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  • #31
    Originally posted by conntaxman View Post
    ----------------
    tonigau,,, did you know that you also can parallel these to 80A, 120A
    and so on.
    John
    let me know when you get yours, and I'll do the same
    I bought a few & will try to hook both up to the same load, Parallel operation should work with most simple chargers because they operate CC (Constant Current) mode initially untill the battery is charged then go into CV mode (float).
    Note: Can not parallel the input, connect separate panel(s) to each charge controller.



    Originally posted by conntaxman View Post
    ----------------
    tonigau ....did you order them after reading about them when I put up the spec.
    John
    I found this supplier on alibaba, it took me a while to purchase because of difficulty confirming product details so I just bit the bit & got some samples.


    toni

    Comment


    • #32
      Originally posted by tonigau View Post
      When I read their manual & specifications I do not get 100% correlation, & some mild conflicting detail anyway. I have learned that specifications can be open to interpretation especially when the detail is a bit vague or not very specific.
      Also the absence of a spec detail does not always mean is or is not so.
      If you can wait, I will try to do some tests this weekend & then we can all get some sleep.
      Correct Tony and that is why I suspect the product is a complete fraud. For example they claim 99.5% efficiency which is impossible


      Originally posted by tonigau View Post
      >>For a 40 amp 12/24 volt device the input limitations would be
      >>500 watts @ 12 volt Battery
      >>1000 watts @ 24 volt Battery

      What you say is correct but is a "requirement" would probably be more accurate term than "limitations".

      The input power required from the solar panel is a result of the output power + any losses in the converter & cables etc...
      This is true for both MPP controllers & "PWM" type chargers.
      Difference is an MPPT charger can increase the energy obtained from the source (SP)
      by way of reducing its duty cycle (or frequency depending on the topology) to allow the SP to operate at its MPP voltage.
      Ok this is where I disagree with your assessments to some respect. I have to separate the two types because they work completely differently. All MPPT controllers have a maximum wattage input vs battery voltage, and maximum Voc. If you look at any quality MPPT controller one of the first things and most important specs is the maximum Voc voltage. Typically th elow current models Voc limits is around 100 volts, while the higher current models have a 150 Voc and soon to be 600 Voc. To the consumer or lay person this might not mean much to them, but the advantage is running very low currents on the input side to minimize wire size, cost, and losses. So for example using a 80 amp controller on a 12 volt battery, if you run say 120 Vmp on 1000 watt panels input current on the controller is around 8.3 amps with roughly 80 amps out to the 12 volt battery

      The big advantage of MPPT other than the tracking ability which is huge, is the overall efficiency because the panels are operated at Vmp at all input levels and overall efficiency including wiring and converter losses is up around 95%.

      PWM is a completely different animal. The panels do not operate at Vmp, rather something lower like around 1 volt higher than the battery voltage at 100% duty cycle. At best if the panels are precision matched, the best efficiency you can obtain is 70% with 50% being typical. The problem with any serial type controller is Input Current = Output current. PWM controllers do not specify maximum wattage. They only specify maximum voltage (Voc) and current input (Imp of the panel).

      So with this SL-40 the max Voc is 55 volts, and input current is 40 amps. So if we had a 12 volt system, and we used say a panel with a Vmp of 40 volts (roughly 55 Voc), and a Imp of say 40 amps would give us a panel wattage of 40 x 40 = 1600 watts. Problem is the Vmp would be pulled down to around 15 volts at the input to give us say 13 volts @ 40 amps out to the battery. So we have a 1600 watt panel, but at best we can only deliver at best around 520 watts to the battery. Roughly 33% efficient under worse case scenario.

      So how can you tell what is really going on. Just a simple test. Connect say a 100 watt panel say made for 24 volt system and a discharged 100 AH 12 volt battery. Measure the input voltage and current and you will have your answer if it is MPPT or PWM. I bet you see the input voltage get pulled down to around 15 volts rather than 34 to 36 volts and input and output current around 2.7 amps knocking you 100 watt panel down to 35 to 40 watts.

      Originally posted by tonigau View Post
      An MPP/MPPT charger is just a switchmode DC-DC converter with an additional control mechanism (usually microcontroller). they typically operate in the "Buck" (step down) mode & this does a current amplification & voltage division function with optimisation of maximum solar panel power(VxA). aka MPPT
      Yep I know I have designed a few switch mode power supplies, and work a lot with PWM motor controllers.
      MSEE, PE

      Comment


      • #33
        Ok,
        I've done a quick test, not a good one tho cos I'm hard pressed for time & space n don't have a decent current supply at the moment.
        But a test it is & can see the results.

        I do intend to do a comprehensive test & graph the results but it will likely be a while.


        Some detail from reading the manual....
        The 40A spec. is output current.
        The unit does do "PWM" mode, but only if the SP voltage is close to the battery voltage (eg: low solar insolation).
        Load current is 15A max

        One thing I noticed when testing & will have to look into further is when winding up Volts on the supply the SL-40A unit cut-out well below 55V with 6V hysteresis to cut-in.


