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Power supply / battery backup with multiple power inputs?

richiev

Supporting Member
I have an electric vehicle that supports Vehicle To Load (V2L), and has a ginormous battery. I have to travel again, and I'd like to be able to use this to serve as a power backup for my tank(s). It can put out enough power, and has enough storage, that it could easily run my tank with lights for a couple days.

The setup on the car is you attach an adapter to the car, and it then gives you a standard power outlet that you can connect anything, such as a beefy extension cord, to.

What I'd like to be able to do is have a setup where my main power strip is somehow plugged into the wall as normal, but also connects to the car's extension cord. In the event that the main supply drops, I'd like it to switch to run off the car's power. At some point I'd want it to switch back, but given how long the battery can run, it'd be fine if it was manual. I'd have a neighbor flip it if needed.

Is anyone familiar with a strategy to do something like that? It's effectively the same idea as a battery backup, but a bit different that from the POV of the switching it's just two power inputs.

I also could just buy a battery backup, but it seems silly in this situation. Particularly because at some point I hope we get solar, and I'd rather save the money up on batteries for various things and instead get a house battery.

Additionally at some point I hope I'd have a car that supports bidirectional charging / vehicle to grid, in which case this also may be irrelevant.

Thoughts?

CC some people who I feel tend to have ideas on this sort of thing @Qwiv @thesassyindian
 

richiev

Supporting Member
I'm guessing the answer would be something like this:

110V 2P 100A Mini Dual Powe Automatic Transfer Switch Dual Power Generator Changeover Switch 50HZ/60HZ (2P 100A NO Power Off) https://a.co/d/hP9feYa

And then cutting the end off a couple extension cords so that it could be attached. Effectively handle it like a generator.
 

thesassyindian

Supporting Member
This is basically a load switch that is powered by mains power, and when that fails it opens the main switch, and closes another? It seems simple enough.
Looking through the videos on the switch you linked, it seems right for your application. Took me a second to see where the load was attached, and looks like you need jumper cable to monitor the power levels. It's also not too pricey, so likely worth a test run.
Personally, I'd look for something with a UL rating.

Fundamentally, I think your solution should work. Though you should look for a make-before-break switching panel. That way, you will have uninterrupted power, else, your peripherals will power cycle.

Another even-more-maker-y route you could take would be to hop on eBay, pick up a used UPS (I see some for ~$30), then hack your car output into it instead of the built-in inverter.
 
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rygh

Treasurer
BOD
Yes, you need a transfer switch like that.
Note that simple transfer switches will drop power for about a second as the switch.
That will usually cause electronics like Apex to reboot.

Price seems really cheap, so you might look into the quality.
 

thesassyindian

Supporting Member
Oh @richiev One main issue I foresee is this:
Your car inverter is not going to be phase locked to the power grid, so there might be some weird behavior during switching.
Depending on the phase difference in the car inverter output and line voltage, you may get a power cutoff or a spike.

Make sure you add a GOOD spike suppressor just in case.
 

rygh

Treasurer
BOD
Oh @richiev One main issue I foresee is this:
Your car inverter is not going to be phase locked to the power grid, so there might be some weird behavior during switching.
Depending on the phase difference in the car inverter output and line voltage, you may get a power cutoff or a spike.

Make sure you add a GOOD spike suppressor just in case.
The cheap transfer switches simply drop out for a second as this switch over to deal with this.
 

Qwiv

Supporting Member
You are not going to want to connect the EV to your tank directly without some pretty good smarts, like an ATS as mentioned above. It will get complicated pretty quick unless you have a larger solution already, such as what is offered on the Ford Lightning and the entire house. Would be cheaper to get a Battery and manually just switch it over. You get a battery out of the deal as well. What happens when the car isn't at the house adn the power goes out? Battery solves that.
 

rygh

Treasurer
BOD
You can do both.
Car + Main house connect to transfer switch.
Output of transfer switch goes to UPS.
UPS goes to fish tank.
 

Qwiv

Supporting Member
If no one will be home, then an AST is what you need but they are not as easy to just buy something and plug it all in. There are some small ones on the market for a home generator that would likely work, but I can't recommend anything in that size range as I have never used them. All my experience is with much larger systems. I would trust anything that is made by Eaton though, so if they have a small one, that is what I would by. Very respected brand.

If someone will be home, I would do the battery thing. I have a Ecoflow Delta you can even borrow if you want. It is the Noisey First Gen, so leave it where noise isn't a problem.

