Go to the Northern Arizona Wind & Sun - Online Solar Store

Announcement

Collapse
No announcement yet.

24v to 12v conversion

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • 24v to 12v conversion

    I have a 24v battery bank. I also have some devices that would operate at 12v directly, or via an AC adapter (120v to 12v converter). What I would like to know is what would be the best way to use my 12v devices? Do I run them through the inverter in the AC current (that then switches back to 12v for the device), or get a 24v to 12v converter and install a few "12v plugs" where needed?

    If the 24v to 12v conversion is best, can anyone recommend a low loss device that I can get to hook up to my battery bank. There will not be a long distance of wire length (15-20 ft) so wire size may/may not be an issue.

    Thanks!

    Roy

  • #2

    Re: 24v to 12v conversion

    Re: 24v to 12v conversion

    that's a tough call for us to make and i think it is more of what is cheaper for you to do. the 24 to 12v converter may be slightly more efficient, but the 120vac inverter may add more versatility with variable or changing needs. make no mistake about it here as both actually invert the dc to a higher voltage and back down with the inverter needing the wall adapters or power supplies to go back down with. higher dc current loads may require a power supply to be connected to the inverter output and some power supplies may be costly so do some research and some math to know which is better for you.
    NIEL

    Comment


    • #3

      Re: 24v to 12v conversion

      Re: 24v to 12v conversion

      How long do you want to do this for? For a short time, you can fuse the 12 volt load, 6" from the 24 volt bank. You will be braking a basic rule and this is a poor practice. However, I have done this or "ok'd" it for someone who is building a house or busy with other things for a short time. There are plenty of 24V appliances, CFL's, pumps, chargers, fans, electronic components, ect. You should not wait long to make the switch if your battery bank is worth it long term!
      http://members.sti.net/offgridsolar/
      "we go where the power lines don't"

      Comment


      • #4

        Re: 24v to 12v conversion

        Re: 24v to 12v conversion

        Roy, what are the devices? That may help determine a viable course of action.

        Eric
        100% Off Grid @ 51* 46' N lat 124* 44' W long

        New House system: coming - 2 arrays @ 2240W
        #1) CL150 & Epanel 12V PVs 4S @140 W , 24V C&D AT-15P AGM @ 950Ah, Linksys wet54g - WiFi bridge, Cotek ST1500W inverter, TBS Omni-charger 30a-24v, ,
        #2) CL150 12V PVs 4S@140W , 24V C&D AT-15P AGM @ 950Ah
        to ADD: E-Panel and inverter
        Honda Eu3000is,Eu1000is

        Guest cabin system: 3 - 70W panels to BS 2000e CC, with 2 - 100 ah 12v SAFT wet NiCd's , 600W TSW Inverter

        Comment


        • #5

          Re: 24v to 12v conversion

          Re: 24v to 12v conversion

          If you've already got the inverter, just go with AC runs. It'll be easier and allow flexibility in placing things, and it will be cheaper than buying a DC-to-DC converter.

          Comment


          • #6

            Re: 24v to 12v conversion

            Re: 24v to 12v conversion

            You can use one of these if power requirement below 25 watts
            http://www.dimensionengineering.com/DE-SWADJ3.htm
            15 assorted solar panels 1800 watts
            MX 60 charge controller
            940 amp hour 2 X 6-100-13 DEKA batterys
            TriMetric battery monitor
            SW4024 inverter
            Basic Stamp computer to control SW4024 from MX60

            MikeO

            Comment


            • #7

              Re: 24v to 12v conversion

              Re: 24v to 12v conversion

              theres some stuff here

              i run a few things directly off 12v for the efficiency factor, but then my bank is 12v for that reason and its small. converting 24 to 12v will really be more efficient and if they are low wattage loads you should be able to do your cable lengths no problem. with a converter rated for a larger draw you could runa bunch of stuff off the 12v directly as long as there isnt too much voltage drop. a few years ago i tried running my office pc off 12v directly and was getting way to much voltage drop, the pc would not power on due to startup draw. i run ac from an inverter now.


              now we charge cell phones, ebook reader, laptops , etc direct off of 12v. (each using its own 12 to whatever converter, 18v for laptop, 5v for cell, etc.. )


              id agree though, now that my system is a little larger , having a AC inverter and running everything off of that is not too inefficient as the thing is running all the time anyhow, so these small charging loads are nothing, and gives super flexibility in running long cable runs.
              1410w PV in two 48v arrays, MX-60 (710W) and Tristrat MPPT-60 (700W), 3 1104AH Rolls 4V batteries in series for 12v battery bank, powering various household LED lights, washing machine, laptop and gadget charging and a super low power server. AC and entire home office (switchable) on sunny days when power available comes from 1500w heavy duty "industrial" samlex sine wave inverter with high surge. Also, 1.9kw(DC) gridtie system (Sanyo HIT's).

