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  • Controling charge while charging battery bank with a shop style battery charger.

    I would like to know if it is possible to add a couple of connections to the existing positive and negative cables that come from my solar panels to my charge controller? The idea is so I can just hook my 30amp shop style battery charger up to the (new) connections and use the same Xantrex pwm c40 charge controller to control and properly charge my batteries off the generator every time to extend their life. Right now the incoming charge from the 30 amp charger is hooked directly to my bank and I feel I am "slam" charging my battery bank every night, and reducing their life. Any ideas would be appreciated. Thanks!

    Mod note: no urls or links for newbies, thank you.
    Last edited by solar pete; 08-17-2015, 12:39 AM. Reason: url

  • #2
    Originally posted by PetRaft View Post
    I would like to know if it is possible to add a couple of connections to the existing positive and negative cables that come from my solar panels to my charge controller? The idea is so I can just hook my 30amp shop style battery charger up to the (new) connections and use the same Xantrex pwm c40 charge controller to control and properly charge my batteries off the generator every time to extend their life. Right now the incoming charge from the 30 amp charger is hooked directly to my bank and I feel I am "slam" charging my battery bank every night, and reducing their life. Any ideas would be appreciated.
    A PWM controller relies on the PV panel current limiting for its operation. Since your shop charger
    doesn't work that way, it would not be a good idea. Might even do damage. Why not just connect
    direct to the batteries? Bruce Roe

    Comment


    • #3
      Most shop type battery chargers work at a lower voltage then solar charge controllers. So your controller would never reach the high voltage limit. Only way to check is to measure what voltage it works at. Fully charge your batteries and see what voltage it's charging at.

      WWW

      Comment


      • #4
        Originally posted by bcroe View Post
        A PWM controller relies on the PV panel current limiting for its operation. Since your shop charger
        doesn't work that way, it would not be a good idea. Might even do damage. Why not just connect
        direct to the batteries? Bruce Roe
        Hi Bruce. Thanks for responding.
        Right now the 30 amp charger is hooked directly to my bank and I feel I am "slam" charging my battery bank every night, and reducing their life.
        With the charger hooked DIRECTLY to the bank my Xantrex controller (that handles the power from the panels only), goes through 1 blink, 2 blinks,...3,4,5 blinks, the comes on solid when my charge is supposedly full. When it is being charged by the sun i trust it. when it is being charged with the genny and shop charger is that reading still accurate even though the shop charger is hooked direct and NOT coming through any type of controller or regulator?
        I am trying to find out now as I have used simple deep cycle walmart batteries for years and now I am considering a bank of Rolls Surretts and I don't want to fry them!

        Comment


        • #5
          Originally posted by PetRaft View Post
          Hi Bruce. Thanks for responding.
          Right now the 30 amp charger is hooked directly to my bank and I feel I am "slam" charging my battery bank every night, and reducing their life.
          With the charger hooked DIRECTLY to the bank my Xantrex controller (that handles the power from the panels only), goes through 1 blink, 2 blinks,...3,4,5 blinks, the comes on solid when my charge is supposedly full. When it is being charged by the sun i trust it. when it is being charged with the genny and shop charger is that reading still accurate even though the shop charger is hooked direct and NOT coming through any type of controller or regulator?
          I am trying to find out now as I have used simple deep cycle walmart batteries for years and now I am considering a bank of Rolls Surretts and I don't want to fry them!
          Perhaps you need a more intelligent type "shop charger". Bruce Roe

          Comment


          • #6
            Originally posted by Wy_White_Wolf View Post
            Most shop type battery chargers work at a lower voltage then solar charge controllers. So your controller would never reach the high voltage limit. Only way to check is to measure what voltage it works at. Fully charge your batteries and see what voltage it's charging at.

            WWW
            Hi www. Thanks for responding.
            My shop charger which I run on 60 or 30 amp pushes the bank voltage up too and over 15 volts when running and getting to the full charge state.
            The charge controller is hooked to the bank, but the shop charger does not run through it, so I question if the solid light or full charge reading is the proper reading.
            I am trying to find out now as I have used simple 27dc deep cycle walmart batteries for years and now I am considering a bank of Rolls Surretts and I don't want to fry them or under charge them. It just seems that if I could run that shop charger charge right into the controller the same way the solar panels come in that it would be a regulated charge and extend the life of my batteries, without overcharging.

