LVD - Good unit that won't break the bank.

Steven LakeSteven Lake Solar Expert Posts: 402 ✭✭
Okay, expanding on another thread from last year, I have a question. I need a simple, Low Voltage Cutoff unit that can handle 15-30amps, 12vdc, but won't break the bank. This needs to be a quality, yet low cost stand alone unit as I'm looking to spin a 12vdc 15amp supply directly off the bank to feed an intermittent water pump (pressure activated) and skip the middle man if possible. I've seen a few units here and there that might do the job, but I wanted your input just to be sure I got one I could trust that didn't cost a fortune. Thanks for your input.

Comments

  • bill von novakbill von novak Solar Expert Posts: 891 ✭✭✭✭
    Re: LVD - Good unit that won't break the bank.
    Okay, expanding on another thread from last year, I have a question. I need a simple, Low Voltage Cutoff unit that can handle 15-30amps, 12vdc, but won't break the bank.

    Xantrex C40. 40 amps, about $110 new if you shop around.
  • cupcakecupcake Solar Expert Posts: 254 ✭✭✭
    Re: LVD - Good unit that won't break the bank.
    Okay, expanding on another thread from last year, I have a question. I need a simple, Low Voltage Cutoff unit that can handle 15-30amps, 12vdc, but won't break the bank. This needs to be a quality, yet low cost stand alone unit as I'm looking to spin a 12vdc 15amp supply directly off the bank to feed an intermittent water pump (pressure activated) and skip the middle man if possible. I've seen a few units here and there that might do the job, but I wanted your input just to be sure I got one I could trust that didn't cost a fortune. Thanks for your input.


    "This needs to be a quality, yet low cost"


    QUALITY

    or

    LOW COST

    Pick one, can't have both.
    ~1.5Kw PV in parallel
    Morningstar MPPT-60 controllers (2) in parallel
    3 Trojan tr-1275's in parallel 450ah total
    Samlex 2,000 watt 12-volt inverter hardwired


  • Steven LakeSteven Lake Solar Expert Posts: 402 ✭✭
    Re: LVD - Good unit that won't break the bank.

    Bill, the Xantrex looks like a charge controller, not a low voltage disconnect, the latter of which I'm after.
  • BB.BB. Super Moderators, Administrators Posts: 32,026 admin
    Re: LVD - Good unit that won't break the bank.

    I believe BnV is correct, from the manual:

    http://www.solar-electric.com/c40.html
    http://lib.store.yahoo.net/lib/wind-sun/Cseries-manual.pdf
    Load Controller
    The C-Series controller can operate as a Low Voltage
    Disconnect (LVD) for DC loads to prevent over-discharge to
    batteries during periods of poor charging or excessive loads.
    The C-Series controller uses the user-adjustable setpoints to
    determine when to disconnect or reconnect loads depending
    on battery voltage.
    When used as a DC load controller, the settings of the LVR
    and LVD are controlled by two rotary potentiometers (also
    called pots) on the circuit board.
    The scale on the adjustment potentiometers differ from the
    scale used for other functions. A decal with the appropriate
    adjustment scale is included with the C-Series. To apply the
    decal, gently pull off the knobs of the potentiometers and
    place this decal on the circuit board. After the decal is in
    place, replace the knobs. The EQ jumper determines manual
    or automatic reconnect when the C-Series is used as a load
    controller. Do not use this decal if using the C-Series
    controller as a PV Charge Controller or Diversion Controller.
    Low Voltage Disconnect
    When configured as a load controller, the C-Series controller
    will disconnect the load from the batteries when it reaches the
    LVD setting. There will be a 6-minute delay after the voltage
    drops below the Low Voltage Disconnect (LVD) setting
    before the controller actually disconnects the load.
    Low Voltage Reconnect
    It can also provide automatic reconnection of the loads at the
    LVR (Low Voltage Reconnect) setting. Reconnection of the
    load is allowed once the battery voltage has exceeded the
    Low Voltage Reconnect (LVR) setting.
    Loads are either automatically or manually reconnected when
    battery voltage exceeds the Low Voltage Reconnect (LVR)
    setting for 6 minutes.
    See “Operating Mode Jumper” on page 20 for instructions on
    enabling this mode.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • zonebluezoneblue Solar Expert Posts: 1,218 ✭✭✭✭
    Re: LVD - Good unit that won't break the bank.

    c40 is one of those pwm controllers that can run in one of three modes. lvd being one of them. Morningstar TS45 is another. You cant do pwm charge and lvd, just one at a time. Uses the same output stage.

