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.

 

[RustyShackleford]

The 240vac inverter would be so I could run the well pump.

I stupidly neglected to measure the AC voltage when the flickering was occurring. Yes, I have mostly LED lights, but does it make sense the flickering would be so regular, one flicker every 4 seconds ?

I just tried to re-create the problem, and it ain't happening. Measuring about 113vac.

@Whitenuckler Yes, EVs have a DC-to-DC converter to step the "traction" battery voltage (about 400v in the Leaf, I believe) down to 12vdc for all the various accessories, lights, etc (although apparently some Teslas use 16vdc). Anyhow, the Nissan Leaf nerdarati (see the link in OP) have determined that its DC-to-DC converter is good for 130 amps or so. My inverter is PROWatt brand, dunno if that's cheap or not. But yeah, maybe get a nice-sized LFP battery and a maybe 3000 watt 120vac inverter. Keep it topped off from the Leaf.

 

[gthomas785]

The pulsing is definitely something that the inverter is doing. Might be due to interaction with a specific load that was on (and wasn't on during your other tests) or it could be going bad. But I really doubt that it's anything on the DC side.

 

[gthomas785]

Oh btw, are these led lights on a dimmer? Are they "dimmable?"

 

[RustyShackleford]

Oh btw, are these led lights on a dimmer? Are they "dimmable?"

It was pretty much all the lights in the house, some on dimmer, some not.

 

[RustyShackleford]

The pulsing is definitely something that the inverter is doing. Might be due to interaction with a specific load that was on (and wasn't on during your other tests) or it could be going bad. But I really doubt that it's anything on the DC side.

Of course that specific load would also be on some of the time when I running off the grid. But obviously the grid is more robust than a little inverter.

 

[RustyShackleford]

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.

Might be better with 24v battery, since it seems like 100amps charge/discharge is very common and that gives me 2kW which is sure to be able to handle everything I want (except that darn 240vac well pump). But do I get an inverter/charger, or just a separate charger (for keeping the battery charged when the grid is up) ?

Really want to run that damn well. This looks too good to be true: https://us.ampinvt.com/products/5000w-dc-48v-pure-sine-wave-power-inverter-with-ac-charger

 

[gthomas785]

Of course that specific load would also be on some of the time when I running off the grid. But obviously the grid is more robust than a little inverter.

Yeah, the inverter has components in it that are finite in size (transistor, capacitors, etc) and trying to maintain a steady voltage in response to a fluctuating load. Now compare that to the inductive inertia of your utility transformer which is probably at least 15 kVA, possibly 25 or 50. A momentary blip in current is going to cause very different voltage responses in these two scenarios.

Switching power supplies are a known culprit for messing with small inverters. Not only that, but inverters produce an artificial sine wave that often has greater THD than what comes in from the grid. This can mess with the switching power supply which in turn does something weird to mess with the inverter.

 

[gthomas785]

Really want to run that damn well.

If it's really just that one 240v load, consider getting a step up transformer or autotransformer to generate the other hot leg. You'd need to rig up a separate way to switch the well over to that when you switch to generator power.
I have not looked into how a transformer sized to your well pump would price out compared to a 240v inverter but thought it was worth a mention.

 

[EbS-P]

The 240vac inverter would be so I could run the well pump.

I stupidly neglected to measure the AC voltage when the flickering was occurring. Yes, I have mostly LED lights, but does it make sense the flickering would be so regular, one flicker every 4 seconds ?

I just tried to re-create the problem, and it ain't happening. Measuring about 113vac.

@Whitenuckler Yes, EVs have a DC-to-DC converter to step the "traction" battery voltage (about 400v in the Leaf, I believe) down to 12vdc for all the various accessories, lights, etc (although apparently some Teslas use 16vdc). Anyhow, the Nissan Leaf nerdarati (see the link in OP) have determined that its DC-to-DC converter is good for 130 amps or so. My inverter is PROWatt brand, dunno if that's cheap or not. But yeah, maybe get a nice-sized LFP battery and a maybe 3000 watt 120vac inverter. Keep it topped off from the Leaf.

You can go round and round about the best way. I’ve settled on the Ecoflow brand for mobile battery power.

Delta pro 3, I believe has 240 V twist lock receptacle. 4kwh

Cheapest plan is to keep 5 gallons of water on hand and get a cheap gas generator to run the well.

