500W Rms Sonar Only Consumes 5W Of Power?

[Bass newb]

How does this work? How can my 500watt rms power fish finder only consume 5 watts? Haven't found a good explanation yet. Or any explanation really.

[MickD]

Great question. I've always wondered the same thing.

[Bass newb]

I suppose it could be a function of depth. ..i.e. max depth uses much more power than the 45' I'm using it at.

[Comfortably Numb]

You mean it draws 5 AMPS not watts?

 

One is input and watts is output

[Josh Smith]

What sonar? I'd like to see the specs.

Josh

[desmobob]

Because it's sending out "pings," not constant output?  That's my guess, and that's just what it is: a guess.  I'll be interested to hear what the correct answer is.

 

Tight lines,

Bob

[Bass newb]

You mean it draws 5 AMPS not watts?

 

One is input and watts is output

No not amps. Watts.

[Josh Smith]

If you give me the model I can answer it.  If not, Dad was a GM electrical engineer and I'll take the question to him.

 

You said 500w RMS (root mean square).  Approximate by multiplying peak wattage by 70.7, though this doesn't hold 100% of the time.

 

W = V * A.  Therefore, with a constant draw of 5 Watts from the power source (assuming a 12v power source) would be roughly half an amp.

 

500 Watts RMS would be a constant draw of about 50 amps.

 

It's either one or the other.  You can't have a draw of half an amp (or even 5 Watts, if that's what you meant to type) and have an RMS power of 500 Watts.

 

Josh

[Bass newb]

What sonar? I'd like to see the specs.

Josh

Garmin 43dv.

Paperwork says something like 5w power consumption. It's more or less verified by usage records from my 9ah battery.

[Josh Smith]

No not amps. Watts.

 

Edit:  Posted while you were posting.  Will look at the unit's specs.

 

Do you have an amplifier of some sort somewhere?  Separately powered transducer?  What system do you have?

 

Josh

[Bass newb]

If you give me the model I can answer it.  If not, Dad was a GM electrical engineer and I'll take the question to him.

 

You said 500w RMS (root mean square).  Approximate by multiplying peak wattage by 70.7, though this doesn't hold 100% of the time.

 

W = V * A.  Therefore, with a constant draw of 5 Watts from the power source (assuming a 12v power source) would be roughly half an amp.

 

500 Watts RMS would be a constant draw of about 50 amps.

 

It's either one or the other.  You can't have a draw of half an amp (or even 5 Watts, if that's what you meant to type) and have an RMS power of 500 Watts.

 

Josh

I typed it exactly correct. Box says minimal consumption of 3 watts or 5 watts, but it brags that the sonar is 500w rms.

I too am an engineer and I would be very interested to see how this actually works. The unit doesn't get hot, so it's not using any appreciable energy, it lasts for days on my 9ah battery, but the instructions clearly show 500w rms powerful transducer.

[Bass newb]

From goggle:

Physical dimensions: 4.0" x 6.6" x 1.8" (10.2 x 16.8 x 4.6 cm)

BlueChart Mobile (planning) compatible: N

Dual-frequency (50/200 kHz) sonar capable: Y

Dual-beam (77/200 kHz) sonar capable: Y

Transmit power: 500 W (RMS) / 4,000 W (peak to peak)

[Bass newb]

5watt power consumption figures on optics planet:

https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.opticsplanet.com/garmin-echomap-sonar-43dv-with-transducer.html&ved=0CDcQFjAIahUKEwiA3-b-3uPHAhXHy4AKHeTQD5A&usg=AFQjCNEefmaghWXEr8J7K7zM0FsL6dyRTA&sig2=yxpo10vXHnLXhzqVzELTLA

[Bass newb]

Weight: 1.6 lbs (0.7 kg)

Water rating: IPX7

Antenna: Internal only

NMEA 0183 compatible: Y

Power consumption: 5W

Mounting options: Bail or flush

[Bass newb]

Edit:  Posted while you were posting.  Will look at the unit's specs.

 

Do you have an amplifier of some sort somewhere?  Separately powered transducer?  What system do you have?

 

Josh

The 43dv comes with a transducer that apparently has three frequencies, 455, 77, 200...something like that iirc. I think they are all in khz, but not positive. I hook up a 12v 9ah battery to it and it will go for hours and hours and hours.

[Josh Smith]

Speaking of heat, guess what went into thermal shutdown while I was looking at the specs? Yup. This one is from my phone while the computer boots back up.

The specs I was looking at had the transducer wired in parallel. Specs said 7.5W max consumption (depending on transducer).

If I'm reading this right, the 7.5W consumption refers to the display. The transducer is wired in parallel and has its own fuse. Look at the fuse rating to figure the tranducer power.

Like you surmised, it looks like a marketing technique. I once had a car stereo amp that claimed 1000W. It was a good amp, but couldn't have been more than 500W RMS. If it peaked to 1000W at all (beyond theory, anyway!) then it was for very short periods.

I'll post the schematic I found when the computer is completely booted.

Josh

[Josh Smith]

Here's from the installation manual:

 

http://static.garmin.com/pumac/echoMAP_4x-5x_Install_EN.pdf

 

I'm not screenshooting it because it may be copyrighted.

 

See how it's wired parallel with the transducer? 

 

What's the transducer fuse rating?  That'll be the final word on its constant draw. 

 

Now, not having the internal schematics, I'm going to guess that it saves up quite a bit in a nice big capacitor between pings and releases it into (up to) 500w bursts.  That's what feels right, though.

 

Internal schematics would be enlightening.

 

Whatcha' think?

 

Regards,

 

Josh

[Bass newb]

Well I did see power rating was dependent on transducer model and depth. That helps a little.

[Wayne P.]

It is also whatever voltage is used to broadcast the SOUND pulse, not the unit power supply.

I have not seen any specs that state that.