# Need advice: easy way to get 110 AC from car's tracktion pack?



## Woodsmith (Jun 5, 2008)

I was asking about this a little while back, not so much for domestic power back up but for running the heating in the car on ac and not having all the control and switching problems.

We didn't come up with a product on the thread but if something is available I would be interested both for heating and for domestic back up.

I did find a 12vdc to 240vac 8kw inverter on Ebay but the supply cables would be massive!

Maybe the people to ask would be those who are making ac motor controllers. They would be converting pack dc voltage into ac voltage.


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## Stunt Driver (May 14, 2009)

12v inverter will force you to re-cable batteries in parallel, since 2kw is ~ 160A.

Having car to power house would be sooo green!
But in worst case I'll fall back to gas generator purchase option - simplest 1kW is $99 here.


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## Woodsmith (Jun 5, 2008)

I was thinking of using the accessories 12v battery for the ac supply to run a heater, would only be looking at a 3kw inverter. Better if taken from the whole pack at pack voltage though.

Just imagining having warning signs for 156Vdc, 12Vdc and 240Vac.



I have an inverter in my ICE car and sometimes when I am working in my drive I plug tools in there rather then run an extention lead from the house.


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## jackbauer (Jan 12, 2008)

What voltage is your traction pack?


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## Stunt Driver (May 14, 2009)

I am at 84 volts now. Ideally, inverter would have wide range of input voltage. Does that exist?


On a second thought - even wtih moderate size 5kWh pacck - you'll only get 5 hours at 1kW. And then you'r done. Maybe this idea isn't worth it for packs of that size, and have to go to ~25 kWh.

So probably EV won't help in my case, but regular car may - alternator on my Dodge is rated at 136A. So puling 1kW to inverter straight out of car's battery with engine running - should be no problem.


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## etischer (Jun 16, 2008)

You could just buy an industrial inverter. I bought a used 2kw inverter for $15 bucks. It outputs 230v 3 phase, then you can step down using a transformer to get 3 single phase outlets. 

I have an Allen Bradley 22A-V2P3N104 here on my desk that might even work. Input voltage is single phase 90-132V, output 0.4kw 3 ph. I have not run this specific inverter off DC, but I have done so with many others.


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## etischer (Jun 16, 2008)

Now that I'm thinking about it, you may be able to configure the inverter to run the motor at 115vac 60hz, or 230vac 120hz and run at 50% speed.


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## Stunt Driver (May 14, 2009)

Looked online - didn't find any matching inverters. Woudl appreciate a hint!
Trying 750w inverter from my ICE car's alternator.


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## Sunking (Aug 10, 2009)

Stunt Driver said:


> Having car to power house would be sooo green!


Huh? Does not compute


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## Sunking (Aug 10, 2009)

Stunt Driver said:


> I am at 84 volts now. Ideally, inverter would have wide range of input voltage. Does that exist?


Your voltage is non standard for commercial inverters. Commercial inverters for the most part run in multiples of 12 volts, but not all multiples. I know off-grid residential inverters come in 12, 24, 48 and and a few rare 96 volts ones around but do not know of any 84 models.

The other problem(s) you would encounter using a inverter, is back-feeding the utility. You can easily turn off your main circuit breaker to solve that problem, but if your inverter is a small capacity you have couple of other problems like: 

1. Any appliances like a refrigerator and other electrical devices would have to be disconnected to prevent over loading the inverter.

2. If the fan motor is say 1 HP which takes roughly 750 watts to run, the inverter would need to be rated around 2 Kw to handle the motor start up currents.

Lot of little things to work around.

As for the 5 Kwh rating of your battery is not as limited as you might think unless your house is so poorly insulated your furnace has to run continuously without cycling on/off.


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## JRP3 (Mar 7, 2008)

I used an old APC computer backup power supply that normally runs off 48 volt internal AGM batteries and just wired it to the 48 volt traction pack in my AMPhibian to run my electric chainsaw from. You could just tap into 48 volts worth of batteries in your pack.
http://amp-phibian.blogspot.com/2008/12/new-mod-portable-120-volt-power-supply.html


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## gdirwin (Apr 7, 2009)

The proper way to do this is to add a special transfer sub-panel (such as this ). Any critical loads (furnace motor, beer fridge etc...) have to be re-wired to go into this panel. You throw a switch to either connect to the main utility load, or to the backup generator (or EV supply in this case). The utility would freak if it knew it was possible to back-feed the grid - definitely a safety no-no and would be against grid code...

