LeftieBiker
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Re: Using the Leaf for power in a Blackout: MY "Leaf to Home"

Mon Jul 01, 2019 10:28 pm

All you need is a good, reliable circuit breaker in the connection between the Leaf's battery and the marine battery. That will limit the current draw from the Leaf. You also have to make sure that the "big" battery is sized large enough, with a CCA rating high enough, to provide both the needed surge current and the continuous load current. Think of the Leaf as a battery charger for the bigger battery, not as the main load provider. As long as the Leaf's charging system can easily keep the marine or AGM battery replenished, you should be ok. The math should be simple enough: you want the marine battery to be able to provide the whole load for at least an hour, with the average load on it over that hour being significantly less than 1.5kw so the Leaf can keep up. But hey, it's my nap time, and my brain is tired.

I turn 61 today.
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RustyShackleford
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Re: Using the Leaf for power in a Blackout: MY "Leaf to Home"

Wed Jul 03, 2019 11:16 am

I think we've figured this out - nice addendum to the original post.

But the cost will be $1000+; that inverter is expensive and then a fairly expensive battery with enough CCA. A man could buy a pretty nice generator for that kind of money. It could still make sense to use the OP: buy a sub-1000 watt inverter for $100-200 or so and use that to power the fridge, cable modem, and a lighting circuit; now the key load is the startup surge of the fridge compressor. I think the auto-defrost cycle can use a lot of juice too.

I'm going to re-direct my attention to making a new PV solar system be "multimode" or hybrid: that is, so you can use the solar panels even when the grid is down. You might think this is obvious or the default, but you'd be wrong. The incremental cost will surely be more than that nice generator, but it should work indefinitely - good for when the revolution comes :-)
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RustyShackleford
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Re: Using the Leaf for power in a Blackout: MY "Leaf to Home"

Tue Jul 30, 2019 12:33 pm

Recall I've been trying to figure out how to use my Leaf as house backup, using the OP's approach; problem is, the well pump, which runs at 240vac and has enormous startup surges. I've investigated two new approaches:

1. Given the high cost of 240vac-output inverters (the cheapest one that looks suitable is almost $1K), I've thought of replacing my well pump with a 120vac one. This seems totally feasible, simply at the cost of heavier wire, probably 10awg for my situation. Something like: https://www.waterpumpsdirect.com/FloTec ... 72430.html . One helpful guy I talked to opined that using a 3-wire pump (with a separate above-ground control box is "easier" on whatever inverter I use. But he said the pump I need (0.5HP, 7gpm) is still recommended to be used with a 2kw generator-set. He was not enthusiastic about running it off the Leaf. (Wish I could talk to someone who had done so). There's also the expense of replacing my perfectly good 26 year-old pump; that is getting pretty long in the tooth, but OTOH I've heard that new pumps just ain't built like the old ones. Anyhow, when the old one dies, I'm probably going to replace it with some 120vac one.

2. Another approach has the advantage of being cheap, and safe (as far as damage to the Leaf or to my main pump). That is to get one of these narrow-diameter 12v pumps (https://www.envisupply.com/pumps/12volt.htm see "standard PVC pumps" like the Tornado). Because the diameter is so small (1.82") I should be able to fit it down the 6" pipe beside the pipe (maybe 1.5" diameter) of the existing 240vac pump. Such a pump has very low flow (maybe 1-2gpm depending upon which one I pick and how deep I set it). But it's still a source of backup drinking water. One could even imagine using it to keep a small water tower (a big tank set up 8ft or so off the ground) filled. Of course, a little arithmetic tells you that you'd need a water tower about 100ft tall to produce the 50psi or so necessary to pressurize the house's water system, so that's probably a non-starter.
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BrockWI
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Re: Using the Leaf for power in a Blackout: MY "Leaf to Home"

Tue Jul 30, 2019 12:39 pm

To throw in a third option, get a 240vac to 120vac transformer and connect that to your well at the panel, then everything existing works as normal, you would just need a 3kw or so inverter to start it.

Or get that new "wall" in the other thread, I believe that is a 7w directly from the leaf.
Last edited by BrockWI on Tue Jul 30, 2019 4:07 pm, edited 1 time in total.
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RustyShackleford
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Re: Using the Leaf for power in a Blackout: MY "Leaf to Home"

Tue Jul 30, 2019 12:48 pm

DELETED
Last edited by RustyShackleford on Tue Jul 30, 2019 8:31 pm, edited 1 time in total.
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BrockWI
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Re: Using the Leaf for power in a Blackout: MY "Leaf to Home"

