Simrad Voltage issues

Papa "J"

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  • May 8, 2003
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    For years I have lived with "that's just how it is" answers.

    I know with 100% absolute fact that I have 13.4 dc volts to the fuse block and the exact to the power cord before it screws into the power outlet on the back of the MFD's.
    But something just never seems right as I always got at least 1 -1.5 volts lower on the display then what's actually and now I am getting a lower reading now on my 16" at 11.9 when I am showing 13.4.

    This is all currently on a Pro-Nautic battery charger/maintainer. And the 2 group 31 house batteries are fully charged.

    the 11.9 voltage in on a 16 EVO3S (used to be 12.6 like the rest of them)
    the 12.6 is on the EVO3S 9" and 12"

    At least they were all the same at 1 point

    Nothing else on the boat is on except for electronics
    All wiring was replaced a few years ago with proper gauge wiring

    Anyone else run into this and tired of the typical CS "it must be the wiring " or something that's your fault.
    I can't see where I am showing a constant 13.4 volts and it shows anything but maybe a 1/10th off at the screen without this being a Simrad component issue or software issue.

    Anyone else have this and have a fix that CS doesn't know about

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    bman440440

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    I have the same issue with my 12 and 9 both evo2's.... It drives me nuts too... I ran a dedicated line to the battery bank that both units use and its a 10ga wire and still same issue... Hell each unit has a different voltage displaying when I have checked it at each unit it shows 14.2 (engines running) at the power cable and 13.6 on the 12" and 13.8 on the 9"... Even bigger difference when I have the engines off.
     
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    ShadowX

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    Try measuring it off the end of the terminal where the wires from the electronics are connected to instead of the main terminal. I had a case where I had sizeable voltage drop and it turns out to be corrosion/oxides on the fuse spade contacts. I had a brand new fuse block but reused the fuse from the old fuse block. I wasn't careful with checking the condition of the terminals since it was late at night. I had nothing but issues on the radio when I transmit until I took the fuse out and cleaned the oxides from the terminal. After that, the voltage drop and problems went away.

    I recall measuring the voltage across the points and it was normal. I think most voltage measurements are not accurate unless you apply a known load across the terminals. Without a load, you may still get a good voltage reading. However, that voltage level drops a lot more once you apply a load. That is why I only use load meters to check my battery condition instead of relying on just the voltage reading on a multimeter.

    You can also measure the voltage going into the unit by unplugging the connector and measuring the voltage directly on the connector itself. It would take into account of any resistance up to the connector.

    The other thing to consider is that the voltage you are reading on the fuse block is when its under relatively low loads. Depending on where the electronic device measures the voltage level, it may be under a load so there is a slight voltage drop. The electronic device has to consume power to make the measurement so that will drop the voltage inside the device where its taking the measurement.

    Another thing to consider is that most electronics use silicon rectifier diodes as a reverse polarity protection system. There is a 0.7V drop across the diode depending on how its connected to the input power. That is completely normal. BMan measured about 0.6V difference on one of his units. It sounds like the diode is the most likely culprit for the voltage measurement difference.
     
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    Papa "J"

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    Try measuring it off the end of the terminal where the wires from the electronics are connected to instead of the main terminal. I had a case where I had sizeable voltage drop and it turns out to be corrosion/oxides on the fuse spade contacts. I had a brand new fuse block but reused the fuse from the old fuse block. I wasn't careful with checking the condition of the terminals since it was late at night. I had nothing but issues on the radio when I transmit until I took the fuse out and cleaned the oxides from the terminal. After that, the voltage drop and problems went away.

    I recall measuring the voltage across the points and it was normal. I think most voltage measurements are not accurate unless you apply a known load across the terminals. Without a load, you may still get a good voltage reading. However, that voltage level drops a lot more once you apply a load and remove some of the surface charge on the batteries.

    You can also measure the voltage going into the unit by unplugging the connector and measuring the voltage directly on the connector itself. It would take into account of any resistance up to the connector.

    The other thing to consider is that the voltage you are reading on the fuse block is when its under relatively low loads. Depending on where the electronic device measures the voltage level, it may be under a load so there is a slight voltage drop. The electronic device has to consume power to make the measurement so that will drop the voltage inside the device depending on where its taking the measurement. That is completely normal.
    Thanks but I already did what you are stating as stated in my post. I also have nothing on that fuse block and powered by the appropriate gauge wire for the run. There is no corrosion anywhere in that system as I check it and place items as necessary at least 2X's per year.
     
