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Thread: Power Inverter (want to permanently install in car -- advice?)

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    Question Power Inverter (want to permanently install in car -- advice?)

    Preface: I'm an apartment dweller and was looking for an alternative to relying on the dealership/garages etc to do a little handiwork on the Scootabout so I came up with the solution of using an inverter to power up to 350 watt tools.

    So, I bought a 500 w power inverter from Crappy Tire (for those that don't live in Canada, that's an automotive chain called Canadian Tire) to make sure that I'm not pushing it to it's limits. Peak power it will output is 1000 w. I'm sorry that I'm stating the obvious to those that know what inverters do and how they work but I did some homework to find this out so it might save someone else some time.

    Down to the nitty gritty. Plugging it into the power supply socket will only give me 100 w of power so it needs to be connected to main battery power by the provided battery clamps to take advantage of the full 500 w capacity. I don't feel like lugging it around every time I want to do something like detailing my car. In other words, I want to permanently install the inverter into the car. It has a power button so it won't be permanently on so I'm looking for thoughts as to whether I should snake the wires through an existing grommet in the firewall and directly connect it to the battery or if I should find a sub-system to hook it into that gets power only when the ignition switch is set to "on". I won't be using the inverter when the car is turned off but I'm not 100% sure that the inverter won't be "ghosting" power when both it and the car are off. Thoughts?

    P.S.- The inverter is a Motomaster Eliminator, model no. 011-1947-6

    Regards,
    Peter



  2. #2
    Curious: What tools are you powering from the inverter?

    Quote Originally Posted by Kineo View Post
    I won't be using the inverter when the car is turned off but I'm not 100% sure that the inverter won't be "ghosting" power when both it and the car are off. Thoughts?
    You could test that easily enough if you have a digital multimeter. Connect one inverter lead to the battery, then the other lead to the multimeter using the "Amps" function to see whether there's current flowing when you contact the multimeter to the other battery terminal.

    EDIT: I would first do a direct inverter connection to the battery (both leads) before the above test, in case the inverter has capacitors which charge up at a high rate (above that of the multimeter), which might blow the multimeter fuse.

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        click to view fuel log View my fuel log 2014 Mirage ES 1.2 manual: 63.2 mpg (US) ... 26.9 km/L ... 3.7 L/100 km ... 75.9 mpg (Imp)


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    Quote Originally Posted by Kineo View Post
    I want to permanently install the inverter into the car.
    Sure, it's possible. Consider asking yourself some questions.

    1. Is there any risk of fire? Any circuit needs a fuse to protect not only the power source (the car) but the wiring to the device, and the electrical load (inverter) itself. The inverter may have a fuse or circuit breaker, but that is to protect the inverter, not the supply wiring or the power source. Be certain that whatever you draw your power from, it is capable of providing the full potential power to the inverter under any/all conditions.

    2. Are you worried about warranty, and insurance? A modification like this might bring increased scrutiny in case of a claim.

    A temporary installation might suit you just fine, with little to no modification necessary.

    Good luck. Let us know which way you go with this. Pictures will help us see what you got.

    Cheers.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.6 mpg (US) ... 21.1 km/L ... 4.7 L/100 km ... 59.5 mpg (Imp)


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    Quote Originally Posted by MetroMPG View Post
    Curious: What tools are you powering from the inverter?
    Thanks for the advice! I don't have a multi-meter as yet but it's on my to-do list. To answer your question, the main tool I plan on using is a Bissell Little Green Machine (without heater) which has a 350 w draw. I also plan on using the inverter for small mods that require small power tools like a drill (not a heavy duty one). It's gonna be occasional use and I'll just use it as-is with the alligator clamps that came with it for now. My reason for wanting a permanent installation is so that I can "hide" it somewhere and have access to it anytime, like if I'm camping and need temporary AC power.

    Quote Originally Posted by Eggman View Post
    1. Is there any risk of fire? Any circuit needs a fuse to protect not only the power source (the car) but the wiring to the device, and the electrical load (inverter) itself. The inverter may have a fuse or circuit breaker, but that is to protect the inverter, not the supply wiring or the power source. Be certain that whatever you draw your power from, it is capable of providing the full potential power to the inverter under any/all conditions.

