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

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I use an interlock instead of a transfer setup. It's cheap and simple. There is a sliding steel plate on my main panel that alternately covers either the main breaker, locking it in the OFF position, or the generator feed breaker, locking it in the OFF position. The result is that it's physically impossible to feed the grid with your generator, because it can't feed anything if the main breaker is on. I'll have to look to see if they are still sold...

... I don't see mine, but I do see several others:

https://www.google.com/search?client=firefox-b-1-d&q=generator+interlock
 
Thanks. I will add one more thing for those wondering why an interlock is needed: if you back-feed the local grid while the power is out, you can kill a line repair person working nearby to restore power. That's reason enough to spend a bit on a simple interlock.
 
LeftieBiker said:
Thanks. I will add one more thing for those wondering why an interlock is needed: if you back-feed the local grid while the power is out, you can kill a line repair person working nearby to restore power. That's reason enough to spend a bit on a simple interlock.
Yeah, I kinda thought that was THE reason for it. I was just curious if shutting off the main breakers would accomplish the same thing, with the huge caveat that you could forget to do that so it's therefore not an acceptable solution. I guess the answer is yes, since the interlock does just that (but in a foolproof way). The issue: does the neutral line need to be disconnected as well ? I'd think not, since it should be grounded at your service entrance, and very likely it is at the transformer as well.
 
Most grids don't include a Neutral line, just a ground, so disconnecting the two Hot feeds is enough. My very first attempt at powering my house (partially) with a small generator included a homemade double-ended extension cord that I plugged into the generator and into a 120 volt outdoor outlet on the porch. It worked, powering whatever outlets were on the same "leg" as the outlet, but it required that we remember to turn off the main breaker. We replaced that with a generator connection port feeding a 240 volt 30A Generator circuit that, along with the main breaker, are covered by the interlock plate. Interlock systems are great, and cheap, but you do have to remember to turn most or all of the breakers off before switching over, then turning on the ones you really need the generator to power.
 
LeftieBiker said:
Interlock systems are great, and cheap, but you do have to remember to turn most or all of the breakers off before switching over, then turning on the ones you really need the generator to power.
Actually, I was thinking of putting in an "essential loads" subpanel (connected to the main panel with an ordinary 2-pole breaker); this panel would be permanently connected to the well pump, the fridge output, and 1 or 2 lighting circuits. The main breaker of the subpanel would be the interlock; this unit is expensive, but could be the subpanel plus interlock all in one (https://www.norwall.com/products/Cummins-100-Amp-Integrated-Load-Center-RA-Series-Transfer-Switch-A051C991/). Then my backup AC is connected to the subpanel via an ordinary 2-pole breaker.

As discussed above, the Leaf can't directly supply an inverter big enough to supply my backup power needs (thanks largely to the surge current of my well pump). So I'm actually thinking of a big 3000+ watt inverter/charger (https://invertersrus.com/product/sp-ic3312/) but unfortunately it needs AC input power to charge the connected battery bank. So I'm thinking of adding a second inverter (much lower power) that is driven off the Leaf's 12v and supplies the AC input to the big inverter. Seems a little screwy, but I can't think of another way to drive the well pump from the Leaf, unless somebody makes an inverter/charger that takes a 12vdc input to the charger.
 
RustyShackleford said:
LeftieBiker said:
Interlock systems are great, and cheap, but you do have to remember to turn most or all of the breakers off before switching over, then turning on the ones you really need the generator to power.
Actually, I was thinking of putting in an "essential loads" subpanel (connected to the main panel with an ordinary 2-pole breaker); this panel would be permanently connected to the well pump, the fridge output, and 1 or 2 lighting circuits. The main breaker of the subpanel would be the interlock; this unit is expensive, but could be the subpanel plus interlock all in one (https://www.norwall.com/products/Cummins-100-Amp-Integrated-Load-Center-RA-Series-Transfer-Switch-A051C991/). Then my backup AC is connected to the subpanel via an ordinary 2-pole breaker.

As discussed above, the Leaf can't directly supply an inverter big enough to supply my backup power needs (thanks largely to the surge current of my well pump). So I'm actually thinking of a big 3000+ watt inverter/charger (https://invertersrus.com/product/sp-ic3312/) but unfortunately it needs AC input power to charge the connected battery bank. So I'm thinking of adding a second inverter (much lower power) that is driven off the Leaf's 12v and supplies the AC input to the big inverter. Seems a little screwy, but I can't think of another way to drive the well pump from the Leaf, unless somebody makes an inverter/charger that takes a 12vdc input to the charger.

The 12V battery can supply a lot of amps on its own and could serve as a startup buffer. If the startup surge is brief and the pump's running consumption is still well below the DC-DC converter output, then driving a larger inverter directly from the 12V might work. Depends on the magnitude of the surge and what the voltage sag on the 12V would be. Or I could be talking out my ass :lol:
 
The 12V battery can supply a lot of amps on its own and could serve as a startup buffer. If the startup surge is brief and the pump's running consumption is still well below the DC-DC converter output, then driving a larger inverter directly from the 12V might work. Depends on the magnitude of the surge and what the voltage sag on the 12V would be. Or I could be talking out my ass :lol:

It would be safer to get a big marine/starting battery to use as the startup buffer, and then charge that from the Leaf's 12 volt system. The OEM Leaf battery is not large or rated for high surge loads. It was designed to crank over little 4 cylinder engines with modest compression.
 
