I have a Coromal caravan at the workshop with one of these Solarking SD2430S controllers fitted. Looking on the web it suggests they are an MPPT controller, but I can't find the exact part number to get the specs, just Solarking products with similar part numbers.
The bit that has me wondering just what control form it uses is that it stops charging every cycle of the display to show battery voltage and that is generally associated with an MPPT controller. The solar voltage displayed is only around 0.1v to 0.2v above battery voltage and that is a characteristic of a PWM controller. The solar output is woeful, so I'm not sure if it should be wired with the panels in series for an MPPT type controller, or parallel for a PWM controller.
Can anybody shed some light on the true make up of this controller?
T1 Terry
dorian said
12:02 PM May 16, 2019
Open it up and show us the PCB. One of us should be able to tell you.
T1 Terry said
12:59 PM May 16, 2019
I'll give that a try as a last resort. Most probably has some sort of security seal that null and voids any warranty claim if the seal is broken.
The latest weird behaviour is the current jumped up to double the previous output when the battery voltage was dragged below 12.6v. Looking at one of the manuals for a different part number unit it mentions the unit returns to boost mode once the battery voltage drops below 12.6v. Strange that it doesn't try to hold the float voltage at 13.8v with all the throughput it has available, but who knows what logic the programmer was using when he set it up.
T1 Terry
dorian said
01:49 PM May 16, 2019
ISTM that your observation of the low difference between panel and battery voltage does point to the device being a PWM controller, assuming that the controller was bulk charging at the time. The positive aspect of the low voltage drop would suggest that the MOSFETs have a low RDSon, which means the MOSFETs are probably genuine (assuming that the panel current was not insubstantial when the measurement was taken).
T1 Terry said
02:37 PM May 16, 2019
Yes, the follow behaviour seems to back that up, along with a sort of work around for the low charging current in float mode.
It appears the battery type can be changed to adjust the end of bulk voltage, but there is no other way of changing this parameter. Set in FLD mode, the end of Boost is raised from 14.4v to 14.6v, not a huge amount but better than nothing. From this point the float voltage can be changed up or down from the base 13.8v. By resetting the float voltage to 14.4v, the full current remains available while it ties to maintain that voltage. The specs say this controller has a Boost, Absorption and Float charging regime, but this does not seem to be the case, just boost and float. The AGM batteries are marked for 14.4v to 14.9v for cyclic use, as the sun only shines for a limited period per day, the 14.4v will become to substitute Absorption voltage in an attempt to get the 2 batteries as close to full charged as possible.
Once the 14.4v was reached, the current dropped back around 2 amps and the solar voltage climbed to 17v. To me that indicated the panels were not returning to open circuit voltage yet not all the current available was being used, this causing the panel voltage to climb. As the absorption stage current began to drop, so the solar panel voltage increased, further confirming that it was acting like a normal PMM controller.
So, it appear it may have been packaged as an MPPT controller, but it is clearly a PWM controller.
Now to figure out the strange load switching on/off settings.
I have a Coromal caravan at the workshop with one of these Solarking SD2430S controllers fitted. Looking on the web it suggests they are an MPPT controller, but I can't find the exact part number to get the specs, just Solarking products with similar part numbers.
I have found a reference relating to the SD2430S but it is not Solarking branded http://www.ldsolarpv.com/2018-china-new-design-5kw-solar-charge-off-gride-inverter-sd2430s-30a-pwm-solar-controller-welead-st.html so maybe Solarking just rebrand them as their product. The specs on this unit say it is a PWM controller, but the owner says the carvan mob that installed it assured him it was an MPPT controller.
The bit that has me wondering just what control form it uses is that it stops charging every cycle of the display to show battery voltage and that is generally associated with an MPPT controller. The solar voltage displayed is only around 0.1v to 0.2v above battery voltage and that is a characteristic of a PWM controller. The solar output is woeful, so I'm not sure if it should be wired with the panels in series for an MPPT type controller, or parallel for a PWM controller.
Can anybody shed some light on the true make up of this controller?
T1 Terry
Open it up and show us the PCB. One of us should be able to tell you.
I'll give that a try as a last resort. Most probably has some sort of security seal that null and voids any warranty claim if the seal is broken.
The latest weird behaviour is the current jumped up to double the previous output when the battery voltage was dragged below 12.6v. Looking at one of the manuals for a different part number unit it mentions the unit returns to boost mode once the battery voltage drops below 12.6v. Strange that it doesn't try to hold the float voltage at 13.8v with all the throughput it has available, but who knows what logic the programmer was using when he set it up.
T1 Terry
ISTM that your observation of the low difference between panel and battery voltage does point to the device being a PWM controller, assuming that the controller was bulk charging at the time. The positive aspect of the low voltage drop would suggest that the MOSFETs have a low RDSon, which means the MOSFETs are probably genuine (assuming that the panel current was not insubstantial when the measurement was taken).
It appears the battery type can be changed to adjust the end of bulk voltage, but there is no other way of changing this parameter. Set in FLD mode, the end of Boost is raised from 14.4v to 14.6v, not a huge amount but better than nothing. From this point the float voltage can be changed up or down from the base 13.8v. By resetting the float voltage to 14.4v, the full current remains available while it ties to maintain that voltage. The specs say this controller has a Boost, Absorption and Float charging regime, but this does not seem to be the case, just boost and float. The AGM batteries are marked for 14.4v to 14.9v for cyclic use, as the sun only shines for a limited period per day, the 14.4v will become to substitute Absorption voltage in an attempt to get the 2 batteries as close to full charged as possible.
Once the 14.4v was reached, the current dropped back around 2 amps and the solar voltage climbed to 17v. To me that indicated the panels were not returning to open circuit voltage yet not all the current available was being used, this causing the panel voltage to climb. As the absorption stage current began to drop, so the solar panel voltage increased, further confirming that it was acting like a normal PMM controller.
So, it appear it may have been packaged as an MPPT controller, but it is clearly a PWM controller.
Now to figure out the strange load switching on/off settings.
T1 Terry