            Comment


            • #7
              No you do not run the shop charger through the Charge Controller. It is not designed to regulate a stiff source of power. Your shop charger on generator should only be used to do maintenance, and CYA for cloudy days. Not day to day charging. ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Your shop charger should be connected directly to the batteries, never through your charge controller. Whenever you run the genny with shop charger it is going to be a stiff source, and you do not want anything but a Single Stage Charger set to EQ voltages so they will charge the batteries as fast as possible to minimize fuel burn. When your charge controller senses the higher voltage will full the controller into thinking the batteries are fully charged up and shut down the panels. That is how it is suppose to work, and you do not want to jack with it. If you use Rolls Batteries you want to set your Charge Controller to act as a Single Stage Charger. To do that you set Bulk = Absorb = Float = 2.5 vpc or 15 volts on a 12 volt system. In the event you do not get fully charged in a day, after a few days you will need to run the genny until your shop charger cycles off and th ebatteries are again fully charged.------------------------------------------------------------------------------------------------------------In fact it does not matter if the FLA or Rolls or not. All FLA batteries on Solar should be set to 2.5 vpc. That would be 15, 30, and 60 volts respectively for a 12, 24, and 48 volt system. Monitor specific gravity and make adjustments accordingly. What 90% of users will notice especially in winter months is there batteries never get fully charged. It is quite common as most people do not have near enough panel wattage or batteries properly sized. So if you notice your Specific Gravity is always low; GUESS WHAT? ------------------------------------------------------------------------------------------------------------------------------------------------- You want to operate your lead acid batteries on the CORROSION SIDE, not SULFATE SIDE of the Charge Curve. Corrosion Side is Longer Lived and adequate power than the Sulfate Side with not enough power. It is your money. Spend it wisely and know WTF you are doing. .
              MSEE, PE

              Comment


              • #8
                Originally posted by Sunking View Post
                No you do not run the shop charger through the Charge Controller. It is not designed to regulate a stiff source of power. Your shop charger on generator should only be used to do maintenance, and CYA for cloudy days. Not day to day charging. ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Your shop charger should be connected directly to the batteries, never through your charge controller. Whenever you run the genny with shop charger it is going to be a stiff source, and you do not want anything but a Single Stage Charger set to EQ voltages so they will charge the batteries as fast as possible to minimize fuel burn. When your charge controller senses the higher voltage will full the controller into thinking the batteries are fully charged up and shut down the panels. That is how it is suppose to work, and you do not want to jack with it. If you use Rolls Batteries you want to set your Charge Controller to act as a Single Stage Charger. To do that you set Bulk = Absorb = Float = 2.5 vpc or 15 volts on a 12 volt system. In the event you do not get fully charged in a day, after a few days you will need to run the genny until your shop charger cycles off and th ebatteries are again fully charged.------------------------------------------------------------------------------------------------------------In fact it does not matter if the FLA or Rolls or not. All FLA batteries on Solar should be set to 2.5 vpc. That would be 15, 30, and 60 volts respectively for a 12, 24, and 48 volt system. Monitor specific gravity and make adjustments accordingly. What 90% of users will notice especially in winter months is there batteries never get fully charged. It is quite common as most people do not have near enough panel wattage or batteries properly sized. So if you notice your Specific Gravity is always low; GUESS WHAT? ------------------------------------------------------------------------------------------------------------------------------------------------- You want to operate your lead acid batteries on the CORROSION SIDE, not SULFATE SIDE of the Charge Curve. Corrosion Side is Longer Lived and adequate power than the Sulfate Side with not enough power. It is your money. Spend it wisely and know WTF you are doing. .

                Thanks for the response sunking.
                Obviously I still have some things to learn.
                I do run my shop charger "directly connected" every day now as i have before. We switch house over and run on a genny in the evening for lights washer, pump, etc...(heavy loads), including the battery charger. This charges the battery bank, (according to the charge controller for the panels) full each night. After a 4 to 6 hour run we shut gen down and switch back over to the inverter and batteries. With the charge full we have the power to run fridge freezer comps etc. through the night, then in the morning when the sun comes back it gives the boost needed to make it through the day and keep things running. I have been as high as a 1400ah bank, which was very nice, but right now I only have about 550 ah. When we had banks of 10, 12, or 14 batteries we could sometimes go 2 or 3 days in the summer without running genny, (except for pumping water) We also switch from inverter to genny manually, as all those switches and connections are expensive and cost is always a factor for us. My tiny little battery bank is taking a beating right now because it is too small to supply our power needs, but we use it hard anyway.
                We are trying to save up to buy some L16s or even surretts as they seem to be the best battery for an off grid application, and they have a better warranty then all the others i have seen so far. I just want to make sure I charge them correctly and get the most life possible out of them. Thanks for the input.

                Comment


                • #9
                  PetRaft - don't take this the wrong way...

                  The red flag here is that by asking these questions, we want to back up a bit. No, using the C40's little gas guage is NOT a precision instrument, and may have nothing to do with your battery health. A highly sulfated battery will charge up to 100%, but have no real load capacity. The led's are a general guide basically.

