Charging Boat Batteries with MorningStar ProStar-Mppt

AnawaAnawa Solar Expert Posts: 211 ✭✭✭

A few weeks ago, I had this “epiphany” that was going to solve a major convience project that I wanted to do for years. I have a covered boathouse sitting over the edge of a lake having a couple of boat slips with a contiguous decked “social” area. I’ve always wanted to be able to charge the trolling motor batteries and have nighttime lighting via PV solar panels, but where/how to house (and maintain) the equipment and batteries was more of a problem than I was willing to try to solve. Not to mention the cost. But things change. I’m getting older and lugging 60# batteries for a 1/4 mile puts a real bummer on the fishing experience. So now, I’m also a bit bummed-out with using my Honda 1000 generator to charge the batteries at the boat dock until the fuel runs out every time after I go fishing.

I now have a small aluminum pontoon boat that runs entirely off of 12volt battery power. The trolling motor will pull about 55 amps full-wide-open thus the marine battery currently on-board get to a fairly deep SOC in short order. I’m looking to mount a couple of 6v golf cart batteries to upgrade. The “epiphany” was that I would use the pontoon battery bank to power both the boat as well as the LED lighting.

After a rather awkward start with receiving damaged solar panels, the installation is pretty much complete - I’m waiting to receive a few odd ball type 10awg 3/8” stud connectors to hook-up the battery bank charging terminations.

did not didBefore I get to my questions, I want to comment on the service and reliability that the NAWS host for this forum provided on this particular solar installation. I’ve done business with NAWS over the last 5 years and have used their technical expertise in refining PV design and then providing most all the parts and pieces on two (2) fairly large off-grid solar installations on my property. The first was a 4.6kW (expanded to 6.1kW) and the other was 8.2kW. They were very helpful and professional every step of the way. On this current installation, the panels I received (2 ea- 320w) were damaged by the shipper and was unknown at the time we unloaded them. NOTE: In spite of all the flags, all the numerous highly visible warning labels on the packaging, the e-mail notices insisting on inspection, we failed on our end to comply with the instructions. I did not know the panels were damaged until after almost 4 weeks after receiving them, right before I was ready to mount on the roof pole. I called NAWS and within a couple of days they shipped me replacements for only the cost of the freight. They weren’t the same panels I originally ordered, but they were the same total wattage/type and I was more than pleased with this exchange. I will continue to do more business with NAWS in the future.

Now my concerns and questions. As usual for me, as I was reading the fine print on the MorningStar PS-MPPT installation/owners manual in preparation for the system start-up, I ran across a statement that read something to the effect: “before disconnecting the battery source, disconnect the PV array FIRST or serious damage could occur to the charge controller”. If this is the case, I will not be able to have a simple process of disconnecting the battery (via locking socket on 10awg cable tether) and casting-off into the wild blue. My questions are: anybody on the forum have any idea what the potential damage would be that concerns MorningStar? Is it the shut-down sequence? What if the battery disconnect is only for milli seconds as it transfers to another 12v source? I have designed a “switching box” to select between two battery banks (regular 12v marine battery) and anticipated switching to the other source when out on the pontoon boat.

Responses appreciated.

Thanks Paul

Paul 
in Georgia

System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k

Comments

  • EstragonEstragon Registered Users Posts: 4,496 ✭✭✭✭✭
    edited April 2019 #2

    The issue is generally the possibility of the CC seeing higher pv voltage without the battery/bank voltage "anchoring" the system voltage. It often manifests by the CC booting into a weird, potentially damaging state.

    On my controllers, they seem to be okay if they're fully booted (but not actively charging) and the bank breaker is opened for a short time. I wouldn't want to do this regularly though. Among other things, absent bank power, a passing cloud could cause the CC to reboot (with the above issue seeing only pv voltage).

    The best way is to turn off CC / stop any charging, then open pv breakers, then open bank breaker, then remove batteries. Reverse the process to reconnect.

    An alternative might be to have a second battery on a make-before-break switch. Such a switch puts two banks in parallel in between A/B settings (as opposed to breaking A before making B). This should keep the CC battery powered and prevent rebooting.

    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • AnawaAnawa Solar Expert Posts: 211 ✭✭✭

    Estragon, thanks for the explanation!

    Looks like I need to be more grateful about things in life and not loose sight of the big picture. It’s far better to just flip a breaker when I disconnect/reconnect the battery rather than what I’ve been doing for the last few years. Toting that battery around get’s harder and harder every year, but flipping a switch is something I can do for a long time.

    Thanks for the info and keep on the sunny side of life.

    Paul 
    in Georgia

    System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
    System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
    System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
    System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
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