I am trying to use a 5V to 12V upconverter with a 5 V USB power bank to run a 12V fishfinder that draws 650 mA (500 W, 4000W peak). The USB powerbank is 5 V and 2A. I checked all my connections for continuity and the adapter shows 12 V from the end of the plug. Shouldn’t this work? It turns on for a couple seconds and then immediately shut back down. The fishfinder works with a 12 V lead battery.

The upconverter was from amazon’s website.

JESSHINY 5V to 9V or 12V Adjustable Up-Voltage Regulator Converter with Switch (5V-9/12V)

Thanks

 

It sounds like you just do not have the power capacity in your converter.
5 V at 2A = 10Watts, and 12V at 650mA = 7.8Watts so on the face of that, it would be ok, but the "500W,4000W peak"????
The peak currents are way over the supply capability. Sticking with the lead battery is the easiest I think.

 

You sure about those numbers? 4000W = 333 Amps at 12V. I'm having trouble seeing that.

 

You sure about those numbers? 4000W = 333 Amps at 12V. I'm having trouble seeing that.

Me too!
It is probably peak acoustic pulse power, multiplied by marketing division factor with extra for how many LEDs and chrome knobs like most audio amps nowadays

 

It sounds like you just do not have the power capacity in your converter.
5 V at 2A = 10Watts, and 12V at 650mA = 7.8Watts so on the face of that, it would be ok, but the "500W,4000W peak"????
The peak currents are way over the supply capability. Sticking with the lead battery is the easiest I think.

I was very puzzled by that too when I read it in the spec sheet. I asked another person about it and they thought that it was probably the wattage output for the transducer head that goes into the water. I also measured voltage at the up converter output to see if there was a voltage drop when the fishfinder turns on but it stayed at 12.2 V without moving. My guess was there is a problem with the up converter not putting enough amps out, but shouldn’t I see a voltage drop? Any other thoughts? I uploaded a picture of the spec sheet. Thanks

 

Well, it could be that they have big caps in there and output millisecond pulses with something like a 0.1% duty cycle. Then 4000 watts becomes 4 watt hours. Still, there should be some seriously fat copper in there.

You wouldn't want to do a teardown now, would you?

 

Power USB without any handshaking = (5 V) * 0.1A)
Fishfinder power (12 V) * 0.650 A
Efficiency: 85% or 0.85

(5 V) * 0.1A)/0.85 is not greater than or approximately equal to (12)*0.650 (units are Watts)

I'll let you do the math.

 

Except that the USB power adapter usually don't have handshaking and deliver what ever they can (though seldom at the "rated" current). But the math is still instructive, especially when factoring in efficiency.

 

Well, it could be that they have big caps in there and output millisecond pulses with something like a 0.1% duty cycle. Then 4000 watts becomes 4 watt hours. Still, there should be some seriously fat copper in there.

You wouldn't want to do a teardown now, would you?

Thanks for your thoughts. A friend of mine mentioned that the odd power output may be related to sound wave frequencies or something similar? I am hesitant to tear that thing down since it is designed to be waterproof, I’m much more likely to do damage than good. Thanks again

 

Me too!
It is probably peak acoustic pulse power, multiplied by marketing division factor with extra for how many LEDs and chrome knobs like most audio amps nowadays

 

I was trying this same thing with a Garmin 4cv Plus with the same results! What noticed is that the unit is fine when the transducer is not plugged in - it powers up no problem. So the transducer appears to be overloading the converter. What I'm wondering is how many amps are needed to support sufficiently powering the unit + transducer... is there a USB 5v to 12v converter that would actually work in this case?

One of the power specs shows "power: 300 watts RMS" which I think is for the transducer. I've also seen "500 watts" on several sites.

I'm guessing that this solution would probably work for older fish finders or units that have a more basic transducer.

 

Why do you want to run from 5V USB?
USB is not for high powered devices. You are at least an order of magnitude to high power wise for USB. Even the new intelligent USB speced ports would not be enough. Just run it off a 12V battery as it was designed to use.

 

Why do you want to run from 5V USB?
USB is not for high powered devices. You are at least an order of magnitude to high power wise for USB. Even the new intelligent USB speced ports would not be enough. Just run it off a 12V battery as it was designed to use.

Was just trying to look for an alternative solution so as to not deal with the sealed lead acid batteries and extra weight (this is on a float tube). I've heard of guys using LiPo packs to power these. But there are also a few other Lithium Ion based batteries out there too... Nocqua, which is pretty expensive and "Blue Brick" device that has a 5.5x2.1 standard female plug and can power 12v devices.

Actually, I stumbled across a guy on Youtube who spliced up two USB cables to work with a couple power banks in series. I went ahead and gave this a shot and it actually works. Although, it's running at 10.2v but works with the transducer connected. I'm currently doing a runtime test to see how long I could roughly get out of it. I have a couple 16850mah power banks that it's running off right now

 

You may find a large electrolytic capacitor across the output will help as it can supply the pulse power.
Something like 40000uF or so.

 

Was just trying to look for an alternative solution so as to not deal with the sealed lead acid batteries and extra weight (this is on a float tube). I've heard of guys using LiPo packs to power these. But there are also a few other Lithium Ion based batteries out there too... Nocqua, which is pretty expensive and "Blue Brick" device that has a 5.5x2.1 standard female plug and can power 12v devices.

I think you're fighting a losing battle. You say the power brick is 5V@2A, but you don't give the mAh capacity.

Taking your numbers at face value, the brick can supply 10W, the fish finder requires 7.8W (ignoring the extraneous 500W, 4000W peak numbers). The brick would barely be able to provide 12V@650mA.

You seem to be posting from 2 different accounts. That's not allowed.

 

I think you're fighting a losing battle. You say the power brick is 5V@2A, but you don't give the mAh capacity.

Taking your numbers at face value, the brick can supply 10W, the fish finder requires 7.8W (ignoring the extraneous 500W, 4000W peak numbers). The brick would barely be able to provide 12V@650mA.

You seem to be posting from 2 different accounts. That's not allowed.

I just have one account. Unless you were confusing me with the original poster? I was just chiming in as I was researching the same idea and stumbled across this post where the OP tried the same thing.

In my case, I'm currently trying out a solution where I spliced two USB cables together with the fish finder/power cable and connected to two identical 16850mah power banks. I'm doing a runtime test right now and so far so good although the display voltage on the unit shows 10.2V rather than the suggested 12v - other than that, it's been running for the past hour and a half and still going. I'll probably want a minimum of 5-6 hours so we'll see if it can go for that long. When drawing power from two power banks in series via splicing two USB cables together I am curious if the mah doubles (in this case to 33700mah) or if it remains at 16850mah - does anyone happen to know?