Leaving the Equalizing Function Turned On?

Here in the north we are at the near-solstice shortest day-length time of the year with lots of cloudy weather (although bitter cold and more sun of late, yippee!)

One thing I have done this past couple of weeks is to turn on the equalling charge setting of my Solar Boost 2000E voltage regulator and leave it on all the time. My rationale is that the voltage rarely gets above 14.01 volts this time of year and when it does it's not for very long, so a little overcharging of the batteries in the 14.x volt range will probably not hurt them.

Am I right about that?

I am also wondering if any possible harm to the voltage regulator can result if the equalizing charge function is left on. I can't see why it would hurt the charge controller, but I'm wondering. Will it? Can it?



  • BB.BB. Super Moderators, Administrators Posts: 28,879 admin
    Re: Leaving the Equalizing Function Turned On?

    Not the battery expert here, but some questions I would ask:
    1. What is the temperature of the batteries? Are you charging to the appropriate voltages (when the sun is out).
    2. Is the controller temperature compensated and monitoring the temperature of the batteries. If the batteries are cold, it is possible that you are undercharging them.
    3. Are these sealed batteries... I assume they are flooded cell batteries and you are monitoring electrolyte levels.
    4. Have you fully charged/equalized the batteries at least once or twice a month (may require generator)?
    5. How do you know your batteries are getting fully charged every few days or week (if not equalizing).
    If your batteries are cold, it sounds like they may be undercharging at this point and that would be your first point to address.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,117 ✭✭✭✭
    Re: Leaving the Equalizing Function Turned On?

    I don't think that you are gaining anything. Unless the battery reaches full charge anyway, no additional power will be put in. If, on the other hand you are reaching full charge, why do you need the extra boost? Your mppt charger should maximize current into the battery regardless of conditions, and especially since it is so cold.

    As to a bit of over charging now and again, I don't think it will hurt much, but I don't see the point either.


    PS I second the opinion of watching the water and the battery temp.
  • System2System2 Posts: 6,290 admin
    Re: Leaving the Equalizing Function Turned On?

    If you have flooded type batteries, a little overcharge probably won't do a lot of harm. AGM or gel are a whole different thing.
    Sounds like your batteries are chronically undercharged, assuming they are out in a cold building or shed. In this cold weather, my MX 60 has boosted the absorb voltage for my L-16 bank from 14.6, to 15.3, likewise, the Float went from 13.8, to 14.6, and you say your batteries rarely get above 14.1?
    We need more information man.
    Type of batteries, type of controller, location of batteries etc.
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Leaving the Equalizing Function Turned On?

    putting the controller on permanent eq is a very bad idea. the problem you have is not enough charge current, but if the batteries do get close to being charged the eq setting could cook the batteries if left on. controllers are regulators and if you're not exceeding the regulation point it can't do its job of preventing overvoltages so get some power into those batteries leaving the controller to be used per instructions. worry about an eq charge when you get your batteries charged and then follow the recommendations for your batteries by the manufacturer. if the battery maker doesn't say then knowing the type of battery with the controller's instructions should be followed. any further questions ask.
  • paulstamserpaulstamser Solar Expert Posts: 86 ✭✭✭
    Re: Leaving the Equalizing Function Turned On?

    More info.

    My batts are wet cell golf car types. Controller is a Power Boost 2000E that does NOT have temp. compemsation but my batts are inside the house at room temp, around 70-80 F.

    In the controller booklet it gives a chart and at 80 f. the voltage cut-out point is 14 volts and that is where mine is set. So are my batts are being fully charged in that scenario?

    Either way maybe I shouldn't mess around by leaving the equalizing charge on.
  • BB.BB. Super Moderators, Administrators Posts: 28,879 admin
    Re: Leaving the Equalizing Function Turned On?

    Since they are wet cell batteries--get/use a good quality temperature corrected (although, probably not needed since your batteries are generally room temperature) hydrometer and measure the charge level. This is the best way to check your charge levels.

    It is possible that your state of charge may read low because of acid stratification (heavy/high specific gravity acid sinks to bottom of battery); equalization with bubbling will remix the acid.

    You can read Wind-Sun's Battery FAQ for a good overview.

    14.01 volts sounds a tiny bit low for daily recharging--but the better question is how long does the charger hold 14.01 volts and does the battery get fully charged and start bubbling or not.... The absorb charging voltage of 14.xx volts is more or less really a current limiting/bubbling limiting voltage and does not indicate the actual level of charge for the battery...

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 8,207 ✭✭✭✭✭
    Re: Leaving the Equalizing Function Turned On?

    Not being familiar with that model of charger, I can't say. I do know that my C-12 controller, counts days, and every 30 days, will initiate an Equalize Cycle. Many other controllers have this automatic cycle option. Only flooded cell batteries should be equalized.
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