power flickering from small 12vdc -> 120vac inverter attached to EV

[RustyShackleford]

Awhile back I rigged up a way to attach a 1000 watt 12vdc to 120vac inverter to the 12v system in our Nissan Leaf EV. It worked nicely during power failures, with enough juice to keep the refrigerator, modem & router, and most lights and A/V stuff working. The 40kWh battery in the EV insured this could last for days. (There's a lengthy discussion of this here: https://mynissanleaf.com/threads/using-the-leaf-for-power-in-a-blackout-my-leaf-to-home.13097/ ).

However, during a power failure earlier today it didn't work so well. Basically, about every 4 seconds the lights flickered once. Any ideas about what might cause this ? It was raining when I set it up - opened the Leaf hood, sat the inverter in there and plugged the 12vdc and 120vac cords in, and then ran the latter to a generator inlet on the side of the house - so things got a little wet. But it doesn't seem like that would cause such a regular pattern to the flickering. I guess later I can dry stuff out good and run another test and see.

 

[EbS-P]

DC voltage fluctuations, or the inverter is not working as intended.

I’d be tempted to get a 30 amp DCDC converter and an LFP battery and hook the inverter to the LFP. That essentially decouples the cars dcdc converter from the inverter. And would allow loads up to the limit of the battery with an appropriately sized inverter.

 

[RustyShackleford]

DC voltage fluctuations, or the inverter is not working as intended.

Yeah, I just don't know why now. Unless the wetness. When I can dry things out well, I'll run a test, see if the inverter has gone to the bad.

I’d be tempted to get a 30 amp DCDC converter and an LFP battery and hook the inverter to the LFP. That essentially decouples the cars dcdc converter from the inverter. And would allow loads up to the limit of the battery with an appropriately sized inverter.

I've been looping around that thought for awhile now. If I'm gonna do that, probably get a 240vac inverter, which is more than $1000 to get a decent one, never mind the battery. At which point why not just buy a generator ?

 

[Whitenuckler]

Awhile back I rigged up a way to attach a 1000 watt 12vdc to 120vac inverter to the 12v system in our Nissan Leaf EV. It worked nicely during power failures, with enough juice to keep the refrigerator, modem & router, and most lights and A/V stuff working. The 40kWh battery in the EV insured this could last for days. (There's a lengthy discussion of this here: https://mynissanleaf.com/threads/using-the-leaf-for-power-in-a-blackout-my-leaf-to-home.13097/ ).

However, during a power failure earlier today it didn't work so well. Basically, about every 4 seconds the lights flickered once. Any ideas about what might cause this ? It was raining when I set it up - opened the Leaf hood, sat the inverter in there and plugged the 12vdc and 120vac cords in, and then ran the latter to a generator inlet on the side of the house - so things got a little wet. But it doesn't seem like that would cause such a regular pattern to the flickering. I guess later I can dry stuff out good and run another test and see.

Awhile back I rigged up a way to attach a 1000 watt 12vdc to 120vac inverter to the 12v system in our Nissan Leaf EV. It worked nicely during power failures, with enough juice to keep the refrigerator, modem & router, and most lights and A/V stuff working. The 40kWh battery in the EV insured this could last for days. (There's a lengthy discussion of this here: https://mynissanleaf.com/threads/using-the-leaf-for-power-in-a-blackout-my-leaf-to-home.13097/ ).

However, during a power failure earlier today it didn't work so well. Basically, about every 4 seconds the lights flickered once. Any ideas about what might cause this ? It was raining when I set it up - opened the Leaf hood, sat the inverter in there and plugged the 12vdc and 120vac cords in, and then ran the latter to a generator inlet on the side of the house - so things got a little wet. But it doesn't seem like that would cause such a regular pattern to the flickering. I guess later I can dry stuff out good and run another test and see.

Maybe it was going into overload?

 

[RustyShackleford]

Maybe it was going into overload?

No, it displays the wattage and it was under 500. And when it does overload, it just shuts off.

There is a separate issue, that I think I've sought advice on here before: Apparently when the refrigerator goes into defrost mode, it draws enough current to overload the inverter, and it drops out; I'm sure that's it, because if I turn off the fridge breaker everything is fine. And I don't think it's the compressor startup surge, since I've seen the compressor cycle with no problems. I've though of putting a normally-closed relay on the defrost heater, so I can just power up the relay with a battery during outages, but the heater is at the back of the freezer section, behind the huge pullout drawer, and it seems like it'd be a bear to access it. I don't think the defrost heater should really be drawing that much juice, but apparently it is. Thnking maybe even a slightly larger inverter would solve this problem.

 

[EbS-P]

probably get a 240vac inverter

I don’t think that’s needed. Who knows how the cars dcdc converter works and a software update could change that. My suggestion could be done with any 12 v battery and cheap 12-12 dcdc converter. I don’t like the idea of putting large dc loads on my cars dcdc converter. Tesla 12v batteries are small.

Led lights flickering to me is a sign of low AC voltage.

 

[Whitenuckler]

I don’t think that’s needed. Who knows how the cars dcdc converter works and a software update could change that. My suggestion could be done with any 12 v battery and cheap 12-12 dcdc converter. I don’t like the idea of putting large dc loads on my cars dcdc converter. Tesla 12v batteries are small.

Led lights flickering to me is a sign of low AC voltage.

I was wondering about that too. I've never had an EV, but the car's batteries are a high voltage, so there must be something (DC to DC) to make this 12V that the inverter is plugged into. I don't know what kinds of watts/amps it rated for.