Page 1 of 3 123 LastLast
Results 1 to 10 of 27

Thread: Suitable mulitimeters

  1. #1
    Join Date
    Jul 2008
    Location
    Federalsburg, MD
    Posts
    1,538

    Suitable mulitimeters

    Whilst visiting Home Depot / Lowes etc for other bits and pieces, I've also been looking around for a multimeter that I can use to reliably monitor the DC current amps etc on my unit, once it is built and in the testing phase, however, the best ones I can find only seem to go to a maximum current of 10 amps DC. I'm hoping to find a multimeter that will measure up to 30 odd amps, but won't break the bank.

    Can any of the electronics guru's recommend a source?

  2. #2
    dennis13030 Guest
    Hi,

    My name is Dennis and I am an electronics engineer. The low cost and high current way to go is this;

    1. Buy a cheap digital multimeter(the max current rating is NOT important). Believe me on this.
    2. Buy a current sensing resistor. See this link. It is a 0.005 Ohm, 7 Watt resistor and it's real cheap($4.16).
    http://www.mouser.com/Search/Product...KYZDPMxg%3d%3d
    3. Put this resistor inline with the +12V against the electrolyzer.
    4. Use the voltmeter to read the voltage across the sense resistor. Whatever value is displayed, multiple it by 200 for the true current value. This calculation is due to the resistor being 0.005 Ohms.

    This gets your cheap DMM an effective maximum current measurement of about 37 Amps.

  3. #3
    Join Date
    Jul 2008
    Location
    Federalsburg, MD
    Posts
    1,538
    Cool! That's an interesting idea.

    I've been thinking about it and I will be wanting to install some kind of amp gauge in the inside the vehicle, once the installation is complete, so I might just go ahead and buy a suitable in-vehicle gauge and use that whilst testing instead. Would save money in the long run.

  4. #4
    Omega Guest
    Wow dennis, you are one smart cookie!!

  5. #5
    BAD MEDICINE Guest
    Id say my biggest weakness in this venture is understanding/measuring the data. Makes me wish I would have made more of an effort to learn it in school.

  6. #6
    Join Date
    Jul 2008
    Location
    Federalsburg, MD
    Posts
    1,538
    I just ordered an automotive amp gauge online from SunPro, it runs +/- 60 amps max which should be ideal. I know that the maxigen systems are pulling well over 40 amps on their setup on a ram just like mine (even same year), so I'm considering working up to that kind of production.
    2006 Dodge Ram 4.7L - 16.5 mpg stock
    My thread Painless Experiment in HHO

  7. #7
    Join Date
    Jun 2008
    Location
    Oklahoma, USA
    Posts
    173
    Dennis, is there a gauge that I can connect to my laptop to see more than 1 reading and track the voltage, wattage and amperage? I t would be cool to plot the time, temp, and electric stats on a chart so as to get the best results with the cells...
    "You don't always have to know ALL the answers, but you do need to know where to find them."

  8. #8
    dennis13030 Guest
    Quote Originally Posted by computerclinic View Post
    Dennis, is there a gauge that I can connect to my laptop to see more than 1 reading and track the voltage, wattage and amperage? I t would be cool to plot the time, temp, and electric stats on a chart so as to get the best results with the cells...
    First of all, thanks to everyone for the compliments. Electronics is what i went to school for and I'm pretty good with it.

    I will try to find this for you. I know they exist. It's a matter of how much $$$ and the spec.s you want. Give me a couple hours.

  9. #9
    dennis13030 Guest
    Quote Originally Posted by computerclinic View Post
    Dennis, is there a gauge that I can connect to my laptop to see more than 1 reading and track the voltage, wattage and amperage? I t would be cool to plot the time, temp, and electric stats on a chart so as to get the best results with the cells...
    Ok, I'm back.

    This is the same kind of automated testing setup that I want to do. It is also the same kind of equipment and procedures that I used to do at an old job of mine.

    To setup for automated testing including;
    1. Source voltage measurement,
    2. Source current measurement,
    3. Temperature measurement,
    4. Output flow rate measurement.

    would require a large investment(about $5000 for equipment) and a significant amount of time/effort.

    The power is Watts are calculated from the current and voltage measurements.

    I would not go this route because there is a better way. My old work does this stuff already.

    Let me know what you think.

  10. #10
    Join Date
    Jun 2008
    Location
    Oklahoma, USA
    Posts
    173
    wow...5K is a bit steep for my wallet, but it would certainly be worth having if it will do all the plotting, especially in a nice graphic...Does it include the PC laptop? Lol
    "You don't always have to know ALL the answers, but you do need to know where to find them."

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •