Bulk and absorption settings

Masterjoe
Masterjoe Registered Users Posts: 86 ✭✭
in Off Grid Solar & Battery Systems #1
Since this is an oversized array with flooded lead acid batteries would setting the bulk and absorption voltages the same for the inverter/charger and CC the same voltage at 29.4? I know I read in the manual the bulk voltage can be set higher than the absorption voltage. I was thinking perhaps bulk 29.4 and absorption voltage at 28.8.
4.5kw 24v System
18 Solartec 250w polycrystalline panels
Xantrex XW4024 Inverter/Charger
Conext MPPT 80-600 Charge Controller
12 Trojan L16G-AC 20 hour 390ah batteries tied in 3 strings at 1170ah total
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #2
    The advantages of the boost charge would be primarily benificial in daily cyclical applications such as off grid, since you are using the batteries for backup, it's probably best to keep the bulk/absorb the same, using the manufacturers recommendations, Trojan L16 is 29.64V, check their website for your particular model. Usually the voltage for the boost would be higher than normal ~30V for the first hour of absorption, then dropping down to normal. Setting a normal value, then dropping to a value too low would likely result in undercharging and loss of capacity over time, which may go unnoticed, until the day the power failure happens. I would highly recommend contacting Trojan and ask the question directly.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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