Hard Wiring Hds To Battery

[KevO]

The voltage drop at my fuse panel is making my units reboot when I start the motor, or hit the trim.  I want to rewire them straight to the battery.  Electrical problems aren't my strong suit, but it seems easy enough to me.  I have 2 HDS units and an LSS-2, My plan was to run one wire from the battery to the bow for one unit with an inline fuse near the battery, and run one to the console with inline fuse to control the other unit and power the LSS with the yellow wake up wire.  Does that sound right?  Do I need a fuse between the LSS / HDS?  Does the LSS need its own power cable to the battery?

[TRYTOFISH]

No need to have separate wire for lss. just take off of one of unit power wires. just make sure you have big enough wire. I would use 14-18 stranded from the battery.

[J Francho]

 

The voltage drop at my fuse panel is making my units reboot when I start the motor, or hit the trim.

 

This usually has meant the cranking batt was going bad, not a drop at the fuse panel.

[KevO]

Ok I was going to use 14 gauge wire.  I already tested the battery it is fine, 6 month old 31 series AGM battery.  There's probably a lose connection in there also, but I want to eliminate the fuse panel all together.  It can't handle everything, when I turn the nav light it drops the HDS down to 7-8V.

[J Francho]

Something isn't right, then.  As far as removing the panel, knock yourself out - my Xpress has no fuse panel, but everything is fused or has a breaker.

[KevO]

I shouldn't say eliminate the fuse panel... That is staying.  all my lights, bilge, livewell are connected there and work fine.  I just meant bypass it and directly wire the units to the battery.

[J Francho]

Make sure you use a fuse or a breaker.

[KevO]

Yes I will be using a fuse.

[Loop_Dad]

KevO, I don't know much about boat wiring, but I too feel something is wrong. Do you have a volt meter? If you don't have one, then you can probably find a cheep analog one at Radio Shack kind of place. I would give a quick check before spending time doing the work.

 

Check the voltage changes at the battery when you crank it and compare that with voltage change at the fuse box. If those two reading looks the same and your unit is still going crazy, then changing the wiring between the battery to the unit doesn't solve the problem.

[Wayne P.]

What you are experiencing is very common with the more sofisticated sonar units. They use more amps..

Typically a boat wiring harness is made up of minimum size conductors and with all the splices/connections involved with a fuse panel supplied by a larger wire with a circuit breaker, the total load on the fuse panel is inadequate for the additional load of those units. It's not about volts, it is the loaded volts (amps) that the accessories use.

Add to that, aging of the wiring and exposure to moisture and you get even more resistance to reduce the capacity of the accessory circuit.

 

What Humminbird recommends for their units is connecting the unit power cord directly to the battery and a 3A fuse at the battery. If the cord is to short, extend that with at least 16 guage wire by splicing, soldering, and waterproofing the connection. Remember the fuse size is to protect the smallest conductor of the circuit.  A larger wire is even better to reduce the voltage loss due to the resistance of wire length.

I used 12 guage marine grade wire to extend my power cords.

 

Another issue that some don't think of is the health of the battery that is connected to the accesories and they depend on the outboard motor to keep it fully charged. Unless you make long runs, you don't replace the loss charge from using your electronics/ pumps or even from starting the engine.

What you are requiring of your starting battery is a quick, powerful discharge to start the engine and then you want it to function like a deep cycle battery to power stuff when the engine is not running.

If your battery is in good condition with clean and tight connections and the units shut down when you start the engine, that means the battery does not have the capacity to handle all the stuff at the same time and/or you wiring is inadequate to handle the load.

 

Your battery size should accommodate the MCA your motor requires plus enough reserve capacity to handle the deep cycle use between charging cycles and additionally use a charger on that battery when off the water just like you would your trolling motor battery/s

[KevO]

I was waiting for your input Wayne.  I cleaned all the connections this evening and made sure everything was tight, both units turned on properly and the one at the console even showed 12.1v, the bow unit only showed 10.5.  Thats a positive for me!  I'm going fishing tomorrow to see how they work when the motor is running.  If they work then I only have one problem and thats the "no source" I get on my LSS.  If they still don't work right I'll be rewiring them on sunday!

[Wayne P.]

The 10.5 is not a positive. It shows you have a lot of resistance in the power connection for that unit. Any draw down of the battery for starting, trimming, maybe even a livewell pump will shut that unit down.

 

If your battery is fully charged and the console unit shuts down, like it did before that means your battery is not big enough to handle the load you have on it.

[KevO]

Looks like the wiring isn't the problem.  Got out this morning everything looked good.  Charged the batteries last night, had 12.4 all day on both units and ran the livewell all day.  Still don't have structure scan, it might be a blown fuse, or a bad ethernet cable (as stupid as that sounds).  I'm guessing fuse since it has no power at all.  Will look into that tomorrow.