130 amps is more than I expected. Maybe it’s worth a 240 v inverter. The sprinter forum has lots of info on choosing inverters. Most people have sprinter money so Victron multi plus inverter is the preferred inverter charger.

Might be better with 24v battery, since it seems like 100amps charge/discharge is very common and that gives me 2kW which is sure to be able to handle everything I want (except that darn 240vac well pump). But do I get an inverter/charger, or just a separate charger (for keeping the battery charged when the grid is up) ?

Really want to run that damn well. This looks too good to be true: https://us.ampinvt.com/products/5000w-dc-48v-pure-sine-wave-power-inverter-with-ac-charger

if you going above 12 just go to 48V. I’d just get the flow with 240v and be done and wire up a dc charging from the EV for it. I’d even get the refurbished one that Eco flow sells on eBay.

 

[RustyShackleford]

I’d just get the flow with 240v and be done and wire up a dc charging from the EV for it. I’d even get the refurbished one that Eco flow sells on eBay.

For $2000, I think I could do a lot better rolling my own.

But then there's this - seems to good to be true: https://www.ebay.com/itm/4067206347...RdZfDt0AvFoi6e57Zm4GMNALFB8SdNbRoCrGsQAvD_BwE
It says "new", unclear if still under warranty.

 

[RustyShackleford]

If it's really just that one 240v load, consider getting a step up transformer or autotransformer to generate the other hot leg. You'd need to rig up a separate way to switch the well over to that when you switch to generator power.
I have not looked into how a transformer sized to your well pump would price out compared to a 240v inverter but thought it was worth a mention.

I've thought of that. If I did it, I'd be tempted to install the transformer permanently. I measured my brand-new soft-start Grundfos well pump at 5 amps with no startup surge, so I'm thinking a 20amp 120vac circuit could handle it - as long as it gets boosted to 240vac before the roughly 200ft trip from the pressure tank in the crawlspace to the bottom of the well. Maybe it works price-wise: a 120vac output Ecoflow with comfortable enough wattage (2000+) is well under $1000, so might be a better solution than the Delta Pro 3.

I can't get a straight answer from anyone on a spec for said transformer, and I'd hate to damage the pump with an insufficient one. Grundfos themselves blew me off and pointed me to a distributor; such BS, does the answer to that question depend on where you live ?!? This one sure seems like it ought to be able to handle it: https://www.vevor.com/voltage-conve...3tBvd8dNqNZMHgRsaM_zb6RseWHGXZaoXvxHQToRS49F0

The rated current of the pump is actually 8.4 amps, but like I said, I measured 5, probably because I'm only 100ft down and the pump is rated for 200ft. Anyhow, double that and some inefficiency is still below 20 amps. I don't think this needs the continuous-load adjustment. Also, the rated voltage is 200-240vac, so should be ok if voltage sags considerably.

 

[EbS-P]

For $2000, I think I could do a lot better rolling my own.

But then there's this - seems to good to be true: https://www.ebay.com/itm/4067206347...RdZfDt0AvFoi6e57Zm4GMNALFB8SdNbRoCrGsQAvD_BwE
It says "new", unclear if still under warranty.

Of course it’s too good to be true! I don’t gamble but, eBay has been good to me on any disputes. Seller has zero feedback. Joined eBay last month. I’m tempted….. but I will pass.

You’re totally paying for convenience. The van lifers that want flexible portable solutions generally land on Ecoflow. If they want a built in system they build their own. It’s cheaper.

 

[Whitenuckler]

For $2000, I think I could do a lot better rolling my own.

But then there's this - seems to good to be true: https://www.ebay.com/itm/4067206347...RdZfDt0AvFoi6e57Zm4GMNALFB8SdNbRoCrGsQAvD_BwE
It says "new", unclear if still under warranty.

