temperature compensation

petertearaipetertearai Solar Expert Posts: 366 ✭✭✭
hi . just installed  new sealed batterys . absorb volt is set to 28.2 volts .
 on my outback fm80 I can set the compensation to wide, or limit the upper and lower voltage . my previous battery's were flooded , and because flooded arnt so fussy on high voltage i set to wide . 
Anyway should i limit the upper temp compensated voltage to  the 28.2 volts . or alow it to go a little above that .
2225 wattts pv . Outback 2kw  fxr pure sine inverter . fm80 charge controller . victron battery monitor . 24 volts 450 ah surette batterys . off grid  holiday home 

Comments

  • littleharbor2littleharbor2 Solar Expert Posts: 1,112 ✭✭✭✭
    That voltage sounds like you have gel batteries. Yes?  Where did you get this setting from? Many AGM batterie mfr. are recommending voltages similar to fla absorb voltages.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • petertearaipetertearai Solar Expert Posts: 366 ✭✭✭
    Shoto exc series 2 volt 400AH-400
    Decided to try these lead carbon battery's.
    That is the voltage specified by manufacturer and supplier. So at this stage will stick to that. But would like to know if others let the compensated voltage to be above the set voltage .
    Thanks
    2225 wattts pv . Outback 2kw  fxr pure sine inverter . fm80 charge controller . victron battery monitor . 24 volts 450 ah surette batterys . off grid  holiday home 
  • EstragonEstragon Registered Users Posts: 3,039 ✭✭✭✭✭
    The manufacturer should spec temp compensation values and limits. I suspect the compensated voltage should be allowed to rise above the non-compensated reference voltage when/if the batteries are colder.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • jonrjonr Solar Expert Posts: 1,132 ✭✭✭✭
    That battery is rated for charging at 2.30~2.35 V/cell only at 77F.   Definitely apply temperature compensation to that figure.   If they don't give a figure, I'd probably use -5mV per ºC per 2 V cell.
  • petertearaipetertearai Solar Expert Posts: 366 ✭✭✭
    Thanks .. yep got confirmation from supplyer .. to set upper limit to 28.6 . So that's what ive done . Actually set to 28.5 to give a little more margin.
    Will be interesting to see how these go.. the specs are impressive. Will be strange not having to top up battery water . Ive recalibrated my battery moniter and with opticsRE working well I can keep a track of them . Got 8 years from my rolls S600 set , but that was with mostly weekend use .. hoping to spend more time at off grid home in future .
    Thanks for your replys .
    2225 wattts pv . Outback 2kw  fxr pure sine inverter . fm80 charge controller . victron battery monitor . 24 volts 450 ah surette batterys . off grid  holiday home 
  • jonrjonr Solar Expert Posts: 1,132 ✭✭✭✭
    You can use 27.9V @77C with an upper limit of 28.5V.  Just keep them above 15C.
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