DC to DC down converter recommendations.

As Solar seems to be a never ending addiction, and figuring out 12v is not a fun space to play in. I am planning at minimum a 24v upgrade. I have quite a bit of 12 gear and was wondering what if any brand or manufacturer of step down converter would be considered good. What are you using ? How many amps ? Looking for user experience with this type of device. Thanks 

Comments

  • westbranchwestbranch Posts: 5,084Solar Expert ✭✭✭✭
    I believe Cotek has some...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge, Hughes1100 Sat Modem
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • mcgivormcgivor Posts: 2,058Solar Expert ✭✭✭✭
    Used a Samlex 24-12 30A years ago on a 24V Land cruiser for a stereo, worked well.
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • mike95490mike95490 Posts: 7,792Solar Expert ✭✭✭✭
    Also consider using a Morningstar MPPT controller (they are rated to work OK with a battery as a source) to downconvert battery voltage to float charge a 12V deep cycle battery, which should last a long time in Float service.  Figure what your average load is , and use a controller rated for 10, 15, 20 40 A as needed, to simply keep the battery in float.
    Powerfab top of pole PV mount | 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 ,

  • tr0ytr0y Posts: 78Solar Expert ✭✭✭
    @mike95490 thanks for that idea, had not thought about just adding back another battery @ 12V and powering a controller with my 24v bank. None of this is cheap is it, but I think that might be a good idea. It also gives me a 2nd controller I can swap in and out if my primary Midnite Solar were to die. 

  • mike95490mike95490 Posts: 7,792Solar Expert ✭✭✭✭
    But not every MPPT controller can handle being connected to a stiff source like a battery.   Morningstar can.
    Powerfab top of pole PV mount | 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 ,

  • jonrjonr Posts: 1,032Solar Expert ✭✭✭✭
    No doubts about Mike being right, but I'm curious how any MPPT charge controller design that does DC-DC could not work with a battery.  The input current is normally limited by the inductor and is cut off before it causes a problem.
  • mike95490mike95490 Posts: 7,792Solar Expert ✭✭✭✭
    Because many controllers are looking for a "soft" source like solar, or they shift the voltage point around to control the power, and you can't do that with a battery. 
    Powerfab top of pole PV mount | 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 ,

  • jonrjonr Posts: 1,032Solar Expert ✭✭✭✭
    edited August 11 #9
    So the MPPT algorithm discovers that the max power point is as much power as the controller can handle.   So what's the failure mode?

    Basically the same question pertains to MPPT controllers that list a maximum solar current input.   Something can't handle more, but it's not clear exactly what.
  • mike95490mike95490 Posts: 7,792Solar Expert ✭✭✭✭
    That assumes the controller can handle a non-solar over-power condition, not many can.   Feel free to get one and try it out,  I'm just posting what has been stated to work.  Likely most of the major players will be able to handle some amount of overpower.


    MS FAQ #3     http://support.morningstarcorp.com/faq/
    Using a DC power supply as a PV panel substitute?

    Morningstar PWM controllers are not designed to properly process input from a DC power supply. This type of input is not recommended and is connected at the user’s risk. DC power supplies have considerably more output capacitance than PV panels and connecting a DC power supply to a Morningstar PWM controller may cause excessive heating and premature failure.

    MPPT controllers can be used for this application with no issue.



    Powerfab top of pole PV mount | 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 ,

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