LeftieBiker said:
The 12V battery can supply a lot of amps on its own and could serve as a startup buffer. If the startup surge is brief and the pump's running consumption is still well below the DC-DC converter output, then driving a larger inverter directly from the 12V might work. Depends on the magnitude of the surge and what the voltage sag on the 12V would be. Or I could be talking out my ass :lol:

It would be safer to get a big marine/starting battery to use as the startup buffer, and then charge that from the Leaf's 12 volt system. The OEM Leaf battery is not large or rated for high surge loads. It was designed to crank over little 4 cylinder engines with modest compression.
Yeah, that's kinda what I was proposing (three posts back); except I forgot to mention there'd be another big battery feeding the big inverter, and then Leaf would keep that one charged. ("Big" in the sense of being able to provide a big surge, but the "big" storage would be the Leaf's traction battery).

I'd hate to screw up the Leaf by trying to suck too much current out of it. Better that it just sees a fairly low (below 1kw) and uniform load to keep the big battery charged.

I dunno if that Spartan inverter I linked is the best way to handle charging the big battery; seems kinda spastic to have a second inverter off the Leaf to go into the AC input of the Spartan. Maybe something like the inverter for an off-grid solar system ? Has one connection to the battery and can either charge it or draw from it to generate AC.
 
You can limit the current flowing from the Leaf with a 15 amp DC circuit breaker. That protects the charging system. You should be able to charge the marine battery directly from the Leaf's battery, as that is how virtually all of the improvised Leaf Power systems work. I have the guts of such a system sitting around, with a cheap 2kw inverter, but that would be the last line of "power defense" after the dual fuel generator.
 
LeftieBiker said:
You can limit the current flowing from the Leaf with a 15 amp DC circuit breaker. That protects the charging system. You should be able to charge the marine battery directly from the Leaf's battery, as that is how virtually all of the improvised Leaf Power systems work.
Do you have a pointer to details of such a system, that can handle big surges like a well pump ?
 
Here are my suggestions (assuming you have a suitable inverter which has 12-volt input and is capable of running the well pump): Use fuses or 2-pole circuit breaker rated about 50 amperes connected to positive and negative battery terminals of the LEAF and something like No. 8 AWG wire to connect that overcurrent protection to the large battery and inverter. A few feet of No. 8 wire will offer enough resistance to help limit current flow toward the large battery and connecting directly to the positive and negative terminals of the Leaf battery will cause the DC-DC converter to charge at about 14 volts instead of the normal float level of about 13 volts. Use suitable overcurrent protection (fuses or breaker to connect inverter for 120-volt lighting/receptacle power to the Leaf battery (or connect to large battery by well pump if that is more convenient). Keep Leaf in Ready mode while using power.
 
RustyShackleford said:
LeftieBiker said:
You can limit the current flowing from the Leaf with a 15 amp DC circuit breaker. That protects the charging system. You should be able to charge the marine battery directly from the Leaf's battery, as that is how virtually all of the improvised Leaf Power systems work.
Do you have a pointer to details of such a system, that can handle big surges like a well pump ?

I'll find a topic.

https://www.mynissanleaf.com/viewtopic.php?f=37&t=9578&start=30
 
GerryAZ said:
Here are my suggestions (assuming you have a suitable inverter which has 12-volt input and is capable of running the well pump)
The Spartan inverter/charger I linked above might do (with the charger turned off). It actually has an automatic transfer switch, so it could be used to connect the essential-loads subpanel, and literally the only other thing needed would be the big battery to handle surge.
 
RustyShackleford said:
GerryAZ said:
Here are my suggestions (assuming you have a suitable inverter which has 12-volt input and is capable of running the well pump)
The Spartan inverter/charger I linked above might do (with the charger turned off). It actually has an automatic transfer switch, so it could be used to connect the essential-loads subpanel, and literally the only other thing needed would be the big battery to handle surge.

I just looked at the 4 kW split phase, sine wave inverter/charger with transfer switch. It looks ideal for your needs. I will bookmark that site for future reference.
 
That does look like a good inverter/charger. I use a similar but smaller setup to keep our sump pump running in power outages. I find that the ones I use (not the same brand) tend to short their battery chargers out after a couple of years, maybe from dust in the cellar. I'm currently running one with charging turned off, and a Battery Tender Jr on the marine battery I use. I know that AGM batteries are better, but we get about 5 years from the marine batteries and an AGM would also be getting old at that point.
 
GerryAZ said:
I just looked at the 4 kW split phase, sine wave inverter/charger with transfer switch. It looks ideal for your needs. I will bookmark that site for future reference.
I was thinking of this one: https://invertersrus.com/product/sp-ic3312/ just 3300 watts and under a $grand. Seems like you'd have to disable the charger (switch setting) though, or it'd be fighting with the DC-to-DC on the Leaf. And it can also handle disconnecting the essential-load subpanel from the main panel, automatically.

But I'm not crazy about your idea (if I understand correctly) of just using wire to limit the current from the Leaf's 12v system to the external battery.
 
LeftieBiker said:
I was thinking of this one: https://invertersrus.com/product/sp-ic3312/ just 3300 watts and under a $grand.

That was the one I meant. 9kw surge, too.
Didn't see the 9kw surge, yep, that'll probably handle the well pump and fridge compressor coming on at the same instant.

I think this issue of maybe the inverter can suck too much power out of the Leaf and possibly damage the DC-to-DC, needs more thought. Yeah, a certain resistance of wire can guarantee the current is limited; seems like there might be a better way though. My original idea of not connecting the surge battery to the Leaf at all, and rather connecting the AC-input of the big inverter to the Leaf via a small inverter, would more or less guarantee the current limitation. But then it requires a separate transfer switch on the essential subpanel. Seems awkward as hell.
 
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