# Garmin FF 120 - am I courting disaster?



## JT (May 25, 2006)

First a bit of an acknowledgment for Garmin's customer service. The screen on my FF120 went down, as in no display. I phoned Garmin who said bring it in. I mentioned that it was a couple of months out of warrantee and the response was "no worries, bring it in and we'll fix it". Took it in and it turned out that it was a 2 year warrantee and not the 1 I thought it was. That was Wednesday afternoon. Thursday afternoon I got a call saying the board was toast and to come in and pick up your new FF120. That's 24 hours! Christmas turn around is usually 3 weeks but when they heard I was going away and needed it they said they would do something special for me. Very impressive I say!

Now to my question. I cut out(i.e. removed) the fuse housing and fuse that ran up one of the wires that you connect to the battery. The reason I did this as it was corroded and a point of failure. Out of frustration and on the verge of facing another trip with an on again/off again sounder out came the pliers. Haven't had a power failure/feed issue since.

Now these things are obviously put there for a reason. Does anyone have any experience/perspective on a sounder without a fuse? Under what circumstances would the thing be fed a jolt of electricity from a standard 12 volt battery? Did this a year or so ago and nothing has happened. Am I dicing with death (of the sounder) or is the fuse largely unnecessary?

Appreciate any thoughts.

JT

p.s. cute Santa hat on the yak at the top of the page Red.


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## Donutslayer (Jun 9, 2007)

Leftys right, A battery that goes short can get mega hot in a short space of time. Put the fuse back.


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## DGax65 (Jun 7, 2006)

The safe thing to do would be to reinstall the fuse. The fuse is there to protect your kayak from potentially dangerous shorts. With the possibility of the FF and it's connectors getting exposed to saltwater, it would just make sense to have some sort of over-current protection in the circuit.


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## fisherdan (Apr 17, 2007)

Hi JT,

http://www.whitworths.com.au/main_itemdetail.asp?item=33548&search123=fuse&intAbsolutePage=1

These little suckers are OK, just snip the wire and fix it inline where the old one was.

Have a great trip!


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## JT (May 25, 2006)

DGax65 said:


> The safe thing to do would be to reinstall the fuse. The fuse is there to protect your kayak from potentially dangerous shorts. With the possibility of the FF and it's connectors getting exposed to saltwater, it would just make sense to have some sort of over-current protection in the circuit.


So Doug do you think that a 12v battery could start a fire in the yak?

Appreciate the feedback from all responders by the way.

JT


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## chrissy (Jul 7, 2007)

Sorry if im a bit slow, but how do you connect the fuses to the power cords? I've just installed my sounder and heard nothing about having a fuse.


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## fisherdan (Apr 17, 2007)

JT said:


> So Doug do you think that a 12v battery could start a fire in the yak?


I don't think fire is the main concern JT, If you short out a 12v 7AH battery with no fuse in the line the wire will basically become red hot almost immediately, It will melt through it's insulated coating in about a second and continue until the wire itself melts and breaks the connection, my guess is that a meter or so of red hot wire inside a plastic yak could do some serious damage in very little time at all..

Just my thoughts and concerns..


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## chrissy (Jul 7, 2007)

Kraley, i have a humminbird matrix 12, and all i did was crimp some spade connectors and connect them to the battery.


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## DGax65 (Jun 7, 2006)

Chrissy
You can get a waterproof fuse holder at Whitworth's http://www.whitworths.com.au/main_itemdetail.asp?cat=123&item=33548&intAbsolutePage=1 or any marine supply place. Just put the fuse holder in-line with the positive lead as close to the battery as practicable.

JT
Electrical system faults on kayaks can produce some very serious problems http://www.bigwatersedge.com/bwevb/showthread.php?t=2216
I've heard of a number of instances where batteries and wires have burned or overheated. I know a guy with absolutely no experience working with any sort of electrical systems who installed and wired his own bait tank pump. Unfortunately, he misunderstood the directions and drawing that he saw on one of the forums. He also committed the cardinal sin of not checking for proper operation before he was on the water. He just expected it to work because he thought he had followed the directions. When he turned on the pump he immediately smelled the odor of burning insulation. He quickly turned off the pump, but the battery was already toast and most of the insulation had melted off the pump wires. I've also seen a number of damaged electrical system components where badly corroded connectors or switches arced or overheated. It doesn't take much to melt through a kayak and a 12V 10Ahr battery has a lot of energy stored up inside. Wherever possible, I try to route the power cables along the underside of the deck. If the cable overheats it will just affect the deck and not open a hole below the waterline.

When I designed the electrical system for my kayak I tried to make it as foolproof as possible. I followed industry standards wherever possible.










All loads are fused, every load has it's own switch, heavy gage wiring is use throughout, all connectors are heavily sealed to prevent corrosion and the battery is kept inside a waterproof box.



















I designed the electrical system using MS Visio and then printed a schematic that I could follow as I wired everything up. I also used wire markers throughout.










An electrical system need not be this complicated. I made these schematics for simple, single-component systems and more advanced, multi-component systems.










Some important items to remember when designing and installing your electrical system.
1. Ensure that all wires are rated for the amount of current that you expect to draw. 
2. Use marine grade wire (tinned conductor, multi-strand)
3. Ensure fuses are properly rated. Fishfinders should use a 2 or 3 amp fuse. Check the owner's manual for specific guidance on this. Bait tank pumps <1000GPH will probably draw 2-3A. the starting surge will be higher than the steady state value. A 5A fuse might work-check with the manufacturer's recommendation.
4. Place fuse as close as possible to the battery (within 6 inches is ideal)
5. Label all wires. This will make installation and later troubleshooting much easier.
6. Seal all exposed conductors. Heat shrink tube, liquid electrical tape and electrical tape should be used to insulate and prevent corrosion. Use di-electric grease on connectors that cannot be insulated.


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## chrissy (Jul 7, 2007)

Thanks heaps DGax65, i will get a fuse and might connect a pump to the same battery aswell. Lots of info there.


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## avayak (May 23, 2007)

Sometimes electronics fail in the field due to ESD (electrostatic discharge). This can happen when the device gets a zap during manufacture and may fail immediately and fail testing but may also pass testing and fail anytime later. Even years later.


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## JT (May 25, 2006)

Sorry for the latish reply. Have been away. Thanks to all of you for the replys. Off to Whitworths now to get that waterproof fuse holder. Thanks in particular to Doug for the detail.

JT


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