Garmin GPSMAP 178 (greyscale) expected battery life? - Kayak Fishing Adventures on Big Water’s Edge

technoyak · 11-24-2008, 05:54 AM

Thanks bajadog, I suspected THAT indeed (pretty much suspected everything thoug!). Yesterday I went to a lake with a fresh battery and the tranducer worked fine (whew). However, I stayed a bit at night and when I turned the screen light on to see where I was with respect to the structure I was fishing the light flickered very rapidly, I think it was doing it at the same rate of the sounder pings! The intensity of the screen light also varied a bit on 2-5 minutes intervals. At this time I had my LED nav lights on. I will run a test without the LEDs and see if it flickers, if it doesn't, I will run a different battery for lights and presto.
I still would like to know how long this setup is supposed to run on a single charge. Fish on !

steveooo · 11-24-2008, 06:37 AM

You should be able to find how long your set up by figuring how many amps your finder draws (available in the owners manual or online) and how many amp hours your battery is rated. It sounds like the battery would be the unknown variable in this case. Unless the battery lists a specific number, i would not assume it is an 8Ah simply because it is bigger than a 7Ah. I am pretty sure that the GPSMAP 178 draws 1.2 amps per hour and needs a minimum of 10 volts to run properly, (but don't quote me) so you could expect 6 1/2 hours of use from a properly functioning 8Ah battery. With the led lights, the unkown battery Ah and life remaining, and an amature giving electrical advice, there are a lot of variables that could affect your system. Good luck.

technoyak · 11-25-2008, 12:38 PM

Thanks steevo, that's more and less in the ballpark of what I have gotten so far. Decent but I may be carrying an extra battery just in case (yep, I am a bit of a water rat/hardcore). I will also carry a separate battery pack for the LED lights ($1.99 from RadioShak). May even get a tricle charge solar panel for the battery not being used/possible bait tank. Although I think the bait can be keep in a mesh in the water, on the other hand, I preffer artificials and have had great results in learning to use the different kinds. It is about learning to use them and choosing the right one for the day and time (which is not written in stone at all, if anything the fish will tell you). Learning to use them is a bit more tricky, yet interesting.
To report back on my tests. When I connected the battery straight into the GPS/sounder it worked fine, I think the LEDs may be helping with the interference when turning the backlight on on the 178. I also learned that it is possible to actually turn the sounder portion off, thus save battery life/backlight time when cruising. Now, to plan next outing . . . thanks to all again.

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11-24-2008, 05:54 AM	#1
technoyak Junior Member Join Date: Nov 2008 Posts: 7	Thanks bajadog, I suspected THAT indeed (pretty much suspected everything thoug!). Yesterday I went to a lake with a fresh battery and the tranducer worked fine (whew). However, I stayed a bit at night and when I turned the screen light on to see where I was with respect to the structure I was fishing the light flickered very rapidly, I think it was doing it at the same rate of the sounder pings! The intensity of the screen light also varied a bit on 2-5 minutes intervals. At this time I had my LED nav lights on. I will run a test without the LEDs and see if it flickers, if it doesn't, I will run a different battery for lights and presto. I still would like to know how long this setup is supposed to run on a single charge. Fish on !

11-24-2008, 06:37 AM	#2
steveooo Senior Member Join Date: Sep 2005 Posts: 1,922	You should be able to find how long your set up by figuring how many amps your finder draws (available in the owners manual or online) and how many amp hours your battery is rated. It sounds like the battery would be the unknown variable in this case. Unless the battery lists a specific number, i would not assume it is an 8Ah simply because it is bigger than a 7Ah. I am pretty sure that the GPSMAP 178 draws 1.2 amps per hour and needs a minimum of 10 volts to run properly, (but don't quote me) so you could expect 6 1/2 hours of use from a properly functioning 8Ah battery. With the led lights, the unkown battery Ah and life remaining, and an amature giving electrical advice, there are a lot of variables that could affect your system. Good luck.

11-25-2008, 12:38 PM	#3
technoyak Junior Member Join Date: Nov 2008 Posts: 7	Thanks steevo, that's more and less in the ballpark of what I have gotten so far. Decent but I may be carrying an extra battery just in case (yep, I am a bit of a water rat/hardcore). I will also carry a separate battery pack for the LED lights ($1.99 from RadioShak). May even get a tricle charge solar panel for the battery not being used/possible bait tank. Although I think the bait can be keep in a mesh in the water, on the other hand, I preffer artificials and have had great results in learning to use the different kinds. It is about learning to use them and choosing the right one for the day and time (which is not written in stone at all, if anything the fish will tell you). Learning to use them is a bit more tricky, yet interesting. To report back on my tests. When I connected the battery straight into the GPS/sounder it worked fine, I think the LEDs may be helping with the interference when turning the backlight on on the 178. I also learned that it is possible to actually turn the sounder portion off, thus save battery life/backlight time when cruising. Now, to plan next outing . . . thanks to all again.