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Thread: 1979 Bayliner/Garmin 547xs Update NMEA 2000 Questions

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    Default 1979 Bayliner/Garmin 547xs Update NMEA 2000 Questions

    Hello folks, I hope everyone is itching to get on the water like we are! Last fall I bought a '79 Bayliner Saratoga (350 Chevy/Mercruiser?) and since it had a Lowrance 5 inch GPS/sounder I wanted to switch it over to Garmin. I got a sweet deal at the show on a 547XS..I wanted larger but I don't have the windshield view space. I am going to run a GFS 10 fuel sensor on it through a NMEA 2000 network. I have a couple questions for you guys that have done some of your own installs. The instructions say you have to have both the GPS unit and the network ran to 12 volts, and that the NMEA cord needs to be switched so it doesn't run the batteries down. They show a switch in the schematic. I guess my question is twofold. First, does it matter if I go straight to the battery bank since it'll be switched, or does it need to be ran another route? I was going to go right to battery 1 of 2 and switch it so I can still have GPS at night for the anchor alarms. The second part of this question is say if I did switch off the NMEA network side, will the GPS still work but without the networking aspects? You know like the anchor alarms, general direction finding, and fishing? I have only 2, group 31 batteries on this boat and they are way up front under the berth bed. The previous owner said he wanted to distribute some of that weight forward but I'm ignorant on that with this vessel. The boat is old but has been well cared for and has had some fiberglass mods done in the last couple years to strengthen the spars near the engine. I might run it like this for a year and see what we think..but I'm concerned that a few days of camping on board might be fairly hard on these 2 little batteries. Any thoughts on this from you all?
    Thanks for any responses.

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    I would, if possible switch the power to the network and the electronics on/off at a switch on the helm.
    Connecting directly to the battery eliminates any circuit protection. If I understood you correctly.

    I am not familiar with the 547, but since it is a "GPS" unit then the network does not have to be on for the anchor alarms to work, same with general direction finding. Those features/functions are part of the plotter.
    Is the fuel sensor the only other item on the network? If so then only important when running the motor, to my understanding the amp draw from the network itself will be negligible.

    Current draw on the plotter looks pretty low:

    Max power usage at 10 Vdc: 27 W
    Typical current draw at 12 Vdc: 450 mA
    Max current draw at 12 Vdc: 2.7 A, this is at max.

    The 10 hour rate on one group 31 is going to be somewhere around 80-90 amp hours, at 10 hours this will gibe you 8-9 amps with one battery, 16-18 with 2. At 50% discharge this will give you 8-9 amps available in a 10 hour period.

    Try to NOT discharge the batteries deeper than 50% on a deep cycle an 80% on a starting battery, your batteries will last longer if you can run them between 50-80% discharge with a complete 100% charge occasionally. This can vary from brand and more so as to type of battery, check the manufactures recommendation.

    Typical amp draw on the 547 is what I would expect at night, listed as 450 ma, so in 10 hours that unit could use 4.5 amps, Other draws may be more of a issue, heaters, lights, refer, radio....
    It all adds up, so it is a good idea to look at the whole picture in terms of what your electric load may typically be.

    Hope this helps, maybe someone else can add or elaborate on more details...
    “Nothing worth doing is easy”
    TR

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    Akgramps, thanks for the reply. Yeah the circuits will be protected no matter where I connect them. The harnesses all have fuse holders plus the boat has a couple different fuse busses too. I just couldn't decide where I SHOULD hook the network up but your comments about that is helpful. The fuel sensor is the only thing on the network so it now becomes clear to me that I'll be be running when the network is needed. On the hook we should be using very minimal power. Thanks again sir!

    Sent from my HTC One M9 using Tapatalk

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    Akgramps, do you have much experience hooking up the DSC from GPS to VHF? My Garmin 547xs has the several open wires in the power cord and the radio I have is a West Marine VHF 550 reportedly made by Uniden. The Garmin instructions say the blue wire is port 1 transmit out. The radio manual shows green as their GPS data in. I have these connected. The radio manual also has a nice chart showing various brands of GPS units and wire colors. This chart says to connect the Garmin black ground to the BARE WIRE on the Radio harness. Can you confirm I need to hook up the Garmin to Uniden grounds to make this work? I have the blue hooked to green as instructed but no signal yet. The last boat going from older Garmin to ICOM VHF was only one wire. Not that that means squat. I just wanted to bounce this off someone else before I make the magic smoke pour out..
    Thanks if you can provide any help.
    MarkAttachment 89143Attachment 89144

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    Akgranps cover just about everything you need to do/learn about the battery system to keep from having a dead battery in the morning. Good job.

    If your the batteries are more than a year old it a good chance they do not have the capacity of a new battery. During the day the charging system needs to have enough power to supply all the current to run the boat and replace what was use in the night or you may end up with a dead battery before you get home after a several day trip. This is a combination of the design of the charging system and how you run the boat. A volt meter is not much help when it come to knowing the condition of the batteries. You could add a amps counter or a generator and charger.

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    You want the TX wire from the GPS hooked to the RX wire for the radio and then the grounds need to grounded together, ie both connected to the same ground for that NMEA 0183 circuit to talk. So you are on the right track.
    Casey
    Yamaha Dealer
    Petersburg, AK

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    Whelenator

    I wish I could be of more help on these two specific units.. You probably have this figured out by now.
    Yes, Garmin GPS 0183 output blue to the green on the 550.

    And I believe you are correct concerning connecting the black from the Garmin (GPS ground) to the bare wire on VHF.

    Let us know
    “Nothing worth doing is easy”
    TR

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    Macgyver,

    Battery monitoring is a interesting study, as you said volts have little relevance but can tell you if the battery is fully charged or if the charging system is likely working. What it doesn't tell you is the capacity of the batteries or the amp output of the charging device.

    A battery can read 12.6 volts but only have 1/2 the storage due to sulfated plates. AMP counters can be misleading as well because they realistically have to be adjusted as a the battery capacity diminishes over time.

    I have been looking at these as they function differently than a typical amp counter and reads in state of charge (SOC), http://www.balmar.net/?page_id=15245

    I thought this was a really good article http://www.pbase.com/mainecruising/smart_gauge

    Compass marine has some great info online..
    “Nothing worth doing is easy”
    TR

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    Gentlemen, thanks for the replies. My main concern was if those respective grounds needed connected. I bet they will chat once I get that done. Haven't been working on it in a couple days. Possibly work on it tomorrow. It seems everything is screaming for attention and maintenance right now!
    As for batteries, I test with a Snapon load tester. it gives a percentage of charge. Pretty accurate but even with a few year old battery with 2/3 capacity you can still run, just have to pay attention. My boat is a '79 with ancient tech so I'm not too concerned with doing too many spendy mods for this particular item. It'll tell me when I need batteries. I'll let ya'll know if the electronics talk after I get those grounds together.

    Thanks again!
    Mark

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