Batteries discharge after sunset (Xantrex Grid-Tied with Battery Backup)

c9482c9482 Registered Users Posts: 6
I am a solar newbie and had my system installed back in June. My system is grid tied with battery backup and consists of the following components:

Xantrex XW-4048 Inverter with SCP and Power Distribution Panel
Xantres MPPT60 charge controller
4 x 255W Sunworld modules
8 x 6v Deka Solar batteries wired into 24V configuration

I have it configured to Sell to Grid. The system appears to be working correctly except for one thing. When I check the battery status every the morning, the meter shows about 66% full. Few hours later, the meter shows 100% again but as soon as the sun goes down, it starts slowly going down.

Attachment not found.

Why would there be such drain on my batteries if the system never fails over into backup mode? My installer, as it turns out, was not very familiar with Xantrex system. I called Schneider Electric few times and spoke to several different techs. They had me try few adjustments and one even told me that my array is to small to completely charge the batteries. Could the system be wired incorrectly? Mis-configured? Bad batteries? My understanding is that as long as the grid is on, there should be no load on the batteries. What am I missing?

I would appreciate any insight that can provide. I can also post any relevant settings (just not sure which ones). Many thanks in advance.
scp.jpg 66.9K

Comments

  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Batteries discharge after sunset (Xantrex Grid-Tied with Battery Backup)

    It looks like that meter is way off, at 26.5 volts your at float Voltage and it's 8:01 AM in the morning. Those meters are NEVER right. You can reset it, but it'll get off again. if you were at 66% the voltage would be 24.2-3 or so. Thats my guess.
  • c9482c9482 Registered Users Posts: 6
    Re: Batteries discharge after sunset (Xantrex Grid-Tied with Battery Backup)

    Thanks for the quick reply. So you're saying the read out is incorrect and there's nothing to worry about? Should I be using something like Trimetric meter to accurately measure the state of batteries?
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Batteries discharge after sunset (Xantrex Grid-Tied with Battery Backup)

    don't assume anything. get a reliable dvm or somebody that has one to verify what you are seeing on that readout.
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Batteries discharge after sunset (Xantrex Grid-Tied with Battery Backup)
    c9482 wrote: »
    Thanks for the quick reply. So you're saying the read out is incorrect and there's nothing to worry about? Should I be using something like Trimetric meter to accurately measure the state of batteries?
    I don't have your exact setup, but if it was inverting you would see it on the SCP. Now thats not to say that your batteries are ever getting charged. Do you ever see the Voltage up to 28-29 Volts ?? It may be just using the re-float setting to bring the batteries back up off the grid.
  • c9482c9482 Registered Users Posts: 6
    Re: Batteries discharge after sunset (Xantrex Grid-Tied with Battery Backup)
    I don't have your exact setup, but if it was inverting you would see it on the SCP. Now thats not to say that your batteries are ever getting charged. Do you ever see the Voltage up to 28-29 Volts ?? It may be just using the re-float setting to bring the batteries back up off the grid.

    I don't see it inverting at all unless I explicitly switch to DC mode. I will check tomorrow to see if get up to the 28-29 volts range. Thanks again.
  • c9482c9482 Registered Users Posts: 6
    Re: Batteries discharge after sunset (Xantrex Grid-Tied with Battery Backup)
    niel wrote: »
    don't assume anything. get a reliable dvm or somebody that has one to verify what you are seeing on that readout.

    To measure the voltage correctly, do I need to disconnect it from the inverter?
  • n4wffn4wff Solar Expert Posts: 48 ✭✭
    Re: Batteries discharge after sunset (Xantrex Grid-Tied with Battery Backup)

    Hi c9482, I am a newbie too, having installed my system in July. Everyone is correct on the meter being almost useless. Last night my meter showed full, and for fun I manually set the inverter to charge. Immediately the meter went down to just over 1/2 when charging started, and did not go back to full until charging finished. This morning I took a pic, and it is similar to the pic you posted, although mine is a 48V system. The contol panel is showing a 6.9a charge, but the inverter is asleep with 3 dashes on the readout.
    Attachment not found.
    You might want to look at the settings and see if you are in Enhanced Interactive Mode. It will only sell back to the grid after topping off the batteries with a complete charge cycle. Here is a thread on EIM
    http://forum.solar-electric.com/showthread.php?15815-XW-6048-Enhanced-Interactive-Mode-Where-do-I-select-EIM
    They are talking about a 48v system but you can get the idea of how it works.
    SCP.jpg 37.2K
  • c9482c9482 Registered Users Posts: 6
    Re: Batteries discharge after sunset (Xantrex Grid-Tied with Battery Backup)
    n4wff wrote: »
    Hi c9482, I am a newbie too, having installed my system in July. Everyone is correct on the meter being almost useless. Last night my meter showed full, and for fun I manually set the inverter to charge. Immediately the meter went down to just over 1/2 when charging started, and did not go back to full until charging finished. This morning I took a pic, and it is similar to the pic you posted, although mine is a 48V system. The contol panel is showing a 6.9a charge, but the inverter is asleep with 3 dashes on the readout.
    Attachment not found.
    You might want to look at the settings and see if you are in Enhanced Interactive Mode. It will only sell back to the grid after topping off the batteries with a complete charge cycle. Here is a thread on EIM
    http://forum.solar-electric.com/showthread.php?15815-XW-6048-Enhanced-Interactive-Mode-Where-do-I-select-EIM
    They are talking about a 48v system but you can get the idea of how it works.