              Comment


              • #8

                Re: 24v to 12v conversion

                Re: 24v to 12v conversion

                Originally posted by westbranch View Post
                Roy, what are the devices? That may help determine a viable course of action.

                Eric
                That is a good question. Some are things like fans and a small colman cooler and that might be easier to replace. But others are cameras and telescope equipment that can't be. For these its either 12v DC or 120v AC.

                I can do everything off the AC, but want to try to save every watt I can since it it all totally off grid and what the sun does not provide, I don't get to use.

                Roy

                Comment


                • #9

                  Re: 24v to 12v conversion

                  Re: 24v to 12v conversion

                  Originally posted by Cariboocoot View Post
                  If you've already got the inverter, just go with AC runs. It'll be easier and allow flexibility in placing things, and it will be cheaper than buying a DC-to-DC converter.
                  I'm beginning to think your right. But I want to make sure I have explored all the possibilities since I need to save every watt I can. I just figured it was wastful to go from 24v DC to 120v AC and then back to 12v DC.

                  Roy

                  Comment


                  • #10

                    Re: 24v to 12v conversion

                    Re: 24v to 12v conversion

                    Originally posted by Dave Sparks View Post
                    How long do you want to do this for? For a short time, you can fuse the 12 volt load, 6" from the 24 volt bank. You will be braking a basic rule and this is a poor practice. However, I have done this or "ok'd" it for someone who is building a house or busy with other things for a short time. There are plenty of 24V appliances, CFL's, pumps, chargers, fans, electronic components, ect. You should not wait long to make the switch if your battery bank is worth it long term!
                    I'm going to try to avoid doing this. I knew it was possbile, but everyone says avoid it becuse it can make the charge in your batteries uneven hence they won't last as long.

                    Roy

                    Comment


                    • #11

                      Re: 24v to 12v conversion

                      Re: 24v to 12v conversion

                      Originally posted by mikeo View Post
                      You can use one of these if power requirement below 25 watts
                      http://www.dimensionengineering.com/DE-SWADJ3.htm
                      Thanks. I'll take a look at the device. under 25 watts is not a probelm for some of the devices. Just need to see what the effiency is.

                      Roy

                      Comment


                      • #12

                        Re: 24v to 12v conversion

                        Re: 24v to 12v conversion

                        Hi Roy, do you know my astronomer friend Al Grauer at Mt Lemmon? He and I used to work together. If you know the DC loads, you could match multiple inexpensive converters for your 12 volt loads.
                        15 assorted solar panels 1800 watts
                        MX 60 charge controller
                        940 amp hour 2 X 6-100-13 DEKA batterys
                        TriMetric battery monitor
                        SW4024 inverter
                        Basic Stamp computer to control SW4024 from MX60

                        MikeO

                        Comment


                        • #13

                          Re: 24v to 12v conversion

                          Re: 24v to 12v conversion

                          I'm interested in the answer to this topic too but don't have a solution yet.

                          What I can add is this:
                          http://bus.getdave.com/Docs/12Von24V/

                          The article mentions a Battery Equalizer like one of these:
                          http://order.waytekwire.com/DATASHEET/80100.pdf
                          Which are 91%-94% efficient at pulling 12v off a 24v battery system

                          Of this one which is up to 97% efficient:
                          http://www.merlinequipment.com/marke...asp?groupid=33

                          SolarConverter makes this autotransformer 20A version which is common among solar shops and can also be connected as a battery equalizer:
                          http://www.solarconverters.com/equal1.htm

                          They aren't cheap but for a constant 12v supply off a 24v battery system they appear to be one of the better options.

                          Articles mentioned that these type of devices are found on old buses so you maybe able to salvage one for much less than new.
                          Last edited by Opti; October 6th, 2011, 18:34.

                          Comment


                          • #14

                            Re: 24v to 12v conversion

                            Re: 24v to 12v conversion

                            Interesting 24 to 12 volt converters/battery balancers.

                            Looks like it should work well... I do wonder if there is any impact on long term battery life between the upper 12 and the lower 12 volt battery banks.

                            -Bill
                            20x BP 4175B panels (replacement) + Xantrex GT 3.3 inverter for 3kW Grid Tied system + Honda eu2000i Inverter/Generator for emergency backup.

                            Comment


                            • #15

                              Re: 24v to 12v conversion

                              Re: 24v to 12v conversion

                              I have a 24v battery bank. I also have some devices that would operate at 12v directly, or via an AC adapter (120v to 12v converter). What I would like to know is what would be the best way to use my 12v devices?

                              I use a converter to run all the 12v DC in my RV from 8 golf cart batteries at 24v. It's rated for 30 continuous amps. Works like a charm.

                              http://www.newmarpower.com/DC-DC_Con...ed_Series.html

                              You can find them on ebay for less than $200, sometimes.

                              Good luck.

                              Comment

                              Working...
                              X