Question about my inverter

System
System Posts: 2,511 admin
in General Solar Power Topics #1
Question about my inverter.

Yes my inverter will power my vacuum cleaner - a good 10amps AC. But it will not output proper power for my RV. The problem (I think) has to do with the way the voltage is created. Bare with me, when I measure the voltage from what would be called the hot side (the black wire) to the neutral side (white wire), with an ohm meter it reads 107vac. When measured from the ground to the hot side - it reads 72vac and when read from ground to the neutral side it also reads 72vac. When I do this at my home - ground to the hot side reads 115vac, and ground to the neutral side reads basically zero. And of course when it is read hot side to neutral side it reads 115vac.

My question is - is my inverter outputing the voltage correctly?
My inverter is an AIMS 2500watt (MSW). It typically is used in vehicles to power stero systems etc, but I was planning on using it to power my RV for critical things during dry camping.
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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: Storage of Backup Solar, Panels, Inverters, Charge Controllers

    Yes, it is probably just fine.

    MSW inverters will typically read ~1/2 line to line output volts from Black or White to ground. They do not have isolated outputs so they cannot ground the White Wire (0 volts) and have the black at line voltage.

    The other issue with MSW is they output a Modified Square Wave which may not read ~115 VAC with a typical voltmeter... It gets into the difference between sine waves and MSW waveforms. And "inexpensive meters" and the more expensive True RMS (Root Mean Square) meters.

    By the way, if you are dry camping on only need to power small stuff / electronics... You may wish to look at getting a small TSW (true sine wave) inverter. They can be more efficient than the larger inverters.

    They are isolated output (you can ground the White/Neutral wire--but you don't usually need to) and they have the same sine wave as utility power. There are some devices that that do not like MSW power.

    Morningstar SureSine, 300 Watt Sine Wave Inverter 115VAC (really nice)

    Some inverter FAQ's:

    All About Inverters
    Choosing an inverter for water pumping

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • System2
    System2 Posts: 6,290 admin
    #3
    Re: Storage of Backup Solar, Panels, Inverters, Charge Controllers

    In hopes to use my MSW inverter for our RV, is there any such product that I could buy that will take the two AC outlets from the inverter - feed them together to produce a 30 amp service (with isolated ground) to my RV? The key is to get to that isolated ground part of the equation.

    The other alternative, to buy a pure sine wave inverter is doable, guess I was hoping to supply 1500 - 2000 watts in case it was needed. And the cost of a pure sine wave in that range is really expensive.

    thanks

    Steve
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: Question about my inverter

    I moved these posts to their own thread for clarity.

    I have a personal dislike of AIMS inverters, but Bill's explanation that you can't get a proper Voltage reading off MSW inverters with some meters is correct. Nothing to do with it being an over-rated, badly-designed, low-quality piece of junk. This time. :p

    Are you sure you need 30 Amps @ 120 VAC? That's quite a bit of power: 3600 Watts.
    Take a look at some of the more powerful of the Exeltech inverters: http://www.solar-electric.com/exsiwain.html

    Otherwise, you can't "stack" inverters unless they are specifically designed for that function. Which, in the short form, means expensive.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #5
    Re: Question about my inverter

    Steve,

    Not as you describe... However, you do have some options.
    1. Perhaps your inverter is a single 30 amp output split to tow 15 amp branch circuits and you just need to require for 30 amp service.
    2. There are "stacking" inverters that can add in parallel (add current) or in series (go from 120 VAC to 120/240 VAC split phase). The market is a confusing mess--so it may take some research and reading to find a "set" that does what you want at your cost point.
    3. Can your A/C go to 240 VAC? That would reduce your wiring requirements (240 15 amps instead of 120 30 amps)--However, your battery and inverter sizing still need to handle the higher wattage rating--120/240 at 5,000 watts is not going to matter.
    4. Look at the Sanyo and other Mini-Split AC systems... They are much more off-grid and RV friendly.
    Sanyo mini split AC (inverter/variable speed)

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    #6
    Re: Question about my inverter

    If you are using the shore power cord plugged into the inverter. That would be a problem.

