Backup Power Sources

I have a small and quiet Honda EU200i 120vac generator, which I believe uses a solid-state inverter to generate ac and also has a feedback loop which controls the motor rpm proportionally to the load. I had hoped that it could be used as an emergency charger for my iMiEV. Sadly, it does not work to power either my Mitsubishi Level 1 EVSE nor my SPX Power Xpress EVSE because the generator ac Ground wire is not tied to the Neutral pin - the EVSE's ground fault detectors thus preclude their use. I was surprised that SPX would do that, as its voltage range is 95vac to 264vac and you'd think the two hot wires are isolated from ground (although in the installation they DO specify which one of the legs is to be Neutral when used with 120vac).

Does anyone know what would happen if one tied the ground and neutral wires together on the Honda generator? The reason I ask is that I once blew up a fairly expensive 12vdc-->120vac inverter when I did that

The other alternative I'll be pursuing is solar --> charger --> battery banks (12v, 24v, 48v) --> inverter(grounded neutral) --> EVSE for off-grid iMiEV charging capability. The grid was down for over a week at my house after the Loma Prieta earthquake. Here's a heartening story about our iMiEVs' post-earthquake use:
http://www.nytimes.com/2011/05/08/automobiles/08JAPAN.html?pagewanted=all

They appear to be addressing this issue for the EU2000i on the Leaf fourm.

http://www.mynissanleaf.com/viewtopic.php?f=26&t=5792&hilit=Ground+wire+is+not+tied+to+the+Neutral&start=20#p136740

jjlink, thank you for pointing me over to the Leaf forum, as I keep forgetting to look there first. They have a one-year start on us in pursuing techie issues. On that forum, "Ingineer" wrote:
"The easy way to make this work is take a screw-on plug (NEMA 5-15P) and install two 1/2 watt 100k ohm resistors. One from neutral (silver screw) to ground (green), and the other from hot (gold screw) to ground (green). Then simply plug this into one outlet on the generator, and your EVSE into the other. This will safely pass the ground detect on the Nissan (and our upgraded) EVSE, while not being a hazard in any other way."

I did that (I had slightly-higher value resistors in my junkbox), and, indeed, our Mitsubishi Level 1 EVSE (a Panasonic unit similar to the Leaf's) did work just fine. This is a good solution for getting the Mitsu EVSE to work with an ungrounded generator.

JoeS: Excellent, I'm glad it worked.

Could you use a modified extension cord with only the the ground pin connected in the plug, and have the other end connected to a piece of rebar or something similar that's shoved into the ground to ground the system? Plug that cord into the generator, and plug in the EVSE to the other socket. Would this work, and if it would, will it also work with a 12 volt sine wave inverter?

Good news regarding charging the iMiEV using an inverter.

I've built a battery bank consisting of two "24v" packs using Headway LiFEPO4 12AH cells in a 4P8S configuration, charged using a couple of PowerLab8 hobby chargers which include fairly sophisticated built-in balancing and monitoring. Nominal 48Ah 48V yielding a nominal capacity of 2.3kWh. Primary uses are to drive a 48v outboard motor, electric scooter, electric bicycle, and serve as home backup power source. Possible future is to use a dc-dc converter and feed the iMiEV battery pack directly as an onboard range-extender...

For the purpose we're talking about, any old 12v batteries would work.

Purchased a number of relatively-inexpensive 48vdc-->120vac and 48vdc-->240vac inverters off EBay. These inverters are "stackable", meaning they can be paralleled to increase their output power. These are NOT "pure sine wave" inverters, but are good enough to run just about everything I have in the house. The iMiEV shouldn't care, as the first thing the onboard charger does is rectify the input to make dc for its internal dc-dc converter.

The fundamental need is to ensure the grounding is correct. The 120vac inverters, despite being "three-prong", do not have N and Ground tied together. I simply used the plug described above (that I had used with the Honda generator) and plugged it into the second inverter output socket.

Hooked up the 120vac inverter and successfully charged the iMiEV using my EVSEUpgraded Mitsu L1 EVSE, using first the 6A setting and then the 12A setting. No problem, and ran it for about 15 minutes with my battery bank holding steady at around 52vdc. The car made all the right noises, with the coolant pump properly cycling. This should also work just fine with an unmodified Mitsu L1 EVSE.

When I get time I'll put two of the 240vac inverters together and see if I can feed the iMiEV at full power (3kW) through my SPX EVSE as well as the EVSEUpgraded EVSE running at 12A 240v.

