Please Review & Comment

System
System Posts: 2,511 admin
in Advanced Solar Electric Technical Forum #1
I'm a newbie that has come up with this basic RV solar system design after reading forums and internet research. The module size is based on a friends 10 year experience. I will add a second when we start serious traveling. I would appreciate comments about wire size, the need for fusing (size and location) and anything else that comes to mind. Right now I'm leaning towards the Xantrex C35 controller with battery temp sensor and the remote monitor. My hope is to have a system that keeps the batteries charged with little attention and one that doesn't burn the RV down. Thanks for your help.

Mike
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
    Re: Please Review & Comment

    You don't mention what sort of loads you will run off the inverter. That becomes important as you draw 12V @ _ _ _ Amps from your battery, the wire needs to withstand that, and not loose energy as heat.

    You should have a Fuse or a fusible link somewhere, close to the battery, so if a + wire gets pinched on the frame, the fuse/link will blow, and not torch your RV. If you are using a circuit breaker as your Battery Disconnect, it needs to be a DC qualified one.

    Wire your batteries on the "diagonal" (sketch attached) which will equalize the wire losses.

    You may want to include some provision for battery charging via "shore power" or off the vehicle's alternator. Often though, the alternator will not provide enough voltage to fully charge the different chemestry of a deep cycle battery, it's about a volt higher than a car's electrical regulator, but it would work to bulk charge a very low battery in a pinch.
    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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  • System2
    System2 Posts: 6,290 admin
    #3
    Re: Please Review & Comment

    Mike,

    Thanks for the input. There is no inverter at this time there is only the existing converter. The current set up from the factory has connections from the vehicle and shore power. Wiring from the vehicle connects where the positive buss will be, connecting to battery leads and the (7) wire on my diagram. The shore power connects directly to the converter which then charges the battery through the (7) wire and feeds 12v demands downstream of the converter. I am not proposing to change the (7) wire which is the factory installed wire from the batteries to the converter.

    Should the fuse/fusible link be installed on the (+) or (-) lead of the battery? What size is recommended?

    I will look into the "DC" qualified circuit breakers.

    I will wire the batteries as shown on your sketch.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #4
    Re: Please Review & Comment
    Giantsfans wrote: »
    Thanks for the input. There is no inverter at this time there is only the existing converter.

    OK, we've got no idea what the "converter" is. Is it 120V battery charger ? 120Vac inverter ? Alternator powered charger ? Any nameplate info would be helpful.

    It's unlikely it has proper 3 or 4 stage, deep cycle charger in it. It may not actually be helpful, except to the salesman in the RV lot.


    The fuesable link depends on your expected load. Say you have an 800W microwave oven you use for heating coffee. The calculation: convert 120V watts to 12.5V inverter Amps

    120Vac 800W (oven load)
    Add 20% for inverter losses : 160W
    convert to 12.5V [960/12.5] Watts divided by Volts

    Requires 76.8 amps @ 12.5V DC. A 100A fuse would be appropriate, I think. You don't want it to blow on a brief transient. Be sure your cable lengths and gauge can handle this, you don't want to waste voltage in creating hot wires. This is why folks often use a 24V system, that 76AMPs drops in half, to about 40amps, and you can use smaller wires, with less losses.

    Good thing you have 2 batteries ! This will be fine for a cup of coffee, but don't expect to cook a whole meal in the microwave, unless you have an aux generator.


    Battery - should have a heavy cable to chassis, and to your inverter -.
    Battery + should have fuse/link as close to battery as practical, and then heavy wire to inverter +
    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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  • System2
    System2 Posts: 6,290 admin
    #5
    Re: Please Review & Comment

    The converter is a WFCO ULTRA III distribution center / model WF-8955 ANP. It has a 3 stage charging system (14.4vdc bulk - 13.6vdc absorption & 13.2 float). Rated at 55 amps DC output and 105-130vac 12.0 amo (950 watt) input. The factory installed #6 wire from the battery to the converter with a 50amp fuse at the battery. I can replace this wire if it is not adequate for the use.

    Our uses will be relatively conservative (lights, limited laptop computer, water pump, refrigeration/water heater igniters, maybe TV).

    Will the existing 50 amp fuse provide the desired protection or should an additional fuse/fusible link/breaker be installed? Is 50 amps correct?

    I will move the grounding wire from the negative/ground bus to go directly from the battery to the frame. I will use battery cable for this.

    Again, thanks for the continued help. I appreciate it very much. Mike
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #6
    Re: Please Review & Comment
    Giantsfans wrote: »

    Will the existing 50 amp fuse provide the desired protection or should an additional fuse/fusible link/breaker be installed? Is 50 amps correct?

    I will move the grounding wire from the negative/ground bus to go directly from the battery to the frame. I will use battery cable for this.

    a) leave the existing factory fuse - it's OK. (at least they think so) carry a spare.

    b) DONT MOVE the neg cable. You don't want to run DC current thru the vehicle chassis.
    WF-8955 ANP http://www.dutchmen-rv.com/scripts/pdfretail/get.php?id=187
    looks like it's just a nice 3 stage 55A battery charger.

    I would ADD an nice fat (automotive ground battery cable) to the setup, so that if a wire got pinched to chassis, it would be sure to blow the fuse, not sit there and cook for hours.

    To run 120VAC appliances, you will need a inverter (pure sine recommended) to power them.
    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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  • System2
    System2 Posts: 6,290 admin
    #7
    Re: Please Review & Comment

    many thanks

    Mike
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  • rrbv
    rrbv Registered Users Posts: 16 ✭✭
    #8
    Re: Please Review & Comment

    I have a fifth wheel rv. I simply put the charge controller under the part that goes over the truck, mounted to the electrical box that supplies the emergency brake. This is already hooked to the battery through heavy wire. I added another battery behind the existing converter(battery charger) and hooked it in parallel. The DC and AC fusing, distribution, etc were left intact. Very simple and very little hardware and wiring required.

    rrbv
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