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    ShadowX

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    Thanks but I already did what you are stating as stated in my post. I also have nothing on that fuse block and powered by the appropriate gauge wire for the run. There is no corrosion anywhere in that system as I check it and place items as necessary at least 2X's per year.

    The 1.5V difference is a bit high on your measurements. Typically, I've seen around a 0.5-0.8V difference on the system I checked.

    I just did some experiments on my Lowrance HDS12 unit.

    1) Unit on: Baseline (about 75% screen brightness)
    a) Measured voltage on terminal: 12.45V
    b) Voltage reading on screen: 12.3V
    c) Measured current: 1.0 A

    2) Unit on: Changed brightness to max
    a) Measured voltage on terminal: 12.25V
    b) Voltage reading on screen: 12.0V
    c) Measured current: 1.8 A

    3) Unit on: Changed brightness to min
    a) Measured voltage on terminal: 12.50V
    b) Voltage reading on screen: 12.3V
    c) Measured current: 0.7 A

    3) Turned Lowrance unit completely off
    a) Measured voltage on terminal: 12.70V
    b) Measured current: 0.0 to 0.10 A
    (Note: Even when unit is off, there is a small amount of standby current used to keep unit ready so it can be turned on by the power button.)

    It seems like the power draw on the unit affects not only the voltage reading on the screen, but also the voltage readings on the power terminals. As the load decreases, the supply voltage goes up and as the load increases, the supply voltage drops.

    My voltage difference was less than yours, but at the highest brightness, there is the biggest voltage difference. The voltage difference with the unit off to when its on is about a 0.7V drop across the power terminals.

    The takeaway is that you should measure the voltage on the terminal when the unit is on at max brightness setting. It draws the most current at the max brightness and drops the supply voltage on the terminals down by close to 0.7V. It provides a more accurate reading. Even then, I still saw a slight 0.2V difference between the measurement on the screen and the meter. The reality is that every device has a measurement error so that small difference is a rounding error since its less than 2% difference.

    BTW, I used a bench power supply inside my home for this measurement so its dead accurate. I can adjust the voltage in 0.01V increments if needed. I set the voltage to around 12.69 to 12.70V on the bench supply with no load (other than the 100mA standby current draw on the Lowrance unit) . On a charger or battery, the voltage may fluctuate slightly if its measured on a boat.
     
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    SilentViper

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    You mention measuring the voltage with the brightness down, and you show a screenshot of sonar stopped, but no measurements I see, does pausing and turning the brightness all the way down have a measurable effect? I'd imagine the "600W" or "1kW" transducers pull a fair bit of current. i know that's not a constant amperage, but the spikes would be smoothed out by the giant capacitors in the device.
     
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    ShadowX

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    Its good to double check all the wires for cuts and nicks. This particular wire looks like it was pinched (yellow wire). I'm not saying this would do it, but sometimes, people nick the insulation on some wires and water gets inside and create corrosion issues. The wires could also get crushed and cause problems. The wire terminal in red looks like it has very little stress relief. What ends up happening is that it gets yanked down and over time you can have issues too.

    I notice that you check the voltage across the two largest terminals. I would check it against the terminal where the positive is getting power and also on the negative terminal on the ground side (blue arrow). There may be a slight difference between those two points. I noticed that you use yellow connectors sized for a 10-12 AWG wires on some of the terminals. When you crimp them down on smaller wires, the crimp does not always form properly because there are gaps between the wires and the crimped portion. It just creates its own set of problems over time if the wires get loose.

    Another thing to do is actually yank/tug on the wires. You might have a few bad strands of wire that is hidden by the connector. It doesn't look like sealed heat shrink connectors, so anything can go wrong once water gets in.

    I try not to assume anything even on my own wiring and test/tug on the wires. I've been burned before with my own assumptions. I try to learn from my mistakes and trust me, I made my share of them. I built wire harnesses at work for a few years in my career and seen my share of problems with wiring.

