PWM shows higher voltage reading

boyet888 Registered Users Posts: 1
Hello all! Newbie here.. I have just recently installed a basic dc system at home using 4pcs 30wp panels in parallel,  64ah lead acid batteries in parallel (2pcs 20ah, 2pcs 12.5ah). My concern is the pwm semper brand i used.. It shows a higher reading by 6volts when charging on peak hours and the same thing even at night when in standby. We just use our system for basic things like cp charging, occassional wifi,cctv and small fan, all in dc 12volts. With the given problem withmy scc, where can i base my float charge, with the scc w/c is off by 6volts higher than actual on the battery, or do i just refer to tha batteries actual voltage reading from a multi tester and just adjust the float charge level on the scc so my batteries show 13.5volts for float charge? 


  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,032 ✭✭✭✭✭
    6 tenths of a volt is not very much. You can't expect any kind of accuracy from a < $10.00 controller.

    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,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

  • Photowhit
    Photowhit Solar Expert Posts: 6,001 ✭✭✭✭✭
    Not a good practice to parallel 2 different type size, or type batteries;

    boyet888 said:
    "... 64ah lead acid batteries in parallel (2pcs 20ah, 2pcs 12.5ah). 
    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, 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.