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Post by nsaspook on Feb 23, 2020 18:31:26 GMT
The Rover Elite 20 amp MPPT replaced the 10A PWM Renogy that was running perfectly for months. The new controller powers up and displays all voltages but will not start a charge cycle and send current to the battery when the Solar input voltage is 33vdc (open circuit) and the battery voltage is 24vdc. The manual is just about useless for troubleshooting. Is there anyway to make it start or is the unit just defective?
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Post by Admin on Feb 24, 2020 17:30:32 GMT
The Rover Elite 20 amp MPPT replaced the 10A PWM Renogy that was running perfectly for months. The new controller powers up and displays all voltages but will not start a charge cycle and send current to the battery when the Solar input voltage is 33vdc (open circuit) and the battery voltage is 24vdc. The manual is just about useless for troubleshooting. Is there anyway to make it start or is the unit just defective? Do you have a 24V battery bank system connected to your Rover Elite 20A MPPT controller, or were you getting an actual reading of 24V from your battery from a voltmeter or multimeter? The Rover Elite controller can accept up to 100VDC of maximum PV input voltage and up to 260W of power when using a 12V system and up to 520W of power when using a 24V system. If your batteries are going through the constant or float charging stages when connected to the controller, it may explain why there is a drop in current or hardly any current, but the controller should be functioning with charging cycles no matter what charging stages the batteries are in. -Renogy Team |
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Post by nsaspook on Feb 25, 2020 3:37:24 GMT
Yes, I have a 24vdc battery bank system. Using an adjustable 10A power supply instead of panels I see MPPT on the LCD screenat about 33vdc on the PV input terminal. The battery bank voltage is 24.30vdc and the charging current to the bank from the controller is about 0.6A. I see no charging stage on the LCD display but I do see a slow MPPT sweep testing the supply with a maybe 10W peak draw before it decreases power from the PV input.
What is the recommended minimum PV input voltage for a 24vdc battery bank system?
I'm an EE, so you can give me detailed specifications.
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Post by nsaspook on Feb 25, 2020 20:49:59 GMT
This the units charging profile. Each data point in the graph is 10 seconds. It waited a long time under about a 150W battery load (negative battery current) before starting any sort of charge cycle with a steady PV voltage of 33VDC. live.staticflickr.com/65535/49584517883_0776852955_b_d.jpg |
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russ
Solar Advocate
Posts: 63
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Post by russ on Feb 26, 2020 1:30:44 GMT
The Rover Elite 20 amp MPPT replaced the 10A PWM Renogy that was running perfectly for months. The new controller powers up and displays all voltages but will not start a charge cycle and send current to the battery when the Solar input voltage is 33vdc (open circuit) and the battery voltage is 24vdc. The manual is just about useless for troubleshooting. Is there anyway to make it start or is the unit just defective? What is your solar panels array voltage?
The advantage of MTTP is that it can take a much higher voltage (and lower current) and convert it to a lower voltage (and higher current) that you battery system needs with resonable efficiently.
For example: Two 100 watt 12 volt panels in parallel at will run current up to about 10 amps under ideal charging conditions. (With a no load voltage of about 20 volts.)
The same two 12 volt panels in series will top out at around 5 amps. That means you can run thinner wire with less voltage drop. (With a no load voltage of about 40 volts.)
A Rover Elite 20 amp MPPT charger can handle up to 100 volts from the solar panels and drop it down to charge a 12 or 24 volt system. A PWM charger can't typically do that.
If you are charging a 24 volt system with 24 volts of solar panels (40 volts, full sun, no load) you are not going to see a big advantage with MPPT over PWM. |
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Post by nsaspook on Feb 26, 2020 3:38:30 GMT
The Rover Elite 20 amp MPPT replaced the 10A PWM Renogy that was running perfectly for months. The new controller powers up and displays all voltages but will not start a charge cycle and send current to the battery when the Solar input voltage is 33vdc (open circuit) and the battery voltage is 24vdc. The manual is just about useless for troubleshooting. Is there anyway to make it start or is the unit just defective? What is your solar panels array voltage?
The advantage of MTTP is that it can take a much higher voltage (and lower current) and convert it to a lower voltage (and higher current) that you battery system needs with resonable efficiently.
For example: Two 100 watt 12 volt panels in parallel at will run current up to about 10 amps under ideal charging conditions. (With a no load voltage of about 20 volts.)
The same two 12 volt panels in series will top out at around 5 amps. That means you can run thinner wire with less voltage drop. (With a no load voltage of about 40 volts.)
A Rover Elite 20 amp MPPT charger can handle up to 100 volts from the solar panels and drop it down to charge a 12 or 24 volt system. A PWM charger can't typically do that.
If you are charging a 24 volt system with 24 volts of solar panels (40 volts, full sun, no load) you are not going to see a big advantage with MPPT over PWM. I understand that. My real question was about the DC to DC converter range but I've answered that by my own with no help from Renogy. live.staticflickr.com/65535/49586436172_5fce1b7cb7_h_d.jpgI needed to spec an input voltage for a external power supply to keep the battery bank charged with the sun won't shine here in Oregon. 33VDC is the trigger point for DC to DC converion using the Elite 20A. My battery DIY monitor will switch voltage inputs from PV to AC power supply as it tracks SOC to keep the system usable for emergency backup power. forum.allaboutcircuits.com/threads/project-solar-wind-pic-controlled-battery-array.32879/post-1472968 |
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russ
Solar Advocate
Posts: 63
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Post by russ on Feb 27, 2020 1:56:14 GMT
Nice project! I wish my bench was as well equipped as yours!
How much current will the external power supply be capable of supplying to the charge controller? And at what voltage?
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Post by nsaspook on Feb 27, 2020 3:28:03 GMT
7.5A It's a 27V switcher that can be adjusted to 33.5 volts so it will work as a PV clone. I like the elite as a functional unit but having additional information about the electrical and software parameters in an addendum would be nice. As I gather logging data from my monitor I should be able to make a few detail charts about efficiency and operational characteristics at varying MPPT points for 24v bank operation. I also have a few rs-232 to rs-485 converters so a peek into the remote port will be next. Do you know the pinout of the data socket on the controller?
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Post by nsaspook on Feb 28, 2020 0:34:48 GMT
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Post by nsaspook on Feb 28, 2020 21:26:23 GMT
A power efficiency chart. The top line GREEN is Elite input power. The next to top line ORANGE is Elite output power. live.staticflickr.com/65535/49596923063_9b1b5e3f6b_b_d.jpgThe power usage seem pretty constant at 8 to 10 Watts across all conditions. Low to mid 90% efficiency power transfer is not bad for the price of the unit. |
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russ
Solar Advocate
Posts: 63
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Post by russ on Feb 29, 2020 1:27:56 GMT
Thanks for posting the information. On your graphs, what is the difference between charge current and battery current? |
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Post by nsaspook on Mar 1, 2020 22:20:50 GMT
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Post by mediadogg on Mar 2, 2020 0:54:54 GMT
Props for this amazing thread.  I have been wanting to understand better what it takes to supply a DC input to a MPPT controller. |
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Post by nsaspook on Mar 4, 2020 22:00:03 GMT
I should have some MODBUS information on the unit today. I've got standard ROVER MODBUS comms with a few test programs after hacking a half-duplex 9600 8N1 interface for the rj45 jack.
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Post by nsaspook on Mar 4, 2020 22:28:43 GMT
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