    I would even disconnect the wire to the fish finder on the terminals, give it a good clean with fine sandpaper and test again. You never know. A lot of these problems may be hidden away and you can't see until you take it apart. Do the same with the terminals on the fuse and spray some CRC contact cleaner on the sockets. Its a 5 minute test that you can do for sanity check. At least if you still have the same problem afterwards, you can check it off as not the cause.

    Another easy test is to switch the power cables on your two fish finders. You mentioned that the 16" seems seems to be lower voltage now. If you swapped the cable, and the voltage drop is now on the other unit, at least you know its not the fish finder's problem and something with the wire. But on the other hand, the voltage shown is still the same, it would be caused by the fish finder itself. If you have a meter that checks current, you can even take some measurements and compare.

    The good part about electrical systems is there are only a few places where it can go wrong. Just keep following that wire down and go from one connection to the next.

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    ShadowX

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    ShadowX

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    I don't doubt anything when it comes to troubleshooting.

    Explain how the power on the NMEA 2K backbone is used to sense the V supply voltage. With the cable completely disconnected, I still get a V supply reading. I applied different voltages to the power on the NMEA 2K backbone during my test and the voltage didn't change at all.

    If there was a voltage on the backbone, it would power up the other devices attached to the backbone. If that is the case, there would be no need for the power cable connection to the backbone. If I disconnect that power connection, the devices that rely on the 12V turns off because there is no longer a voltage on the power pins.

    The easiest test is to disconnect that NMEA2K cable to the fish finder. If you still read a voltage, it means its not reading off the voltage off the NMEA2K cable.

    Its not troubleshooting, its just making up crap that doesn't make sense at all. There is not even a logic to your reasoning.
     
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    SeaHawk IV

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    Take it easy ShadowX, too much caffeine this morning? I had a gut feeling you would jump on my suggestion to the OP.

    You seem to know what you're talking about so why don't you offer the OP a visit to his boat and solve the problem for him.

    I was also referring to the NEMA2000 Power cable location on the network. Best to have NEMA2000 power cable connected to middle of the NEMA2000 Network to balance the load.

     
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    sickcat

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    I saw a post on PapaJ's thread on another site that suggested to install a voltage sensor on the network and have the Simrad head use that for the voltage it displays. Said post was from someone who I believe was/is employed by Simrad and had nothing else to offer on why the problem is happening or a possible fix. PapaJ is not the only one with this issue.
     
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    ShadowX

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    Take it easy ShadowX, too much caffeine this morning? I had a gut feeling you would jump on my suggestion to the OP.

    You seem to know what you're talking about so why don't you offer the OP a visit to his boat and solve the problem for him.

    I was also referring to the NEMA2000 Power cable location on the network. Best to have NEMA2000 power cable connected to middle of the NEMA2000 Network to balance the load.


    I would love to, but he is near San Diego and that is about a 140 mile drive for me. I didn't mean to jump on you. Problems like these are harder to figure out unless you see it in person and run some tests.
     
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    Papa "J"

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  • May 8, 2003
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    Shadow I appreciate some of your feedback but I am pretty well educated when it comes to electrical connections. Even when you zoom in my pics your pointing out stuff that are maybe's and all of my connections are right and tight. I am pretty familiar with these Simrad systems as I have helped installed many systems over the past 6 years and get calls and messages on a weekly basis for help.

    So as far as Im concerned this is a Simrad software / Product issue. I have also bench tested with IOTA engineering regulated constant power supply. And to have 1 -1.5 voltage drop for no reason without Simrad being able to answer seems like they are just trying to sweep it under the rug.
     
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    ShadowX

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    Shadow I appreciate some of your feedback but I am pretty well educated when it comes to electrical connections. Even when you zoom in my pics your pointing out stuff that are maybe's and all of my connections are right and tight. I am pretty familiar with these Simrad systems as I have helped installed many systems over the past 6 years and get calls and messages on a weekly basis for help.

    So as far as Im concerned this is a Simrad software / Product issue. I have also bench tested with IOTA engineering regulated constant power supply. And to have 1 -1.5 voltage drop for no reason without Simrad being able to answer seems like they are just trying to sweep it under the rug.

    You would think they can easily add in a software option to "calibrate" the voltage value or adjust it like other sensors or parameters. I wasn't able to find any on the setup menu. I don't really pay attention to the voltage gauge on my fish finders. If I want something accurate, I would get an external voltage and current meter.
     
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