    Allot of trailer converters have the ground and neutral wire tied together. Plus the battery charger starts when on shore power.
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  • PopeyeDCFD
    PopeyeDCFD Registered Users Posts: 6 ✭
    #7
    Re: Question about my inverter
    n3qik wrote: »
    If you are using the shore power cord plugged into the inverter. That would be a problem.

    Allot of trailer converters have the ground and neutral wire tied together. Plus the battery charger starts when on shore power.

    Hello, my name is Andy and I am having this problem, LOL! I have an RV with a shore line and I tested the inverter by hooking it up with jumper cables and plugging in the shore line... I even grounded it to the chassis. It worked with no problem. Now that I have properly installed the inverter. 1/0 AWG to the positive terminal. 1/0 AWG to the negative terminal and 8 AWG from ground post to chassis. When I plugged in the shore line I got all kinds of popping and frying! Energized the chassis too. SOOO my questions are exactly what is going on and am I doing something wrong? I know that I can redo the electrical system but I am running up against a hard leave date for our drive out west from MD and I dont have the time, (or money for that matter) to completely rewire the system and take out the converter the shore line runs to, etc. Help...?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #8
    Re: Question about my inverter
    PopeyeDCFD wrote: »
    Hello, my name is Andy and I am having this problem, LOL! I have an RV with a shore line and I tested the inverter by hooking it up with jumper cables and plugging in the shore line... I even grounded it to the chassis. It worked with no problem. Now that I have properly installed the inverter. 1/0 AWG to the positive terminal. 1/0 AWG to the negative terminal and 8 AWG from ground post to chassis. When I plugged in the shore line I got all kinds of popping and frying! Energized the chassis too. SOOO my questions are exactly what is going on and am I doing something wrong? I know that I can redo the electrical system but I am running up against a hard leave date for our drive out west from MD and I dont have the time, (or money for that matter) to completely rewire the system and take out the converter the shore line runs to, etc. Help...?

    Welcome to the forum Andy.

    What you've just done is fry your inverter.
    Here's the thing: no battery-based inverter should have its AC OUT connected to another AC source (anyone "correcting" me by mentioning AC coupling at this gets a kicking).
    Your inverter probably does not have an AC IN (no built-in charger). It is probably also an MSW type. That means you can fry it by having the shore power connected even with the "hot" off; the neutral-ground bond that is common to standard AC wiring is instant death to an MSW type inverter.

    You're probably going to need a new inverter. Then you are going to need to wire up the DC side as you did, and avoid connecting the AC side to the RV's wiring just to be sure. This becomes a big pain, because anything you want to run off the inverter has to be plugged in to it directly. Or you spend the extra $$ and get a sine wave inverter. Even so, you have to be very careful about RV wiring - especially when there's a "converter" in place. Usually you end up tossing that in the trash and getting a quality inverter/charger to run the whole show with.

    BTW the jumper cables on the DC wasn't a good idea either; they really can't handle the current an inverter can draw due to poor connection points. It probably saved your inverter during the test by not allowing it to actually power up.
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  • PopeyeDCFD
    PopeyeDCFD Registered Users Posts: 6 ✭
    #9
    Re: Question about my inverter

    Mr Cariboocoot,

    Thank you for the welcome and the quick reply! If I could borrow a few more minutes of your time I would much appreciate it!
    Cariboocoot wrote: »
    Welcome to the forum Andy.

    What you've just done is fry your inverter.
    Here's the thing: no battery-based inverter should have its AC OUT connected to another AC source (anyone "correcting" me by mentioning AC coupling at this gets a kicking).
    Your inverter probably does not have an AC IN (no built-in charger). It is probably also an MSW type. That means you can fry it by having the shore power connected even with the "hot" off; the neutral-ground bond that is common to standard AC wiring is instant death to an MSW type inverter.

    Yes it is a MSW inverter, and no it does not have an AC in but I think I managed to disconnect it (when I got the SNAP when the prongs touched home, not even fully plugged in, I immediately pulled them apart, pretty much as knee jerk reaction from the noise! LOL) in time. I plugged in a vaccum cleaner and turned it on and it worked, so here's fingers crossed that it keeps working! For my knowledge and edification would you mind explaining a little further the "neutral-ground" relationship you mentioned? Why does it mean instant death with inverters? I am guessing this is why I energized the chassis. My wife was next to it with her leg just brushing it and got a tickle she wasn't too fond of! LOL.

