Battery charging

Plucka
Plucka Registered Users Posts: 130 ✭✭
edited June 2019 in Solar Beginners Corner #1
Output at the charge controller is a total of 40 amps over a 9 hour day-How many amps does tthis actually put into the 12 volt lithium battery over this period ?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,639 admin
    #2
    You really need a Battery Monitor or Amp*hour/Watt*Hour meter to know... But, for example:
    • 80 Amp*Hours of capacity (or charging capacity) / 9 hours = 8.9 amps of fixed current (for that 9 hour period).
    True Battery Monitors are expensive, but if you want something quick and dirty (and amazingly cheap)--There are DC AH meters that work pretty nicely:


    Otherwise, you have to check the actual current draw (i.e., 20 amps first hour, 10 amps second hour, 2 amps third hour ~ 32 AH of stored current).

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Plucka
    Plucka Registered Users Posts: 130 ✭✭
    edited June 2019 #3
    I don't have the setup at the moment -just working out what I need. Plan is a 200 watt panel with an ouput of 40 amps to recharge 100 amp/hr lithium battery if I discharge up to 80% .  Thanks
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,639 admin
    #4
    What Vmp and Imp of solar panel.

    What charge controller (MPPT or PWM)?

    What voltage li ion battery bank?

    Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • PNW_Steve
    PNW_Steve Registered Users Posts: 79 ✭✭
    #5
    Plucka said:
    I don't have the setup at the moment -just working out what I need. Plan is a 200 watt panel with an ouput of 80 amps to recharge 100 amp/hr lithium battery if I discharge up to 80% .  Thanks
    Reality check......  A 200watt panel with an output of  80amps.....?

    Not sure if I have ever seen one of those. 
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  • Wheelman55
    Wheelman55 Registered Users Posts: 246 ✭✭✭
    edited June 2019 #6
    Plucka...give the team here the data on your system and they’ll then actually help you.

    I am an amateur, however I do have specific experience charging a 100ah Battleborn lithium battery with a 180 watt Zamp Solar portable/folding panel.  I use this to power two ARB dc fridges.

    Zamp rates this panel w/PWM controller at 10 amps, which is close.  In full sun I get up to 9.9 amps.  Full sun happens on a clear day, with the panels pointed directly at the sun, between approximately 10am to 2pm.  Google search for more info.  During non “full sun” hours this system will harvest fewer amps.  On cloudy days my system produces very few amps...less than 1 amp usually.

    I use 15 to 25 amp hours from dusk to dawn.  If I’m willing to “chase the sun” with my panels by keeping them aimed at the sun, I get my battery charged up by noon.  This is on a full sun day.  

    To make it simple, a system that produces 10 amps in full sun would harvest 10 amps x 1 hour or 10 amp hours in that hour’s time. Replacing 80 amp hours would take 10 full sun hours with a 10 amp system, which would take two days of full sun.

    If you really do need 80 ah per day, you’ll need a stronger system than the one that I use.  A 20-25 amp output might be needed.  

    Once again...provide the experts with your info and they’ll guide you.

    Good luck!
    Off-Grid in Terlingua, TX
    5,000 watt array - 14 CS 370 watt modules. HZLA horizontal tracker. Schneider: XW6048NA+, Mini PDP, MPPT 80-600, SCP. 390ah LiFeP04 battery bank - 3 Discover AES 42-48-6650 48 volt 130ah LiFePO4 batteries
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  • Plucka
    Plucka Registered Users Posts: 130 ✭✭
    #7
    Solar panel=IMP 11.11A---VMP 18v-----mppt-----12 volt
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #8
    Plucka said: Solar panel=IMP 11.11A---VMP 18v-----mppt-----12 volt
    Not many MPPT controllers are going work with an 18V input on a 12V battery
    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 ,

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,639 admin
    #9
    For an PWM charge controller, very roughly, with a fixed array for Perth Australia, your charging with this panel would look like:
    http://www.solarelectricityhandbook.com/solar-irradiance.html

    Perth
    Average Solar Insolation figures

    Measured in kWh/m2/day onto a solar panel set at a 58° angle from vertical, facing north:
    (For best year-round performance)

    JanFebMarAprMayJun
    7.51
         		7.31
         		6.53
         		5.46
         		4.29
         		3.89
     
    JulAugSepOctNovDec
    4.05
         		4.69
         		5.80
         		6.54
         		7.06
         		7.39
     

    June with 3.89 hours of sun, on a PWM charge controller would be roughly:
    • 11.11 Amps Imp * 3.89 hours of sun (June average day) = 43 Amp*Hours per average June Day into a "discharged" Li Ion battery bank
    Li Ion batteries tend to charge "more ideally" than Flooded Cell Lead Acid batteries... (typically no "absorb" time for Li Ion).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Plucka
    Plucka Registered Users Posts: 130 ✭✭
    edited June 2019 #10
    I'm so dumb-I took measurements every 1/2 hour and added them up as hourly.80 amps is 40 amps on a flat roof that gets very hot .
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  • mike_s
    mike_s Registered Users Posts: 157 ✭✭
    #11
    Plucka said:
    I'm so dumb-I took measurements every 1/2 hour and added them up as hourly.80 amps is 40 amps on a flat roof that gets very hot .
    It seems you mean Amp-hours. When you say simply "amps" it's completely wrong and confuses the discussion. 
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