    2. Are you worried about warranty, and insurance? A modification like this might bring increased scrutiny in case of a claim.

    A temporary installation might suit you just fine, with little to no modification necessary.

    Good luck. Let us know which way you go with this. Pictures will help us see what you got.

    Cheers.
    I was asking for advise for just these kinds of reasons. I was thinking of hooking it up through the power point wiring so that it would shut off when the ignition is off and so that it's on a circuit with a fuse. I need to look at the manual again but I believe the power point is on a 15 amp fuse. I plan on doing my homework before I attempt to do anything permanent but thought that posting here would be a good place to start, in case anyone else here has tried or successfully attempted this before on a Mirage or other car. I'm gonna go with the temp installation (as mentioned above) for my initial uses.

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    Quote Originally Posted by Kineo View Post
    Thanks for the advice! I don't have a multi-meter as yet but it's on my to-do list.
    Check if your meter is capable of measuring the high inrush currents associated with electromagnetic devices such as with electric motors. While most power supplies and inverters can handle these surges, some can't, and budget multimeters often do not sample fast enough to catch them. A few other things to consider, is check to see if your meter is capable of recording MIN/MAX/AVG figures. Also, compare the maximum amperage the meter can measure. For example, my multimeter is rated for measuring 10 amps DC, and it's original fuse was either a 12- or 15-amp fast acting. I'll let you guess as to how I know that...

    My point is, unless you have a good understanding of and trust in the multimeter, it might be better to guess at worst-case scenarios than to be misled by an underperforming measuring device. A crummy meter can cause more harm than it's worth.

    Quote Originally Posted by Kineo View Post
    I was asking for advise for just these kinds of reasons. I was thinking of hooking it up through the power point wiring so that it would shut off when the ignition is off and so that it's on a circuit with a fuse. I need to look at the manual again but I believe the power point is on a 15 amp fuse. I plan on doing my homework before I attempt to do anything permanent but thought that posting here would be a good place to start, in case anyone else here has tried or successfully attempted this before on a Mirage or other car. I'm gonna go with the temp installation (as mentioned above) for my initial uses.
    Quote Originally Posted by Kineo View Post
    P.S.- The inverter is a Motomaster Eliminator, model no. 011-1947-6
    I looked at the manual for your model inverter, and it claims a no load current draw of about 1.7 amps. Looks like it will drain your battery if left connected, and the inverter's manual says as much.

    Quote Originally Posted by Manual for Motomaster Eliminator, model 011-1947-6
    Disconnect the power cable whenever the engine is switched off for extended periods of time. In some vehicles, the power does not turn off after the engine has been switched off. If the plug is left connected, the vehicle battery might become discharged or damaged.
    Though it also says this, which is helpful:

    Quote Originally Posted by Manual for Motomaster Eliminator, model 011-1947-6
    IMPORTANT!
    When the mobile power outlet is switched off, it draws no current from the battery. When the outlet is switched on without any load connected to it, the outlet draws approx.1.5 A from the battery.This low current draw will eventually discharge the battery.
    The manual does not specifically warn against a permanent installation, but I saw at least four warnings or caution notes against leaving it connected when not in use (probably to avoid draining the vehicle battery.)

    Here are my rough electrical calculations for your inverter. These are assuming the inverter's rated output of 115VAC, and a battery output of 12VDC.

    POWER RATING MAXIMUM WATTAGE Calculated Amperage (for 12VDC supply)
    Continuous power rating (RATED WATTAGE) 500W 41.6DCA
    Surge rating max. (SURGE WATTAGE) 1000W 83.3DCA

    Notes:
    1. Looks like you will need a circuit capable of delivering 100DCA to reliably power your inverter. Granted, surge current draw will not likely reach 83.3DCA, depending on the inverter's internal circuitry design. But that's a lot of power to supply to the inverter.
    2. I believe the surge rating of your inverter is close to exceeding the Mirage's alternator capacity.
    3. My calculations of a battery voltage of 12VDC is conservative. Most fully charged batteries will show a no-load voltage in excess of 13.5VDC, but when loaded the battery voltage is expected to drop some. It is my understanding that a device like an inverter can draw more current to supply it's loads when it's input voltage is sagging.
    4. There are products made for trucking and camping that are designed to run on 12VDC. Consider some of those products instead of using inverters. Google: 12V appliances There's some pretty cool stuff running on 12v.
    5. Sorry for the long post! Good luck.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.6 mpg (US) ... 21.1 km/L ... 4.7 L/100 km ... 59.5 mpg (Imp)


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    I thanked you from the link but that doesn't say enough. You saved me time and headache with your post and I'm grateful for that. You've given me some guidelines that are hella useful.

