny day.    Your grid support will keep the house powered.

I'm calling, the Manufacturer today, I have their email stating what I said above is true, but as you say after some digging about the batteries specs, for me it feels like a lot lower than 50% SOC, I mean I'm currently at 10% and that's unacceptable for the batteries health, actually I own 16 Alphacell 3.5HP, I will test your approach, Thanks WaterWheel.

Xeyrruken · January 2019

@WaterWheel may you send me the 48v SOC Chart?

WaterWheel · January 2019

Battery State of charge chart
https://www.bing.com/images/search?view=detailV2&ccid=sGyHUY6z&id=D6CCC788AE313D7E651F7083060AFC8C616481B0&thid=OIP.sGyHUY6zuCW8XVq0YE9lsgHaDy&mediaurl=http://modernsurvivalblog.com/wp-content/uploads/2013/06/battery-state-of-charge.jpg?x12845&exph=333&expw=650&q=battery+state+of+charge+chart&simid=608012370959467216&selectedIndex=0&ajaxhist=0

Xeyrruken · January 2019

WaterWheel said:

43.4v for 48v bank sounds like a lot lower than 50% SOC.    My chart shows that to be a dead battery.

With your LBCO set at roughly 50% SOC and a desire for grid charging to enable at roughly the same point I'd make sure your LBCO delay is fairly long, like the 300 second max.

I set my LBCO at 47.2, about 30% SOC.    Long power outages are common here, often we don't notice that the grid has been down for over a day.    If the neighbors don't have power we often don't notice because the neighbors are too far away to hear a generator and nobody panics because power outages are common.    The well pump may run dipping battery voltage so I went with the long 300 second delay.

May I suggest that instead of having the charger automatically cutting on you instead enable grid support.    The inverter will pull about 80 watts constantly but with grid support voltage set at about 49.4v your inverter will automatically increase the use of grid voltage to supplement the battery power until it goes almost totally to grid power with very little drain on the battery when the battery gets below the set voltage.    49.4v works out to about a 70% SOC battery before the grid fully steps in and handles 98% of the load.

The roughly 100 watts is about 2.5 kwhs/day so about 25 cents a day worth of grid power used each day that the batteries stay above the set voltage.

By enabling the charger manually if you know the next day will be sunny you don't need to charge the batteries. It won't really hurt your batteries to let them sit a day at 70% waiting for the next sunny day.    Your grid support will keep the house powered.

I tried your suggestion it is working pretty good, I will opt for not enabling charging, the manufacturer of the batteries told me that there was an error due that their calculations were based on DOD percent, and that those batteries are not recommended for solar, those batteries are designed for Float Charge applications and even when those are Deep Cycle and met all solar specs, they don't have that much cycling life. Here in Puerto Rico 1 kwhs is 23.2 Cents, so those 2.5 kwhs/day would be 58 cents haha. Thanks for the help!

WaterWheel · January 2019

We've got at least 2 other people from Puerto Rico on this forum but I can't remember their names. But if you can track them down perhaps they can help you with battery selection when your batteries get old.

XW+ 6848, 48v bat bank, use grid as backup

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