    Cariboocoot wrote: »
    You're probably going to need a new inverter. Then you are going to need to wire up the DC side as you did, and avoid connecting the AC side to the RV's wiring just to be sure. This becomes a big pain, because anything you want to run off the inverter has to be plugged in to it directly. Or you spend the extra $$ and get a sine wave inverter. Even so, you have to be very careful about RV wiring - especially when there's a "converter" in place. Usually you end up tossing that in the trash and getting a quality inverter/charger to run the whole show with.

    BTW the jumper cables on the DC wasn't a good idea either; they really can't handle the current an inverter can draw due to poor connection points. It probably saved your inverter during the test by not allowing it to actually power up.

    :-( Unfortunately getting a new inverter/charging system was the plan for next year... There is no way to use the inverter with the house wiring of the RV huh... Interesting that we didnt fry it with the battery cable test, because we drew a load on it by using the microwave, and it cooked my breakfast! LOL
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
    Re: Question about my inverter

    You must be leading a charmed life! :D

    The whole MSW inverter problem with the neutral-ground bond comes up a lot around here. It has to do with the way the internal circuitry of the inverter is connected. Ordinarily an AC circuit has this bond, which causes the neutral line to have zero Voltage potential in respect to ground and makes it safe to touch. With a true sine wave inverter the output is isolated and the bonding issue doesn't come up. With a modified square wave inverter the output is not isolated and connecting one side to ground also connects it to the negative DC, creating a feedback loop through the inverter. Needless to say it doesn't like finding pulses of 10 times its normal operating Voltage on the input. Usually the magic smoke comes out right away and then its all over but the crying.

    Now RV's have another issue here in that they don't actually have any Earth ground except when connected to shore power. So you can actually install an MSW inverter and have it appear to work fine until you plug that cord in with the inverter on. If the transfer switch doesn't switch both hot and neutral (and keep the bond external) you get that smell of frying capacitors. Otherwise you might have the bond in the RV (shouldn't) and the only noticeable effect is what your better half felt; the "neutral" side of the inverter energizes everything because the "ground" (chassis) it is connected to isn't literally connected to ground. This is called "dangerous" and should be avoided because someone might touch the RV outside and form a good path for the Voltage to real ground. Normally the AC in a mobile application is left "floating" for this reason. It is safer that way.

    You actually pulled microwave power through jumper cables? On a 12 Volt system that's like 80 Amps! (Regardless of the "cooking power" rating, microwaves tend to use around 1000 Watts.) You are lucky that didn't send sparks flying.

    Good thing the inverter still functions. But don't try tying it in to the RV's AC wiring until you know exactly how that is configured. Frankly the people who set those things up need a few lessons in wiring basics and good practice standards. It can be dreadfully convoluted, as posts on this forum have shown. Not unusual to end up with the inverter powering the converter which is charging the batteries that are running the inverter which runs the converter which ... just depletes the batteries needlessly.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #11
    Re: Question about my inverter
    PopeyeDCFD wrote: »
    :-( Unfortunately getting a new inverter/charging system was the plan for next year... There is no way to use the inverter with the house wiring of the RV huh... Interesting that we didnt fry it with the battery cable test, because we drew a load on it by using the microwave, and it cooked my breakfast! LOL

    Did you have the shore cable plugged in when you did the test?
    Plugging in the shore cable but opening the breaker so that it does not supply power still grounds the neutral of the AC wiring.
    Your RV may not, by itself, connect the neutral to the ground, but rely on that connection being made in the shore panel.
    Or if you tested the inverter while the RV's AC neutral was connected to its ground wire but the chassis of the inverter was not connected to the ground of the RV and neither battery post was grounded, there would not have been a conflict (but the inverter chassis might have been hot at one-half the line voltage.)
    SMA SB 3000, old BP panels.
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  • PopeyeDCFD
    PopeyeDCFD Registered Users Posts: 6 ✭
    #12
    Re: Question about my inverter
    Cariboocoot wrote: »
    You must be leading a charmed life! :D

