Topic: Power source

[Fish2eat]

Just got a Tracker TF. Love the boat.  Mounting my 798 on the front and transducer on trolling motor.  Service tech at BPS said I could use the trolling motor power wire for my 798.  A little concerned about this.  Will this work or should I pull a power wire straight to the battery just for the 798.

[ITGEEK]

The absolute best scenario to prevent interference is to have your 798 run off a battery
that nothing else on the boat is hooked to.
Also, try and route your 798 wires away from the trolling motor wires.

If that is not possible, you may have to hook it up the best you can,
then add devices that will help cut down the interference.

Search on this site for those devices.

You may get lucky and have no interference, but
9 times out of 10, sonars and trolling motors usually can't
co-exist on the bow without the sonars suffering interference.

[Humminbird_Greg]

Do not connect your 798 to the trolling motor power wires!
Doing so will make it more susceptible to trolling motor interference as well as low power issues.

[sonar2000]

I agree with ITGeek..

"You may get lucky and have no interference, but
9 times out of 10, sonars and trolling motors usually can't
co-exist on the bow without the sonars suffering interference"


Chuck

[Bob B]

Also, use twisted pair wiring for the unit....12 or 14 guage marine grade would be best.  You can twist the wire yourself if you cant find marine twisted.  You could use an outdoor grade extension cord and cut the ends off......this should be twisted wire, and unfortunately the only way to tell is to cut and end of to find out.  Larger wire = less voltage drop and a happier unit.  Twisted pair wire = less chance for interference and a happier unit.  Use stranded wire for better durability.

Make sure you have an inline spade type fuse.  Humminbird recommends a 3amp fuse.  I am not sure what guage wire the power unit is, it may be 16 guage, but since it is short the resistance of it is negligable compared to the longer run to the battery.  12 guage wire has about 1/3 the resistance of 16 guage wire and more about 3 times the amperage rating for power transmission.  (see the wire guage chart here: http://www.powerstream.com/Wire_Size.htm )  According to it, 16 guage wire has a max amp rating of 3.7 amps for power transmission.

Do it right now and you will have less chance of voltage drop or interference problems.

 

[BrianRHCT]

14 or 12 ga seems like an enormous overkill. The thing draws less than 2 amps on the meter and if you think all that heavy peak power is going to the transducer take a look at the 20 ga (or smaller)  power wire running to that.  I'd go with maybe 16 just for the sake of overkill.  And don't forget to fuse it with the fuse being near the battery.  I hate unexpected fires and they can ruin your day if you are a mile off shore when they happen.
I totally agree with the idea that you should run any electronics as direct to the battery as you can for more than a few reasons.  Interference is one but biggest reason is total destruction.  The counter EMF kicks back on the electrical system from things like electric motors can be substantial. That "kick back" from the motor could easily put the lights out permanently on any electronic device. Kiss it good-by, toss it over the side. 
I don't know if there are a lot of rigorous design standard on things like "fish finders".  I have done electrical design for automotive products and our specs for power were 5 volts to 15K volts with limited duration on the 15K.  Still the point is 15,000 volts is a reality because of various motor or inductive loads in the car. Same for the boat.  Especially when using trolling motors.  Bad nasty beasts on the electrical system.  Keep any electronics far away from those wires. I wouldn't even run my 798 power wires in the same wireway as the trolling motor power. Keep trolling motor power wires away from everything else in the boat electrical system.

[Bob B]

It's all about reducing voltage drop and increasing noise resitance.

If you know electronics, the Ohms law formula for voltage is E=IR.

Every every connection, the fuse, and the wire itself has resistance.  Just 1/2 ohm of total resistance with a 2 amp draw would be a voltage loss of 1 volt.  Solder all wire connections, use a spade fuse, clean your battery terminal, use larger guage wire, and you will be a happier camper.....boater in this case.

Twisting the wire gives it an inductive characteristic similar to a choke.

[BrianRHCT]

Yes. Good advice.  Hey you're the senior member here I'm just a newbee tossing my 2 cents in. Probably didn't choose my words as carefully as I should have.

I read about ohms law someplace in my 35 years of electrical design engineering.  So okay lets see what we need.  I see that 16 ga standed is about 4 ohm per 1000 feet so with a fuse and a couple of connectors going up to the unit and back (gotta count the distance twice since there is a plus side and a return) ya will probably get up close to 1/2 ohm on a 50 foot run of wire. Seems like a lot of wire on a 30 foot boat but who knows the route it must travel.  There is pretty big drop in the fuse so the higher the fuse rating the better as well. I would definately fuse ANY wire I ran on my boat.   Generally I would pick the fuse based on the wire size not the load so bigger wire means less drop in the fuse as well so that's a reason to up the gage a bit if you can.   
Still 1 volt outta 13 or so for the average battery voltage seems pretty reasonable.   If it is 2 amps.  And it is less.  I just tossed that out there for a number to work with.  So I'm still good with 16 ga minimum in this application but if you wanna run 12 that's great if your wire conduits have the spare room. 14 is about 1/2 the resistance of 16 and 12 is even a bit less.  Certinally won't hurt anything to go with the bigest ga you can fit.  I just find 12 ga or larger marine rated wire to be getting a bit cumbersome.  Oh and as a side comment. Get the marine rated stuff.  Don't pull out that old monster speaker wire and run it on your boat. 
 
Anyway not trying to start an argument here about wire gage just sayin'. 
So go for the 14 or 12 if you have it and have the space and have the wallet for it.  It does cost a bit more.  Heck run 10 or 6 if you have the room and coin to buy it.  Can't go too big. Just a trade off.  I'm sticking with the 16 min for a max 50 foot run up and back for this box.