        PS, Sorry John for getting a bit off topic with your post for info on the SL-40A, Maybe Sunking & me can start a new post for our game of tennis .....

        Toni
        Attached Files

        Comment


        • #34
          mppt /algorithm

          Originally posted by tonigau View Post
          John,
          When I get time I will check the data pins & maybe put the picoscope on the TX pin to see if it is outputting some data on the RJ connector. If it is TTL output then it will definitely require a Dallas chip or some TTL to RS232 converter.
          It is strange how they have a serial port & mention that it can be used for data-logging but no information on how to use it.

          Good luck in your communication. With regards to tech support, the lady has already advised that the persons in this department do not speak english so she will have to translate technical enquiries.

          Sunking
          When I read their manual & specifications I do not get 100% correlation, & some mild conflicting detail anyway. I have learned that specifications can be open to interpretation especially when the detail is a bit vague or not very specific.
          Also the absence of a spec detail does not always mean is or is not so.
          If you can wait, I will try to do some tests this weekend & then we can all get some sleep.


          >>For a 40 amp 12/24 volt device the input limitations would be
          >>500 watts @ 12 volt Battery
          >>1000 watts @ 24 volt Battery

          What you say is correct but is a "requirement" would probably be more accurate term than "limitations".

          The input power required from the solar panel is a result of the output power + any losses in the converter & cables etc...
          This is true for both MPP controllers & "PWM" type chargers.
          Difference is an MPPT charger can increase the energy obtained from the source (SP)
          by way of reducing its duty cycle (or frequency depending on the topology) to allow the SP to operate at its MPP voltage.

          An MPP/MPPT charger is just a switchmode DC-DC converter with an additional control mechanism (usually microcontroller). they typically operate in the "Buck" (step down) mode & this does a current amplification & voltage division function with optimisation of maximum solar panel power(VxA). aka MPPT


          >>The TL2843 is a PWM Comparator that drives the MOSFET switches. I suspect the HC908 PIC is the control for the Comparator.

          TL2843 is a "current mode PWM controller", definitely not a comparator. This is the DC-DC switchmode controller.
          There is a comparator IC LM339 & an opamp IC TL074 opn the control board, both these would be to process analog signals for the HC09 inputs

          Toni
          -----------------
          Tony again tks for the look see into this.You guys are much smarter in this then I. All I could do is take someone's word on this matter, untill I can see with a volt meter or amp meter. Im going to try today to take readings of 2 panels and then hook them up in series and take another reading and then hook it up to the SL-40 and see what I get, And it looks like that Really isn't a good way to do it either.lol
          But thanks to both or all that are talking about this.I still say that they made the cir. to use both pwm and mppt.
          John

          Comment


          • #35
            Originally posted by tonigau View Post
            The unit does do "PWM" mode, but only if the SP voltage is close to the battery voltage (eg: low solar insolation).
            Toni beg your pardon but that does not jive with IR curves. Vmp knee voltage does not vary very much if at all with respect to irradiance (amount of sun light). It is the Imp current that varies proportionally to irradiance level, not the voltage.
            MSEE, PE

            Comment


            • #36
              tried to test the sl-40

              I tried to test this controller. I had 2 panels. panel A was17.10 volts@3.1 amps panel B was 17.54 volts@2.3 amps
              Battery to start was 12.5 volts
              I have a cheap volt ohm meter, and you can test up to 10 amps dc.
              I hooked up the panels in series and it was 39.4 volts [few min later] hooked up the bat and panels to it. going into the bat first was 13.16 then little while later was 15.2
              I put my meter on amps and hooked one end to the controller and the put the other lead to the battery, and my probe wire on the meter ha ha fried, and smoked. so I pulled it off quick, but too late, now i need another meter. I guess I will have to get a regular amp meter.
              Only in about 10 to 15 min the battery was charged, I was only a motor cycle battery.
              so I still have NO idea . ha ha ha
              Let me add this, I took off the wire that was from the controller to the pos, and THEN i checked for the amps, by taking one lead and hooking it up to the controller and then the other lead to the battery. So to run the current through the meter. I think that is how you do it.
              Last edited by conntaxman; 06-03-2011, 05:22 PM. Reason: add comment

              Comment


              • #37
                Originally posted by conntaxman View Post
                I put my meter on amps and hooked one end to the controller and the put the other lead to the battery, and my probe wire on the meter ha ha fried, and smoked. so I pulled it off quick, but too late, now i need another meter. I guess I will have to get a regular amp meter.
                Only in about 10 to 15 min the battery was charged, I was only a motor cycle battery.
                so I still have NO idea . ha ha ha
                The meter was not the problem, it was you not knowing what you are doing. Try that same thing with an expensive meter and you will get the same exact result

                FWIW the battery you tested with was already fully charged up, so very little if any current flowed. That is why you seen the voltage go up so quickly.
                MSEE, PE

                Comment


                • #38
                  mppt /algorithm

                  Originally posted by Sunking View Post
                  The meter was not the problem, it was you not knowing what you are doing. Try that same thing with an expensive meter and you will get the same exact result