    The whole MSW inverter problem with the neutral-ground bond comes up a lot around here. It has to do with the way the internal circuitry of the inverter is connected. Ordinarily an AC circuit has this bond, which causes the neutral line to have zero Voltage potential in respect to ground and makes it safe to touch. With a true sine wave inverter the output is isolated and the bonding issue doesn't come up. With a modified square wave inverter the output is not isolated and connecting one side to ground also connects it to the negative DC, creating a feedback loop through the inverter. Needless to say it doesn't like finding pulses of 10 times its normal operating Voltage on the input. Usually the magic smoke comes out right away and then its all over but the crying.

    Now RV's have another issue here in that they don't actually have any Earth ground except when connected to shore power. So you can actually install an MSW inverter and have it appear to work fine until you plug that cord in with the inverter on. If the transfer switch doesn't switch both hot and neutral (and keep the bond external) you get that smell of frying capacitors. Otherwise you might have the bond in the RV (shouldn't) and the only noticeable effect is what your better half felt; the "neutral" side of the inverter energizes everything because the "ground" (chassis) it is connected to isn't literally connected to ground. This is called "dangerous" and should be avoided because someone might touch the RV outside and form a good path for the Voltage to real ground. Normally the AC in a mobile application is left "floating" for this reason. It is safer that way.

    You actually pulled microwave power through jumper cables? On a 12 Volt system that's like 80 Amps! (Regardless of the "cooking power" rating, microwaves tend to use around 1000 Watts.) You are lucky that didn't send sparks flying.

    Good thing the inverter still functions. But don't try tying it in to the RV's AC wiring until you know exactly how that is configured. Frankly the people who set those things up need a few lessons in wiring basics and good practice standards. It can be dreadfully convoluted, as posts on this forum have shown. Not unusual to end up with the inverter powering the converter which is charging the batteries that are running the inverter which runs the converter which ... just depletes the batteries needlessly.

    HAHAHAHA!! Boy do I wish I led a charmed life! Everything that can go wrong with preparing/working on the RV has gone wrong!!!:grr I had wanted to leave yesterday but now its looking like I wont be able to leave until Friday with all these delays! We just purchased this RV used (its a twenty year old Econoline Class B that only had 60K on it and was in really good shape) in February for this trip, but were surprised it was not set up to provide AC to power the rear while in motion. We had bought our inverter and hooked it up in our mini van two years ago for our western trip and it worked very well to power a coffee pot, toaster and mini-microwave(not all at once LOL), and wanted that capability again. But I guess I will have to make other arrangements to make that happen until we can redo the electrical system. :-( The alternator is beefed up (130 volts) because it is an RV and it is pushing great voltage to the inverter, and runs stuff great with the engine running, but I guess now I will have to run an extension cord to a surge protector where we will have things plugged in... I had wondered why I was getting 72 volts on my meter when I plugged it into hot and neutral on the inverter... guess that is cause of the absence of the neutral-ground bond... If I may ask another question, if we redo the electrical system and get rid of the converter and have a alternator/vehicle battery to battery bank to inverter setup, can an MSW inverter be used then? Or will the same problem still result? How, if I may ask, would one go about wiring the elec system to have 120 etc with a battery bank, shore line and maybe even some solar panels, since that is another thing we are going to look into for next year...
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #13
    Re: Question about my inverter

    Let me throw some loose bits of knowledge at you. :D

    Your alternator is probably 130 Amps, not Volts. If it put out 130 Volts the whole thing would go up in smoke the minute you start the engine.

    Inverter works great with the engine running but not on its own? Suspect wiring and/or battery capacity. The kind of loads you are using (coffee pot, toaster, microwave) are all on the "don't do this with 12 Volts" list; they are major power consumers. When you are trying to draw upwards of 100 Amps @ 12 VDC as you would need to for those items you need really good wiring and a stout battery bank to back it up. Honestly the connections should be with 00 AWG or better and under 6 feet. The battery needs to be very large as well; a single ordinary starting battery will be seriously depleted trying to put out that much current for any length of time. Think of it like cranking over the engine continuously while waiting for your coffee pot to boil; it's that bad (worse, actually).