To go a step further, there is a lot of talk about using batteries in cars to store energy (and pay you for this use) for the utility to "shave off" its peak load... This would require a special meter from your utility (and it would have to be a very progressive utility at that). Charge at night (when the electricity price is dirt cheap) and allow the utility to buy some energy back (for more than you paid) once you get home and plug in (supper time is often the peak load). If you do this on a big scale, then wind power, solar etc... can be leveled and can be relied on (whereas now these power sources are intermittent and there must be sufficient conventional nuclear/coal/hydro generation to meet the load). This probably can be a new thread now that I got going...


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## Stunt Driver (May 14, 2009)

gdirwin said:


> The proper way to do this is to add a special transfer sub-panel (such as this ).


Sorry, I just don't have that money to throw away on something 1-time a year use. I rely on myself and circuit breaker panel. Mine has most appliances on separate circuit breakers. And on my knowledge of limitations. I need something in back pocket that can help in rare outages, so it wan't cost much, won't age and won't take much space. 


Today I have tried running house off 750W cont/1500w peak 12v inverter connected to ICE car. I did what you shouldn't do - disconnected main 200A breaker to isolate from grid, and turned off all appliance breakers except light and furnace. And another one I did from a no-no list - I have back plugged inverter into wall outlet. (knowing that 750w is very well under limits for wall outlet)


Inverter I used turned out to be too cheap - from HarborFreight. 
Lights work on, but furnace doesn't want to start in normal mode... If I turn on FAN independently, and then hit HEAT option - then furnace starts ok. During start it draws about 800watts, and quickly falls back to 550W. So if tonight I loose power again - I can use it, but this woodoo dance around starging furnace - is not right. 
I guess cheap $50 inverter gives bad sinus.

I'll try more expensive inverter next time, luckly HF accepts returns with no questions asked.


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## Sunking (Aug 10, 2009)

Stunt Driver said:


> Today I have tried running house off 750W cont/1500w peak 12v inverter connected to ICE car. I
> 
> Inverter I used turned out to be too cheap - from HarborFreight.
> Lights work on, but furnace doesn't want to start in normal mode...


That is because of the start up currents I mentioned earlier. The inverter has to be rated several times higher than the run load to start a typical AC motor. There are AC motor designs that use soft start circuits to dampen the effect, but you don't have one. 




Stunt Driver said:


> I guess cheap $50 inverter gives bad sinus.
> 
> I'll try more expensive inverter next time, luckly HF accepts returns with no questions asked.


Well your Harbor Freight inverter does not generate a sine wave, more like a square wave called a Modified Sine Wave. Motors do not behave well well with MSW, and you run the risk of burning up your motor if left to run off a MSW for extended periods. Even True Sine Wave inverters can have problems with motor circuits due to the power factor limitations of inverters. 

Your best bet is a ICE generator IMO as it is the least expensive and most effective.


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## icec0o1 (Sep 3, 2009)

Stunt Driver said:


> Today I have tried running house off 750W cont/1500w peak 12v inverter connected to ICE car. I did what you shouldn't do - disconnected main 200A breaker to isolate from grid, and turned off all appliance breakers except light and furnace. And another one I did from a no-no list - I have back plugged inverter into wall outlet. (knowing that 750w is very well under limits for wall outlet)
> 
> 
> Inverter I used turned out to be too cheap - from HarborFreight.
> ...


I'm not sure the inverter is at fault here. A regular ICE alternator can produce about 70 amps * 12v = 840 watts. That's if you're revving the car at least some. At idle speed, the alternator won't make that much. Figuring in 10% losses in the inverter and you're left with 756 watts or far less if the car's just idling. Hooking up that inverter to a battery pack would be far better.


