Help with xw6048 selling off my battery

grunt

I have a XW6048 with a Outback flex max 60.
They power and maintain 8 6volt sun extender batts for a total of 48 volts off of 2.7k worth of PV. All grid tied.

Here is my problem that I seem to be having. My XW want to sale off my battery power to the grid when it is in "sell" mode.
Now I have done some searching on the net and the answer does not seem to make sense to me nor has it fixed my problem.
In the outback Manual for the flex max it states that if you are using another manufacture inverter that you need to set your sale to voltage 1 volt lower (for a 48 volt system) then the Float voltage. Now I am assuming that this is the float voltage that is programmed in to the out back so according to the battery brand and that would be 6.6-6.70 per battery x8 with a total of 53.2-53.6. So the
"Grid support voltage" for selling back would be 52.2-52.6. Now here is the problem when you program that in to the xw it in turns sales off every thing above that voltage. Which in turns kick the out back in to MPPT float since it is trying to maintain the preset float voltage and it keeps on running and running.. fan going on fan going off all day long. Not only that on my xw display interface you can see that amperage is reading negative for the batteries.

See in my mind the sale voltage would have to be above float that way once float voltage is achieved you could sale off any remaining power above that voltage and since the out back is a 3 phase charger, there will always be a float voltage.

I am also assuming that the XW’s charger needs to stay in the off mode since the Outback does all the work.

Solar Guppy

Re: Help with xw6048 selling off my battery

Its working correctly, the XW's sell voltage works by drawing energy from the battery's to maintain the selected voltage, the charge controller is not the one regulating the battery voltage as the XW is sell ALL the energy through the charge controller to the grid.

The Outback fan kicking on and off is just how that controller works to keep the unit from overheating while operating.

grunt

Re: Help with xw6048 selling off my battery

So the negative read out on xantrex display in the battery line is nothing to worry about. Also the same with Float being MPPT float.

grunt

Re: Help with xw6048 selling off my battery

also one more question. It is now 9pm and the out back is snoozeing but the XW shows -3.6 amps on the battery line and -800 watts (roughly) on AC1. Now according to the XW6048 manual any time that there is a negative on that line power is be sold back. So if that is happening where is the power comming from? The battery voltage still show the same as it has been since I lowerd the sell to grid voltage one volt below floating.

Solar Guppy

Re: Help with xw6048 selling off my battery

The XW-6048 only shows watts with its 4 digit display, if your referring to the SCP, a negative value is what is the load on the inverter, not what it is selling. So you have something on the load side of the inverter drawing power from AC1 ( line ).

By the way, AC1 value is the net value, if you have a load and are selling, the exported watts display value ( AC1 ) is your solar production minus what ever the load is drawing and will be a positive value if your exporting to the grid.

As far as the OB staying in float, as long as its proving full power, the charge state has no meaning.

grunt

Re: Help with xw6048 selling off my battery

thanks for your help guppy. The amp draw stopped some time durring the night there must a been a small bit of extra capacity left in the battery and the voltage on the bats is right where I set it. 51.2. One volt below float.

Solar Guppy

Re: Help with xw6048 selling off my battery

51.2 is too low IMHO, float typically is 54 volts , I wouldn't go lower than 52.5V for sell to compensate for cell to cell variation and ripple current

grunt

Re: Help with xw6048 selling off my battery

ok I went and uped it a bit.
Float according to my Sun extender are 53.2-53.6
Then one volt below float per OB for sale back and I have it 52.6.

RCinFLA

Re: Help with xw6048 selling off my battery

In sell, the XW6048 will act as a regulator on battery to hold battery voltage to float level. Anything that pushes current to batteries attempting to raise the voltage above XW's float setting will result in XW sucking off the extra charging power and push converted AC to grid/ACout node. You either consume it with your ACout loads or excess will be pushed to grid.

You set charge controller float level higher to ensure it always will push current to battery when available from PV system. The charge controller will likely never be able to raise the battery voltage to its higher float voltage setting because XW will cap the voltage at XW's float setting. So it's XW that rules the float voltage, not the solar controller. Setting of 52.8v to 54.0 volts is right range. Temp comp will change this set number which is referenced to 25 deg C, higher when cold, lower when hot. You need to use temp sensors on both charge controller and XW to ensure float setting changes in temp coordination for both units.

At night, or periods of no solar production, if the battery voltage drops below float level the XW will charge batteries.

When I say solar charge controller will 'likely never be able to raise battery voltage to its float level', in can get to solar charge controller float setting if grid goes down and there is little load on XW ACout. So you don't want it set it too much higher then desired battery float level.

Solar Guppy

Re: Help with xw6048 selling off my battery

RC, I think it might be best to keep the terminology correct, the XW uses the value called sell voltage, not the charger float setting for the regulation voltage for gridtie operations.

SG

RCinFLA

Re: Help with xw6048 selling off my battery

Okay, in sell mode the XW uses 'sell voltage' register instead of 'float voltage' register.

Question for you. If grid goes down for a minute during sell, when it comes back up does the XW take batteries to absorb voltage level or pick back up on sell at sell voltage level, charging battery back to sell level first?

Second, if someone sets XW float level above sell level, I assume float setting is ignored while in sell mode.

Solar Guppy

Re: Help with xw6048 selling off my battery

I always have the charger turned off since I go gridtie ... so I don't know the logic on the interaction when you have the charger on and sell on, only one function at a time works ( its just the inverter on in both conditions )

grunt

Re: Help with xw6048 selling off my battery

Yes mine is grid tie so I dont use the charger feature on the xw. So If the charger controller never realy gets enough power to charge since all the power is either being used or sold, what concerns do I have about maintaining the batts. Is haveing the voltage sell back set higher enough to do the chore of battery maintance. Since I dont record any float or absorb time on the OB.

