Inverter over volt alarm

PluckaPlucka Registered Users Posts: 128 ✭✭
I increased my solar panels and now my inverter shows 15 volts [was always .2 of a volt difference to the battery reading ] and it's alarm goes off but my lithium batteries show 14.6 volts. Voltage  drops when I turn appliances on. The question is my inverter faulty or is there another problem. I have split the system into two feeding one set of batteries -Solar controllers are are epever and renogy 30 amp each. Thanks.     PS.   just noticed Renogy has stopped charging but Epever is still putting out 8 amps when it should have stopped charging. I'll replace it .


  • BB.BB. Super Moderators, Administrators Posts: 32,601 admin
    Plucka, I know you know all of the stuff I am going to type below--But just to make sure the bases are covered---

    A good place to start is to measure the DC voltage at the major points in your system... At the Battery Bus, at the terminals of each of the charge controllers, at the DC input to the inverter--Etc... Hopefully under charge and/or under load. (check all terminals are clean and tight--You can even, carefully, touch each set of terminals/wires/connections and make sure they are not getting warm/hot--Higher than normal resistance generates heat when current is flowing).

    What is the brand/model of your AC inverter... Many of them are set to alarm at 15.0 volts... This has been an issue with industrial batteries which require 16 volts or more, and for our friends in the great white north (cold batteries, elevated charging voltages).

    Some of the more sophisticated inverters can have programmable alarm points. Newer (it seems) inverters are rated to 17 volts or so max...

    And any alarm point has its own errors... A few 0.10's of a volt off one direction or another can make the alarm trip more often (even your voltmeter may be off by a 1/10 of a volt or so)...

    Lithium Ion, no temperature offset--So make sure the charge controllers do not have the -0.003/-0.005 mV per C per cell offset. 

    I suggest "star" wiring... All the major components (each charge controller, each AC inverter, etc.) is "home run" back to the battery bank... Don't (for example) start the wire at a charge controller, then daisy chain to the AC inverter, then to the battery bank--The "voltage rise" of the current from charge controller to inverter to battery bank can raise the voltage a few 1/10's too (current, wire AWG, length, etc.) all can make things better or worse.

    If your inverter is not an inverter-charger, and is alarming when the battery bus is at 14.6 volts--And you measure the same on the inverter's DC input, and in the inverter alarm is not programmable--Then it may be time to get a new inverter with a ~17 VAC max input voltage anyway... The inverter may be repairable... Under warranty, just cost of shipping(?). If not under warranty, may be difficult to get repaired/if older than 5 years/if obsoleted/if built overseas/etc... May not be able to get required or worth repairing (assuming 5-10 year typical life of power electronics).

    And if you are looking at a new inverter--Is this the time you want to look at 24 or 48 volts? 

    Before replacing the Epever--Disconnect array, then the battery bus connection (or turn off breaker(s))--Wait 1 minute and connect battery bus first, then the array (reset controller). Check programming (something changed, corrupted settings memory, etc.).  Check charging voltage @ 8 amps on Vbatt terminals (just make sure that Epever is reading correct Vbatt voltage)...

    I don't think you have any noise on the battery bus (brush DC motor making a lot of electrical noise on battery bus), Check all electrical connections for tightness. If inverter alarms, and Vbatt is less than Vmax input--Clip the buzzer out of the inverter and get on with life.... Save money for new inverter...

    Any recent lightning? If DC wiring is not routed side by side (+/- cables)--And there are big loops (+ and - take different routes)--The loops can act like antenna and feed spikes into the DC Bus (nearby lightning strikes can have a lot of RF energy). If lighting in the area--Do you have nice surge suppressors on the DC Battery bus, Solar Bus, and AC inverter output? (lightning tends to "take out" AC inverter output more often than anything else). If fixed installation, DC negative tied to earth ground/water pipe/etc... As well as AC ground/AC neutral to ground bond... Check inverter for dust and literal "bugs" (blow out with compressed air--Fans can draw a lot of dust/dirt/pet hair into electronics). If taking inverter apart, re-seat connectors.

    About all I can think of at the moment...

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PluckaPlucka Registered Users Posts: 128 ✭✭
    Thanks Bill, I was working my way through your suggestions when in frustration I pressed both buttons on the epever solar controller together several times and BINGO everyting corrected it's self and has been working fine since but i'm still lost as to what caused the problem.
  • BB.BB. Super Moderators, Administrators Posts: 32,601 admin
    Perhaps hidden reset button combination?

    As always, check the programming and make sure set points are correct/still correct.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • paul12345paul12345 Registered Users Posts: 6 ✭✭
    I have this issue whenever I equalize the batteries. There a remote switch I use to switch off the inverter, otherwise the over-voltage alarm goes off. Bit of an issue as my fridge is then turned off, but 2 - 3 hours of equalizing and it's done so could be worse.
    5x 150w panels through PWM TriStar TS-45, additional 2x 150w panels through 2x unbranded PWM controllers, all charging 440 AH battery bank.
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