    Thanks for the useful information. I've experienced similar behavior when I disabled SELL mode, changed the charge cycle to 3 stage and power cycled the inverter - SCP battery meter immediately goes down some and inverter starts charging from the grid. Also, during the day when the battery meter starts showing the full charge, I see the amps alternating between positive and negative values along with voltage. The voltage can change from 26.9 to 28 within seconds. However, the inverter ALWAYS shows 5 green dots (battery fully charged). I used voltmeter to confirm that battery voltage shown on the SCP is correct. So perhaps the built-in battery meter is useless?

    I have a solar panel on my motorhome and I ended up having to install Trimetric battery meter with shunt to get accurate reading. Perhaps this is similar situation.

    BTW: How do you like the Connext ComBox? Is it worth getting?
  • n4wffn4wff Solar Expert Posts: 48 ✭✭
    Re: Batteries discharge after sunset (Xantrex Grid-Tied with Battery Backup)

    The ComBox works great for me. My system is in the barn behind the house. I can monitor the system, or change anything from sitting in the recliner. Also open the firewall on your router and you can monitor the system from anywhere in the world. They have an Android tablet app which works well, I just wish they would come with a phone app.

    Attachment not found.
    I have never watched the battery amperage while selling. That seems to make sense though. When I am monitoring via the web, the animated ball showing current direction reverses depending on battery voltage.
    I had trouble getting sell mode to work at first with EIM enabled. After calling tech support, we set the inverter charger on 2 stage, and the solar on 3 stage. This seems to work well.
  • NorthGuyNorthGuy Solar Expert Posts: 1,925 ✭✭
    Re: Batteries discharge after sunset (Xantrex Grid-Tied with Battery Backup)
    c9482 wrote: »
    So perhaps the built-in battery meter is useless?

    Completely useless.
  • c9482c9482 Registered Users Posts: 6
    Re: Batteries discharge after sunset (Xantrex Grid-Tied with Battery Backup)
    NorthGuy wrote: »
    Completely useless.
    So can someone explain to me what it means when SCP battery readout shows 25.9V and (negative) -3.9 amps when not inverting?
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Batteries discharge after sunset (Xantrex Grid-Tied with Battery Backup)
    c9482 wrote: »
    So can someone explain to me what it means when SCP battery readout shows 25.9V and (negative) -3.9 amps when not inverting?
    If it's correct, then it shows your battery voltage and a draw on them. The way to check it is with a Digital Volt Meter and a Clamp on amp meter, you want to check the battery voltage, you want to check the amp draw on the battery cables with the clamp meter. Then you want to check the amp readings in and out on the AC wires with the clamp meter to see if you can find the draw on the batteries. If nothing is going out then it being consumed by the system. Most Inverters use 15-30 watts unless in standby and that does not show up on the SPC.

    That seems like way to much draw in system overhead to me, then again I don't have your setup and you have to verify it's correct. Thats a lot going somewhere 24/7.

    25.9 volts, if you have 2 stage charging and no-float is just above standing voltage and isn't a problem in itself. Whats the Voltage at 8:00 in the Morning ??
    .
  • BB.BB. Super Moderators, Administrators Posts: 29,639 admin
    Re: Batteries discharge after sunset (Xantrex Grid-Tied with Battery Backup)

    A very handy and pretty cheap DC Current Clamp Meter (really an AC/DC clamp DMM) from Sears. "Good enough" for most solar DC and AC debugging. You can start tracing down the current draws/drains and see what is really going on.

    The only issue I have with the meter, is how to Zero the DC current is "different" than any other meter I have used... Read the instructions or we can talk about it here.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • n4wffn4wff Solar Expert Posts: 48 ✭✭
    Re: Batteries discharge after sunset (Xantrex Grid-Tied with Battery Backup)

    The rain slacked off so I can go out to the barn and see my system. Two questions: Is the breaker from the grid to the inverter on? Are you sure you do not have any loads on your inverter. The reason I ask, when I walked out here, the inverter had 3 dashed lines on the display meaning it was in AC pass through, with the camper being the only load. The meters showed 80W from the grid, with 26W going to the camper. Battery draw was 0 amps. After I turned off the grid breaker, and the load breaker, totally isolating the inverter from the grid, battery draw went up to .8 amps and the inverter started humming slightly. The display on the inverter fluctuates from 0.02 - 0.03KW or 20 - 30W. If I turn the camper breaker on, The amp draw from the batteries climbs to 2.4A and the inverter shows 0.09KW. (Battery level is just below F at 51.7v.) When I turn the grid breaker on, it switches into charge mode, but before it does, battery draw is back a 0A, the inverter stops humming, and the three dashed lines appear. If I manually stop the charge, it takes a minute to switch back into pass through mode.
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