depth guage

[s1jor]

i am just fitting a depth guage to my 18ft mariah bowrider, the readings i'm getting when the engine is running are all over the place, reading 20 metres plus when in 1 metre of water, when i stop the engine it reads correctly. the depth guage is hooked up to the engine battery. is this the cause????? solving problem will be i guess to run the guage of a seperate battery????

 

[bossee]

Re: depth guage

Hi,<br /><br />Do you get erratic readings just by running the engine? Or is it when You move through the water?<br /><br />What depth guage is it You are using - make and model (sender and display)?<br /><br />You may try to use one separate plus and one minus wire (both rather thick in diameter) from the battery to a fuse block like Blue Systems:<br /><br /> http://www.bluesea.com/product.asp?Product_Id=23629&d_Id=7463&l1=7463&l2= <br /><br />Maybe You should also orginize the on/off switches also, like this:<br /> http://www.bluesea.com/dept.asp?d_id=7997&l1=7460&l2=7997 <br /><br />Also make sure You have a main on/off battery switch, for example:<br /> http://www.bluesea.com/dept.asp?d_id=7458&l1=7458 <br /><br />And a main battery fuse.

 

[s1jor]

Re: depth guage

no this is all stationary, its a nasa depth guage, first time i've run it off the main battery, used to run it off 2 6 volt battery's and this worked fine. tryed to plum it in to the main bettery and it goes haywire. must be battery spiking from the engine charging ????

 

[bossee]

Re: depth guage

Hi,<br />Check with a voltmeter how much volt you get at the battery leads while running the engine.<br />Do You have a inboard or outboard engine? Make and model, and year.<br />Does it have a voltage regulator (alternator)?<br />If to high voltage is produced while running your engine it might be to high voltage for your depth sounder. Check specifications for your sounder what voltage range it can handle.<br />What happen if you turn on the navigation lights so the voltage drop slightly (hopefully)?<br /><br />Have You checked for bad connection at the battery connections?

 

[s1jor]

Re: depth guage

sorry its a volvo 4.3 gs (97) connection are fine on the battery, yeah the voltage is high 13's when running, guess this may be to high for the depth guage, i'll have to have a look at the instructions if i can find them, i'll post back when i've had a look<br /><br />thanks

 

[bossee]

Re: depth guage

Hi,<br />The description of the Volvo Penta 4.3 GS 1997 is here:<br /> http://www.volvo.com/NR/rdonlyres/A...0/43Gi_43GS_43GL_PD_SAV1_DPS_my98_1997_en.pdf <br />It has a "65 A alternator with outlet for voltage sensor cable for optimum charging capacity."<br />The alternator has "internal transistorized voltage regulator"

 

[waterone1@aol.com]

Re: depth guage

I don't think this is a voltage problem. It is most likely " noise" being induced into the power system by the engine. It could even be radio frequency noise generated by the engine electronics. I would suggest going to Radio Shack and getting a noise eleminator kit (RF choke and capacitor) and installing it on the power cord as close to the depth finder as possible. This should clear up your problem.

 

[s1jor]

Re: depth guage

thanks i'll have a go with that, i'll post back how it went,

 

[s1jor]

Re: depth guage

how do you wire the capacitor????????

 

[waterone1@aol.com]

Re: depth guage

The choke gets wired in series with the depth gauge positive wire, the capacitor gets wired in parallel with the depth guage (+ of cap. to + of gauge, - of cap to - of gauge), after the choke.

 

[g0snj]

Re: depth guage

thanks i'll have a go

 

[s1jor]

Re: depth guage

thanks i'll have a go

 

[s1jor]

Re: depth guage

got a noise filter, and it made absolutely no difference. the guage still reads all over the place when the engine is running and fine as soon as i switch the engine off?????<br /><br />any other ideas????

 

[gss036]

Re: depth guage

Check the connections,make sure the wire for the transducer is solid, no chafing or open insulation.<br />Next question, when you say the engine is running, is the propeller engaged or just idleing? Maybe the transducer is picking up air dependingon its location.<br />If that is not the case, borrow a battery from someone and just hook up the depth sounder to the isolated battery. If that solves your problem, maybe a bad diode in the alternator.

 

[waterone1@aol.com]

Re: depth guage

Sorry the noise filter didn't work. Is the transducer and the transducer wiring away from the engine and engine electrics ? If it is wire tied along with other cabling, or the transducer is just below the engine, you might try moving things around to see if that helps.

 

[s1jor]

Re: depth guage

the transducer is mounted away from the engine, and the wiring is on its own no where near the engine,the engine is just in neutral on the muffs when the interference is happening. but the transducer is in the hull, so no where near the propeller. i can have it hooked up on another battery and it works fine, what ya mean bad diode actually in the alternater itself???????

 

[chuckz]

Re: depth guage

You still have a noise problem. Since the depth gauge works fine when connected to a separate battery, the noise is coming in on the power lines. The Radio Shack filter is a one size fits all. Unfortunately this isn't true. The choke and capacitor values have to be selected to filter out the noise in the frequency range that is giving you the problem. Without the use of an oscilloscope or spectrum analyzer it is very difficult to determine what the proper values are that you need.<br /><br />Check with the manufacturer and see if they have a recommended filter configuration. They should know what frequencies their product is susceptible to.