    Quote Originally Posted by Eggman View Post
    For example, my multimeter is rated for measuring 10 amps DC, and it's original fuse was either a 12- or 15-amp fast acting. I'll let you guess as to how I know that...

    My point is, unless you have a good understanding of and trust in the multimeter, it might be better to guess at worst-case scenarios than to be misled by an underperforming measuring device. A crummy meter can cause more harm than it's worth.
    Preach! My Dad always taught me, buying cheap tools results in cheap work. He told me that you don't necessarily have to buy top-of-the-line tools but to buy the best quality for your budget/work. I'm not a professional but when buying tools I will buy mid to high quality tools, not the cheapest. If I don't know the quality of the tools, I do research before I buy.

    Quote Originally Posted by Eggman View Post
    The manual does not specifically warn against a permanent installation, but I saw at least four warnings or caution notes against leaving it connected when not in use (probably to avoid draining the vehicle battery.)

    Notes:
    1. Looks like you will need a circuit capable of delivering 100DCA to reliably power your inverter. Granted, surge current draw will not likely reach 83.3DCA, depending on the inverter's internal circuitry design. But that's a lot of power to supply to the inverter.
    2. I believe the surge rating of your inverter is close to exceeding the Mirage's alternator capacity.
    3. My calculations of a battery voltage of 12VDC is conservative. Most fully charged batteries will show a no-load voltage in excess of 13.5VDC, but when loaded the battery voltage is expected to drop some. It is my understanding that a device like an inverter can draw more current to supply it's loads when it's input voltage is sagging.
    4. There are products made for trucking and camping that are designed to run on 12VDC. Consider some of those products instead of using inverters. Google: 12V appliances There's some pretty cool stuff running on 12v.
    5. Sorry for the long post! Good luck.
    I am not sorry for the long post! It was very informative. I shortened it down in the quotes for brevity but you posted a lot of great info.

    So, I'm gonna look at the manual and see what circuits have which fuses. I believe that the highest rated fuse is a 40 amp but I'll check to make sure. I'm also going to be looking for which circuits are cut dead on ignition cut-off. Worst comes to worst, I can always do the permanent installation in the car and have it hooked up straight to the battery like I would with the alligator clamps but install a switch along the wires in the cabin somewhere that would kill all current going to the inverter.

    I'm not ignoring your advice about the 12v appliances. If there is something in there that I know I would use at, let's say, camping, I'll probably invest in it. I just can't justify spending the money on a whole new set of appliances that I'll only be using occasionally at home when I can't have access to grid power.

    Again, thanks for the great advice!

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    I think it would be best to connect it directly to the battery rather than splicing into another circuit. It is easier to reverse that way. You can also install an inline fuse and a disconnect switch under the hood. You might be able to find an existing entrance through the firewall which will fit the cable, and then from there it is simple to route the cable through the interior under the trim. Pay attention to the wire gauge you use for the cable as it will need to be bigger if you are running longer than the provided cables.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 automatic: 46.2 mpg (US) ... 19.6 km/L ... 5.1 L/100 km ... 55.5 mpg (Imp)


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    Also make sure you have a good ground.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 automatic: 46.2 mpg (US) ... 19.6 km/L ... 5.1 L/100 km ... 55.5 mpg (Imp)


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    Quote Originally Posted by jbarr View Post
    I think it would be best to connect it directly to the battery rather than splicing into another circuit. It is easier to reverse that way. You can also install an inline fuse and a disconnect switch under the hood. You might be able to find an existing entrance through the firewall which will fit the cable, and then from there it is simple to route the cable through the interior under the trim. Pay attention to the wire gauge you use for the cable as it will need to be bigger if you are running longer than the provided cables.
    Thanks for the tips!



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