JoeS said:

Does anyone know what would happen if one tied the ground and neutral wires together on the Honda generator?

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Nothing; as long as you don’t back feed your house. I noticed that a lot of generators do not tie their neutral to the ground. And some do. I prefer the ones that don’t as this allows house back feeding (in case of a power outage). Recall all the ground wires and neutral wires are tied at one point on your house CB panel--- and ran to a ground rod. Thus Neutral and Ground are at similar potential. If the generator had its neutral and ground tied together (at the generator) and you back-fed your house, a ground loop would occur AND this would force ½ your neutral current down your ground line --- which is a no no. No current should be on that ground line. And that ground line should not be floating. That is a nice safety feature which EVSE, GFCI outlets, and most safety power strips checks.

I made a neutral-ground bonding plug embedded in a 6’ generator extension cord and labeled it as such --- because I don’t want to use that cord anywhere else but the generator (when not back-feeding the house).

I’m surprised the Leaf Forum (Ingineer) recommended a 100kΩ resistor divider to put on the generator’s floating ground. OSHA states “Bonding is the intentional connection between the grounded circuit conductor (neutral) and the grounding means for the generator, which includes the generator’s frame. Thus, effective bonding of the neutral conductor to the generator’s frame is also a concern for the safe use of the equipment. As with grounding terminal connections, proper bonding of the neutral terminal of a power receptacle may be confirmed via testing by a competent electrician with the correct equipment, and the ohmic resistance should measure near zero and must not be intermittent, which indicates a loose connection.”

Most equipment checks to see if ground is ‘close’ to the neutral; not 60Vrms above neutral. And the generator casing needs to be tied to a ground rod to help keep that neutral/ground near earth potential. And I prefer a low impedance to earth potential for noise reasons (Initially I didn’t realize OSHA also required it). And if you use a GFCI on your generator (which I added in the extension cord), then power will trip with only a 5mA accident conduction to ground. Thus to be safe, I wouldn’t use 100kΩ resistors but use a direct bond from neutral to ground and a GFCI.

-Barry

Sorry to bump an older thread. I figured fellow TED users were best to ask this question.

When Charging your 'i' with level 2 charging how many watts is it drawing in real time??

The onboard charger is listed at 3.3kwh. But measuring several ways (TED being one of them) I'm seeing a maximum real time consumption at the panel of 3053 watts or 3.053 Kw.

I need to know accurately since I'm shopping generators. I know many will suggest getting a 5k genset. However generators are far more efficient very close to their continuous rated load. Most will use 75% to 80% of the fuel to run at 50% load as they will at 100% load. So you get 50% more electricity produced for only 25% more fuel burned if you can size the genset very close to your continuous load. Plus smaller gennies are lighter!

So does anyone have numbers corroborating or contradicting mine? If so what are they?

Aerowhatt

Aerowhatt said:

Sorry to bump an older thread.

Click to expand...

To me, that's actually preferable to starting a new thread on the same topic. Easier to find in the future.

Aerowhatt said:

When Charging your 'i' with level 2 charging how many watts is it drawing in real time??

Click to expand...

I measure 3.07kW at almost exactly 240vac. That power stays constant well into 16 bars, which makes me think that the balancing circuitry is capable of bypassing more than just milliamps. Within the accuracy of the measuring equipment, I think it's safe to say that our i-MiEVs draw about 3.1kW continuous. It's also got a soft-start so it won't overload the genset at startup.

BTW, what we're discussing is power draw and gensets, not TED5000. :roll: :lol:

For example:

http://myimiev.com/forum/viewtopic.php?f=24&t=358&p=1446

JoeS said:

Aerowhatt said:

Sorry to bump an older thread.

Click to expand...

To me, that's actually preferable to starting a new thread on the same topic. Easier to find in the future.

Aerowhatt said:

When Charging your 'i' with level 2 charging how many watts is it drawing in real time??

Click to expand...

I measure 3.07kW at almost exactly 240vac. That power stays constant well into 16 bars, which makes me think that the balancing circuitry is capable of bypassing more than just milliamps. Within the accuracy of the measuring equipment, I think it's safe to say that our i-MiEVs draw about 3.1kW continuous. It's also got a soft-start so it won't overload the genset at startup.

