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Which inverter do I need?

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  • Which inverter do I need?

    So I posted a thread earlier but I was mistaken about certain issues related to the amount of energy I was going to be using. I wanted to post here as the information in that thread was just too wrong and I didn't want the thread to get too convoluted. Hope that's cool.

    I am trying to run a pottery wheel that has a 100w DC motor but it plugs into an AC outlet (I guess it has a built in inverter? I've thought about rewiring so that I can plug it straight into my batter but I'd rather not mess with it). It is 1/3 hp and has variable speed.

    I know of one person running the same wheel off of a 93ah deep cycle battery with a 1000w inverter and can run it for up to 10 hours.... I'm going to have 2 6v 230ah batteries so am hoping for up to 20 hours of operation without sun. Anyways, what I am wondering is, do you think a 1000w inverter would be ok for this wheel + turning on my rv water pump + having a phone plugged in and charging? I am new to this stuff so am confused about the math... and I don't know how much energy a 100w dc motor like this can surge up to.

    Thanks for any help you might be able to provide me with!
    Kadin

  • #2
    Well none of your numbers make much sense.

    100 watt motor with average efficiency is roughly 1/8 Hp
    10 hours run time on a 12 volt motor 93 AH motor is roughly 10 watts or 1/80 HP

    FWIW 1 HP Electric Motor = 746 Watts at 100% efficiency which is not possible. At an extremely high 90% efficiency would be 828 watts. That is why your numbers do not jive. A 1/3 Hp motor would be around 300 watts.

    Anyway with a pair of golf cart batteries (6-volt 230 AH) will work and you will need at least a 300 watt Solar panel and a 25 amp MPPT charge controller to keep it charged. Yes a 1000 watt Inverter will be overkill, just make sure you get a True Sine Wave model. Do not buy 12 volt battery panels unless the $/watt is less than grid tied panels. Wire panels in series if more than one is used. Grid tied panels are much less expensive and much higher power. In fact you can get a 300 watt panel. Expect to pay around $200 for a good 25 amp MPPT controller. A pair of golf cart batteries will be around $300. If you shop around you can get a 300 watt GT panel for around $300 or rless or up to $600 if you use 12 volt battery panels. Whatever you do is DO NOT USE a PWM or cheap charge controller.
    Last edited by Sunking; 04-13-2018, 08:06 PM.
    MSEE, PE

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    • #3

      Thanks Sunking,

      They aren't my numbers... This is copied and pasted from the manufacturer of the Shimpo Aspire pottery wheel:

      MOTOR 100W DC
      HP 1/3 HP
      SPEED CONTROL Lever Handle
      WHEEL-HEAD 7
      Last edited by Kadin; 04-13-2018, 08:34 PM. Reason: My message keeps getting cut off for some reason

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      • #4
        Trying to make a full post but it keeps getting cut off for some reason... don't know whats wrong...

        Here is the end of the previous post... hopefully it shows up...

        7



        EDIT, ugh I give up... going to a different website

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        • #5
          Originally posted by Kadin View Post
          Trying to make a full post but it keeps getting cut off for some reason... don't know whats wrong...

          Here is the end of the previous post... hopefully it shows up...

          7



          EDIT, ugh I give up... going to a different website
          Because you are copying and pasting, and this site does not allow that. Look and I bet you will find it cuts off with punctuation marks.

          MSEE, PE

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          • #6
            Originally posted by Kadin View Post
            Thanks Sunking,

            They aren't my numbers... This is copied and pasted from the manufacturer of the Shimpo Aspire pottery wheel:

            MOTOR 100W DC
            HP 1/3 HP
            SPEED CONTROL Lever Handle
            WHEEL-HEAD 7
            I understand they are not your numbers, just explaining why so you would know.

            MSEE, PE

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            • #7
              Thanks. I didn't realize copy and paste wasn't allowed. Thanks for your help. What size inverter would you recommend? I'd rather not spend more on a huge inverter if I don't need to.

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              • #8
                I tried to say: It is confusing that everyone is giving me wrong numbers! I really appreciate your advice!

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                • #9
                  The appliance you're trying to run is DC, check into wiring a directly like you suggested.

