Midnite solar meter

DConlyGuy
DConlyGuy Registered Users Posts: 80 ✭✭
in Solar Product Reviews & Opinions #1
for last 8 or so months, been thinking my battery's were off for some reason. now i found out why. bought one of those midnite solar meters and the darn thing says im down to 60% most nights before i shut down for the night. for some reason never looked at a chart for battery state of charge chart,just belived the meter and bang there it is, my battery's never go below the 90% mark on all the charts ive seen  asmy battery voltage very rarely go below 12.5 on any other meter i have. From now on im just  gonna  use the meter that goes with my charge controller and stick with it. just gonna chalk it up to  55$ loss
600 watts of solar panels,Epever 30 mppt , 2 PWHR12500W4FR battery's in 24 volt setup
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #2
    The Midnite BCM battery monitor is a voltage based monitor. Voltage based battery monitors are NOT a good method of determining the State of Charge (SOC). This would include checking the voltage at any point in the system for the same information. When you are shutting down your system for the night, it likely has loads running or recently run and not at rest. It might do you some good to first check to be sure the monitor is setup correctly and then check the voltage at the monitor when you are about to shut down.

    I don't know how you have the monitor wired or setup, but likely the Midnite should be in the ballpark at the monitor. If you are checking the voltage at the battery, understand that this is NOT the voltage that the monitor is seeing.
    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 backup...lol), 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.
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #3

    Hi DC..,

    The MNBCM  monitors how long since the battery has received a full-charge,  and from that point,  is uses only battery voltage,  which is not compensated (by measuring actual battery temperature with a  BTS):
    http://www.midnitesolar.com/pdfs/batCapMeter_frontBack.pdf

    So,  there will be the temperature effects on battery voltage,  causing inaccuracy,  AND  the inaccuracy of measuring battery voltage of a battery that has not been Rested (Resting is when a battery has not received any charge or discharge for many hours,  like 12 hours).

    Voltage is generally not an accurate indication of State Of Charge (SOC) of a battery.

    If your 235 Ah batteries are Flooded,   SG measurements are the Gold Standard of battery SOC.

    Vic

    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • DConlyGuy
    DConlyGuy Registered Users Posts: 80 ✭✭
    edited November 2016 #4
    the battery and the monitor and charge controller all with a foot of each other and they are inside the house so no big temp swings. i knew it was just a voltage measuring thing but im still sitting at 12,54 volts at 10 pm and darn thing saying i used 40%, i just think i got a defected one and didnt know it.
    600 watts of solar panels,Epever 30 mppt , 2 PWHR12500W4FR battery's in 24 volt setup
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #5
    DConlyGuy said:
    the battery and the monitor and charge controller all with a foot of each other and they are inside the house so no big temp swings. i knew it was just a voltage measuring thing but im still sitting at 12,54 volts at 10 pm and darn thing saying i used 40%, i just think i got a defected one and didnt know it.

    What are you using to measure the voltage? just the charge controller?

    Did you setup the jumper on the monitor for your battery type?

    Midnite is pretty good about replacing or helping people, have you contacted them or posted on their forum?
    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 backup...lol), 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.
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  • DConlyGuy
    DConlyGuy Registered Users Posts: 80 ✭✭
    #6
    checked voltage with charge controllers monitor it victron blue stuff and a regular volt/ohm meter ,yes jumper for 12 volt was on and the jumper for battery type was off for fla battery's as it should be 
    600 watts of solar panels,Epever 30 mppt , 2 PWHR12500W4FR battery's in 24 volt setup
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #7
    DConlyGuy said:
    checked voltage with charge controllers monitor it victron blue stuff and a regular volt/ohm meter ,yes jumper for 12 volt was on and the jumper for battery type was off for fla battery's as it should be 

    Midnite forum;

    http://kb1uas.com/mnsforum/index.php?PHPSESSID=02e3232812c9935674cf2fc388a9dd2b&

    Midnite Support;

    http://www.midnitesolar.com/support.php
    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 backup...lol), 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.
    · Share on Twitter

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