                  What exactly are your settings in the C40? What is your system voltage? 12 / 24 or more? You may be murdering them prematurely. I sure hope you have the temperature-compensation probe attached.

                  Your shop charger sounds like an old constant-current only device, and without even a hydrometer to keep an eye on things, you are likely murdering them. Constant-current, linear taper chargers are hell on batteries if you aren't up on your maintenance. Most manufacturers really suggest using a CC/CV charger as the ideal algorithm.

                  Previously you had 10-14 batteries in a bank? How did you keep them in balance or check on them without owning a hydrometer? That is hugely problematic. Don't even think of doing this with Rolls for the time being - being too simplistic is going to cost you big-time after purchase.

                  Basically what I'm saying is to back up - see how to simplify and keep your existing bank healthy with a more modern charger. Evaluate your CC and see if your settings are correct. As it stands now, the C40 is *barely* able to keep up with the minimum demands of a 550ah bank with the CC running full-tilt and putting more money into your solar array instead of murdering innocent Rolls Surrettes is the best way to go.

                  Comment


                  • #10
                    Originally posted by PetRaft View Post
                    I do run my shop charger "directly connected" every day now as i have before. We switch house over and run on a genny in the evening for lights washer, pump, etc...(heavy loads), including the battery charger.
                    Then you have a very poorly designed system if you have to use a genny everyday, especially this time of year. Buying new batteries is not going to solve a thing.
                    MSEE, PE

                    Comment


                    • #11
                      Originally posted by PNjunction View Post
                      PetRaft - don't take this the wrong way...

                      The red flag here is that by asking these questions, we want to back up a bit. No, using the C40's little gas guage is NOT a precision instrument, and may have nothing to do with your battery health. A highly sulfated battery will charge up to 100%, but have no real load capacity. The led's are a general guide basically.

                      What exactly are your settings in the C40? What is your system voltage? 12 / 24 or more? You may be murdering them prematurely. I sure hope you have the temperature-compensation probe attached.

                      Your shop charger sounds like an old constant-current only device, and without even a hydrometer to keep an eye on things, you are likely murdering them. Constant-current, linear taper chargers are hell on batteries if you aren't up on your maintenance. Most manufacturers really suggest using a CC/CV charger as the ideal algorithm.

                      Previously you had 10-14 batteries in a bank? How did you keep them in balance or check on them without owning a hydrometer? That is hugely problematic. Don't even think of doing this with Rolls for the time being - being too simplistic is going to cost you big-time after purchase.

                      Basically what I'm saying is to back up - see how to simplify and keep your existing bank healthy with a more modern charger. Evaluate your CC and see if your settings are correct. As it stands now, the C40 is *barely* able to keep up with the minimum demands of a 550ah bank with the CC running full-tilt and putting more money into your solar array instead of murdering innocent Rolls Surrettes is the best way to go.
                      My current system is as follows
                      8- 80 watt 4.6 amp solar panels wired in parallel.... 6 are photowatt pw-750-80, and 2 are Lavie 80p

                      these are connected to

                      1 Xantrex c40 pulse width modulated 3 stage charge controller with the add on led screen which shows/reads incoming power from the panels as
                      amps being made/watts being made/and current voltage...
                      (current voltage flucuates when sun is out, or shop charger is on)
                      it also shows amp hours and total amp hours (This was a c60 until it blew, then I downsized a little)

                      this is connected to the battery bank which currently is 5 Everstart 12 volt 109 ah deep cycle marine trolling motor batteries
                      these are connected to
                      1 - 3000 watt Power Express 12v to 110v modified sign wave inverter.

                      My charger that runs off the generator is a Schumacher 30/60/300 Heavy duty charger.

                      That is my entire system except for the generator.
                      I have no probes or sensors automatic switches or anything else.
                      My house is either PLUGGED in to the inverter running off the battery bank, or the generator which feeds directly into the breaker box inside the home.
                      (( I manually switch the cord from 1 plug to the other))

                      I have replaced the inverter once like 8 years ago as it was struck by lightning and the charge controller about 2 years ago as i 'm pretty sure it was struck by lightning also.
                      I usually get about 2 years from my battery bank before it needs replaced, but I was told that is actually more cycles then these everstart batteries are even designed for!
                      I have noticed if I have more batteries they last a little over the 2 year mark where as if I have less then 10 they don't last quite to the 2 years.

                      I know what you are thinking and please don't tell me this won't work. I know its not the exact way you are to build/run this type of system, and that its not a proper design "Sunking", but I have lived TOTALLY OFF the electric grid since 1997 and raised 3 kids here using this setup. As I stated before, cost is always a factor. It is easier to come up with $1000. to buy walmart batteries then $3000 to buy the same amount of amp hours in a trojan or rolls battery.

