Float Voltage Climbing

Alaska Man
Alaska Man Solar Expert Posts: 252 ✭✭
in Solar Beginners Corner #1
My Float Voltage was always 13.6, but it has been climbing 13.8 13.9 14.1 last night. Is this something I should be concerned about?

I thought perhaps my absorb time was to long so I set it back 1/2 half hour, the next day when I came home from work it was .1V higher.

When I'm not at home there is very little voltage just the inverter draw and 1/2amp from misc. stuff. The sun has been just pounding on the panels all month. It's been great.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #2
    What is the CC set at and is there temp compensation in play?
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • Alaska Man
    Alaska Man Solar Expert Posts: 252 ✭✭
    #3
    Yes temp sensor is installed, Classic is set to 13.6. Classic going?

    ETA............. I have been keeping that room colder lately.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #4
    Alaska Man wrote: »
    I have been keeping that room colder lately.

    THAT is probably what is going on. How cold and what is your temp adjustment per *C/*F set to?
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • Alaska Man
    Alaska Man Solar Expert Posts: 252 ✭✭
    #5
    I would have to check to be sure, but once you mentioned the Temp Sensor I had a (Doh'). moment. I'll check when I get home, if I remember. ;-)

    Temps out there have been in the 40°F range. Until recently the battery bank was kept about room temp. 64°-72°F for most of the winter months.

    Thanks.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #6
    Right, the longer you have the 'door open', the cooler the bank gets each day , reflected by the day to day small, increasing rise in Float voltage...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #7
    I'm sure you'll find it is related to temperature and therefore quite normal. My batteries are in an outbuilding, unheated, and although the controllers set to float at around 13.5 at room temp, when the batteries get really cold, the float makes it's way up to 14 and above. Then come Summer, it drops back down again.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,654 admin
    #8
    For example 45oF (7oC):
    • Vbatt = Vset - (0.005 volts per oC * per cell * # cells * (Tbatt - Tstc))
    • Vbatt(7oC) = 13.6 volts - (0.005 v/oc/c*6 cells * (7oC-25oC)) = 14.14 volts
    Note--You can insulate the remote battery temperature sensor with a block of Styrofoam (hollowed out) if attached to the side of the battery.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Alaska Man
    Alaska Man Solar Expert Posts: 252 ✭✭
    #9
    Right on!! Thanks gentlemen.
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