 

Thales

Past President
If someone will be home, I would do the battery thing. I have a Ecoflow Delta you can even borrow if you want. It is the Noisey First Gen, so leave it where noise isn't a problem.

None of these automatically switch over?
 

richiev

Supporting Member
@richiev As a carnerd myself, and possibly in the market to replace my wife's lemon hatchback, I am very interested in what EV you have.
I picked up an EV6. Very happy with it.

My main reason was I wasn't willing to buy an EV unless I could test drive it, or at least sit it in once. I can't bring myself to drop thousands of dollars on a vehicle I never even see in person. The EV6 I was able to test drive, and also get the federal discount on. I did get royally screwed by the dealer markup though, but at this point that's pretty unavoidable right now.

I almost got a Kona, but the EV6 is bigger and hopefully we'll find it's good enough to replace our Honda Odyssey van.
You are not going to want to connect the EV to your tank directly without some pretty good smarts, like an ATS as mentioned above. It will get complicated pretty quick unless you have a larger solution already, such as what is offered on the Ford Lightning and the entire house. Would be cheaper to get a Battery and manually just switch it over. You get a battery out of the deal as well. What happens when the car isn't at the house adn the power goes out? Battery solves that.
You can do both.
Car + Main house connect to transfer switch.
Output of transfer switch goes to UPS.
UPS goes to fish tank.
Oh @richiev One main issue I foresee is this:
Your car inverter is not going to be phase locked to the power grid, so there might be some weird behavior during switching.
Depending on the phase difference in the car inverter output and line voltage, you may get a power cutoff or a spike.

Make sure you add a GOOD spike suppressor just in case.

RE the transfer setups. I'm ok with the power dropping out and cutting back. I control all my devices through Google home and smart switches, so I'm constantly power flipping them anyway, and I'm ok with a blip in the event of a power outage. My main concern is that my house doesn't burn down somehow.

Regarding long term setup, my hope from the car is bidirectional charging / Vehicle to House (V2H) / Vehicle to Grid (V2G). The car (EV6) supposedly has all the capabilities to do it already, but outside of Ford no one seems to be willing to release it in the US. I believe the Ioniq/EV6 have V2G internationally. I actually had put in my $100 deposit on a lightning, but I got wait listed untill 2023 so I cancelled.

Towards the case where the car isn't home, that is a good call as well, but that's one I'm not concerned with right now. My expectation is I'm likely going to get solar, and unless V2G gets rolled out more broadly I'll get a battery. So I'd rather save the funds on a little UPS and spend them towards the battery. Even though the price difference between the two is likely high enough that a little UPS is a rounding error.

The bigger thing though is if I can get the car to do it, then a power outage on this vacation becomes a no-op. I'd not need anyone to do anything, and I could even see the car's battery status from my phone.
 

richiev

Supporting Member
I picked up an EV6. Very happy with it.

My main reason was I wasn't willing to buy an EV unless I could test drive it, or at least sit it in once. I can't bring myself to drop thousands of dollars on a vehicle I never even see in person. The EV6 I was able to test drive, and also get the federal discount on. I did get royally screwed by the dealer markup though, but at this point that's pretty unavoidable right now.

I almost got a Kona, but the EV6 is bigger and hopefully we'll find it's good enough to replace our Honda Odyssey van.




RE the transfer setups. I'm ok with the power dropping out and cutting back. I control all my devices through Google home and smart switches, so I'm constantly power flipping them anyway, and I'm ok with a blip in the event of a power outage. My main concern is that my house doesn't burn down somehow.

Regarding long term setup, my hope from the car is bidirectional charging / Vehicle to House (V2H) / Vehicle to Grid (V2G). The car (EV6) supposedly has all the capabilities to do it already, but outside of Ford no one seems to be willing to release it in the US. I believe the Ioniq/EV6 have V2G internationally. I actually had put in my $100 deposit on a lightning, but I got wait listed untill 2023 so I cancelled.

Towards the case where the car isn't home, that is a good call as well, but that's one I'm not concerned with right now. My expectation is I'm likely going to get solar, and unless V2G gets rolled out more broadly I'll get a battery. So I'd rather save the funds on a little UPS and spend them towards the battery. Even though the price difference between the two is likely high enough that a little UPS is a rounding error.

The bigger thing though is if I can get the car to do it, then a power outage on this vacation becomes a no-op. I'd not need anyone to do anything, and I could even see the car's battery status from my phone.
And yes, with my final statements there I'm guaranteeing when I leave home this weekend that suddenly there will be a massive power outage across the bay area and I'll eat my words.
 