BTW, what we're discussing is power draw and gensets, not TED5000. :roll: :lol:

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Yeah that's how forums get so screwed up. But isn't what TED shows . . . on topic with the TED thread? Speaking of Gensets What do you think TED would say about this one on a cargo platform? 121lbs without the wheel kit and 3200 watts continuous. Thanks for the conformation on wattage readings by TED. Always a source of solid info and sensible topic sorting, Thanks JoeS! Promise, that's my last word on gensets on this thread.

http://www.electricgeneratorsdirect.com/Subaru-SGX3500-Portable-Generator/p5883.html?preferred_placement=1

Aerowhatt

Aerowhatt said:

I need to know accurately since I'm shopping generators. I know many will suggest getting a 5k genset. However generators are far more efficient very close to their continuous rated load. Most will use 75% to 80% of the fuel to run at 50% load as they will at 100% load. So you get 50% more electricity produced for only 25% more fuel burned if you can size the genset very close to your continuous load. Plus smaller gennies are lighter!

Click to expand...

Yes, but... how close to the limit are all the other components being stressed? Unless it can be proven otherwise, I personally would derate something like this to between 50%-70% of its max rating - I simply don't trust manufacturer's specifications, especially for steady-state full-load operation. :evil:

Aerowhatt said:

... Speaking of Gensets What do you think ... about this one on a cargo platform? 121lbs without the wheel kit and 3200 watts continuous.
http://www.electricgeneratorsdirect...le-Generator/p5883.html?preferred_placement=1

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Cutting it way too close for my liking. Besides, I'm assuming you want to use this as a charging backup in an emergency, so I presume you would want to draw power for other loads in addition to the i-MiEV? Notice they spec run time at 50% load.

Still thinking of moving this discussion to a genset thread.... :roll:

JoeS said:

Unless it can be proven otherwise, I personally would derate something like this to between 50%-70% of its max rating - I simply don't trust manufacturer's specifications, especially for steady-state full-load operation. :evil:

Aerowhatt said:

... Speaking of Gensets What do you think ... about this one on a cargo platform? 121lbs without the wheel kit and 3200 watts continuous.
http://www.electricgeneratorsdirect...le-Generator/p5883.html?preferred_placement=1

Click to expand...

Cutting it way too close for my liking.

Still thinking of moving this discussion to a genset thread.... :roll:

Click to expand...

Concerns noted and valid, But it is a Subaru Robin (manufacturer with integrity IME). That's why I wanted to be absolutely sure about the 3,100 or less watt draw of the i. I agree it's close, maybe too close, but it's 30 pounds, $300.00 more cash and less fuel efficient for the next step up. It would be a dedicated single load for sporadic mobile usage (at various destination sites) to L2 charge the car. Other home emergency loads are covered by a solar charged battery system.

Most anything off of Amazon and eBay of Chinese origin, I would agree with you, derate to at least 70%, maybe less. perhaps I'll give tech support a call next week and tell them I plan to run it 4 hours at time at 3100 watts/240volts and see if they flinch. FYI the full rated load run time per tank is 8 hours VS 10.8 hours at half load.

Looks like it will have to be moved now (sorry)

Aerowhatt

Aerowhatt said:

...But measuring several ways (TED being one of them) I'm seeing a maximum real time consumption at the panel of 3053 watts or 3.053 Kw...

Aerowhatt

Click to expand...

If using TED it would be nice to know if you can give us an Apprent Power reading (in VA). Then that will need to be your generator power in KW.

For example, if the charger is drawing 3.3KVA apparent power but only uses 3.053Kw real power, then that generator needs to put out 3.3KW.

-Barry

FYI, Harbor Freight has a 125cc, 4.7 HP 2500/2200 continuous inverter/generator on sale right now for only $400 - Regularly $700. Weighs just 64 pounds . . . . the perfect back-up power source for the iMiEV'er on the go!! :mrgreen:

Don

BarryP said:

Aerowhatt said:

...But measuring several ways (TED being one of them) I'm seeing a maximum real time consumption at the panel of 3053 watts or 3.053 Kw...

Aerowhatt

Click to expand...

If using TED it would be nice to know if you can give us an Apprent Power reading (in VA). Then that will need to be your generator power in KW.

For example, if the charger is drawing 3.3KVA apparent power but only uses 3.053Kw real power, then that generator needs to put out 3.3KW.

-Barry

Click to expand...

According to TED in my measurements the PF for the "i" During L2 charging is 98% which yields a somewhat small difference of 61 watts, or so, between the two. Good point though! Anyone else have anything different?

Aerowhatt

Charging on a Honda inverter generator:

https://endless-sphere.com/forums/viewtopic.php?f=34&t=89806