Oh crap, how much damage did I do to this UPS unit? reversed polarity?

Discussion in 'Power Electronics' started by eddie500, Sep 28, 2016.

  1. eddie500

    Thread Starter Member

    Nov 5, 2011
    21
    2
    Hi, I bought a 2000 watt Dell UPS unit on ebay to run on a custom 72 volt battery I have.

    I accidentally used a C19 plug instead of a C20 plug. This means the Neutral and Live were reversed! The battery was not connected when I plugged in the AC power.

    The left plug is a C19 and the right is a C20.

    [​IMG]

    I tripped my 20 amp breaker twice and the unit obviously did not go on using AC power.

    Good news is that the unit works with my 72 volt battery and I am actually typing this post now powered from my electric bike battery.

    My question is, will the unit ever work on AC if I do get the right plug? How bad did I probably damage the unit by reversing polarity? Why did it keep tripping the house breaker?

    It will not be the end of the world because I only need it for running stuff on my 3.3 KW electric bike battery. But it would be nice to know if it would work on AC.

    Thanks.

    [​IMG]

    [​IMG]
     
    Last edited: Sep 28, 2016
  2. crutschow

    Expert

    Mar 14, 2008
    13,014
    3,234
    Normally reversing hot and neutral in an AC circuit should not cause a problem or damage (it's just a safety consideration) so I'm confused as to why your breaker tripped. :confused:
     
  3. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
    1,145
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    Something is fishy. The C19 is the power cord and the C20 is the receptacle. See: http://www.signalandpower.com/search/?group_1=C20&search=search_go
    So, they should mate.

    I would read the manual. Sometimes there is weirdness when putting the UPS online after replacing batteries.
    Some won't even run without doing something different.
     
  4. eddie500

    Thread Starter Member

    Nov 5, 2011
    21
    2
    Oh Crap, I think you are right.

    I guess I must have bought a defective unit on Ebay. Not worth returning this 40LBS monster if I don't need it hooked to AC anyway.

    The question remains, if the AC circuit is defective, but it seems to work normal on batteries only, would you consider the unit still usable and safe?

    I don't want this to damage my computer or anything. I already powered my computer for a few hours on battery without any issues.
     
  5. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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  6. eddie500

    Thread Starter Member

    Nov 5, 2011
    21
    2
    I found something where others have said that arc fault breakers sometimes cause problems with certain UPS units. I think i may have an arc fault breaker.

    The problem is my unit trips the breaker immediately, even before I press the power on button.
     
  7. tcmtech

    Well-Known Member

    Nov 4, 2013
    2,035
    1,660
    More than likely it's got a short in the AC power supply side of things.

    Open it it up and do some poking with a ohm meter and see what you find. It might be an easy fix.

    I just fixed a 2500 watt cont (3000 watt 5 minutes) rated commercial power inverter I got off eBay for $75, including shipping, that was 'burned out' as the listing said that had nothing wrong with it but a bad connection on the small power switch circuit board on its front. 1 minute fix after 10 minutes of taking it part and poking at it. ;)
     
  8. atferrari

    AAC Fanatic!

    Jan 6, 2004
    2,648
    764
    Hola eddie,

    Not to derail your thread but surprised by such a bike. Looks like a heavy thing to handle. Is it?

    BTW, out of curiosity: what is the fun or the good of having one? What is the maximum speed you can do? How many Km can you do starting with a full battery? And the most awful question: if your battery dies in the middle of nowhere, how heavy is pedaling?
     
  9. eddie500

    Thread Starter Member

    Nov 5, 2011
    21
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    The electric bike is more like a light weight dirt bike. It weighs about 115 lbs, which makes it too heavy to pedal but extremely easy to handle and move around. It can be pedaled on straight ground but not up any incline. The suspension and geometry is based on downhill bicycles, mostly all components are from those type of bikes.

    The bike is a dream to ride around, it is so comfortable and easy to handle, the suspension soaks up everything, and is completely silent. It has a lot of power also, depending on how you set the controller it can reach speeds of 60 MPH, and also acceleration is very good with the instant torque of the electric motor. I have it set to run at around 7000 watts peak which is about 10 horse power, on a 110 lbs bike. I could set it to run as high as 14,000 watts which would give me 20 HP.

    Range is extremely good with its 3.3 KW pack, I built this huge pack in this small framed bike to give me a ridiculously high range. Riding the bike hard like a dirt bike, fast street riding at 40 MPH, lots of off-road use will give me about 45 to 50 miles range. If I rode it slowly at bike speeds it would be as high as 150-200 mile range.

    If the battery dies I would have to push it up any incline. But pushing it isn't all that difficult because it doesn't weigh all that much. I've built it so reliable that I have not yet had to push it on this build.

    All that said this is probably the most advanced "hub motored" electric bike in the world when compared to any other builds out there. I made sure to put the best of everything into this current build. The bike is really a technological marvel on what it can do. It is like having the power and handling of a dirt bike, yet is light weight and handles like a bike, completely silent and can be used stealthy where bicyles are.
     
    Sinus23 and atferrari like this.
  10. eddie500

    Thread Starter Member

    Nov 5, 2011
    21
    2
    Yes I will try and locate this.

