What happened while I was away for 2 1/2 weeks?

softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
A month ago the absorb was 58.8, float was 54.6 - per battery specs. AM waking voltage was 50.5 - all seemed great. Then I left for 2 1/2 weeks. This is what I returned to a week ago:
Absorb: 59.1
Float: 55.0
AM waking voltage: 50.1

Pretty remarkable changes in 2 1/2 weeks. All without being here and very light battery usage as a result. 

I have checked everything else - figuring it was impossible for charge controller settings to change themselves. I will check CC settings soon.

Can a 3rd party change the setting via the Outback Flexnet (designed for remote monitoring via internet)? I just don't understand that much change while being away for a mere 2 1/2 weeks. It had been extremely consistent.

Checked CC - settings were not changed. Yet Absorb was charging at 59.1 instead of the set 58.8

All batteries show very low resistance levels. 
First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries

Comments

  • 67chevelle67chevelle Registered Users Posts: 6 ✭✭
    Temperature compensation?
  • AmpsterAmpster Registered Users Posts: 172 ✭✭✭
    Temperature compensation?
    Yup. When I inadvertently had temperature compensation enabled on my Outback Skybox that is how the Absorb voltage changed. 
  • BB.BB. Super Moderators, Administrators Posts: 32,027 admin
    That would be my first guess too.

    In years past there were some solar charge controllers that would display temperature corrected battery voltage (adjust displayed voltage to 25C/75F "room temperature voltage").

    You would not notice this unless a separate voltmeter was used to measure actual voltage).

    Is the battery back/room temperature falling now? (Something like +0.030 volts per falling degree C for a 23 volt battery bank... Or something like 10C/18F cooler now vs a few weeks ago).

    Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 9,363 ✭✭✭✭✭
    With all the smoke from the fires, we had a bit of a cool spell, which let my battery bank cool down about 6 degrees.  but this sunday, it's going back up !! heat wave.  fire season.    what could go wrong
    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 ,

  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    The battery temp did fall about 10F - I figure that explains about 1/2 of what has happened at most. 

    I disconnected the Outback Flex internet interface - made no measurable difference. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • AmpsterAmpster Registered Users Posts: 172 ✭✭✭
    Did you change your battery temperature compensation slope? That is how it is labeled in my Outback Skybox which has the charge controller integrated into the inverter.  Setting it to zero made all the difference to my system voltage deltas. 
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    No - not my style. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • AmpsterAmpster Registered Users Posts: 172 ✭✭✭
    No worries. When you get your SHTF Lithium pack finished you could change the slope then because Lithium doesn't need any temperature compensation. In the meantime keep an eye out for those temperature compensating gremlims that have been know to lurk when people are away.  :)
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    I'm going to try resetting to factory pre-sets for a couple days. Then probably try an equalize of the old 8Ds.

    This makes no sense. The batteries test the same as before. I went to great lengths to lower night time power usage - this was very successful until I left for a couple weeks. 

    Thanks!
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    edited September 2020 #11
    BB. said:
    That would be my first guess too.

    In years past there were some solar charge controllers that would display temperature corrected battery voltage (adjust displayed voltage to 25C/75F "room temperature voltage").

    You would not notice this unless a separate voltmeter was used to measure actual voltage).

    Is the battery back/room temperature falling now? (Something like +0.030 volts per falling degree C for a 23 volt battery bank... Or something like 10C/18F cooler now vs a few weeks ago).

    Bill
    Taking a closer look at this while wondering why colder weather had insignificant impact on voltage levels last year.

    10F is approx 4C.
    4 x .03  (BBs formula above) = .12
    .12 x 4 (48 volt system) = .48

    If this is correct then 10F temp drop should change 48V voltage from 50.5 to 50.1 (approx. ,48)

    But why didn't this happen last year? 

    If this is correct I should expect AM voltage levels of approx. 48.6V when the temps drop to the 35F range. (!!!)
    Was at 75F.
    Returned to 65F with a .4 drop in overnight voltage. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
Sign In or Register to comment.