                  FWIW the battery you tested with was already fully charged up, so very little if any current flowed. That is why you seen the voltage go up so quickly.
                  ........
                  Im going to get another meter, and also just a amp meter that you tie inbetween and the amps go through.
                  How low should the battery be to test it when everyone says, the voltage will be low and the amp's will be high.
                  Wait. with the pwm if the panels are putting out will say 3 amps in series that is all you will get even if the voltage is high. with the mppt were the voltage is high and it WAS 3 amps , now it will lower the voltage and increase the amps./
                  John

                  Comment


                  • #39
                    For testing , if your battery is fully charged, hook a couple of headlights to it, or rig the panel up on the car, and connect to the battery under the hood, turn headlights on, that will now pull power from the controller.

                    Most controllers, you connect to the battery first, and then attach the PV. If you have more than one panel, cover them with a blanket while attaching wires, cuts down on the sparks!
                    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                    solar: http://tinyurl.com/LMR-Solar
                    gen: http://tinyurl.com/LMR-Lister

                    Comment


                    • #40
                      mppt /algorithm

                      Just did another test. Same 2 panels [[[[readings from the other day.I had 2 panels. panel A was17.10 volts@3.1 amps panel B was 17.54 volts@2.3 amps]]]] in series.
                      Started with battery voltage or 8 volts. This time I put an amp meter in series with the controller and + battery.Test voltage off panels was 36 then when I hooked everything up I took a reading off the plus and mins while it was charging. and it started out at 18volts and read 2 amps. Then while the voltage was raising in the battery to 12vdc the amp's went up to 4 amps.It seemed like that more battery voltage the more amps would be going in, Then the amps started to decrease, then the panel voltage would be going up and down.
                      Im still charging the battery. Sun is not quite as bright as the the other day, And panels are in a different location.
                      John

                      Comment


                      • #41
                        Quote Originally Posted by tonigau View Post
                        The unit does do "PWM" mode, but only if the SP voltage is close to the battery voltage (eg: low solar insolation).


                        Toni beg your pardon but that does not jive with IR curves. Vmp knee voltage does not vary very much if at all with respect to irradiance (amount of sun light). It is the Imp current that varies proportionally to irradiance level, not the voltage.

                        Very true, It would have been more correct for me to state " When power is low" (assuming the tracking algorithm is doing its job)

                        At very low solar irradiance levels the DC-DC converter would unlikely be operating at its optimum efficiency, thus there will be a point where it is more efficient to connect the solar panel direct to the battery in series PWM mode.

                        Here is the wording from the manual
                        [QUOTE]When conditions are such that insufficient PV power is available to produce an
                        increase in output current, the unit will stop it

                        Comment


                        • #42
                          Originally posted by tonigau View Post
                          Here is the wording from the manual
                          Toni that is what set me off the manual, which I have not read and the specs are bologna.

                          Regardless of irradiance level the Vmp is always Vmp as anything below or above is less than maximum efficiency which is the huge problem with of any PWM charging algorithm. Anytime you pull the the voltage down from Vmp is a loss of power, even minute power levels. 17 volts @ .1 amps, is greater than 16 volts @ .1 amps. All quality MPPT controllers operate from Vmp to Voc, not Vmp to Isc.

                          Do not misunderstand I am not arguing with you, but the claims of the manufacture are silly like 99.5% efficient, 55 Voc max, no max power input vs battery voltage. Hogwash!
                          MSEE, PE

                          Comment


                          • #43
                            mppt

                            ok, so now both you have a good idea of what this is. So now tell me ., so if it ISN'T do what the mppt dose let me know so that I could "" CALL them s of a B. 'es up and tell them I want my money back. Im one guy that dosen't like getting F' ed over.
                            tks
                            John
                            Next will be the BlueSky I think it was a 1225 A or something. But that said it was a boaster.

                            Comment


                            • #44
                              Originally posted by conntaxman View Post
                              ok, so now both you have a good idea of what this is. So now tell me ., so if it ISN'T do what the mppt dose let me know so that I could
                              John I am not testing the unit so I cannot answer with certainty. From the little bit of test results Toni preformed, it might be in some capacity with some significant limitations.

                              As for me personally I would never consider using such a product just because the manufacture specs are so vague with missing information, low Voc input, and a few of them outright fraudulent like 99.5% efficient. Also from what Toni is reporting the RS-232 port is not compliant with TIA-232-F making it useless.
                              MSEE, PE

                              Comment


                              • #45
                                John,
                                Sorry about that...

                                It does put out more amps than input so I would say yes on the MPPT, also the design "looks" like MPPT, I have nothing to convince me that it is not MPPT charge controller.
                                What is unknown at this time is how good it is at tracking the MPP under all operating conditions & its real efficiency spec. , which considering it is a low priced product is not very relevant anyways.

                                A far as charging a battery from sunlight with acceptable efficiency, the SL-40 will do what I want for now, its better than what I had previous.
                                I also wanted some hardware to experiment with.

                                Toni

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