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Danger to battery using 18w, 1.2a panel with no controller?

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  • Danger to battery using 18w, 1.2a panel with no controller?

    I just dug up a old, never used, 18w panel and 7a controller I bought at HF 4 years ago. I was going to just use it to charge a 600amp jump-starter bat I take with me camping. The cheap controller stopped working after a few hours. If I am monitoring the battery voltage while charging, do I really need a controller at 1.2amps charging?
    Last edited by manich; 10-08-2016, 11:17 PM.

  • #2
    if you can monitor the voltage to keep the battery happy, great.
    Powerfab top of pole PV mount (2) | 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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    • #3
      Yes you do!

      Without a controller, what will eventually happen is that the battery terminal voltage will try to come close to the HF panel's voltage, which is typically 18-22v. That little agm inside is only rated for 15v max, quite frankly no more than 14.4v if you don't want it to expire real fast. And, most "600a" jumpstarters contain a 9-10ah agm in the first place. I know my Duralast 600 does.

      This is what can happen, although all you have to do is scale the application - the same will happen to your jumpstarter:

      https://www.youtube.com/watch?v=z5RtZe9AW2E

      So, what I'd recommend as a controller here is either a Morningstar SunGuard 5A pwm controller (potted and sealed - no adjustments), or a slight step up to the Morningstar 6A Sunsaver SS-6-12v model, because you can remove the jumper for a 14.4v absorb, vs a 14.1v non-adjustable absorb on the potted Sunguard. You'd want to protect the 6A cc from the elements of course.

      Seems ridiculous to take a solar jumpstarter seriously, but why not try? The CC is the brains of your system, so don't skimp on it.

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      • #4
        Forgot to mention it - an upgrade from the 7A HF controller to either of the Morningstars is worth it.

        The HF / Coleman / Sunforce 7A controllers are the very old school 1970's hysteresis type. That means it just charges to 14.2v, and then lets the battery voltage fall naturally to about 13.2v and "ping pongs" slowly back and forth - faster when nearing fully charged. Build quality is on the low side.

        But, this is really inefficient from a solar standpoint, and a much better job can be had by going with a PWM upgrade, which the inexpensive Morningstar's are. To top it off, they are ambient temperature-compensated, which the HF controller isn't.

        I wouldn't throw a lot of money at this, but a simple upgrade to a quality pwm like the Morningstars are an inexpensive upgrade to get you into 90's tech.

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        • #5
          Thanks. I will probably just give the 18w amorph away. Would rather spend any extra "solar money" on upgrading wires, frames, etc. on my 200w mono panel system.

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