Death of a charge controller?

softdownsoftdown Solar Expert Posts: 2,904 ✭✭✭✭
Declining voltage on forklift battery led a check on incoming voltage from panels. Bouncing, ultra low, readings is always bad. Went up on the roof and found over 41 volts from each panel in early morning sun. Combined voltage the same for use on a 24 volt system.

Voltage dropped to 36.5 volts incoming to charge controller. Declining readings while holding meter tips to panel wires. Low battery on voltage meter? Or? 

Reinstalled panel wiring to charge controller hoping that a faulty connection had been successfully addressed. Still no voltage reading at charge controller inputs for panels. 

Electrical stuff dies given enough time. This is probably something very small but hard to fix. No incoming voltage reading at charge controller is surely time to replace the charge controller. No? 

Charge controller is an Renogy MPPT Tracer. Roughly 4-5 years old. Used on a "screw around" back up system.

Could I have damaged the charge controller while charging/equalizing the battery with high amps? 

Going out - I'll be back hoping for good, ole trusty BB to weigh in. Perhaps others? 
First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries

Comments

  • BB.BB. Super Moderators, Administrators Posts: 30,037 admin
    5-10 year life for power supplies--About what I would expect for life.

    I am not sure I understand your array wiring.  One panel in series by x panels in parallel? 36.5 volts Vmp sounds about right for a 72 cell panel running MPPT or even a PWM (close to what I expect) charging a 24 volt FLA battery bank.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • EstragonEstragon Registered Users Posts: 4,451 ✭✭✭✭✭
    Seems to me it's at least possible for there to still be a connection or panel problem.  Measuring voltage open circuit (little/no current flowing) might read fine.  When current flows, resistance/heating/arcing in the bad connection causes voltage to sag?
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • softdownsoftdown Solar Expert Posts: 2,904 ✭✭✭✭
    BB. said:
    5-10 year life for power supplies--About what I would expect for life.

    I am not sure I understand your array wiring.  One panel in series by x panels in parallel? 36.5 volts Vmp sounds about right for a 72 cell panel running MPPT or even a PWM (close to what I expect) charging a 24 volt FLA battery bank.

    -Bill
    Used a couple spare 72 cell panels to run this auxiliary bank. Parallel connection so voltage runs ~40 - 45 volts at the panels. Lost five volts between the panels and the charge controller with this mornings readings - from 41 volts down to 36. Seems a bit high for line loss. But when hooked into the CC - reading 0 volts using CC terminals. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • PhotowhitPhotowhit Solar Expert Posts: 5,101 ✭✭✭✭
    I suspect   what you are seeing is the difference between Open circuit and working voltage (VOC  vs VMP)

    So did you check the voltage coming into the charge controller? If you are reading 36.5 volt  VOC  at  the charge controller,  you likely don't have enough voltage for the charge controller  to work or at least to work properly.  Reading zero volts by the CC is ugly though. I assume  you had connected the  battery  bank first?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • NANOcontrolNANOcontrol Registered Users Posts: 169 ✭✭✭
    Pop it on ebay, I'll buy it.  Still confused. You say it drops five volts and then say 0V at controller.
  • Raj174Raj174 Solar Expert Posts: 728 ✭✭✭✭
    Yup, those panels are perfect for charging a 24V battery with a PWM controller. MPPT, not so much.
    3600W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 54.4V 195AH LiFePO4 no BMS, Kohler Pro 5.2E.
  • softdownsoftdown Solar Expert Posts: 2,904 ✭✭✭✭
    Thinking we all missed this: "Went up on the roof and found over 41 volts from each panel in early morning sun." 

    Jumped the gun with measurements. Perhaps by a couple hours. Have too many projects going on I guess.

    Now questioning that voltage meter. Instead of declining readings, I am getting readings that grow while the meter beeps. 

    But something is clearly wrong since the battery has lost voltage. Just charging it half at a time with a 12V charger now - my 24V charger was stolen by somebody that my dogs clearly knew. 

    Guess it is time to try swapping out the CC.  Got a couple dozen projects going on right now....

    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 30,037 admin
    DMMs with weak/bad batteries--Can give very weird readings. Measuring voltage on your car battery, AC mains, etc. can give you some verification of your meter's accuracy.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • softdownsoftdown Solar Expert Posts: 2,904 ✭✭✭✭
    BB. said:
    DMMs with weak/bad batteries--Can give very weird readings. Measuring voltage on your car battery, AC mains, etc. can give you some verification of your meter's accuracy.

    -Bill
    Sounds like a really weak connection in the solar cable connections is quite possible. Wondering how to address that. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 30,037 admin
    If you have two or more parallel strings--You can use the circuit breaker to connect one string at a time and see which performs well or not... Then you have to start taking the connections apart one by one on the bad string (or all strings if nothing is working correctly) until you find a loose/corroded/etc. connection or failed crimp.

