Powering 12 volt fence energizer from 24 volt battery

mryimmers
mryimmers Solar Expert Posts: 117 ✭✭✭
in General Solar Power Topics #1
Hi, what would be the most efficient way to power a 12 volt electric fence energizer from a 24 volt battery? I have a fencer running to protect a bee hive and have to leave it unattended for a couple weeks at a time, I currently an leaving a small exeltech xp250 running with a battery tender 12v, 750mA charger to keep a regular sized car battery charged, which in turn powers the fencer. The fencer uses 500mA @ 12 volts.
I am thinking either a 24-12volt converter of some kind, or a small charge controller?? It would need to be able to input up to 30+ volts, but not much for amps.  Thanks, HH 
510 watt pv, TS-MPPT 60, Exeltech XP1100, XP600 & XP250 @ 24V, 4x Trojan 105RE, Trimetric 2030, Yamaha EF2400i gen.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #2
    How much does that fencer use in amp hrs in a day?  the Parmac fencers I have seen have a tiny PV that keeps a charged battery 'up' for the whole Bee season up here... I am thinking a 5W panel should be in the ball park for 2 weeks load on the battery..
     
    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,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • mryimmers
    mryimmers Solar Expert Posts: 117 ✭✭✭
    #3
    at 500mA @12 volts, I guess 12 amp hrs a day at 12 volts? I would like to run it off my 24v battery bank which is already there and not doing much most of the time anyway. I have just started using this fencer  and don't really know how long it will run on the battery, but I have to go to work, and don't want to find out the hard way haha.
    510 watt pv, TS-MPPT 60, Exeltech XP1100, XP600 & XP250 @ 24V, 4x Trojan 105RE, Trimetric 2030, Yamaha EF2400i gen.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #4
    Hmm, 2 days = 1 amp x 48 Hrs so 48Ahr. 50% of 100 Ahr (avg car batt.) = 50 Ahrs so it should take~ 2 days to use 1/2 of an average car battery total capacity...
     
    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,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • mvas
    mvas Registered Users Posts: 395 ✭✭✭
    edited June 2017 #5
    Something like this?  Up to 40 Volts IN to 12 Volts OUT for $10.00
    http://www.ebay.com/itm/24V-to-12V-DC-DC-Car-Power-Supply-Inverter-Converter-Conversion-Device-/382068953412?hash=item58f5159144:g:jIoAAOSwYIxX99Zm
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  • cow_rancher
    cow_rancher Solar Expert Posts: 117 ✭✭✭✭
    #6
    If you're not big on building your own voltage regulator with a 3 pin LM317 (there used to be 3 pin non adjustable regulators not sure why I couldn't find one...)
    Image result for 12 volt 3 pin regulator LM

         or you could buy this module, Texas Instruments TPS74901EVM-210, from DigiKey

    Rancher

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  • mryimmers
    mryimmers Solar Expert Posts: 117 ✭✭✭
    #7
    sorry rancher, but that looks like Egyptian hieroglyphics to me, haha,  I guess I'd best just get something like mvas pointed out, thanks guys!!
    510 watt pv, TS-MPPT 60, Exeltech XP1100, XP600 & XP250 @ 24V, 4x Trojan 105RE, Trimetric 2030, Yamaha EF2400i gen.
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  • garynappi
    garynappi Registered Users Posts: 120 ✭✭
    edited July 2017 #8
    cow_rancher said:
    If you're not big on building your own voltage regulator with a 3 pin LM317 (there used to be 3 pin non adjustable regulators not sure why I couldn't find one...)
           or you could buy this module, Texas Instruments TPS74901EVM-210, from DigiKey

    Rancher

    That would be an LM7812. They are OK up to 35 volts in 1.5a out, but heat loss may be high and a heat sink would be needed.

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  • mryimmers
    mryimmers Solar Expert Posts: 117 ✭✭✭
    #9
    I got this, works great                  http://www.ebay.com/itm/TRANSLECTRIC-SM2412-5-HEAVY-DUTY-VOLTAGE-CONVERTER-5A-AMP-18-50V-DC-TO-13-8Vdc/232021258432?ssPageName=STRK:MEBIDX:IT&_trksid=p2055119.m1438.l2649
    510 watt pv, TS-MPPT 60, Exeltech XP1100, XP600 & XP250 @ 24V, 4x Trojan 105RE, Trimetric 2030, Yamaha EF2400i gen.
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