Qwiv

Supporting Member
None of these automatically switch over?
The one I linked to does Lefty. A lot of the EcoFlow ones do actually and pretty much all the current generations from other manufacturers. It isn't a UPS. It does "pass though charging" which is actually different. They pass through power to the outlets while being plugged in and switch over to battery when the power drops. The EcoFlows are unique in that the inverter is the battery charger so they work different then basically all the others out there, but they work similar in practice and I think better. There is a delay when the power drops (relays switch over), but it is fractional seconds.
 

Qwiv

Supporting Member
And yes, with my final statements there I'm guaranteeing when I leave home this weekend that suddenly there will be a massive power outage across the bay area and I'll eat my words.
Can't imaging you finding a reliable ATS before this weekend unless you buy something from the Computer Word like a server rack solution.

This would likely do what you want long term:
But you are going to need to get it and have an electrician install. If you can find one, I could probably jerry rig it temporarily to just run the tank. ATS is a good brand, so I would trust it at least.

All the other small ones I found are some no-name I would need to really research or ones designed for a generator, which all have data to start a generator. Not sure they would work decoupled from the generator they are designed for. I'll ask around for other options.
 
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Thales

Past President
The one I linked to does Lefty. A lot of the EcoFlow ones do actually and pretty much all the current generations from other manufacturers. It isn't a UPS. It does "pass though charging" which is actually different. They pass through power to the outlets while being plugged in and switch over to battery when the power drops. The EcoFlows are unique in that the inverter is the battery charger so they work different then basically all the others out there, but they work similar in practice and I think better. There is a delay when the power drops (relays switch over), but it is fractional seconds.
Thanks. I'll watch them a little more closely. Maybe it is time...
 

Qwiv

Supporting Member
Thanks. I'll watch them a little more closely. Maybe it is time...
You are paying for the Solar controller, USB everything, display, the app/wifi. All that stuff likely adds 100 bucks and size to these small battery packs. Really looking for one that has a inverter with pass thru charging only and isn't a UPS as it should be cheaper not having all the other stuff and easier to hide on a normal tank. If I find one I think is legit, I'll be sure to post, but for the size of your system you might want this :cool:


You would be hard pressed to buy all these parts yourself and make this. Pretty good deal that you could just shove under your house. When looking at these things, expect to pay about $1 a kWh so that is a really good price and should last a really long time in a crawl space. Crazy guy on youtube who tests all this stuff:
 

richiev

Supporting Member
Honestly, there's a decent chance that given more time I would just build this out of the cheap ATS I found on Amazon. The other options certainly seem better, and if I was doing a permanent setup wired into my house I'd for sure do that, but in this instance I'd be doing a temporary setup with extension cords and I believe I could mitigate the risk by placing the ATS in a safe location, even outside my house. That'd mitigate the burn it all down risk, and the other things like phase matching and instant cutovers I wouldn't desire. For the legit setup I would do it as part of the true home setup with solar & battery.

The guidance here definitely helps me understand the trade offs, and what's involved in the actual setups. However, given I'm going next weekend, I'm not going to have time to do the diy, and either way I'd not want to spend a bunch when I'll replace it with a house setup.

So this all helped me decide on a much easier setup. I have a 77,200wh battery on my car. A mp10 uses 8-18w, which I'll round up to 20. 77,200÷20÷24 = 116 days.

The easiest solution is I just plug my pumps into the car before I leave, and I would be fine for months.

I'll likely plug into my car:

* My return pump
* My controller with the DC fans plugged in
* My wifi router & modem
* My heater on a smart strip

I'll leave the lights powered by the house, though I think I could actually plug them in too. Even with all that, I should pretty easily be able to leave it running for far beyond my travel. If the power went out I'd have temp control + water movement and if my fiber stays active I could even control it remotely.

The other Internet option is I have an old phone still attached to my Google Fi account. For $10 or so I could flip it on for the month and could run it as a hotspot and have remote connectivity regardless too.

Anyway, thanks for the input. Made me realize there's a trivial solution to this that I was completely looking past.
 

Prestondeeply

Supporting Member
I use a Goal Zero. They come in a half dozen different capacities now. My older yeti 1000 can drive over 30A at 12V. That is enough for me to drive all of my gear. Plugs in to the wall full time, cought add solar if I wanted to wire it to the roof. But mostly, I can just plug and forget.
I went directly to DC so I don't have to have a bunch of AC/DC converters.....and if the power goes out, I'm not running the a AC converter from the DC battery in the yeti and just blowing the capacity on conversion x 2.
Probably also UL certified.
 
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