Conext XW6848 Charger Settings Questiond



  • ELYNN4
    ELYNN4 Registered Users Posts: 137 ✭✭
    Thanks Mike.  This is the challenge of Alaska.  Very little solace to be had for four months out of the year.  The batteries are held at 1.277 for 8 months, then lose ground when the charge is more dependent on the generator.  How hard are EQ’s on the batteries?  Should they just be done in the winter since the SG is fine in the summer?
    Off Grid, 4.5KW array, 9&6KW Gens, 6848XW inverter, Midnite Classic 150, 2 strings - 48V - Trojan FLA L16 2V, located in Talkeetna, Alaska
  • wellbuilt
    wellbuilt Solar Expert Posts: 763 ✭✭✭✭
    You have to get the sq up  my system will bulk charge with solar and genarator 
     I have to be carful that I don’t get full sun when I’m charging with the genarator . 
     The sun is dropping fast here so there is not much chance of that . 
     Keep charging , set all your setting to bulk and 
      Let it go . 
     I watch my bank with a heat gun . 
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
  • ELYNN4
    ELYNN4 Registered Users Posts: 137 ✭✭
    Well things continue to be interesting.  Ran the generator for 12 hours, including an hour Equalization.  The refractometer readings got up to 1.26.  I got frustrated and grabbed one of my hydrometers and it read 1.275.  I grabbed a second hydrometer, different manufacturer and it read 1.280.  So I grabbed a third hydrometer from yet another manufacturer and it read 1.275.

    So now I wonder if my “gold standard” refractometer could be the problem.  I checked its calibration with distilled water and it is spot on.  The battery bank got up to 78 degrees so all of the device’s readings should be accurate as that’s close enough to 77 degrees.

    Anyone have a tool for testing their SG that they feel is better than the rest?
    Off Grid, 4.5KW array, 9&6KW Gens, 6848XW inverter, Midnite Classic 150, 2 strings - 48V - Trojan FLA L16 2V, located in Talkeetna, Alaska
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Are you apply the temperature correction for each device correctly ?
    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

    gen: ,

  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    For something like a refractometer--They only use a drop of electrolyte--So the "temperature" of the sample is probably pretty near room temperature/prism temperature of the insturment, not the temperature of the battery bank.

    The refractometers I have looked (specifications) at needed a sample that was near the value of SG to be measured. The ones I looked at did not even have a scale that went down to 1.00 SG units.

    You can buy a 1 quart container of "battery acid" from an auto parts store for around $10.00 for SG: 1.265 (certainly close enough for calibration use)... You might even be able to get a calibration amount from your local battery distributor.

    Tables of Sulfuric Acid + Water mix.

    I am not sure I would pull my hair out over 0.005 difference in readings between hydrometers--Probably the limit of accuracy/resolution for most if not +/- 1.0%--And even more error (1.x10 to 1.x20 error in sg measurements?) if adding temperature compensation.

    A "high end" refractometer is something like +/- 0.2% accurate (1.xx2 I think?) for >$200 instrument: Master Refractometers Datasheet.pdf

    Our host's hydrometer and manual (talks quite a bit about accuracy and this unit's integrated temperature compensation--No tables):

    When using float type hydrometers--Always have to be careful to ensure that any gas bubbles (from charging) are not adhering to the float.

    Another recommendation from one of our other members here--Always remember to rinse a hydrometer (with floats) using a few squirts of distilled water before putting unit away. Otherwise, the electrolyte left behind tends to make the floats stick.

    I like this truism:

    Segal's law - Wikipedia

    A man with a watch knows what time it is. A man with two watches is never sure.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ELYNN4
    ELYNN4 Registered Users Posts: 137 ✭✭
    Thanks - since the batteries were 78 degrees according to my heat gun, no temperature compensation was needed for the readings.  One of the hydrometers I was using was the Morning Star, which is temperature compensating.  The refractometer as I understand it is temperature compensating as well.

    I’ll try buying some acid and see what it measures.  The refractometer I’m using is good for antifreeze as well, they recommend calibrating it with distilled water.  

    I always flush my hydrometers with distilled water and when using them I make sure that I have the proper amount of acid in the unit and that there are no bubbles.

    Thanks for the other links - I’ll continue to research…

    Off Grid, 4.5KW array, 9&6KW Gens, 6848XW inverter, Midnite Classic 150, 2 strings - 48V - Trojan FLA L16 2V, located in Talkeetna, Alaska
  • ELYNN4
    ELYNN4 Registered Users Posts: 137 ✭✭
    I tested the SG first thing in the AM, after the long Gen run time, with the refractometer and it read the same as the hydrometers the previous PM.  I have no idea why I’m getting these sporadic erroneous readings from the refractometer.  I’ve ordered a new one to see if it does any better.
    Off Grid, 4.5KW array, 9&6KW Gens, 6848XW inverter, Midnite Classic 150, 2 strings - 48V - Trojan FLA L16 2V, located in Talkeetna, Alaska