    The 72 Volts on your meter isn't due to the wiring; it's due to the fact most meters will read low Voltage from an MSW type inverter.

    The big problem you've got is not with the DC side. So ditching the converter and using the vehicle alternator to recharge the battery can work with an MSW inverter. You will want a lot more battery capacity, and it is preferable that the "house" battery be kept separate from the starting battery so that the latter is not depleted leaving you stranded someplace horrible like Vancouver or something. :p

    The big problem you have is on the AC side. Step one is to be sure there's no neutral-ground bond in the RV. Step two is to be sure that when shore power is in use the MSW inverter's output is entirely isolated from the AC system - neutral and hot disconnected. This requires a two pole transfer switch. At that point you would want a battery charger to run off the shore power and replenish the batteries (taking the place of the converter).

    By comparison, adding solar panels to recharge batteries is easy. Although that can get messed up too, especially if you try to connect the house and starting batteries.

    At least you get a vacation. I could tell you such stories .... But you're depressed enough already.
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  • Jim45D
    Jim45D Solar Expert Posts: 102 ✭✭
    #14
    Re: Question about my inverter
    How, if I may ask, would one go about wiring the elec system to have 120 etc with a battery bank, shore line and maybe even some solar panels, since that is another thing we are going to look into for next year...

    Yes, it can be done. My RV is setup to use both. I'd say first get the AC working properly, go with a inverter that has a built in charger with transfering switching. Mine when plugged into shore power switches the inverter to standby mode. As soon as the plug is pulled it goes automatically to inverter mode. For example; we have had the power to go out during a monsoon storm while watching TV. The TV never flickers, keeps on keeping on like nothing happened. The only way of knowing that the inverter has kicked in is because the telephone cord is plugged in, and it makes a beep. That's the only reason we have a land-line, not in service....is just for the beep. We use Skype, cellular, or Magic Jack for phone service. The Link instrumentation has a lite that comes on when the inverter is active, but we seldom pay attention to it. Lastly, whatever you do disconnect, sell or throw out the converter. You won't need it. Also keep the starting and house batts seperate.

    Incidently I use a MSW 2k Heart Inverter 458 series, and have going on 9 years.
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  • PopeyeDCFD
    PopeyeDCFD Registered Users Posts: 6 ✭
    #15
    Re: Question about my inverter
    inetdog wrote: »
    Did you have the shore cable plugged in when you did the test?
    Plugging in the shore cable but opening the breaker so that it does not supply power still grounds the neutral of the AC wiring.
    Your RV may not, by itself, connect the neutral to the ground, but rely on that connection being made in the shore panel.
    Or if you tested the inverter while the RV's AC neutral was connected to its ground wire but the chassis of the inverter was not connected to the ground of the RV and neither battery post was grounded, there would not have been a conflict (but the inverter chassis might have been hot at one-half the line voltage.)

    Hello there! :D

    No, the shore line cable was not plugged in during the test. I even had to increase the engine RPM to get enough voltage to the inverter to provide enoughAC to the microwave. I figured this was cause of the battery cables not being designed to carry the load (as was mentioned earlier) it did not give me any kind of problem :roll:, and would be remedied with the correct 0 gauge wire when properly installed. Go figure, that is why I didn't do this research before I hooked up the inverter to the shore line... I did not open any breakers or anything, and I was touching the frame of the vehicle to hold the battery cables and did not feel the shock my wife did... Like I said earlier, I even grounded the inverter chassis, but maybe I didn't get it fully grounded to the vehicle chassis...... I just don't understand how what happened today didn't happen then....... I looked in the converter box where the shore line comes in and it has a dedicated ground bar, white neutral bar and red hot bar... It looks like the coach (AC) portion of the vehicle wiring is set up exactly like a standard home, and is designed only to function from the shore line. The shore line ground wire will carry ground outside the vehicle to a RV 30 hookup. Pretty standard. I am convinced that what 'coot said was correct, and that I created a feedback loop into the inverter, through the vehicle battery and thus 120v back into the positive side of the inverter.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #16
    Re: Question about my inverter
    PopeyeDCFD wrote: »
    Hello there! :D

