12 Vdc lighting off of 48Vdc battery bank

Island Mon
Island Mon Solar Expert Posts: 29 ✭
in Off Grid Solar & Battery Systems #1
Does anyone have any experience running 12Vdc lighting off of a 48 Vdc bank?

I did some searching and found this...
http://forum.solar-electric.com/showpost.php?p=30482&postcount=9

I would most likely be running 10x 12Vdc LED lights with one of these 48V-12V converters.

Would I simply run positive and negative lines off of the battery bank terminals to the positive and negative on the converters?

I will be running the battery bank to a 120V/240V split phase inverter as well.

Thanks.
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Comments

  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #2
    Re: 12 Vdc lighting off of 48Vdc battery bank

    Why not use 48 vdc LEDs? http://www.superbrightleds.com/BA9S6_specs.htm

    Tony
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  • TnAndy
    TnAndy Solar Expert Posts: 249 ✭✭
    #3
    Re: 12 Vdc lighting off of 48Vdc battery bank

    Or tap your battery bank with a 12v takeoff ?

    Think you were gonna run 6v batteries.....you could simply tap pairs of them ( But I'd do all so you pull evenly ) in series, then bundle that together in parallel giving you 12v leads, then run that thru a fuse/breaker and on to your lighting circuit.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #4
    Re: 12 Vdc lighting off of 48Vdc battery bank

    Andy,

    I was going to suggest that as well, since LED loads are tiny,,, but from what I have read,, it is pretty hard to evenly draw 12 vts out of a bigger bank,, and setting up a bank with a consistent differential draw is pretty tough. I suppose you could,, as you suggest, pull off of all the batteries in a series parallel arrangement,, but it could lead to a tangle of wires. Most people just pull the load of of 2 batteries and are done with it,, not a very good idea.

    The only reason that I have stuck with a 12vdc bank all these years is that so many of my loads (and things that you can buy and use) are 12vdc normally. Radios, lights, fridge igniters, fans etc. Since there is a thriving 12vdc market mostly from the RV industry it may make some sense to use that to advantage. My 12 volt car radio/ipod interface works/sounds as well as any home unit,, but because it is native 12 vdc,, it draws considerably less power than a 120 vac unit, but the time all the conversions are done. (At less cost too!

    I do use a voltage doubler to run my pump off of 24 vdc to reduce the line loss however,,, at some cost and loss of efficiency.

    Tony
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  • lorelec
    lorelec Solar Expert Posts: 200 ✭✭
    #5
    Re: 12 Vdc lighting off of 48Vdc battery bank

    You should be able to run four of the 12v lights in series and connect them to a 48v battery bank. That would mean that you'd have to choose your number of lights in multiples of four.

    Marc
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #6
    Re: 12 Vdc lighting off of 48Vdc battery bank

    I would be a bit careful of just placing 4 LED 12 volt fixtures in series and connect to 48 volts--It all depends on the type of "ballast" that the LED fixtures use.

    If the fixtures use simple resistors to limit current--not a big issue.

    However if you don't know what the ballast is or they are electronic (current mode)--then slight differences in the strings/temperatures/ballasts could cause one or more of the fixtures to fail (over voltage) as the ballasts hunt for optimum V*I placement on the curve.

    Constant power type devices look like "negative resistors--as the voltage drops, they want more current so their "resistance drops"--while the other strings may see rising voltage, so their resistance increases--and they will get too much overall voltage, and the other low voltage ones will eventually fail to light because of not enough voltage.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • TnAndy
    TnAndy Solar Expert Posts: 249 ✭✭
    #7
    Re: 12 Vdc lighting off of 48Vdc battery bank
    icarus wrote: »
    Andy,

    I was going to suggest that as well, since LED loads are tiny,,, but from what I have read,, it is pretty hard to evenly draw 12 vts out of a bigger bank,, and setting up a bank with a consistent differential draw is pretty tough. I suppose you could,, as you suggest, pull off of all the batteries in a series parallel arrangement,, but it could lead to a tangle of wires. Most people just pull the load of of 2 batteries and are done with it,, not a very good idea.

    The only reason that I have stuck with a 12vdc bank all these years is that so many of my loads (and things that you can buy and use) are 12vdc normally. Radios, lights, fridge igniters, fans etc. Since there is a thriving 12vdc market mostly from the RV industry it may make some sense to use that to advantage. My 12 volt car radio/ipod interface works/sounds as well as any home unit,, but because it is native 12 vdc,, it draws considerably less power than a 120 vac unit, but the time all the conversions are done. (At less cost too!