    Other small controllers sub 30 amp, usually have lvd built in, and can do both at once.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


  • Steven LakeSteven Lake Solar Expert Posts: 402 ✭✭
    Re: LVD - Good unit that won't break the bank.

    Ah, okay. Yeah, I didn't see that in the description when I looked it up. Even so I've already got the charge controller part well covered and don't need more than an absolute maximum of maybe 15 amps, possibly 20 tops. Plus, my thinking with a dedicated unit was to keep things as simple as possible. IE, single small and single purpose for a single circuit, sorta like this: www.amazon.com/Seco-Larm-Voltage-Battery-Cut-Off-Adjustable/dp/B0058M0SSY/

    IE, LVD and nothing else at a good price, but good enough quality that I know it won't vanish in a cloud of happy smoke two weeks after I start using it, or forget to do its job and kill my battery bank.
  • BB.BB. Super Moderators, Administrators Posts: 32,026 admin
    Re: LVD - Good unit that won't break the bank.

    The amazon part is just the control circuitry (with some sort of small mechanical relay????), you still need a relay (or digital relay) of some sort to control larger DC current flow directly. Those are not (usually) inexpensive (and relays draw a few Watts to 6 watts when "on"--addition loads on the system--Unless you use some form of latching or digital/silicon relay, again another added cost).

    Also the Xantrex unit is adjustable and has temperature correction of the battery output voltage.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SolInvictusSolInvictus Solar Expert Posts: 138
    Re: LVD - Good unit that won't break the bank.

    The C35 controls up to 35 A, works with 12 V or 24 V battery arrays and costs less than the C40.
  • inthejungleinthejungle Solar Expert Posts: 91 ✭✭
    Re: LVD - Good unit that won't break the bank.

    I have always liked the guys at Digi Key 1-800-344-4539 they sell something like this

    http://www.digikey.com/us/en/ph/crydom/LVD-DC-solid-state-switches.html

    The other option that buddies of mine have used before with great success is something like this from Waytekwire 800-328-2724 , they have two options one

    is made by cooper bussman here

    http://www.waytekwire.com/item/80029/SURE-POWER-130512-LOW-VOLTAGE/

    the other one is made by Cole Hersee found here

    http://www.waytekwire.com/item/75525/COLE-HERSEE-FLEXMOD-48610/http://www.waytekwire.com/item/75525/COLE-HERSEE-FLEXMOD-48610/

    One other option that I really like because it lets you configure the cut out voltage is here

    http://www.powerwerx.com/batteries-chargers/dc-low-voltage-disconnect-lvd.html

    They all run about 60-80 dollars, but we have had good success with these

    The other company that I have found to have something like this is

    Painless Performance Products LLC 2501 Ludelle Street Fort Worth, Texas 76105 Phone (817) 244-6212


    When I bought some in the past from Waytek wire, gave them a call told them specs and they helped me find these. If not exactly right give them a call, Waytek wire and digi key they have tech guys who can find the exact spec you are looking for.
    If you order from Waytek make sure you tell them everything you need. I ordered some parts once and forgot one small item. I called 15 minutes after placing the order and they had already processed, packaged and were ready to ship nothing could be done. Need less to say they are very quick!

    The other thing I was thinking. . . do you have a battery monitor installed most have a way to hook up a relay based on voltage. Maybe this is an option.

    Hope that helps

    ITJ
    In Niger, trying to keep a LG FMA 102NAMA fridge(This has the inverter compressor) backed up with solar using a Victron Multi-Plus Inverter/Charger Compact 12v 1600w with a 70a charger built in.I want to back it up for 4-8 hours. I am also running a few O2 cool fans and a few Thin Lite LED's of my batteries for when the grid is down so my kids can sleep.
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