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Thread: Charging without a Charge controller

  1. #1
    Join Date
    Jun 2007
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    Williams Lake, BC
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    Default Charging without a Charge controller

    I have a need to connect, short term, a PV or 2 to my camper battery. We are demolishing our old cabin and using the camper for sleeping in, a bit of cooking and showers etc... both my CC's are still in use and I don't want to buy another one for this temporary setup.

    Is there a rule of thumb to use for this hookup?

    ~ 660 amp battery, 25 W and 70 watt panels available. not direct sun as in the shade.

    thanks
    Eric
    Last edited by westbranch; June 21st, 2011 at 14:32 PDT. Reason: typos
    100% Off Grid @ 51* 46' N lat 124* 44' W long

    New House system: coming - 2 arrays @ 2240W
    CL150&Epanel 2 @140 W 12v PVs , 24V C&D AT-15P AGM @ 950Ah
    + CL150 2@120W 12 V panels, 24V C&D AT-15P AGM @ 950Ah
    Cotek ST1500W inverter, TBS 30a-24v Omni-charger, Honda Eu3000is,

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

  2. #2
    Join Date
    Sep 2006
    Location
    Willits, CA
    Posts
    5,750

    Default Re: Charging without a Charge controller

    panels in the shade will never charge a battery You have more chance, without a charge controller, of the panels discharging the batteries at night (backfeed)



    660A of battery, 100W of panel, even in full sun, you won't keep up with self discharge.
    http://tinyurl.com/LMR-Solar
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    Grundfos 10 SO5-9 with 3 wire Franklin motor (1/2hp 240V 1ph # 214505 ) on a timer for 3 hr noontime run - Runs off PV
    Powerfab poletop PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe battery | 15, Evergreen 205w "12V" PV | Midnight ePanel || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT

  3. #3

    Default Re: Charging without a Charge controller

    Eric;

    The only thing you can do is put a Voltmeter on it and watch. Together those two panels might produce 5 Amps? Not much for a 660 Amp hour battery (assuming the extra 'm' was superfluous), but even a small charge on a not-so-drained battery can push the Voltage too high. That's really all a PWM does; you'll have to stand in for connect/disconnect. But you don't have to do it dozens of times per second, okay?
    1220 Watts of PV, OB MX60, 232 Amp hrs, OB 3524, Honda eu2000.

    Ohm's Law: Amps = Volts / Ohms
    Power Formula: Watts = Volts * Amps

  4. #4

    Default Re: Charging without a Charge controller

    I have to ask a simple question. Is that battery a 660 amp hour battery or 660 cranking amps? At 660 Ah, that is a massive battery for a camper. Is it is 660cca, running a panel directly to it should keep it charged depending on the amp produced by the panel. I have a couple 100w panels hooked directly to a couple of marine batteries and the most I have ever seen them produce was 17a, and it was short duration.

    ***edit***
    Be sure to run a diode if the panels stay hooked up an night.
    Classic 150 and 3x Kyo 210 and 3 kyo 215s. I have miles to go before I sleep.

  5. #5
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    Williams Lake, BC
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    Default Re: Charging without a Charge controller

    sorry, that is 660CCA as Leper pointed out. Probably in the ~100 A range of most car type batteries.

    Ya, caught in the PV panel trap of hi Voltage/low amperage output.

    It is a 'marine battery' used for the camper and the fishing trolling motor.

    Just ordered a cheapo 10a PWM CC off Ebay. Now I can put the panels in the full sun without too much worry.

    thanks for the quick comments.

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

    New House system: coming - 2 arrays @ 2240W
    CL150&Epanel 2 @140 W 12v PVs , 24V C&D AT-15P AGM @ 950Ah
    + CL150 2@120W 12 V panels, 24V C&D AT-15P AGM @ 950Ah
    Cotek ST1500W inverter, TBS 30a-24v Omni-charger, Honda Eu3000is,

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

  6. #6
    Join Date
    Sep 2006
    Location
    Willits, CA
    Posts
    5,750

    Default Re: Charging without a Charge controller

    Since that battery is a "hybrid" and contains the worst of both starting and deep cycle, avoid discharging below 70%, or you may not get started some morning !

  7. #7
    Join Date
    Jun 2007
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    Williams Lake, BC
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    Default Re: Charging without a Charge controller

    Mike I think you are confusing a camper with a "Winnebagel".

    The camper slides on and off the pickup and has its own on board, independent battery, hence the 'marine type' as it is a bit better for long slow use... the main drawback is there isn't enough room for a couple of real deep cycle 6 volt batteries.
    We only get about 2 days before needing to charge up. Water pump gets left on all day, Fridge and water heater are pilot-less units, the furnace fan is the big one and then lights and radio... oh and there is a magic fan that is temperature activated and the seldom used bathroom fan
    100% Off Grid @ 51* 46' N lat 124* 44' W long

    New House system: coming - 2 arrays @ 2240W
    CL150&Epanel 2 @140 W 12v PVs , 24V C&D AT-15P AGM @ 950Ah
    + CL150 2@120W 12 V panels, 24V C&D AT-15P AGM @ 950Ah
    Cotek ST1500W inverter, TBS 30a-24v Omni-charger, Honda Eu3000is,

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

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