    I do use a voltage doubler to run my pump off of 24 vdc to reduce the line loss however,,, at some cost and loss of efficiency.

    Tony

    I liked the 48v LED.....didn't know they made them.

    And I know what you mean about 12v stuff.....you can go to a good truck stop and get ANYTHING in 12v from a microwave to TV to you-name-it
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  • lorelec
    lorelec Solar Expert Posts: 200 ✭✭
    #8
    Re: 12 Vdc lighting off of 48Vdc battery bank
    BB. wrote: »
    I would be a bit careful of just placing 4 LED 12 volt fixtures in series and connect to 48 volts--It all depends on the type of "ballast" that the LED fixtures use.

    That's a good point, Bill. Four lights in series that use boost regulators for internal power might not share that 48v equally -- which may or may not cause a problem.

    Some of the newer high power LED arrays are being made for 12v typical (11.6v-16.4v range) and don't need a resistor or regulator of any kind (i.e. Osram's Ostar). These, although not mounted in a fixture, would be ideal for series configurations so long as you're careful not to overpower them.

    Marc
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #9
    Re: 12 Vdc lighting off of 48Vdc battery bank

    Osram's 24 volt Ostar LED assemblies (PDF) do carry warnings about series connections:
    • Only parallel connection allowed
    • Parallel connection of up to 6 modules (12 W version) or 9 modules (8 W version) with the power feed in the center to one OT75
    And, their 24 VDC (23-25 VDC min/max range) is not large enough to safely run on a Solar RE system Battery Bank (~22-30 VDC).

    I do not see any technical information on the Ostar modules--so I cannot guess what their internal's may include.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #10
    Re: 12 Vdc lighting off of 48Vdc battery bank
    Island Mon wrote: »
    Does anyone have any experience running 12Vdc lighting off of a 48 Vdc bank?

    I did some searching and found this...
    http://forum.solar-electric.com/showpost.php?p=30482&postcount=9

    I have a longish slide show about building these up. If you are just going to use a couple of LED's, the converter will be wasting a fair amount of idle power, as it has all it's overhead losses. The converter needs at least one resistor to set the voltage to precisely what you want, and you need to provide a couple of capacitors at the input and output. I mounted my modules on a circuit board to make them easier to handle and deal with. I can supply you with the prints for the boards and the parts list if you want.

    My $100, 120 watt 48-12V DC-DC converter slideshow. A 94% efficient converter, used to down-convert a 48V solar battery bank, to power 12V LED drivers for a Burning Man project.
    http://www.naturalstudies.org/Photo_galleries/LED_driver/
    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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  • lorelec
    lorelec Solar Expert Posts: 200 ✭✭
    #11
    Re: 12 Vdc lighting off of 48Vdc battery bank

    Bill,

    I was thinking more along the lines of the individual LED modules, with which you could build your own lights for nearly any voltage you want (it would probably be a good idea to throw a resistor in there for regulation at max expected voltage). Hopefully this link comes through right! I didn't see anything advising against series use there.

    Osram LE_CW series

    ...OR do like Mike did and build your own regulator to suit the application ;)


    Marc
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  • PV person
    PV person Registered Users Posts: 1
    #12
    Re: 12 Vdc lighting off of 48Vdc battery bank
    Island Mon wrote: »
    Does anyone have any experience running 12Vdc lighting off of a 48 Vdc bank?

    I did some searching and found this...
    http://forum.solar-electric.com/showpost.php?p=30482&postcount=9

    I would most likely be running 10x 12Vdc LED lights with one of these 48V-12V converters.

    Would I simply run positive and negative lines off of the battery bank terminals to the positive and negative on the converters?

    I will be running the battery bank to a 120V/240V split phase inverter as well.

    Thanks.

    Try this converter. It's more efficient to use 48V battery bank and a MPPT solar charge controller, then switching step down converter (about $2, £1.38 each) after each switch. If you buy a couple of higher power (5-10A) converters, you can also supply your 19V Laptop from the 48V battery too! You can then use 10-50W dimmable LEDs in each room, replacing the conventional light fitting, giving up 180deg light spread.
    The potentiometer replaces the voltage set resistor on the board. (making it a variable voltage convertor, as the high power LED chips need 30-33V
    DC converter: http://www.ebay.co.uk/itm/290686270849 10-50W LED chip http://www.ebay.co.uk/itm/151382951190
    DC LED chips (about 99p-£1.49 for 10W dimmable)
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