Anyway the twisting does more than just create an inline inductance. Actually the series inductance in a minimal efffect. The major factor is that it helps in canceling out capacitive or radiated coupling and creates a situation where coupled noise is more "common mode" which is a good thing.  Anyway twisted pairs are good. So twist that sucker up. 
Don't pay the extra for twisted pairs.  Do it yourself.  Take the two strands, tie them off to something, run them over the floor, pull them even, then fold over the ends and stick them in your drill motor. Then twist that sucker up pretty tight but don't over do it. Over doing it stresses and cracks the insulation.  Be prepared for the length to shrink up a bit when you do the twist so cut the lengths about 20% more than you actually need.  I like your twisting idea for a lot of reasons.  Very good advice.
Oh yeah another tip that I'll agree on.  Solder.  And some anti-corrosion grease or something.  No-Ox for copper or whatever.  There are a ton of marine type anti-corrosions goops out there just use it on your connection lugs or redo them later when they turn green and start flaking out when the boat is bouncing.
Peace there senior member.  Didn't mean to pick a fight.

[Bob B]

No offense taken....I was just trying to clarify my reasoning.....you don't really need 14 guage wire for the current capacity, just need to do everything possible to reduce the resistance.  These electronics don't like low voltage.  Reducing that voltage drop may be enough to keep the unit from crashing if the battery gets weak, or if running off the starting battery when you start the main motor.
You are right on about putting the fuse at the battery.....a nick in the wire causing a short 1/2 way down the power wire may save a burned up wire with the fuse at the battery.

[pontooner]

Hi,
Got a new 798c si and want to know...would connecting the power via a properly fused cigarette lighter plug to my pontoon dash console be a really bad idea, a mildly bad idea or try it and see if it works idea.  I've read here the gold standard is straight to the battery, but I had to ask !

[Bob B]

I wouldn't, but you could try it and see what you get.......look closely at the voltage your unit show.

If you get interference or low voltage or any other intermittent problem...go straight to the battery.

[sonar2000]

Lighter plug ins do not have a good reliable connection. They can lose connection with rough water or wave bumbing. Not a big deal with your lighter or radio but the sonar is even more sensitive to power jiggles.
I would suggest a more robust connection for the sonar.

Chuck

[ITGEEK]

I would agree with Chuck.
I wouldn't take any chances with the sonar power connections.

Straight to the battery is the simplest, easiest, and
most trustworthy connection.

[pontooner]

As always, my apologies...I'm sure it's been asked before but...what small battery to serve as a dedicated power source for the 798c is a good choice?

[sonar2000]

Dont go too overboard with an expensive battery.  Most car batteries will do fine. Marine batteries are always good but extra costs.
Motorcycle batteries work good.
Do use a sealed battery and keep well charged.
We use a battery in the 650 CCA range.

Chuck

[pontooner]

I was hoping to go toward the other end of the scale.  I have a Tekkeon 3450i battery for other stuff that appears to to be 4.5 amp hour. That is probably to low for a day of searching but the kayak or canoe folks may have a good handle on the lower end of the battery scale.  I didn't know if there was a "go to" solution.

[Gattlin]

 I use a sealed gel battery with about 55 aH it's the size of a lawnmower battery. The bow 858 that's hooked up to it has never run out of power even on the longest days out on the water.

[sonar2000]

4.5 will probably be a bit small. We have used the 7.5 motorcycle batteries but that will not get thru a day of use. when we used them we had three in parallel...
Chuck

[pontooner]

Maybe I'm looking at this the wrong way. My reluctance to power my 798 off the boat battery is because I will be running the boat motor (90 horse Honda) while I search.  That's going to give me interference on the 798 right? Nothing else runs...gauges of course, but nothing else.

[sonar2000]

You are looking at it in the right light.  All indications we have seen for the HB units strongly suggest a dedicated battery and wiring.
The current (amp) draw of the units vary somewhat but over all they are not great power hogs. So depending on space and convience of location it is generally suggested to use a dedicated battery.
Again the units do not use a whole lot of power but do required an amount of storage so the battery does not drain its capacity.
This leads most to a good 12 volt marine battery of good amperage.  It all depends on length of use.

I think you are on the right track.

Chuck   

[ITGEEK]

Your 90 HP Honda motor will most likely have a built in alternator to
charge the battery while the motor runs.
This will no doubt cause interference with your sonar if
you hook to the same battery.
Think of it as electrical vibrations traveling through the wires.

In order to get the absolute best from your sonar, it needs to be on
an isolated circuit with no other devices hooked to it.

The smallest 12volt marine battery you can find would
be more than adequate to power your sonar for a long time.

Also, try and keep the sonar wires away from the main motor,
and trolling motor wires.

[pontooner]

Back to West Marine I go...I'll have my own personal parking space when all is said and done...

[sonar2000]

welcome to the world of water.  Most of us have reserved parking places... and at several different marinas, shops and stores........ ...

Chuck

[ITGEEK]

BOAT:
 Bring
 On
 Another
 Thousand
 

[Humminbird_Greg]

Personally I would connect it to the boat’s cranking battery and see if there is any interference or not.

[massillonbuckeye]

welcome to the world of water.  Most of us have reserved parking places... and at several different marinas, shops and stores........ ...

Chuck

My local West Marine loves me that's for sure!  And I love them right back! 

[Roddy]

 Parking Place! Some of us have dubble long spaces with shop tool carts and coffie pots. See more of the BABE at the check out then my wife!