RCinFLA

Re: Help with xw6048 selling off my battery

The solar charge controller is charging the battery (or should be if set to high enough float voltage).

Again, the battery voltage will not be allowed to rise above XW's sell voltage setting (unless grid goes down or you push more power then XW sell capability), so XW, in effect, sets the float level on the batteries. If you want the batteries float maintained at 52.8 vdc then set XW sell voltage to 52.8 vdc.

The solar charge controller should be set to higher float voltage, so it will keep pushing out available solar produced current to battery terminals.

Normally the solar charge controller will first try to go to absorb voltage setting, so should never switch to float voltage. Some charge controllers do have a bulk and/or absorb timeout for safety abort in case of bad battery.

grunt

Re: Help with xw6048 selling off my battery

RCinFLA wrote: »

The solar charge controller is charging the battery (or should be if set to high enough float voltage).

Again, the battery voltage will not be allowed to rise above XW's sell voltage setting (unless grid goes down or you push more power then XW sell capability), so XW, in effect, sets the float level on the batteries. If you want the batteries float maintained at 52.8 vdc then set XW sell voltage to 52.8 vdc.

The solar charge controller should be set to higher float voltage, so it will keep pushing out available solar produced current to battery terminals.

Normally the solar charge controller will first try to go to absorb voltage setting, so should never switch to float voltage. Some charge controllers do have a bulk and/or absorb timeout for safety abort in case of bad battery.

I guess one of the issue I have is that the the battery voltage is lower then the sell to voltage I program on the XW. I can let it charge up and then set the sell voltage and once I hit enable for grid support it drops the battery voltage down to 51.8-51.7ish via reading the SCP.

You stated "the solar charge controller should be set higher float voltage, so it will keep pushing out available solar produced current to battery terminals" Well in "sell" mode that will never happen since the voltage will all be sold off before there is enough voltage to get the batterys charged.

mikeo

Re: Help with xw6048 selling off my battery

You stated "the solar charge controller should be set higher float voltage, so it will keep pushing out available solar produced current to battery terminals" Well in "sell" mode that will never happen since the voltage will all be sold off before there is enough voltage to get the batterys charged.

I am not familiar with the xw but with the sw series I have set my MX60's programmable output to control the sw inverter using the solar array current settings of 1 amp and 6 amps. The inverter doesn't get turned on until the array is producing more than 6 amps and turns the inverter off in the evening whenever the power drops below 1 amp so I have no idle losses at night. In the morning when the sun comes up the CC starts making up for the battery self discharge losses at night then when 6 amps is reached, the inverter is turned on and goes into bulk mode for 20 minutes before dropping to float mode. Float and sell are set to the same value so the batteries have reached full charge before sell mode starts, and then CC float is set about 1 volt higher then sell which means the CC nevers goes into float the rest of the day. IHTH

RCinFLA

Re: Help with xw6048 selling off my battery

mikeo wrote: »

I have set my MX60's programmable output to control the sw inverter using the solar array current settings of 1 amp and 6 amps. The inverter doesn't get turned on until the array is producing more than 6 amps and turns the inverter off in the evening whenever the power drops below 1 amp so I have no idle losses at night.

Curious to know what you are connecting MX60 aux output to on SW to shut off inverter? Only SWplus units have remote shutdown and that would also cut power to ACout.

mikeo

Re: Help with xw6048 selling off my battery

Curious to know what you are connecting MX60 aux output to on SW to shut off inverter? Only SWplus units have remote shutdown and that would also cut power to ACout.

Hi RCinFLA. In my configuration AC out is only used in "sale" mode, and is manually switched in case of a power outage to take care of my house loads. As far as the control of the SW goes, I use the SWCA connected to a very low power Basic Stamp computer board that checks the state of the MX60 aux control port and sends the appropriate ASCII codes to the SW to turn it off and on.

RCinFLA

Re: Help with xw6048 selling off my battery

Okay, understand, it is a custom setup. The MX aux output setup is based on controller output current, not PV current, same functionality for your purpose.

MX abandons MPP tracking in float and absorb so it is important that you ensure their settings are higher then SW's, with SW's couple tenths of volt bounce, and not let MX even intermittantly hit float voltage.

grunt

Re: Help with xw6048 selling off my battery

The only place that current (ie..amps) has a place in my programing is in reguards to AC fuse sizes. Other then that I have not programed any current values.

grunt

Re: Help with xw6048 selling off my battery

Ok. I am thinking this is what I might try. I was rereading the manual and I came to the part that talks about charger Blocking. Normaly this feature is used to stop chargeing from the AC line durring peak price hours of electricity.

Now in theory I could block off the whole part of the day that the sun is out and when the sun goes down..lets say 7pm ish the charger would be unblocked and charging could start.

What do you think?

The only things I would need to change is that the battery charging would be ran on the xw.
Right now it is disabled.

Solar Guppy

Re: Help with xw6048 selling off my battery

If your only issue is the reset voltage on the battery's, then just raise both the float and sell voltages by one volt, currently I have my sell at 53.5 which keeps the battery's 100% charged

I have run for years with no charging on my AGMS, just sell to the grid, I do once every couple of months enable the XW-6048 charger and then do a force bulk charge, doesn't even run more than 15 minutes before going into absorb

There is absolutely no need to try and get fancy with either relays, or time of charge setting if all you are doing is selling to the grid.