Absorb time and such..

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ywhic
ywhic Solar Expert Posts: 621 ✭✭
in Off Grid Solar & Battery Systems #1
Um..

I need a recommended Absorb min/max TIME for when I get the Midnite Classic 150 in next weekend..

I'll be doing 14.4 Absorb Voltage.. the battery bank will be starting at 440ah worth of FLOODED battery..
(4 * 6v GC2 220ah types).. wired 2 in series then 2 in parallel..

So is 30 mins and 2 hours the standard numbers to plug in here?? I saw a Midnite video showing those numbers as default..

Also, What should be my FLOAT voltage??

I figure I will set the Equalize to 15.3 volts..

Suggestions??
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  • silvertop
    silvertop Solar Expert Posts: 155 ✭✭✭✭✭
    #2
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    Re: Absorb time and such..
    ywhic wrote: »
    Um..

    I need a recommended Absorb min/max TIME for when I get the Midnite Classic 150 in next weekend..

    I'll be doing 14.4 Absorb Voltage.. the battery bank will be starting at 440ah worth of FLOODED battery..
    (4 * 6v GC2 220ah types).. wired 2 in series then 2 in parallel..

    So is 30 mins and 2 hours the standard numbers to plug in here?? I saw a Midnite video showing those numbers as default..

    Also, What should be my FLOAT voltage??

    I figure I will set the Equalize to 15.3 volts..

    Suggestions??
    This all depends on your batteries. I set my system when it was 12 v ( now 24v) like this: Bulk/Absorb 14.8v Float 13.2v EQ 15.6v. I use 4HR Absorb max. time in the summer/ 5 HR Absorb Max time in winter I also use the exit current of 2% of battery cap, ( Ex: 440 AH= 8.8 A exit cur.)this will send it to Float if Amps drop below this setting. Exit cur. doesn't allways send you into float if you are running loads all day so this 4 Hr is a failsafe .......
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #3
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    Re: Absorb time and such..

    What does your battery manufacturer recommend for their batteries? Different types/designs/makes and models often have different recommendations to match their product.
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  • petertearai
    petertearai Solar Expert Posts: 471 ✭✭✭✭
    #4
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    Re: Absorb time and such..

    absorb time set to batery manufactures recomementation. End amps is a good thing to set also. Set the absorb to forever, then watch the amps it will get to a pont where the amps gets to a steady point for 15 minutes or so . This is then what you set the end amps to(maybe 1 amp above that). This has to be done with no loads.
    The beauty of having a time as well as end amps is, that while your not there the amps will get to this end amps set point very quickly, and the change over to float.
    2225 wattts pv . Outback 2kw  fxr pure sine inverter . fm80 charge controller . Mate 3. victron battery monitor . 24 volts  in 2 volt Shoto lead carbon extreme batterys. off grid  holiday home 
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #5
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    Re: Absorb time and such..
    waynefromnscanada wrote: »
    What does your battery manufacturer recommend for their batteries? Different types/designs/makes and models often have different recommendations to match their product.
    It's hard to know with Proposed / Hypothetical batteries, things seem to change often. If they are Interstates their recommended Absorb is 15.5 v on every charge cycle is crazy at best.

    http://www.batteries-faq.com/activekb/questions.php?questionid=1
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  • ywhic
    ywhic Solar Expert Posts: 621 ✭✭
    #6
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    Re: Absorb time and such..

    I figured 14.4 Absorb and 13.6 Float for the battery.. based on the numbers I got form the mfg sheets..

    I read online someone said 30 minutes for every 100Ah of battery bank for absorb time settings..

    I will be running an 550 watt window A/C during the summer time months at peak SUN hours (using the panel juice mostly).. so the beating on the battery bank will be about 30-40% DOD..

    Rather not get into End Amps yet.. I don't have a shunt to test and want to a basic number to plug in for min/max for the time.
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  • jeffkruse
    jeffkruse Solar Expert Posts: 205 ✭✭✭
    #7
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    Re: Absorb time and such..

    Set the Absorb for the max amount of time. Try 14.6V for absorb. Measure your SG every day. I think you will find it slowly getting less and less if you use your AC much. Then you may even need to set your absorb V to 15V. You need to get every watt you can.
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #8
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    Re: Absorb time and such..

    I know your looking at lower end inverters, you might check the high voltage shut down/alarm some go off at 15/30volts, the Classic has a push button equalize, which might be easier, so you know you can just shut down your inverter...
    ...things to think about.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • ywhic
    ywhic Solar Expert Posts: 621 ✭✭
    #9
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    Re: Absorb time and such..

    Yup... thank you for the reminder..

    The ones I am looking at are 15.3 and 15.5 V for overload (Samlex or Xantrex).. but correct better maybe just to shut off the inverter for the EQ when needed..
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #10
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    Re: Absorb time and such..

    Hi Al,

    The required Asorb time depends upon the DOD of the battery bank. The deeper the DOD, the longer the required Asorb.
    End Amps is a good way to end Asorb, but using EA from a CC can be difficult depending upon other loads on the system -- usually Inverter loads.

    A smart battery monitor can help, because the BM uses a Shunt in the neg lead of the batts to measure actual charging current into the batts.

    Monitoring the SGs often is the best was to tell how you are doing in recharging your batteries. Many of us are waiting for a good monitoring/control solution from MidNite Solar, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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