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Posts: 334
Location: Long Prairie, Minnesota | Hey all…..hope someone smarter than myself can throw me a bone here. Bought myself a 681VS late last summer and it came with a Helix 12 on the console all wired up. Here is the problem….when I am running the big motor going between spots, it works fine. When I get fishing it will run for a bit, but within 15 minutes it says there isn’t enough volts and shuts down. Figured I fix it this spring. Pulled the boat out this weekend and got everything going. Fired up the Helix and right away said “low voltage” and displayed 8.2V. Grab the multimeter and tested the battery and it was at 12.59V. So looking at the power wires for the Helix, there are three wires coming from the graph. White (which is hooked to the positive terminal with 30 amp inline fuse), black to the negative terminal, and a green wire that they just have hanging there not hooked up to anything. Should it be hooked up to something? Why would the graph read such a low voltage when the battery is charged and working fine? Any help/suggestions would be appreciated. |
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Posts: 1677
Location: Mt. Zion, IL | You need to upsize the wiring with today’s finders. Run 10 awg marine tinned copper (not aluminum) wire from the battery direct to the helix power cord. Voltage drop occurs because of small wire size, poor connections, and even being run in conduit.
Your situation is not the first with a severe voltage drop and won’t be the last. It is a relatively easy fix. Use the 1% drop charts since fish finders are computers (critical voltage components). |
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Posts: 120
Location: Twin Cities Metro | 14 AWG wire (the typical wire used in sonar power wires) has a resistance of 2.5 Ohms per thousand feet of length. If your wire length is about 20 feet total, that would be a resistance of 0.050 Ohms. Helix 12 has a typical draw of 3.2A (according to Humminbird). With that resistance and current draw, you should be looking at a voltage drop of about 0.16 Volts from one end of the wire to the other.
A drop of more than 4 Volts along that wire, like you appear to be experiencing, indicates a poor connection or faulty wiring of some sort. Hoping it is an easy fix, I would check the connections at the battery and the sonar unit for corrosion or wear. Check the fuse for proper connectivity (sometimes the connections to the fuse will have corrosion, or the fuse itself will be faulty). [By the way, a 30 Amp in-line fuse seems like WAY too high of a rating to me if this is the in-line for the graph.] If not those things, try a load test on your battery to verify that it is as good as you think it is. When a battery is unloaded, it can still show 12+ volts on a voltmeter even though it is not able to effectively supply steady current. If this is your cranking battery and it is able to start your outboard, then the battery is almost certainly fine. If it is not any of those things, then you almost certainly have a continuity problem in the wiring. That involves running new wire which is usually annoying. That's why I suggest you check other things first that are easier to deal with.
The only reason to got to 10AWG wire is if the wire in question is feeding multiple units (eg. the "supply" wire from a battery to a fuse block). In that case, it really isn't the resistance and subsequent voltage drop that you should be worried about. It is the current limitation of the wire. 14AWG is rated to safely draw up to 15 amps. 10 AWG is rated for 30 Amps. Most modern electronics draw between 1.0 Amps and 5.0 Amps each, so if you have 3 or more units with large-ish current draws, 14 AWG starts to be "unsafe". If you are wiring just one unit directly to a battery, 10AWG is overkill. Perfectly safe, of course, but overkill.
Edited by RobertK 3/12/2024 10:17 AM
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Posts: 523
| If it comes to the point where you need to run new wires, connect the new wires to the old ones at the connection end nearest to the battery. I use electrical tape to secure them together. Next pull the old wires from the end nearest the graph and the new wires will come out right in the place they need to be. Be sure to leave yourself enough wire to be able to put the appropriate connectors and fuse(s) on the wires. I have used this method on multiple boats with great success. |
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Posts: 1677
Location: Mt. Zion, IL | 10 awg is far from overkill. I have a 0.5v drop from the battery to my HDS 9 in the bow in a 17 ft boat. My connections are all soldered. 4 awg is used to feed multiple units, not 10. Capacity on a chart that allows 10% drop is not for computers. This also does not consider the voltage drop of starting the outboard motor(s) to prevent voltage alarms. Each connection, no matter the type also adds a voltage drop. Bus bar, fuse, ring terminals, splices to the power cord…. Theories are great, trust an engineer and an installer with experience. Call Russell Marine and talk with them if you have doubts.