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                  • #10
                    I wonder how much you would need to run a Dyson vacuum for maybe 10-20 minutes every week or so? I have two Duracell Ultra 100Ah batteries right now. I was hoping to get a 3000 watt pure sine inverter in the future. For now I am temporarily using a 300 watt power inverter. I'm only using it to charge my cell phone and sometimes run my iMac 27". But every time I run the computer, the fan comes on and runs like crazy. As long as the sun is shining good, the batteries stay topped off.

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                    • #11
                      Originally posted by RenewablesRock View Post
                      I wonder how much you would need to run a Dyson vacuum for maybe 10-20 minutes every week or so? I have two Duracell Ultra 100Ah batteries right now. I was hoping to get a 3000 watt pure sine inverter in the future. For now I am temporarily using a 300 watt power inverter. I'm only using it to charge my cell phone and sometimes run my iMac 27". But every time I run the computer, the fan comes on and runs like crazy. As long as the sun is shining good, the batteries stay topped off.
                      A possible reason for your computer fan to be running could be due to that modified sine wave inverter. It could be delivering dirty power which creates more heat and therefore requires more cooling.

                      Using a pure sine wave inverter for electronic loads is a better plan.

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                      • #12
                        I have a question related to the subject. Do the OEM cigarette DC adapter chargers for laptop computers give clean power?

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                        • #13
                          Originally posted by Brian53713 View Post
                          I have a question related to the subject. Do the OEM cigarette DC adapter chargers for laptop computers give clean power?
                          Since that cigarette adapter just converts the car 12 volt battery to the DC voltage the laptop requires there is really no "inverting" being done.

                          When you invert DC to AC you run the risk of not having a nice clean AC cycle so it can create issues with sensitive electronics as well as AC motors.

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                          • #14
                            Originally posted by SunEagle View Post

                            A possible reason for your computer fan to be running could be due to that modified sine wave inverter. It could be delivering dirty power which creates more heat and therefore requires more cooling.

                            Using a pure sine wave inverter for electronic loads is a better plan.
                            Yeah, I bought this thing days before Hurricane Irma and there was nothing left. I was at Brandsmart and ended up buying this 300 watt inverter for like $26. It was the only thing I could find anywhere. But it saved us after the storm. I bought two of them but this 300 had two USB ports and was able to charge the phone. The two batteries kept our light on all night and I ran a small 25 watt fan that kept us cool while we slept with no air-conditioning. I felt like I was camping.

                            I am trying to expand on what I have here and make two of my bedrooms off the grid. I have all of my equipment on the floor just to test it out. This time I want to mount it really nice on the wall now that I know everything works and then buy like a 3000 watt inverter. I don't plan to run anything big on it. I will eventually buy pairs of 100 Ah batteries to keep adding onto the system until I hopefully have 800 to 1000 Ah of standby power. Then when we clean the rooms, we should be able to plug in a vacuum cleaner, TV or anything for small usage. Right now I have my two 310 watt panels hooked up in series in the backyard. I have a long 12 or 16 ga. wire running into my room here that plugs into my EPEver Tracer 40 amp charge controller. I bought one of those little MT50 add-on's as well. I talk to Hatian's and other people who live out of the country who are all very interested in what I am doing and wish to copy my efforts. I want to make a setup nice enough here for people to come and see and I want to teach them how to build stuff like this to bring over to their countries.

                            This one lady told me that she wants to spend $1000 and power a couple of freezers. She has no idea how much that would cost. The batteries seem to be the deal killer. Then people end up using car batteries that are not safe from the emissions and won't last long. If I showed these Hatians how much AGM batteries cost, so they would scoff, "forget that" and give up on the whole idea of solar power. I got to get them to start small. I feel so bad for these people that live with no light or power. I have the knowledge to help them at least have a little light during the night and the ability to charge cell phones. Even the Harbor Freight system can do that for like $150. Maybe I'll show the lady this so she can learn on it.

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                            • #15
                              Originally posted by SunEagle View Post

                              A possible reason for your computer fan to be running could be due to that modified sine wave inverter. It could be delivering dirty power which creates more heat and therefore requires more cooling.

                              Using a pure sine wave inverter for electronic loads is a better plan.
                              This is what I'm using. I have to wait for the Kill A Watt to get here to see how much real power this iMac hogs up. I unplugged the computer for now and just charge my phone up with it.

                              I just saw a GoPower 300w inverter for $171. I paid $26 for this inverter from Brandsmart USA in South Florida.
                              Attached Files

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