                      After reading the info everyone is sharing here I can see I obviously need to get a Specific Gravity tester and better track and adjust the electrolite to the recommended setting. This alone probably could have saved the premature death of some of my batteries that only lasted a year and a half instead of 2 years.
                      Also I have been considering an underground room for the batts. to protect them from the awful temperature fluctuations here in NW PA.
                      Everything comes with a price tag though.
                      Just like hooking to the grid, when I moved in here in 97 they wanted $6000 up front to hook me up, or $220. a month plus electric usage for 4-1/2 years, (which came out to more then I paid for the property) and when i got a second estimate 5 years ago they want $10,000, even though someone had moved in half way between me and the power lines after me and paid to construct over half the line that was needed to get to me.
                      SKIP THEM AND THEIR MONTHLY BILL!
                      i WILL REMAIN OFF GRID! =)


                      Thanks for responding PNj.
                      C40 is set for 12 volt and set on factory settings as I have never adjusted any of those settings.
                      Sulfating is what happens near the 2 year mark to my batts. the controller says they are charged, but they have NO load capacity, and pop the inverter for low voltage as soon as anything kicks on. LOL @ mudering the suruttes!
                      That is why I am here!
                      I want to be sure NOT to murder the surrettes...If I can finally afford them!
                      That is why I thought running my 30 amp shop charger through the Xantrex would help me avoid that.
                      I was hoping someone would say just add a + and - terminal to the incoming solar panel cables with a blocking diode going back towards the panels then clamp on shop charger and charge away!

                      Comment


                      • #12
                        Just a suggestion to your charging regime:
                        Run the genset in the morning and bulk the batteries up, and then by the end of the day, the solar will have topped them off to full. If you use a lot of power at night, using the generator for that will spare the batteries some too.

                        Batteries: instead of 5 parallel 12V 109ah boating batteries (545ah)
                        you could improve the load sharing by using 4 or 6
                        6v, 200ah golf cart batteries wired 2 in series, 3 parallel strings (600ah) and they are a much better battery for about the same cost. A couple new cables for the series interconnect, wire the series batteries on the "diagonal" (see http://www.smartgauge.co.uk/batt_con.html )
                        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


                        • #13
                          Originally posted by PetRaft View Post
                          My current system is as follows
                          8- 80 watt 4.6 amp solar panels wired in parallel.... 6 are photowatt pw-750-80, and 2 are Lavie 80p
                          Holy cow! You know that when you parallel more than two panels, you MUST use fusing to protect the wiring! For instance, Panel 2 shorts, and now all 7 panels are dumping into that short. If this was made of speaker wire, you have a major fire hazard on your hands.

                          Speaking of wire, at 12v we are always dealing with the issue of voltage drop. A long run from the panels to the controller without an adequate gauge means poor efficiency. Likewise, keep the controller VERY close to the batteries, and with an adequate gauge of wire. There are online charts for this to keep voltage drop below 2%. Be sure to note the difference between "one way" and "round trip" distances if given in the charts.

                          My charger that runs off the generator is a Schumacher 30/60/300 Heavy duty charger.
                          Ok, I'm not familiar with that model to see if it is a CC/CV charger, or just CC alone. If just CC, then you'll want to have *some* way of monitoring the voltage, and try not to let it get above 14.5v, unless you are doing an "EQ" on purpose.

                          C40 is set for 12 volt and set on factory settings as I have never adjusted any of those settings.
                          YIKES! Dude, you HAVE to check those potentiometer settings. All the C series pwm controllers that I have seen came with their voltage adjustment pots merely set to the middle of travel, and not anywhere near what you want. For a flooded, that would be about 14.5v bulk/chg. 13.5v float is ok for right now, since you are never really finishing bulk/absorb anyway!

                          If you want to get the voltages more precise than just using the pointer, there are test-points on the board you can use with an *accurate* voltmeter - not a shirt-pocket type. But for now, at least rotate that pot to get that voltage away from center, which on the C40 is only 14.0v !! See P.23 of the manual for the C35/C40/C60 online.

                          Definitely get the accessory temperature-compensation probe.

                          Let's tighten this thing up. Mike has made some great suggestions about a battery upgrade, and the configuration of such. Avoid "ladder" type charger connections to paralleled batteries, ie charging and loading taking from just one battery or side of the bank only. Do "diagonals" or other configs to balance the system.

                          Fuse your panels since you have more than 2 in parallel for safety, and review your wiring runs and thickness gauges. You MUST visually check the C40 voltage pots at least.

                          Comment


                          • #14
                            P.S. When taking the cover off the C40, to check to the voltage pots, be gentle with the front panel led is just sitting in a header on the board, and if you yank the cover off lengthwise, you'll rip and possibly destroy the led. Try to lift up-and-out, and do the reverse when reassembling.

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