P30L overcharging

Discussion in 'Charge Controllers' started by vermontaircooled, Jul 7, 2019.


Do you run “big” charge and panel cables? 3 choices:

Poll closed Feb 7, 2020.
  1. 10ga charge cables?

    0 vote(s)
  2. 8ga charge cables?

    0 vote(s)
  3. 10ga panel cables?

    0 vote(s)
  4. 8ga panel cables?

    0 vote(s)
  5. extra point: 6ga for 30A output?

    0 vote(s)
Multiple votes are allowed.
  1. I’ve had my two 100 W panels running for a few weeks but just 2 days back replaced the panel cables with 20’ of the 8 gauge Windy Nation made-up cables w/MC4s already installed.

    It made such a big difference! I never saw 13.8V until yesterday (day two on 8ga; display read, “PV Off,” and was very startled today to see 14.0 volts but with a 4.5A charge rate. Previously (on the smaller cables) I’d had seen a best of 5.2A, never saw the panels “off,” and had what I considered to be a low performing system. Yesterday I saw 8.4A at one point - maybe only a few amps more but that’s a nearly 50% performance gain. A pretty big deal imho.

    I joined the WN forum today after reading for a while here. To wit, what I’ve read discusses the P30L auto equalizing to 14.4-14.8V. I’ve not seen that voltage. It made me ask questions.

    My concern is that I don’t want to be “boiling” my batteries.
    My batteries are older marine deep cycle flooded cell batteries. One of them admittedly is “weaker” but holds 12.3/12.5V fine. I know one is supposed to match/pair them equally...

    Q: Will the P30L maintain 14.0 volts like “all day” if my batteries won’t absorb to 14.4V? Or does it just ‘try’ for an hour and move on so to speak?

    I wish the user manual discussed the operating characteristics further.

    Thank you
    Mark - in Vermont
  2. Tuicemen

    Tuicemen Solar Guru

    Although I dont use the pl30 I do use large diameter cables (larger then your poll choices) for all my runs. DC loses can be lessened with using the larger cables but also keeping them as short as possible. My charge controler and inverter are less then 5 feet from my batteries. My panels are 75 feet from my charge controler using 2 gauge wire. I've also switched to 24 volt which allows smaller gauge wire for the same distances.
    Most charge controlers continue the equalization for only a set time however they require the voltage for that time. If your not seeing the 14.4 voltage from your panels at the controller it will not go into equalization mode. However I suspect the controller will keep trying.

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