Power Converter

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System
System Posts: 2,511 admin
in Solar Beginners Corner #1
Just starting with solar, plan on using 2 - 135 watt panels on travel trailer. Has anyone thought about or tried tapping into built in charger controller with double throw switch to change from panel charge to onboard charger.
My RV has WFCO 8955, 3 stage Power convertor / Load center. I added 2- 100 Ahr batteries and 2000 watt pure sine inverter
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: Power Converter

    If I understand the question correctly (and I may not) there is no need for a switch. PV's run through their own charge controller directly to the batteries. That those batteries are also attached to some other charging source makes no difference.
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  • System2
    System2 Posts: 6,290 admin
    #3
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    Re: Power Converter

    My thoughts were to share existing charge control circuit in Power converter with PV.
    Just trying to save buying separate charge controller for PV. I did plan on adding battery monitor. Sorry about the confusion
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,448 admin
    #4
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    Re: Power Converter

    It depends on what the presently installed charge controller is... If it is a 120 VAC shore power converter, or some other non-solar panel type charge controller (like an Inverter/Charger)--Then it is very unlikely that you can use it to "control" the charging current from your solar panels you want to add.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Shadowcatcher
    Shadowcatcher Solar Expert Posts: 228 ✭✭✭
    #5
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    Re: Power Converter

    I do not know of a power converter that does anything more than convert "shore power" 110AC to 12V DC, at least in the RV context. Power centers that include fuses and circuit breakers handle that AC and DC.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #6
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    Re: Power Converter
    Shadowcatcher wrote: »
    I do not know of a power converter that does anything more than convert "shore power" 110AC to 12V DC, at least in the RV context. Power centers that include fuses and circuit breakers handle that AC and DC.

    actually what you describe is more of what we might call a power supply or wall adapter (wart). most converters usually handle less common conversions like 24 to 12 or 5 to 12 or even 48 to 24 and can be all dc or some combo of dc and ac too. technically the terms can be interchangeable to some extent as take for example an inverter that is going from 12v to 110vac that this is technically a form of a converter, but we term these as inverters for battery dc to household ac. these converters could technically be power supplies too.
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  • Kamala
    Kamala Solar Expert Posts: 452 ✭✭
    #7
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    Re: Power Converter
    niel wrote: »
    ... what you describe is more of what we might call a power supply

    yes.
    niel wrote: »
    or wall adapter (wart). ...

    no.

    In a RV (even marine) context, a converter is a power supply and often incorporates a distribution panel. Also AC breakers and a DC fuse block. In RV PV installations they are, IMHO, an anachronism. My Elixir ELX-25 puts out 13.8 volts. Safe for devices but totally unacceptable for charging my AGM batteries. My converter has been disabled for the 1.5 seasons that I have been evaluating my PV system.

    This winter I plan to pull my converter and modify it. The plan is to do the following:

    1. I know that the converter is on one AC breaker. I'll remove it from the existing AC bus and connect it ahead of the transfer switch directly to shore power. That way, the converter will never operate from inverter power.

    2. Isolate the DC output of the converter from the PV charge controller/battery bank. Either through a switch or relay. That way, when shore power is available, the AGM bank will be charged only. All 12VDC will come from the converter.

    RV mfgrs are not on board with PV.

    Kamala
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #8
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    Re: Power Converter

    kamala,
    my only point was that it is a semantics thing with minor differentiations we impose.

    here's a definition of a wall wart i found.

    "A "wall wart" is a small low-voltage power supply that is self-contained and plugs straight into the wall."

    http://www.horrorseek.com/home/halloween/wolfstone/Power/powwal_WallWarts.html

    not enough? then here's another.
    http://www.catb.org/~esr/jargon/html/W/wall-wart.html
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  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #9
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    Re: Power Converter

    As the OP stated, his converter/charger has a 3-stage charger:

    http://www.wfcoelectronics.com/index.php?option=com_content&task=view&id=46&Itemid=77

    To the OP - no you can't run the PV through the RV converter/charger. The converter/charger takes AC on the input, but solar panels put out DC. So you'll need a dedicated solar charge controller.

    You can hook up both the AC powered converter/charger and the solar charge controller to the same battery bank - they'll both do their jobs independently and won't conflict with each other.
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  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    #10
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    Re: Power Converter
    dwh wrote: »
    You can hook up both the AC powered converter/charger and the solar charge controller to the same battery bank - they'll both do their jobs independently and won't conflict with each other.

    Yes, within restriction of, if simultaneously used, stay within reasonable max charging currrent rate of battery array.

    I looked up the manual for the WFCO 8955, 3 stage Power converter. It has pretty squirly specs. It is suppose to be able to supply 55 amps output. From the manual:
    "
    The three modes/stages of operation include:
    Absorption mode/Normal operation
    Nominal battery charge and supplies power to appliances
    Bulk mode/Charge mode
    Fast battery charge and supplies power to appliances
    Float mode/Trickle charge
    Trickle battery charge during storage

    Absorption Mode:
    During this mode, the converter output is in the
    13.6 Vdc range. This is the normal operation mode. This mode
    provides the 12 Vdc and current required by the 12 Vdc RV appliances,
    as well as slow charging the battery.

    Bulk Mode:
    When the converter senses that the RV system voltage is
    less than 13.2 Vdc (equivalent to less than 50% of battery charge) the
    converter will automatically go into the “Bulk mode.” In this mode, the
    output voltage of the converter will switch to 14.4 Vdc for a maximum
    of four hours. If the converter cycles between “Absorption and Bulk
    mode,” there could be a shorted battery cell or other issues.
    If the output voltage drops below 13.2 Vdc, the converter automatically
    changes to a “Bulk mode” 14.4 Vdc (unless the converter is in overload
    condition). There are two signs of an overloaded converter:
    Low output voltage, and full converter fold back or shutdown. In both
    cases, the converter will automatically turn ON, once the complete load
    is removed. For low output condition, removing the extra (over the
    current rating) load will be sufficient. If it is impractical to remove all
    the load, resetting the main breaker will have the same effect.

    Float Mode:
    If the RV is not being used for approximately 48 hours,
    with a “no load” condition and the shore power is plugged in, the
    converter will automatically go in to the “Float mode.” In this mode,
    the converter is charging the battery with a trickle voltage of 13.2 Vdc.
    When the converter senses a demand (by turning on lights), the
    converter automatically returns to the “Absorption mode” 13.6 Vdc.
    "

    No where in the manual does it talk about how the 55 amps is used. It appears 55 amp limit is available for each of the modes. If you run the battery down to 12.4 vdc and then plug in the shore power what happen? If it pushes 55 amps at batteries and you have two 100 AH batteries in parallel you are pushing things a bit for that AH capacity.

    It may assume you have a large battery array typical to a Marine situation where someone buys a 55 amp converter for two 240 AH marine batteries.
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  • Shadowcatcher
    Shadowcatcher Solar Expert Posts: 228 ✭✭✭
    #11
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    Re: Power Converter

    I did say in the context of an RV, and the one that RV user mentioned the WFCO 8955 is a power center. We are using a Progressive Dynamics power center.

    I am aware of DC of DC converters and inverters...
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