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## Sunking (Aug 10, 2009)

icec0o1 It really doen't matter if the engine is running or not as I assume the vehicle has a good battery since it started. With the engine running and the battery, between the two were pretty good sources capable of supplying the inverter with sufficient power. What he describes is normal reaction of an undersized inverter supplying an electric motor.


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## Stunt Driver (May 14, 2009)

Sunking said:


> What he describes is normal reaction of an undersized inverter supplying an electric motor.


Thanks for comments but let me correct you: 

what I describe is not reaction of motor, but reaction of control module.



Becase: if I start blower independently, and then hit "heat" button - furnace will start gas flow. Otherwise it just doesn't start anything, not the gas, not the motor. So looks like control module doesn't like modified sine wave, but when 500W blower motor runs - it evens out the wave.


Also, I watch voltage on inverter's 12v contacts - it stays at 13.6v at 800W load and car at idle.

So it is not the sizing or current supply, but a modified wave that's the problem.


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## few2many (Jun 23, 2009)

Hey stunt, you hit it dead on, alot of electronics dont like the modified sine wave. Sure the box says most will work, but most wont. The motor does a very good job cleaning up the sine waves. Also, transformers with caps help, but not much. Ive been playing around with my cheap, harbor freight 2000w(4kw max) inverter.
What does everyone think of just wiring in an extra 12v bat, paralell, to one bat in the pack. this could be used for a 12v source and maybe a wannabe dc-dc converter like set up?
Maybe a simple pwm pulsing an igbt feeding a cap bank. You could set the duty cycle of the pwm to where the cap bank would have 13.5 volts.
(kind of like a motor controller, just restricted to the lowest voltage)
Also, as sunking mentioned, There are motors with the soft start built in, and ones that are external. Look at hvac, the compressors have alot of these set ups. My home a/c is old and did not have one. The lights in the whole house would dimm when it kicked on. I picked up an add on kit. It consists of a start cap, run cap and potential(or start) relay. The cap is charged, the motor uses the cap for start power. then the relay drops out and its on the run circuit.


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## dtbaker (Jan 5, 2008)

try looking at photovoltaic invertors typically used off-grid. they come in all sizes... but are not cheap for high enough capacity to run the house. You also have to get a pretty big switch to isolate your house from the grid.

This is something I have been thinking about as a general answer to storing solar energy for use at night.... if more people charged electric cars while at work, came home and could use their cars to get the house thru the night..... and have enough juice to get back to work in the morning.


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## Amberwolf (May 29, 2009)

Well, it would be a little wierd, and not very efficient, but you could take the actual electric generator off of an ICE generator setup, and build it into your EV. Set it up so that it requires manually engaging the generator onto the front shaft of your motor via a belt and pulley. (just leave the belt off when normally driving around)

Setup a switch with a safety cover on it under the hood, which will only operate if the belt is in place and under tension (so that the motor can't be overrevved due to no-load) that will provide the correct throttle resistance or voltage to your motor's controller to run it at the right speed for the generator. 

Then the EV motor will, in park (or neutral with wheel blocks and/or emergency brakes), drive the generator to produce your household power for the outage.

No, it's not easy to do for that once-a-year kind of thing, but it would work, and the power it provides would be sinusoidal.
________
Redheaded live


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## Stunt Driver (May 14, 2009)

I think it's not a bad idea, but one issue to solve - some electronics required to drive motor at constant RPM, and throttle will have to change based on load. To hit the most efficient point, ideally, motor and generator would have to be geared 1:10 at least.
Not saying no, but will keep looking for 1000w used portable generator from craigslist for $60 or so.


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## azdeltawye (Dec 30, 2008)

gdirwin said:


> ..... The utility would freak if it knew it was possible to back-feed the grid - definitely a safety no-no and would be against grid code...
> 
> To go a step further, there is a lot of talk about using batteries in cars to store energy (and pay you for this use) for the utility to "shave off" its peak load... This would require a special meter from your utility (and it would have to be a very progressive utility at that). .......


This is becoming common practice to install a "grid-tied" inverter and net-metering on homes with PV panels. This allows the customer to generate their own power via solar panels and sell the excess back to the utility. Net metering allows bi-directional flow of power to or from the customer. Check out the wiki:
http://en.wikipedia.org/wiki/Net_metering


BTW, what is "grid code"?


