Inverter electrical question

Discussion in 'Trucking Electronics, Gadgets and Software Forum' started by Tallahassee, Sep 4, 2021.

  1. Tallahassee

    Tallahassee Bobtail Member

    10
    2
    Dec 9, 2020
    0
    I work for a company that has their own inverters. They are not bad (2000W) but they are not pure sign wave. They are really choppy modified sine wave. So choppy microwave motor struggles. My question is they will not install my own equipment, nor can I remove their equipment. Their inverter on the back where it steals the battery has big termination blocks, so big they got the cigarette lighters near bunk for phone charging in the back wired to it with reasonable room. My idea is and photo is attached that the inverter draws from the termination block when turned on right? Rather than running a second inverter replacing theirs myself because it has been not working sometimes is to buy a 3000w pure sine wave inverter and do a short run from the back of it directly to the terminal block on the back of that inverter that the zero gauge heavy duty wielding wire they got going to the battery’s and just keep the modified sine wave inverter off. The circuit is not completed thus that inverter is not drawing anything and it would be just as if I was doing a jumper from a metal terminal block. Any risk in this electrically? I can’t think of any. I’m not going to be using both just piggy backing of the termination block maybe a 1 ft run and then mounting the pure sine wave inverter above the old one.
     

    Attached Files:

  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  3. skallagrime

    skallagrime Road Train Member

    1,798
    3,697
    Apr 10, 2012
    Indiana
    0
    Have a pic of how the wires come in and hit their inverter?

    I would be leery of going much above 2k without knowing for certain the alternator and wiring job into the cab
     
    feldsforever Thanks this.
  4. Tallahassee

    Tallahassee Bobtail Member

    10
    2
    Dec 9, 2020
    0
    Sure I’ll attach one on this post. The other positive and negative wires branching off the termination block go to the cab cigarette lighter port in the back. 12v 10a. Followed it to the back. Truck is wired as a 12v system not a 24. I live in my truck so clean power is pretty important. I run a media server that I can stream on with SSD’s that I custom built but it does not like the dirty power.
     

    Attached Files:

    feldsforever Thanks this.
  5. skallagrime

    skallagrime Road Train Member

    1,798
    3,697
    Apr 10, 2012
    Indiana
    0
    I am cautious of advising you to do anything here because i dont know your proficiency with electrical and toolkit for wiring.

    But i will say IF WIRED APPROPRIATELY with properly crimped and sealed lugs of appropriate wire size it *should* be quite safe to run one or the other inverter tapping those terminals.

    I stand by my recommendation of 2k or lower, and suggest double checking that there is a low voltage cutoff and fuse on the positive side next to the battery, seeing the way its wired i have little trust in whoever wired it in the first place
     
  6. Snailexpress

    Snailexpress Road Train Member

    2,443
    5,148
    Apr 28, 2014
    Rocky
    0
    Don't do it!
    Every additional connection will add resistance in circuit. Small, 0.01 ohm. Do we have to worry about such small things? Yes!
    If you using microwave or coffee maker it's require about 1,200 watt power what is require 100 amps circuit current in 12 volt system.
    0.01 ohm resistance in circuit will cause voltage drop exactly 1 volt.
    The voltage drop will generate heat exactly 100 watts. Keep in mind this is spot heat on wire terminal.
    Heat will cause terminal connection even more bad and resistance will rise as the time goes due to loosening and oxidation.
    The numbers I have using is for example but you should understand the science.
    From posted pics I see wire size is too small. Looks like they use one from the kit. It's need to be doubled. And when the last time connections were cleaned?
    I have probably the same 2000 watt inverter from TS and have no problem to run microwave. Every 3 -2 months I do terminal wirebrush cleaning. Otherwise it will struggle.
     
    feldsforever Thanks this.
  7. Six9GS

    Six9GS Heavy Load Member

    955
    2,060
    Dec 3, 2012
    Yuma, AZ
    0
    I was an electronics technician for 15 years, your theory sounds fine to me. It's in the details you have to worry. Mainly ensuring it is properly installed and hooked up. Dealing with those input wires that are capable of handling alot of amperage, alot can go wrong and most are pretty bad. So, be darn careful!! I'd start by disconnecting them from the source battery strips FIRST before doing anything else. Also, double and triple check anything and everything with them before you reconnect them for the 'smoke test'. If you are not really trained in such things, I highly recommend you get a professional who knows what their doing. Like I said, sounds OK in theory, but alot can go wrong and most of those wrong things are really bad! There's alot of amperage available in those wires.
     
  8. Six9GS

    Six9GS Heavy Load Member

    955
    2,060
    Dec 3, 2012
    Yuma, AZ
    0
    Unsure how you're getting your figures here. An 1800 watt microwave at 120 volts going to draw 15 amps. 15 amps at 12 volts is going to be 180 watts. I have no idea where you're getting a 100 ampere figure in the mix.
    And, I have no idea where you're getting the 0.01 ohm and how that effects everything? And, 100 watt 'drop' voltage. IDK, I was an electronics tech for 15 years and what you stating makes no sense to me.
     
  9. skallagrime

    skallagrime Road Train Member

    1,798
    3,697
    Apr 10, 2012
    Indiana
    0
    I beleive hes saying that connections tend to act as resistors, similar to lengthening the run of a wire will cause a voltage drop, that loss will typically be discharged as heat at the resistance point. When its a connection point, heat tends to localise there and has the possibility of being a fire hazard.

    From the hack jobs ive seen in wiring, this is beleiveable, but i usually see hack connections in tandem with undersized wiring too. A GOOD connection *tends* to also have appropiate wire sizing for application as well.
     
    Snailexpress Thanks this.
  10. Snailexpress

    Snailexpress Road Train Member

    2,443
    5,148
    Apr 28, 2014
    Rocky
    0
    What did you do as an electronic technician if you don't understand Ohm law and circuits.
    P(power) = I (current) x V ( voltage)
    If you draw from inverter 1200 watts the current is 1200 / 120 = 10 amp.
    How much inverter current draw from batteries 1200 / 12 = 100 amp
    In real life current draw from batteries will be higher due to inverter efficiency loss and circuit loss.
     
  11. Six9GS

    Six9GS Heavy Load Member

    955
    2,060
    Dec 3, 2012
    Yuma, AZ
    0
    I think you have the second calculation wrong. Watts ÷ Amps = Voltage. So, you're 1st one is right, 1200 watts ÷ X amps = 120 Volts, X is 10 Amps as you say. But, X watts ÷ 10 Amps = 12 Volts, or X Watts = 10 Amps × 12 volts. Which is 120 Watts, Not 1200 Watts. Looks like you made the assumption that 1200 watts is the same for 120 volts or 12 volts. I don't think that's the right assumption. As wattage is the product of volts and amps.
    If I'm made the wrong assumption, please explain. I think I'm right, but wouldn't be the 1st time I'm mistaken. And, All this ignores power usage and stuff from the inverter itself. So, only looking at ideal conditions to make sure we get the theory correct.
    My Electronics training was with the US Air Force. But, for 5 years I worked as a tech directly for engineers designing and modifying analog electronic circuitry. I did very little "swaptronics". The repair work I did was almost always down to component level repair. Basically, I if I couldn't fix it, it went in the thrash. I was good at what I did. But, it was a few years ago now and no one is perfect.
     
    Last edited: Sep 26, 2021
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  • Draft saved Draft deleted