    Do you have a DC current clamp meter? If so, you could always eliminate the charge controller and connect the array directly to the battery bank and measure the current from the array (Imp--From 50% to 100% typical readings in full sun near noon).

    Or get some power resistors (or a few 12 volt bulbs connected in series (2x12 volt = 24 volts, 3x12 = 36 volts, etc.). A 12 volt filament brake lamp will draw about 2.1 Amps. Usually enough loading that will help you figure out where the bad connections are and when you have fixed them. An 1157 dual filament bulb brake and tail lamp (the tail lamp is probably around 0.2 to 0.3 amps or so) is only ~$1.00

    You may have to test each panel--It does happen that one panel or J-Box gets water inside/fails. And in relatively rare cases, you could have a shorted by-pass diode (diodes can fail either open or shorted).

    Testing each panel for Voc and Isc (open circuit voltage and short circuit current) will find 80-90% of the bad panels... Adding a load (like a 12 volt battery or 12/24 volt brake lamp load) will weed out the other 10-20% of failures.

    If you do not have a DC Current Clamp Meter, now is a great time to get one... $50 or less for cheaper ones, $100 or so for pretty nice ones, or >$350 for a nice Fluke meter.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • softdownsoftdown Solar Expert Posts: 2,904 ✭✭✭✭
    edited August 2019 #12
    BB. said:
    If you have two or more parallel strings--You can use the circuit breaker to connect one string at a time and see which performs well or not... Then you have to start taking the connections apart one by one on the bad string (or all strings if nothing is working correctly) until you find a loose/corroded/etc. connection or failed crimp.

    Do you have a DC current clamp meter? If so, you could always eliminate the charge controller and connect the array directly to the battery bank and measure the current from the array (Imp--From 50% to 100% typical readings in full sun near noon).

    Or get some power resistors (or a few 12 volt bulbs connected in series (2x12 volt = 24 volts, 3x12 = 36 volts, etc.). A 12 volt filament brake lamp will draw about 2.1 Amps. Usually enough loading that will help you figure out where the bad connections are and when you have fixed them. An 1157 dual filament bulb brake and tail lamp (the tail lamp is probably around 0.2 to 0.3 amps or so) is only ~$1.00

    You may have to test each panel--It does happen that one panel or J-Box gets water inside/fails. And in relatively rare cases, you could have a shorted by-pass diode (diodes can fail either open or shorted).

    Testing each panel for Voc and Isc (open circuit voltage and short circuit current) will find 80-90% of the bad panels... Adding a load (like a 12 volt battery or 12/24 volt brake lamp load) will weed out the other 10-20% of failures.

    If you do not have a DC Current Clamp Meter, now is a great time to get one... $50 or less for cheaper ones, $100 or so for pretty nice ones, or >$350 for a nice Fluke meter.

    -Bill
    Thanks! Looking at my Ideal 61-768 - appears to be a Clamp Meter. https://www.tequipment.net/Ideal61-768.asp

    What I need - learn another "skill" right now. When it rains, it pours. 

    Looking at the pdf in the above link - it shows ac clamp meter capabilities. Then it says this: Note: 61-768 model also measures DC Current.  
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 30,037 admin
    The -768 model is discontinued--If you can find one for a reasonable price, it looks good.

    Note, the link to a "replacement" meter--But that one is an AC only Current Clamp meter.

    I highly suggest playing with your car electrical system. Put the clamp on one of the battery leads, and play with lights/radio/engine off/engine running/etc. so you can get some practice.

    Note that most (all?) DC Current Clamp meters set on DC need to use a "ZERO" button of some sort... They use a Hall Effect Transistor which "drifts" over time and temperature.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • NANOcontrolNANOcontrol Registered Users Posts: 169 ✭✭✭
    I have a UNI-T UT210E and for $40 it has a pretty nice DC current clamp that goes down below 10ma and up to 100A.  Quite handy for quick measurements of current without disrupting the wires too much.
  • softdownsoftdown Solar Expert Posts: 2,904 ✭✭✭✭
    BB. said:
    The -768 model is discontinued--If you can find one for a reasonable price, it looks good.

    Note, the link to a "replacement" meter--But that one is an AC only Current Clamp meter.

    I highly suggest playing with your car electrical system. Put the clamp on one of the battery leads, and play with lights/radio/engine off/engine running/etc. so you can get some practice.

    Note that most (all?) DC Current Clamp meters set on DC need to use a "ZERO" button of some sort... They use a Hall Effect Transistor which "drifts" over time and temperature.