4 volts is more than just insufficient wiring, I agree, but wiring in wet environments, especially old wiring, has substantially higher resistance than any wiring chart would show.
http://assets.bluesea.com/files/resources/newsletter/images/DC_wire... |
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Posts: 334
Location: Long Prairie, Minnesota | RobertK - 3/12/2024 10:13 AM
14 AWG wire (the typical wire used in sonar power wires) has a resistance of 2.5 Ohms per thousand feet of length. If your wire length is about 20 feet total, that would be a resistance of 0.050 Ohms. Helix 12 has a typical draw of 3.2A (according to Humminbird). With that resistance and current draw, you should be looking at a voltage drop of about 0.16 Volts from one end of the wire to the other.
A drop of more than 4 Volts along that wire, like you appear to be experiencing, indicates a poor connection or faulty wiring of some sort. Hoping it is an easy fix, I would check the connections at the battery and the sonar unit for corrosion or wear. Check the fuse for proper connectivity (sometimes the connections to the fuse will have corrosion, or the fuse itself will be faulty). [By the way, a 30 Amp in-line fuse seems like WAY too high of a rating to me if this is the in-line for the graph.] If not those things, try a load test on your battery to verify that it is as good as you think it is. When a battery is unloaded, it can still show 12+ volts on a voltmeter even though it is not able to effectively supply steady current. If this is your cranking battery and it is able to start your outboard, then the battery is almost certainly fine. If it is not any of those things, then you almost certainly have a continuity problem in the wiring. That involves running new wire which is usually annoying. That's why I suggest you check other things first that are easier to deal with.
The only reason to got to 10AWG wire is if the wire in question is feeding multiple units (eg. the "supply" wire from a battery to a fuse block). In that case, it really isn't the resistance and subsequent voltage drop that you should be worried about. It is the current limitation of the wire. 14AWG is rated to safely draw up to 15 amps. 10 AWG is rated for 30 Amps. Most modern electronics draw between 1.0 Amps and 5.0 Amps each, so if you have 3 or more units with large-ish current draws, 14 AWG starts to be "unsafe". If you are wiring just one unit directly to a battery, 10AWG is overkill. Perfectly safe, of course, but overkill.
Thanks.....I will start poking around when I get home. No matter what the voltage reads on the unit, the big motor fires right up with no problems, that and the battery was new last year. Wondering about the fuse tho. Guessing that a 3 amp fuse or 5 amp would be a much better fit there? I looked at the fuse last night and have never seen a fuse like they had wired in. Sounds like I need to wire a new fuse in and go from there. |
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Posts: 120
Location: Twin Cities Metro | Was thinking about the fuse after I posted that. Is the fuse you are talking about the fuse to the outboard? Or is it the in-line fuse to the sonar unit? The in-line fuse for that Helix unit is supposed to be 5 Amps. If it is to the outboard, that is very different. Just didn’t want to steer you wrong on fusing. Best of luck finding your electrical gremlins! |
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| While I realize rewiring might be the correct option, you can adjust or turn off the low voltage alarm if the unit is otherwise running fine. Some units go into 'night' mode upon low voltage/alarm, others shut down. |
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Posts: 479
Location: Northern Illinois | Another reason to run larger than needed wire, i.e. awg 10 or 12 versus 14, is to allow for future additions. Take it from someone who has done it more than once. |
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Posts: 270
Location: SE WISCONSIN | Run mew wires straight from the battery to your helix. And a 30 amp fuse is way to big I think I have 7 or 10 amp fuses on my helix 10s. |
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Posts: 600
Location: Michigan | Humminbird has information on fuse size, wire gauge, etc as well - https://humminbird-help.johnsonoutdoors.com/hc/en-us/articles/906554... |
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Posts: 334
Location: Long Prairie, Minnesota | After a bunch of testing and working with Humminbird the problem was finally figured out. All along the issue was the battery. Gave a “good” reading so we figured that was a nonissue. New wiring, connecting to wall plug in and problem was still occuring. Took the battery back to a different store to be tested and it came back as good, needs recharging. He asked me how long it had been since I charge the battery and told him I had just taken it off the charger. Said that reading, if battery is fully charged, means there are weak plates in the battery causing it to lose charge very fast. Bought new battery and back in business. |
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Posts: 117
Location: Roscoe IL | I run 8awg to my graphs, and everything is off a 100ah lithum battery. 10 is minimum in my mind, but you have to make sure you've got solid connections, which are heat shrinked with dielectric grease in the tube. |
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