Tesla + Ecoflow River = backup for longer outages?

Ribbit74

New Member
Question: has anybody used the 12V socket from an EV to offset the energy consumption from a portable power station?

More details on my use case below:

I'm sort of new to this game, but I've been looking at ways to keep at least one of my refrigerators running during outages.
Now, I live in the suburbs in the southeastern US, so we don't have issues with regular extended blackouts; but we had a hurricane last year which knocked out power for around 36 hours. I saved most of the food the low-tech way, in a cooler with ice cubes.

However, a few things occurred to me since then. My GE garage fridge (which is rated for up to 110F ambient temp) has low power consumption - averaging ~50wh per hour according to the energy guide, I will confirm this in a few days when my Kill-a-watt arrives, so I can determine the running/surge watts required.

As of now, I'm assuming the Ecoflow River could handle this since it's known to handle larger refrigerators.

Ecoflow River Max should give about ~10 hours on this fridge; but I'll assume 6 hours due to defrost cycles, as well as frequent opening of the refrigerator since we will have to relocate food during an outage.

I also have a Tesla Model 3 sitting in the garage... it's a shame to let that massive battery go to waste during an outage! However, Model 3 has no inverter, and the best power output is only via the 12V socket. Technically you can bypass the socket and directly hook up to the 12V battery, but then you risk draining the 12V auxiliary battery. It does not recharge quickly from the high voltage battery.

Per the Tesla manual, continually powering a 12V accessory will not drain the auxiliary battery. You do have to leave the car on (which can be done by enabling Sentry Mode). So parasitic losses will also drain the car's high voltage battery, but that's no concern unless the outage is longer than a few days.

So, napkin math: it *should* be possible to keep the refrigerator running for a very long time (days) by charging the River via 12V car adapter while powering the refrigerator.

Ecoflow accepts up to 96W DC via the car charger. So that's 96wh per hour.

In theory, it should be about break-even. The River would handle spikes in power consumption from the refrigerator, the Tesla would keep it supplied with a steady (albeit low) current, with enough buffer to occasionally drive the car to a nearby Supercharger if needed. Even the smaller 288wh River might work in this use case.

Again, this would be a very rare use case where I live, as these extended outages only last every few years. I'm talking about spending a few hundred dollars to keep food from spoiling, while making the best use of a massive EV battery that I already have.

Also the River Max is only $420 on Amazon right now... which is why I'm considering this option.
 
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svetz

Works in theory! Practice? That's something else
I believe Will has a video about how to use the battery in a Tesla to drive an inverter.
 

svetz

Works in theory! Practice? That's something else
Don't forget that compressors on most refrigerators have a significant in-rush current the inverter would need to supply. Not sure, but I think the average is 15 amps for 1/2 second (~1800W).
 

Ribbit74

New Member
The River can handle the surge of a large fridge. My question is mainly around simultaneously charging via the 12V socket while the generator powers the fridge.

Will's video used a Model S; the Model 3 may be similar, but if you directly access the 12V terminals, you still have to make sure the car remains powered or else you will drain the 12V battery.

What's the current limit of the DC/DC converter on the Tesla? My understanding is that the aux 12v battery is only trickle-charged from the HVP, if Will is able to pull that much power then his concern about messing up the car is very real. The DC/DC converter may not be designed for that use and could void the warranty.

At a minimum, it should be safe to use the 12V socket, as long as it's enough power - which in my case I think it is, without having to pull panels off to access the 12V terminals directly.

It's nice to have that option, but hopefully I'll have a Cybertruck within a couple of years and it's a moot point, because the truck will have rather massive onboard inverters for 120/240V. So will the Ford Lightning. I think high-capacity inverters should be standard on all EV's though.
 
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Hedges

I See Electromagnetic Fields!
How about setting up a PV system?
The 96W you're thinking of getting, about 2400 Wh/day, can be provided in the summer with with about 600W of PV panels; you could pick up panels locally for around $150 or so.
What PV charging options does the Ecoflow River have?
 

Ribbit74

New Member
How about setting up a PV system?
The 96W you're thinking of getting, about 2400 Wh/day, can be provided in the summer with with about 600W of PV panels; you could pick up panels locally for around $150 or so.
What PV charging options does the Ecoflow River have?

That's an option too, however sunlight is very inconsistent here; lots of trees in the yard, so I'd need to constantly move panels around in order to chase the sunlight, and we have frequent cloudy days. River will definitely accept solar panels though. I really want solar panels on the roof but given the amount of shade on my property, they need to get a LOT cheaper to make it worth the investment.

Just for shits and giggles I might see if my ancient Wagan Powerdome EX will run my fridge. It's rated at 400W/1000W surge and has a new SLA battery I replaced 2 months ago. And unlike more modern options it even has a built-in AM radio!

The only thing I've previously used it for is powering my modem and wifi router.

My goal right now is to see if I can spend <$500 and have a way of keeping my refrigerator running for long periods, given that I also already have a Tesla sitting next to it. I can hack the car with some additional investment (separate DC/DC charger) but I might be able to just use the onboard 12V socket, running through a portable power bank (Ecoflow) to handle the intermittently high power requirements from the appliance.
 

Hedges

I See Electromagnetic Fields!
If you have an ice maker in the freezer, that can be turned off. There will be a timer for defroster; you could add a switch to disable it. I recently repaired mine (had a bad thermostat intended to turn off heater above a certain cooling coil temperature) and observed 4A draw as I recall. The defrost cycle seemed to be about 30 minutes.