Seems to good to be true. Here is something to compare, not that I would order it from them.

https://www.aliexpress.com/p/tesla-landing/index.html?scenario=c_ppc_item_bridge&productId=1005011758446254&_immersiveMode=true&withMainCard=true&src=google&aff_platform=true&isdl=yhttps://www.aliexpress.com/p/tesla-landing/index.html?scenario=c_ppc_item_bridge&productId=1005011758446254&_immersiveMode=true&withMainCard=true&src=google&aff_platform=true&isdl=y&src=google&albch=shopping&acnt=631-313-3945&isdl=y&slnk=&plac=&mtctp=&albbt=Google_7_shopping&aff_platform=google&aff_short_key=UneMJZVf&gclsrc=aw.ds&&albagn=888888&&ds_e_adid=&ds_e_matchtype=&ds_e_device=c&ds_e_network=x&ds_e_product_group_id=&ds_e_product_id=en1005011758446254&ds_e_product_merchant_id=5734887449&ds_e_product_country=CA&ds_e_product_language=en&ds_e_product_channel=online&ds_e_product_store_id=&ds_url_v=2&albcp=19366866438&albag=&isSmbAutoCall=false&needSmbHouyi=false&gad_source=1&gad_campaignid=17337458112&gbraid=0AAAAACbpRIkzOzy4J0dg-fs-gzo4f4elc&gclid=EAIaIQobChMIzJuY5OickwMVOlD_AR35VANJEAQYBiABEgJ43PD_BwE

 

[zrock]

Long conversation just to find out you are at the limit of your equipment.. You could have purchased a good quality generator that would have been more capable and not have to worry about battery power or limitations.. My 4500w gen will run everything i need without coming off a idle

 

[Whitenuckler]

Long conversation just to find out you are at the limit of your equipment.. You could have purchased a good quality generator that would have been more capable and not have to worry about battery power or limitations.. My 4500w gen will run everything i need without coming off a idle

Some small generators that are 120V can hook up as 240 volts too with a special cord.

 

[RustyShackleford]

I can't get a straight answer from anyone on a spec for said transformer, and I'd hate to damage the pump with an insufficient one. Grundfos themselves blew me off and pointed me to a distributor; such BS, does the answer to that question depend on where you live ?!? This one sure seems like it ought to be able to handle it: https://www.vevor.com/voltage-conve...3tBvd8dNqNZMHgRsaM_zb6RseWHGXZaoXvxHQToRS49F0

So I called the distributor that Grundfos pointed me to, and of course they were clueless, But they did give me the number of Grundfos' contractor hotline. They wouldn't recommend anything, but allowed as how the full load amperage is 6.4, he's unsurprised I measured only 5, and the rated voltage goes down to 200 and the speed doesn't actually start dropping until 149 volts. IOW, he thinks it's reasonable to use a transformer.

Tempted to buy the VEVOR one, could hook it up right quick and see what happens. Does the transformer overheat ? Is the output voltage good ? No way to tell if the output waveform is distorted I guess (without a 'scope), but is that even a thing with something as dead simple as a transformer ? Anyhow, if I don't like what I see, return the thing.

I wish I could find a transformer that's just a big hunk of metal with two wires coming out of each side, and not pay for box and outlets and meters, but can't seem to find one.

 

[Whitenuckler]

So I called the distributor that Grundfos pointed me to, and of course they were clueless, But they did give me the number of Grundfos' contractor hotline. They wouldn't recommend anything, but allowed as how the full load amperage is 6.4, he's unsurprised I measured only 5, and the rated voltage goes down to 200 and the speed doesn't actually start dropping until 149 volts. IOW, he thinks it's reasonable to use a transformer.

Tempted to buy the VEVOR one, could hook it up right quick and see what happens. Does the transformer overheat ? Is the output voltage good ? No way to tell if the output waveform is distorted I guess (without a 'scope), but is that even a thing with something as dead simple as a transformer ? Anyhow, if I don't like what I see, return the thing.

I wish I could find a transformer that's just a big hunk of metal with two wires coming out of each side, and not pay for box and outlets and meters, but can't seem to find one.

https://ca.rs-online.com/product/hammond-power-solutions/c1f1c0les/70191800/?srsltid=AfmBOop0Eva3TnN89AoVz4fxUtF3EQFD_zyUJzEkNt62xjjSgH8YYydz

 

[RustyShackleford]

https://ca.rs-online.com/product/hammond-power-solutions/c1f1c0les/70191800/?srsltid=AfmBOop0Eva3TnN89AoVz4fxUtF3EQFD_zyUJzEkNt62xjjSgH8YYydz

Thanks, mighty expensive though. Spending that much I'd buy the Victron auto-transformer. Was looking for bare bones thinking it'd be cheaper.