Tue Jul 30, 2019 4:12 pm

Sorry I typed 12v should have been 120v. But basically if you search amazon or ebay for step up transformers they are lots of them that will take 120 vac in one side and output 240vac the other side. You could get one of these and wire it where the pump would normally come in near the panel, thus converting the 240vac well put to a 120vac well pump. The catch is if the well pump draws 10 amps at 240vac it will draw 20 amps at 120 vac. Then you could use a good sized "regular" 12 vdc inverter to get you to 120vac. I would recommend at least 3000w unit for this application.
3 kw solar pv - XW6048 - eight L16's
4 ton GSHP - 1 ton ASHP
2003 VW TDI 200k miles - 52 mpg lifetime
EVSE level 2 - Clipper Creek HSC-40
2013 S model with QC package Mar of 2013
lost first bar @ 72k
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Oilpan4
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Re: Using the Leaf for power in a Blackout: MY "Leaf to Home"

Tue Jul 30, 2019 5:20 pm

That's not something a normal power inverter can easily handle.
Then there are added inefficiencies if it's a modified sine wave trying to power an induction motor and the added inefficiency of going through a transformer.

Also the start up inrush is probably going to draw at least double the running amps, that's best case scenario. It may hit 3 times running amps briefly.
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BrockWI
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Re: Using the Leaf for power in a Blackout: MY "Leaf to Home"

Tue Jul 30, 2019 5:39 pm

I agree a minimum of a 3000w true sine wave would be recommended. I personally never use or would suggest modified sine wave inverters.

Yes there will added standby losses using a step up transformer, but if this isn't for constant use or backup situations it could work. I did this in one of our houses years ago before we switched over to split phase 6k true sine wave inverters. At that time I wanted to be able to switch things back to "normal" so when we sold it was all set to go.
3 kw solar pv - XW6048 - eight L16's
4 ton GSHP - 1 ton ASHP
2003 VW TDI 200k miles - 52 mpg lifetime
EVSE level 2 - Clipper Creek HSC-40
2013 S model with QC package Mar of 2013
lost first bar @ 72k
@90k miles - 54.71Ahr - 83.64SOH - 78.44Hx - 237GID

RustyShackleford
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Re: Using the Leaf for power in a Blackout: MY "Leaf to Home"

Tue Jul 30, 2019 8:21 pm

BrockWI wrote:
Tue Jul 30, 2019 4:12 pm
Sorry I typed 12v should have been 120v. But basically if you search amazon or ebay for step up transformers they are lots of them that will take 120 vac in one side and output 240vac the other side.
Yeah, this option has crossed my mind (or even this thread ?) before. It's certainly cheaper and simpler than switching to a 120v pump. Do we know for sure that a step-up transformer can handle something like a well pump gracefully ? Seems plausible.

As far as the 3kw inverter, I am just worried about damaging the Leaf, or even the well pump, trying to drive a big inductive load with something that doesn't like driving such a load. The car is obviously the bigger concern. Which brings me back to using the car as a charger for a separate battery+inverter system. Maybe even coupling it via AC (having a 1000w inverter and use its AC output to drive the battery+inverter).
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BrockWI
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Re: Using the Leaf for power in a Blackout: MY "Leaf to Home"

Wed Jul 31, 2019 7:09 am

That's what I do. We have eight L16's at 48v and a xantrex xw 6048 (6kw 48v) split phase inverter power a second panel in our house. That panel has 95% of the house on it. The geothermal, big EVSE, electric dryer, two of the big pool / hot tub pumps and then the inverter input are on the grid panel. That inverter will use the grid if it is present and automatically switch over if it goes out, a very large UPS. I also have a load shed lead from our utility that when they hit a peak demand it shuts off the grid to the inverter to avoid any peak charges (and it helps the grid by shedding our load).

But getting back to the Leaf, I use a xantrex sw2000 connected to the Leaf that in turn feeds a iota dls 54-13, 13 amp 48 volt battery charger. It draws about 800w from the Leaf and supplies a bit more than the house uses to keep the main 48v bank full. Last weekend we were without power for 2 days and of course it was rainy / overcast with no solar coming in, so I did use the Leaf to keep the battery bank with a good state of charge. We also have a Honda 2000i that can run that same iota charger if need be. I did run our Leaf from 85% to 30% over the two days with a few short trips around. If the power stayed out longer I was going to have to start up the Honda or drive the Leaf to a part of town that had power and let it charge up. But the power came back on.

The advantage of this is our main big inverter deals with the big load starting no problem and the Leaf only has to supply the 800w, which nothing even got warm to the touch on the Leaf or inverter. I do have another 6 amp 48 volt charger adding another 350 watts and I have tried running both of them at once and the Leaf again handled the continuous load of 1150 watts without getting warm, but to error on the safe side I usually only use the 800w. When I run the Honda genset I do run both 48v chargers without any issues.
3 kw solar pv - XW6048 - eight L16's
4 ton GSHP - 1 ton ASHP
2003 VW TDI 200k miles - 52 mpg lifetime
EVSE level 2 - Clipper Creek HSC-40
2013 S model with QC package Mar of 2013
lost first bar @ 72k
@90k miles - 54.71Ahr - 83.64SOH - 78.44Hx - 237GID

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