    -Bill
    I also own the Ideal 61-766 https://www.tequipment.net/Ideal61-766.asp

    Too bad I don't know how to use 90% of the functions. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 30,037 admin
    The -766 is also an AC only current clamp meter...

    Many of the functions, you really only learn to use the ones you need to use... The rest, can be neat for debugging (frequency for genset RPM/AC line frequency issues), and capacitor function is nice for capacitor start/run induction motors and finding out why the motors are not starting/running at speed (possible bad capacitor).

    This meter (and similar) has a ~3,000 Ohm resistor on the voltage meter leads (selectable resistor on or off)... It does not draw much current, but it is nice for that "problem" with DMMs when you measure a voltage that seems good, but the DMM draws so little current (uAmps) that you don't know if you have "good connections" or are just reading the leakage current through a corroded connection (sort of your "possible" problem with the array).
    • Low Impedance (LoZ) mode for identifying and eliminating ghost or stray voltages
    https://www.amazon.com/gp/product/B019CY4FB4

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • softdownsoftdown Solar Expert Posts: 2,904 ✭✭✭✭
    BB. said:
    The -766 is also an AC only current clamp meter...

    Many of the functions, you really only learn to use the ones you need to use... The rest, can be neat for debugging (frequency for genset RPM/AC line frequency issues), and capacitor function is nice for capacitor start/run induction motors and finding out why the motors are not starting/running at speed (possible bad capacitor).

    This meter (and similar) has a ~3,000 Ohm resistor on the voltage meter leads (selectable resistor on or off)... It does not draw much current, but it is nice for that "problem" with DMMs when you measure a voltage that seems good, but the DMM draws so little current (uAmps) that you don't know if you have "good connections" or are just reading the leakage current through a corroded connection (sort of your "possible" problem with the array).
    • Low Impedance (LoZ) mode for identifying and eliminating ghost or stray voltages
    https://www.amazon.com/gp/product/B019CY4FB4

    -Bill
    Says this for the 768 though: "Note: 61-768 model also measures DC Current" Not sure what hoops may have to be run through for that functionality however. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 30,037 admin
    There is an AC and a DC current setting. You just flip to the mode you wish.

    Now, here is where it gets tricky. "Cheap" meters just message peak voltage, and if AC mode assume sine wave and divided by the square root of 2 to get the RMS value. Of course, this is only accurate for sine waves.

    And most meters I have used (non-true RMS reading) use a blocking capacitor so the meter measures only AC values on AC mode and DC values for DC mode.

    The few true RMS reading meters I have used will actually calculate RMS value of wave form. Where this matters is when you have AC+DC values added together. Not common around the home but can be a pain if you want to (for example) measure ripple voltage on a 12 VDC battery bus (RMS of 12 VDC with 0.5 volts of AC ripple is just a little over 12 volts RMS).

    A cheap meter will measure 12 VDC in DC mode and 0.5 volts in AC mode.

    What happens with AC vs DC in current clamp mode... I have no idea.

    "Knowing your tools" can be very important when you are pushing the envelope.

    Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • softdownsoftdown Solar Expert Posts: 2,904 ✭✭✭✭
    The Renogy MPPT Tracer charge controller seems to be fine. Except for the demon goat eating the manual of course

    I just can't find satisfaction when I try to use the BP solar panels. When I replaced the BP panel feed with extra Grape Solar panel feeds, everything was fine. 

    The BP panels read comparable voltage but they don't power the charge controller. They were all part of various experiments involving some inexpensive solar power cables. Then I replaced the MC3 connectors with MC4 and those connections may be sub par. Nothing worse than reading voltage and not being able to use it. Could be panels. Could be wiring. Could be connections. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • littleharbor2littleharbor2 Solar Expert Posts: 1,481 ✭✭✭✭
    Are they BP 170 or 175 watt panels? Those vintage size panels have been failure prone, to the point that they pretty much put BP out of business. You should take them, one by one and test their output. Be especially observant of voltage output while wiggling the wires at the back of the panels. Their strain relief wasn't effective and allowed the output cable connections to fail. Some of their panels would seem ok while performing these simple tests but would fail under load in the array.

    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, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • softdownsoftdown Solar Expert Posts: 2,904 ✭✭✭✭
    I suspect they are 170 watt panels. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 30,037 admin
    My BP 175 panels failed current testing (probably Isc)... They were obviously bad because they could not even carry 50% of Isc on a sunny day.

    Compare panels. You may have some that are fine and others that have failed--That will give you a good way of "validating" your testing.

    Even if you are doing voltage tests, I would still have some sort of load/resistor/old electric heater/etc. to get some current flowing while you are testing under full sun. If connections are going higher resistance, you need to pull current to get a voltage drop across the failure.

    Just measuring voltage with a DMM (draws micro amps of current) will generally not show high resistance failures.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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