    No, the shore line cable was not plugged in during the test. I even had to increase the engine RPM to get enough voltage to the inverter to provide enoughAC to the microwave. I figured this was cause of the battery cables not being designed to carry the load (as was mentioned earlier) it did not give me any kind of problem :roll:, and would be remedied with the correct 0 gauge wire when properly installed. Go figure, that is why I didn't do this research before I hooked up the inverter to the shore line... I did not open any breakers or anything, and I was touching the frame of the vehicle to hold the battery cables and did not feel the shock my wife did... Like I said earlier, I even grounded the inverter chassis, but maybe I didn't get it fully grounded to the vehicle chassis...... I just don't understand how what happened today didn't happen then....... I looked in the converter box where the shore line comes in and it has a dedicated ground bar, white neutral bar and red hot bar... It looks like the coach (AC) portion of the vehicle wiring is set up exactly like a standard home, and is designed only to function from the shore line. The shore line ground wire will carry ground outside the vehicle to a RV 30 hookup. Pretty standard. I am convinced that what 'coot said was correct, and that I created a feedback loop into the inverter, through the vehicle battery and thus 120v back into the positive side of the inverter.

    If there is no connection between the neutral bar and the ground bar inside the converter box, then the two will only be connected when attached to properly wired shore line. But at that point your outlets should be getting both neutral and hot from the shore line and any connection you might make with the inverter would conflict with that. I guess there must be some sort of transfer relay inside your converter box and it does not switch the neutral. One side (negative) of the vehicle battery being grounded will only cause a problem if the inverter output neutral is also grounded.

    Most likely you had to rev the engine to get the alternator to drive the battery voltage higher to make up for the voltage loss in your jumper cables.
    SMA SB 3000, old BP panels.
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  • PopeyeDCFD
    PopeyeDCFD Registered Users Posts: 6 ✭
    #17
    Re: Question about my inverter
    Cariboocoot wrote: »
    Let me throw some loose bits of knowledge at you. :D

    Your alternator is probably 130 Amps, not Volts. If it put out 130 Volts the whole thing would go up in smoke the minute you start the engine.

    Inverter works great with the engine running but not on its own? Suspect wiring and/or battery capacity. The kind of loads you are using (coffee pot, toaster, microwave) are all on the "don't do this with 12 Volts" list; they are major power consumers. When you are trying to draw upwards of 100 Amps @ 12 VDC as you would need to for those items you need really good wiring and a stout battery bank to back it up. Honestly the connections should be with 00 AWG or better and under 6 feet. The battery needs to be very large as well; a single ordinary starting battery will be seriously depleted trying to put out that much current for any length of time. Think of it like cranking over the engine continuously while waiting for your coffee pot to boil; it's that bad (worse, actually).

    The 72 Volts on your meter isn't due to the wiring; it's due to the fact most meters will read low Voltage from an MSW type inverter.

    The big problem you've got is not with the DC side. So ditching the converter and using the vehicle alternator to recharge the battery can work with an MSW inverter. You will want a lot more battery capacity, and it is preferable that the "house" battery be kept separate from the starting battery so that the latter is not depleted leaving you stranded someplace horrible like Vancouver or something. :p

    The big problem you have is on the AC side. Step one is to be sure there's no neutral-ground bond in the RV. Step two is to be sure that when shore power is in use the MSW inverter's output is entirely isolated from the AC system - neutral and hot disconnected. This requires a two pole transfer switch. At that point you would want a battery charger to run off the shore power and replenish the batteries (taking the place of the converter).

    By comparison, adding solar panels to recharge batteries is easy. Although that can get messed up too, especially if you try to connect the house and starting batteries.

    At least you get a vacation. I could tell you such stories .... But you're depressed enough already.