    I actually have ground faults which trip the breaker if it detects shorts to ground. APC had an article about how they may cause issues here.

    http://www.apc.com/us/en/faqs/FA158850/
     
  11. eddie500

    Thread Starter Member

    Nov 5, 2011
    21
    2
    Would anyone recommend a way to apply power to the UPS unit to bypass the ground connection to check to see if it is the ground fault circuit breaker causing this?

    checking the ohms between line & neutral and ground show that it is not shorted. Yet my UPS trips the breaker as soon as I plug it in.

    I'm wondering if there is a way to safely bypass the ground connection and give it power and see if it still shorts and throws the breaker.

    Should i maybe use a resistor in line with the AC power to limit damage, yet see if it is still shorting?
     
  12. tcmtech

    Well-Known Member

    Nov 4, 2013
    2,035
    1,660
    Just unhook the wire inside the unit.

    More than likely that unit has MOV's on both the live and common lines that are tied to the ground and that what's causing your GFI to false trip,

    It's a fairly common problem associated with overly sensitive GFI's on circuits where they don't belong.
     
  13. eddie500

    Thread Starter Member

    Nov 5, 2011
    21
    2
    So you think it is safe to just disconnect the ground wire and plug it in again?

    Should I take any other precautions like limiting the current flow into the UPS?
     
  14. tcmtech

    Well-Known Member

    Nov 4, 2013
    2,035
    1,660
    Don't lick your fingers after using the bathroom before you wash them and don't pee on the cat either.

    Don't worry about the rest until it actually gives you a problem.
     
  15. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
    1,145
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    An "order of magnitude" value from L to H is 120/0.005 or about 24K. A number close to that may mean problems. A reminder is leakage current is additive. Refrigerators or motor driven stuff may have bigger values, so trying another outlet might be useful. The resistance may not even be DC, so it isn't a useful test unless it discovers something.

    Lifting the ground is OK as long as nothing else uses ground. RS232 ports, USB ports, Laptop power supplies with a ground connection are problematic. Some might ground the laptop and some might not.
     
  16. schmitt trigger

    Active Member

    Jul 12, 2010
    36
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    I'm with Tcmtech. The only way to trouble shoot, is by opening the unit and poking around.

    I'm also on the market to purchase an e-bike.
    But I don't want to hijack this thread.
     
  17. eddie500

    Thread Starter Member

    Nov 5, 2011
    21
    2
    I think the AC part of the unit is not worth fixing. I cut off a computer cable and used alligator clips to connect to the back of the unit.

    Doesn't work and didn't blow a circuit breaker this time. I even connected ground wire.

    Still works fine on DC electric, which is what I need it for. It just bothers me that it doesn't work on on AC.

    If everything seems to work fine on DC, should I consider the unit safe to use for DC battery purposes only? Or should I consider getting another unit?

    The other question is I payed $40 shipping + $60 for the unit from ebay. Should I consider asking for some concession because the unit does not work when plugged in? If so what would you ask for?

    Thanks.
     
  18. tcmtech

    Well-Known Member

    Nov 4, 2013
    2,035
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    Was it listed as a working unit? If so you have an legitimate issue to file a complaint about. If not then you got what they were selling. A defective unit.

    As far as output goes it's generating the power from within itself so if it puts out what you need leave it alone and all it good but if it's that much of a concern to you maybe you should have spent the money to buy the correct type of inverter to begin with. :rolleyes:

    Personally, I don't get the buying the bulky UPS inverter to run things at home off your electric bikes batteries of which are charged from AC utility power to begin with.

    It seems like wasted step going forn AC line power to battery and then back to AC line power again by using a large not so portable inverter system.

    Did you spend so much money on your electric bike that you now cant afford to pay your utility bills so you have to pirate charge the bike battery someplace else and bring that power back to your home to run your personal stuff? o_O
     
    Last edited: Sep 29, 2016
  19. eddie500

    Thread Starter Member

    Nov 5, 2011
    21
    2
    My electric bike battery is pretty big at 3.3 KW. I thought it would be cool to be able to power my computer if there is a power failure. I calculated I could run my computer for over 10 hours off my bike battery during a power failure. I could then recharge my bike in 3 hours at anyone who has power or at someone place I know who has a generator, and then have another 3.3 KW of power.

    I was looking at those inverters from china / aliexpress that would work at my bike voltage but I heard they were cheap and didn't trust the quality coming from china. Although the Dell unit I bought says made in china.

    So for $100 bucks i picked up this Dell unit that would do up to 2000 watts. It does work perfectly for my bike voltage from 84 volts to 65 volts. Hard to find inverters at these voltages, so the UPS 72 volt system is perfect.

    It is heavy, but not a big deal to pull out of my basement the few times I need it.

    Basically I bought it for the rare power failures to have AC electric, and to mostly power my computer.

    I wish I had a telsa car with a huge 85 KW hour battery, that thing would power my whole house for days. My bike battery is ridiculously big at 3.3 KW hour, but a tesla with a 85 KW hour is just down right enormous.
     
    Last edited: Sep 30, 2016
  20. tcmtech

    Well-Known Member

    Nov 4, 2013
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    And who's going to let you regularly charge that off them for free? o_O
     
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