controller connection

firesine
firesine Registered Users Posts: 3
Hi,
New to the forum and could use a little help.

I'm looking to replace my SS20L I have mounted on my TT w/a unit that will have to be installed out of the weather. I'm replacing my 130w Kyocera, got shattered when a 30+mph gust drove it into some gravel at big bend, w/2-24v 130w panels I now have. My ideal install location is about 12ft from my battery close to my converter and inverter. I have 2 heavy welding cables running from my battery to my set up, along w/the trailers original wiring, and additional ground cables already in place. (That wasn't fun to do!)
Do I need to connect my controller directly to my battery w/new wire or can I just connect to the cable that's already run from the battery?
I've gotten 2 different answers so far. Someone I spoke w/at NAW&S told me I didn't have to run a new cable back to the battery and someone at backcountry solar told me I did! Id rather be safe than sorry on this one.
The correct answer will affect the type of controller I end up with and it's location .
Thanks ahead of time.
john,

Comments

  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: controller connection

    Have you asked Morningstar? they are good at responding. What configuration are you going to use?
     
    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
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: controller connection

    Welcome to the forum John.

    It's a matter of how the circuits are laid out in respect to over-current protection. You basically have two separate circuits that interact: the charging circuit and the inverter or load circuit.

    Normally the two would "meet" at the battery, and there each would have its own fuse/breaker according to the wire sized for the expected current on the circuit. In your case you want them to "meet" at the inverter or load center. This works if you take some extra precaution with the current protection.

    What you do is treat the battery cables as "extensions" to the battery posts. Where the two circuits meet you put in the appropriate size CP for the charging and load circuits. But you also want to have a fuse such as the Blue Sea terminal post fuse back at the battery to protect that long, heavy cable run to the junction point.

    Do that and it will be fine.

    BTW if you're going to use "24 Volt" panels on what is most likely a 12 Volt system you'll need an MPPT controller. If they really are 130 Watts (small for a 24 Volt panel) and total 260 you'll be just over the max on a Morningstar 15 Amp MPPT, but it would probably work fine. If it's more than that, Rogue is about to release its new 20 Amp MPPT controller.
  • firesine
    firesine Registered Users Posts: 3
    Re: controller connection

    Sorry, I don't get this and I don't want to misunderstand. "Where the two circuits meet you put in the appropriate size CP for the charging and load circuits"
    Where I intend to splice on to the battery cables would be about 18" before my converter(ac to dc power supply/battery charger/breakers/distribution panel for ac and dc loads including battery). This is also where my 1200w inverter ties in. There is a 50a breaker, about 2ft from my battery, that all the + cables are connected to. If I'm understanding correctly, I should have another fuse. Between the charge controller and where I intend to splice into?

    They are 24v panels, 44v voc, and according to MS tech support the excess voltage won't harm the MS 15a MPPT and it would just put out the rated 15a. It's a great unit and If I went w/this I would have a non issue as it would be mounted next to and connected to the battery. The unit I'm considering has to be mounted out of the weather though, a heliotrope 22b.
    jm

    Haven't asked MS, Their tech dept has been tied up on some big R&D project.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: controller connection

    A little sketch that may help you understand what I'm talking about.
  • firesine
    firesine Registered Users Posts: 3
    Re: controller connection

    Thanks,
    Got it now.
    much appreciated!

    jm