    130 Amps, yes. I realized my mistake when I re-read it just after I posted it. The inverter runs great without the engine running for the lighter things like TV etc, but I need it to be running to give me the six to ten minutes to use the microwave or coffee pot (again, not at the same time). We did this with 4 AWG wiring in our mini-van two years ago and it worked fine. I figured by increasing to 0 awg wiring with a slightly longer run (5 feet instead of 4) this time would yield similar results by plugging in the shore line. Little did I know! LOL
    Anyway, I was running a vacuum cleaner off of it earlier today (to test whether I blew it up or not after connecting the shore line!) and drawing only a few amps so I think we will do ok as long as we power things separately from the coach wiring. I have looked into some different opinions on re-wiring the system for next year, and they make isolators that don't allow the coach battery bank to pull off the vehicle battery (this is how it is wired now, as a matter of fact. I wanted to know what some weird solenoid looking thing under the hood next to the battery was, and turns out that's what it was...). Sounds like that transfer switch Jim mentioned is the way to go to keep it separated from shore line and such....

    As a matter of fact my wife and I would LOVE to get stranded in Vancouver LOL! We have been there twice now and love it. It is a beautiful city! We have also been to Port Moody, Lake Chilliwack, and Victoria and Lake Cowichan on the island. We actually plan to move to Seattle if we can make it happen. We would prefer sooner rather than later, but at some point we will! The Pacific Northwest is actually where we feel most at home! Now if only my job was there and not here...
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  • PopeyeDCFD
    PopeyeDCFD Registered Users Posts: 6 ✭
    #18
    Re: Question about my inverter
    inetdog wrote: »
    If there is no connection between the neutral bar and the ground bar inside the converter box, then the two will only be connected when attached to properly wired shore line. But at that point your outlets should be getting both neutral and hot from the shore line and any connection you might make with the inverter would conflict with that. I guess there must be some sort of transfer relay inside your converter box and it does not switch the neutral. One side (negative) of the vehicle battery being grounded will only cause a problem if the inverter output neutral is also grounded.

    Most likely you had to rev the engine to get the alternator to drive the battery voltage higher to make up for the voltage loss in your jumper cables.


    No idea on the transfer relay, but I did not see any connection between the neutral and ground bars... I think the inverter output neutral is grounded through the DC negative, which is why the DC positive was feeding 120v back into the inverter and making sparks fly! I am also surprised I didn't blow any fuses in the vehicle either, but I didn't!
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #19
    Re: Question about my inverter
    PopeyeDCFD wrote: »
    No idea on the transfer relay, but I did not see any connection between the neutral and ground bars... I think the inverter output neutral is grounded through the DC negative, which is why the DC positive was feeding 120v back into the inverter and making sparks fly! I am also surprised I didn't blow any fuses in the vehicle either, but I didn't!

    1. The inverter output neutral is really a hot wire with respect to ground. It is almost as if the inverter output is two phase 60 volt DC with respect to the battery ground. Nothing special is coming through the positive terminal of the battery. What you did, in effect, was short out one side of the two phase 60 volt, with enough current flowing that it took the inverter case to 30 or more volts AC with respect to ground. Not quite sure why the sparks were flying inside the inverter since you were shorting it out rather than feeding stray voltage into it.
    2. There are no fuses in the AC neutral wires, and no fuses between the battery and the full-current DC loads like the starter motor and the inverter, on either the + or - side. And there was no fault current flowing is the AC "hot" wire to blow a fuse there.
    SMA SB 3000, old BP panels.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #20
    Re: Question about my inverter

    In a related story...

    A friend of mine bought a used travel trailer which had been wired by its handyman previous owner who had (apparently) connected neutral to ground. He made up an "Aggie extension cord" (apologies to my Tx A&M friends) with a male connector on both ends to connect it to shore current which was only hot and neutral, but he (apparently again) got them reversed. My friend didn't check it out but luckily realized something was wrong before anyone got hurt; he had the trailer parked next to his house and was running a cable TV drop out to it, and he accidentally contacted the grounding nut on the cable drop with an aluminum window frame on the trailer. Bang.
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #21
    Re: Question about my inverter

    To the OP - one possible source of the loud arcing you heard could have been the converter charging up. The one I had in my previous camper had such a large initial surge when you plugged it in, it would sometimes make me jump. It would also sometimes trip my old 6 kw inverter which had a 12 kw surge! Once the internal capacitors were charged up there was no surge no matter how many times you plugged/unplugged it. And that same inverter had no problem running everything in the camper after that point. My current 2010 camper's converter has a noticeable surge, too, but not nearly as bad as that 1997-era converter.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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