Xantrex XW charge voltage way too high. Help.

wirenutwirenut Registered Users Posts: 22 ✭✭
I just hooked up a generator to an Xantrex XW system I installed earlier this year. When I fired up the gen. to test the inverters went into charge mode like they should. The batt voltage went up to 62.3 v. I quickly verified the reading with my meter to rule out a display problem. I then disconnected the AC so as not to cook the batteries.
My absorption voltage is set to 57.6 and the float to 53.6. The battery temp was 55F at the time. The temp. compensation should have put the charge voltage at about 59v by my calculations.

The batteries are AGMs that were fully charged. I expected the charger to quickly switch to float mode since they were already full. The solar array was also still connected to the batteries. The charge controllers parameters are set exactly like the inverter/chargers.

I'm at a loss to explain why the voltage went up to 62.3 volts unless it was just too many charging sources connected to already full batteries.


  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Xantrex XW charge voltage way too high. Help.

    Having multiple regulated charge sources will not push battery Voltage too high. If the programming set points are all the same and data is shared between sources (in this case via the Xanbus) they should all agree on battery Voltage, battery temp, and what to try to take the Voltage to.

    One thing that might cause this is if there's too much current potential for the size of the battery bank. This will sometimes push the Voltage high until the regulation has a chance to adjust. It should not last long.

    Happily I do not use Xantrex equipment, so perhaps you should wait for a response from someone who does.
  • mike95490mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Xantrex XW charge voltage way too high. Help.

    You can control the charge voltage, by programming the AC2 input for the XW inverter/charger, to a lower amperage breaker. (You need to tell the inverter what size breaker you have, and it will limit power to below that value). But even then, you should not have see such a high voltage, because it should have throttled back. Do you have the system control panel (SCP) ?
    How long are the battery cables? Too much drop in them ?
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • wirenutwirenut Registered Users Posts: 22 ✭✭
    Re: Xantrex XW charge voltage way too high. Help.

    Maybe I just didn't wait long enough for the voltage to fall back. As soon as I saw it and verified it I disconnected the generator.
    The batteries are 24 Sun Extender PVX-915T 2v in series. They are 915 Ah. The cables are 4/0 and probably only 10 feet long or so. The solar array is 8,460 watts. I guess with the PV running and then connecting the generator the voltage just shot up there before everything could reduce power. I'll have to try it again and take the PV off line first.

    Keep the information coming.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Xantrex XW charge voltage way too high. Help.

    That array has a potential for 135 Amps @ 48 Volts. That would be a 14.8 % charge rate on those batteries. The Sun Extenders can take it, but if you add that input (on two charge controllers?) with generator input from (I'm guessing here) two inverter-chargers there could well be a Voltage surge even with a Xanbus allowing everything to "talk".

    Are we looking at seconds of higher-than-expected Voltage or minutes?
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Xantrex XW charge voltage way too high. Help.

    be sure that nothing is possibly set to do an eq charge. a really brief time that high in voltage won't hurt the batteries, but it doesn't take long to open the valves with that voltage and with that much current it would surely outgas. be sure of what raised the voltage, the inverter's charger or the pv array to start the trouble shooting. i hope there isn't a charging circuit on it like on my c40 as it goes way high too and i don't advise using the c series controllers on agms in light of my experience.
  • Solar GuppySolar Guppy Solar Expert Posts: 1,989 ✭✭✭
    Re: Xantrex XW charge voltage way too high. Help.

    The XW has windows where as part of the sell to grid it loads the grid which send energy into the battery's. If you have fully charged AGM's, they will rise for 30-45 seconds as I have seen this as well.

    Also, you should NOT have the charger enabled in the XW and be sell to the grid,

    If by chance you have the generator connected to the oiutput of the XW, ( vs AC 2 in ) that would cause a similar voltage rise as that's AC coupling to the inverter
  • wirenutwirenut Registered Users Posts: 22 ✭✭
    Re: Xantrex XW charge voltage way too high. Help.

    I definitely have the gen. connected to AC2 in.

    Why should I not have the charger enabled? If, during an outage, the solar doesn't keep up with the demand in the house the generator will come on. I then want the XW to charge the batteries from the gen. while it's running to feed the house. I don't see how to do that with the charger disabled. What am I missing?
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