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## icec0o1 (Sep 3, 2009)

Electrical code which electricians need to abide by to keep everything safe. All of the grie-tie inverters have a safety feature where they stop working if the grid goes down. That's so the electricians working on a pole don't get electricuted thinking there's no power there and instead you're feeding a couple of KW with your inverter. 

If you have a non grid-tie inverter, don't connect it to your house wiring without disconnecting the main feed.


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## Woodsmith (Jun 5, 2008)

The grid tie also ensures that the ac cycles are in sync otherwise you could have huge variation in voltage if the cycles are out of sync.


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## Stunt Driver (May 14, 2009)

Hey, let's keep all safety warning is separate topic.

Instead, can you point me to "industrial inverter" for 12 or 24 volts? 

And another question - anything, like a 1:1 transformator can fix that modified sine into normal one?

I have tried 1200W inverter, it's even worse on furnace - it won't start even with blower running, clearly because of signal form. There is plenty of 12v power for inverter to work happily.


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## AntronX (Feb 23, 2009)

If you can increase your battery voltage to 120V, there is the inverter for you: http://www.exeltech.com/xpspecs.htm


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## Amberwolf (May 29, 2009)

I dont' know if a transformer would work, but the right inductance in series with it probably would help. The problem is figuring out what that should be, and then making it (or scrounging something that will work). I'm guessing that you would need to work it out mathematically, but I have no idea how to do that. 

My brain tends to shut down when confronted with remembering and transforming math more complicated than the Eagle sees the Indian next to the Rock, or the Indian sees the Eagle over the Rock, or the Rock sees the Eagle over the Indian.
________
Amazingprincess


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## few2many (Jun 23, 2009)

Maybe a 1:1 transformer with a large ac run cap will smooth it out.


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## dataman19 (Oct 7, 2009)

I know this is crowing in the Chicken Coop...
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Having Electric cars as backup Power during a blackout was a heated source of activity last year.
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The NREL has an on-going program to research and lay down specifications for a Hybrid Vehicle Fleet that is capable of powering homes and businesses during periods of prolonged power outages and natural disasters.
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I know the FEMA crowd was really excited at the program announcement last June in Colorado.
..
The same could be applied to EV's - but the battery pack voltages would have to be around 144V to make the inverters efficient enough to be practicle. Assuming that you could get the inverter to say 85% efficiency - your Output Voltage would ve around 120VAC (better than the average inverter which only produces 110VAC-115VAC).
..
There is also a company marketing government surplus inverters that are interconnectable, syncable and capable of running in syn and 180 degrees out of phase (purpose being to provide 220-VAC). They run on 48VDC, and as I understand it were capable of running off up to 192VDC if the front regulators were modified.
..
I will try and find a link to the company selling them (if they still have any) and dig into the ole tech archive and see if I can came up with a few of the tech articles that were presented to DARPA when the government bought these for the Army and Navy.
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I have four out at our Tonopah Site, and four more at the Kingman site. If I get a chance I will take some pictures, they really are neat. Ours are cionfigured to run small 220VAC Aic Conditioners, they are comprised of two 1.8KW Inverters in each half of the 220V, synchronized and chained so that during low or no load they idle with the idle current of a 1200W inverter (ie they draw about 8Amps at idle) and when the demand increases kick on the secont 1,800 watts to give sustained power. They are then sync'd with a crossover cable which gives the second set a 180 degree phase shift.
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They will peak at over 3KW each, but as inverter folks will tell you - Never Run Your Inverters at over 70% of rated power.
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Anyway, the idea of an EV or Hybrid acting as an Emergency Power source is novel - but not all that new.
..
dataman19


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## JRP3 (Mar 7, 2008)

Since you can get 12VDC-120VAC inverters at various wattages I'd think it would actually be easier to do with a higher DC voltage since you wouldn't have to deal with higher amps that you'd pull with 12VDC. Other than the production volume we have with 12VDC inverters I'd think a 120VDC-120VAC inverter should be cheaper.


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