Roof mount of 2 to 4 used panels would be good. Not a lot of money if you don't order new, retail. To be less expensive than grid power they would need to be used 5% to 50% of the time (depending on utility costs of $0.50 down to $0.05/kWh.)

Access to power from the Tesla would be nice, but I think only some U.S. maker vans and pickups offered that (on hybrids the made some years back, and future all electric vehicles.) Since Tesla like some others have a charger for their 12V battery, that seems worth using. If tapping off a 12V accessory battery I would think of putting PV/SCC on the same circuit.
 

Ribbit74

New Member
OK, I just placed my order for the Ecoflow River Max... $429 on Amazon was too good to pass up.

Then I'll do a test to see how long it can power my garage fridge when supplied with a constant feed from my Tesla's 12V socket.

My prediction is that given the lower power requirements of the garage fridge (Freezer on top, no ice maker), I will be able to provide power indefinitely as long as the car has a charge.
 

GXMnow

Photon Sorcerer
I can't speak for the Tesla, but both my Ford C-Max Hybrid and the Chevy Bolt EV both use a DC-DC converter to act like an alternator and maintain the 12 volt battery. They seem to be rated up to about 200 amps or so. But that may be short term power. I would expect 50 amps should not be a problem. Think of it just like a normal car alternator. My brother ran his refrigerator with a 700 watt inverter connected to the 12 volt battery terminals in his Chevy Bolt. He just left the key on and it had no issues. The load is not really any different than if you install a big sound system with external amplifiers. Just the 700 watt inverter alone worked just fine and had no issues with the compressor starting in the refrigerator.

I also tried it in my hybrid and it worked, but I did not do it for long as my car only has a little 1.4 KWH battery pack, so it would be firing up the engine fairly quickly. The Chevy Bolt has 60 KWH, but he only ran it for about an hour and the power came back on. My C-Max has lugs for jump starting a normal car off of the 12 volt system. The battery is a little smaller than a similar sized gasoline car, but t is not tiny. And for some reason, they charged over double what a normal car 12 volt battery would cost. That makes no sense as it does not need any "cranking amps" It takes only about 4 amps to make my car turn on. I "jump started" it with #12 gauge wire when the 12 volt battery failed.
 

Ribbit74

New Member
I can't speak for the Tesla, but both my Ford C-Max Hybrid and the Chevy Bolt EV both use a DC-DC converter to act like an alternator and maintain the 12 volt battery. They seem to be rated up to about 200 amps or so. But that may be short term power. I would expect 50 amps should not be a problem. Think of it just like a normal car alternator. My brother ran his refrigerator with a 700 watt inverter connected to the 12 volt battery terminals in his Chevy Bolt. He just left the key on and it had no issues. The load is not really any different than if you install a big sound system with external amplifiers. Just the 700 watt inverter alone worked just fine and had no issues with the compressor starting in the refrigerator.

I also tried it in my hybrid and it worked, but I did not do it for long as my car only has a little 1.4 KWH battery pack, so it would be firing up the engine fairly quickly. The Chevy Bolt has 60 KWH, but he only ran it for about an hour and the power came back on. My C-Max has lugs for jump starting a normal car off of the 12 volt system. The battery is a little smaller than a similar sized gasoline car, but t is not tiny. And for some reason, they charged over double what a normal car 12 volt battery would cost. That makes no sense as it does not need any "cranking amps" It takes only about 4 amps to make my car turn on. I "jump started" it with #12 gauge wire when the 12 volt battery failed.

Good info... and I also found this thread dealing with the model 3 in particular:


Basically the overall "budget" is 193 amps of 12V power. Some of that has to go toward powering the car's electronics etc., but Tesla also seems to be good about detecting when the battery is draining more than it should be if you try to access the 12V leads directly. That might cause warranty issues if a code is thrown, which likely will immediately notify Tesla via the car's direct communication path. The owner's manual specifically states that using the car as a stationary power source will void the warranty.

However, like you mentioned, another option is to use the 30amp audio circuit, giving you 250W-300W of AC inverter capability so long as you aren't listening to loud music. That's kind of a gray area for warranty, because it's using "budgeted" power than the MCU knows about - no different than just having the car play music through your beefy amp.

The safe approach is to use only the ports the car gives you, which could be fine for more efficient appliances, or could at least extend runtime even for heavy duty appliances as long as the portable power bank has an appropriately sized inverter. For a full-size fridge it might mean 10 hours of runtime instead of 6, using the same ~580kwh battery. No different than extending runtime by plugging in a solar panel.

So for a smaller household fridge or freezer - as long as the appliance's average consumption (after inverter loss) is < 96 watts, the Ecoflow should maintain a steady level of charge while powering the fridge. It'll dip up and down as the fridge cycles on and off, with high current spikes mixed with periods of zero power usage. The Ecoflow's battery should absorb all that and come close to breaking even over the long term.
 

Daybyday

Solar Enthusiast
Regarding use of the vehicle‘s 12 volt socket, I experimented with recharging an Ecoflow Delta from the 12 volt socket of a Kona EV running in utility mode. After a couple of hours the socket got very hot. I had been pulling about 130 watts according to the Ecoflow Delta.
 

solar8484

Solar Enthusiast
Keep in mind Tesla Model 3 has a minimum 200W overhead to stay awake to keep 12V supply active. So, it's quite inefficient to keep it on continuously for small loads.
 
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