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Discussion Starter · #1 ·
Can anyone share their experience of Installing a 500 watt (or more) inverter in a PHEV? The PHEV has a 12 volt battery in the rear of the vehicle making it perfect for the kind of AC generation many Prius owners have enjoyed.

Primary utility is in a power outage to power basic household needs. Here in Virgina some folks power has now been out more than a week. It also makes it possible to have highly efficient AC wherever one might need it. Because these engines are so efficient folks have powered significant parts of their homes for days on one tank of gas.
 

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2022 Bolt EUV Premier
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No, never did it. However, while the PHEV has a 12v lead acid battery, it's extremely limited in power, and even with normal use only has a 2-3 year expected life span. Putting a heavy inverter load on it is not going to improve its longevity, and it's not an inexpensive battery to replace.
 

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I don't think the 12v. is really what you want to do. You should consider being able to plug into the whole car to use it like a portable generator. When I was on Prius Chat for many years that seems to be what a lot of Prius owners do. They wanted to be able to use their Prius as a portable generator to power their house when the lights went out. Is that what your talking about? There was a kit for the Prius for this haven't heard if there's one for the Niro?
 

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Discussion Starter · #4 ·
I don’t have any reason to believe the outcome would be different for the Niro than the hundred or thousands of Prius vehicles that have done this. Every day the Niro’s DC to DC converter floods the 12v with energy to run the lights, the AC, the sound system, defrosters, heated seats, 120 watts from the cigarette lighter, whatever. I’ll soon test the amperage draw of those loads if no one has already done so.

You turn off those loads and hook up an inverter to the rear 12v and the DC to DC converter simply knows it has to replace the power flowing out (obviously you leave the vehicle on the whole time). As long as you respect the amperage limits in every direction harm to the system is no more than driving down the road. The Prius confirms this. The consensus with the Prius is a maximum of about 1000 watts continuous.

Surely someone has already tried it?
 

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I believe the PHEV and the HEV both use the same 130 amp DC to DC converter. On my HEV, I have a moderate size subwoofer amplifier that can pull around 100 amps when the volume is cranked up. At that time, the voltage will drop from 13.8 volts down to 13.2 volts. This tells me that at that point, power consumption pretty much equals power production capabilities. This goes right along with what the Prius guys are saying. Just keep in mind that if voltage is already dropping hard at about 100 amps, there’s no room for any surge requirements (like starting electric motors).

So, a 500 watt power inverter should be just fine with room to spare for starting some electric motors.
 

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Discussion Starter · #6 · (Edited)
Thanks. That’s perfect. It’s wild to think you could possible run the car while also drawing 100 additional amps on the subwoofer (or is that total amps?). Pushing that close to the 130 amp mark makes me nervous but confirms the capacity. Any other subwoofer or amp meter stories out there to confirm further?

I’m thinking an 80 amp circuit breaker on a 1000 watt inverter with all the other loads on the car turned off (lights, hvac, stereo, etc). That’s a lot less than your subwoofer.

The Niro can provide that until it runs out of gas a few days later (hopefully after your power is restored - although a trip to the has station provides another few days). Just google “emergency backup power” for a Prius. You’ve got to get your wiring right but folks have been doing this for a decade. It’s one of the interesting aspects of the PHEV model.

And I think they put the 12v back under the hood in recent models of the Prius - rather than in the rear where it was easier to add an inverter.
 

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If I recall correctly, it says somewhere in the manual for my 2022 Niro PHEV (or maybe something else I read that Kia provided) to not plug an inverter into the power port. I'm sorry that I can't remember exactly where I saw that but will post that info if I find it. Meantime, I suggest calling Kia's Customer Support phone number to ask them.
 

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Discussion Starter · #8 ·
The cigarette lighter is limited to 120 watts. So any AC inverter plugged into one of those has to be tiny. The wiring is not robust enough to carry more amps.

We are talking about wiring an inverter directly to the 12v battery in the rear of the PHEV. That’s where you can (carefully) tap 1000 watts.
 

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Discussion Starter · #9 · (Edited)
In the closeup you can see the 150 amp fuse connected to the 12 volt battery. So goal number one is to never blow that fuse.
Automotive lighting Motor vehicle Hood Automotive tire Automotive design
 

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Discussion Starter · #10 · (Edited)
Update:

If you turn off the Batterysaver you can measure some amp draws off of the 12 volt in the back of the PHEV.

Amps as follows:
Interior lights: 4
Running lights: 9
Accessory mode: 5
Radio, Running lights, Interior lights: Max 10
Headlights: 19
Start up: 35 max everything on before DC to DC converter kicks in close to instantly.

As soon as you start the car the DC to DC converter starts to flood energy into the 12 volt to recharge it from any losses and maintain it’s charge regardless of the draw. So you can’t really assess how much is being drawn for the heater (for example). I don’t intend to use the inverter with anything else on anyway (heater or headlights). I don’t think it will be easy to blow the 150 amp fuse when the DC to DC converter is constantly equalizing the amps coming in against the amps drawn.

I’ll soon be running tests with the inverter connected. Of course the vehicle will be on. First a 200 watt heater, then two of them, three, etc. The inverter maxes out at 1000 watts. I’ve decided to put a 120 amp circuit breaker on it for more flexibility, I’ll be able to monitor if there is any point where the DC to DC converter can’t keep up.

Might take a week to report back. Please let me know if you think I’m missing something other than the obvious risks.
 

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Discussion Starter · #11 ·
Didn’t notice before that this was already done on an EV:

Thanks @aginzu! @atc98092 seems like you might have tried this?
 

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Discussion Starter · #12 · (Edited)
First round of tests went flawlessly (this would be the final round but I’m waiting on the 120 amp circuit breaker for higher wattage tests). This test went to 400 watts.

Peak amps on the inverter with a 200 watt heater start is 34, stabilizes at 17.
Peak amps at the inverter with a 400 watt heater start is 46, stabilizes at 33.

DC to DC converter equalizes whatever the draw is by pushing equivalent amps into the 12 volt system. Ran the system at 400 watts for five minutes and the gas engine never turned on. However the traction battery was drawn down. I’ll try to quantify that more carefully next time. If the traction battery was low the engine would turn on to maintain the DC to DC converter charge.

So everything works as expected. 1000 Watt tests soon.

In addition to providing emergency power one observation is that if you were camping in a cold area, and didn’t want the car to keep starting for heat, an inverter would permit a 200 watt heater to heat the car without the gas engine turning on until the traction battery was exhausted. With a full 8.9 kWh traction battery that’s going to last a long time.

Another observation is that having the battery in the rear hatch makes this much more feasible than a battery under the hood (unless you have a garage and run a tube out for monoxide). The Prius was attractive in this way. But the Prius moved the 12v under the hood starting in 2016.

So the Niro is probably the ideal affordable camping car. Any simple hybrid is turning the gas engine on and off all night to maintain interior climate. But the 8.9 kWh traction battery allows for overnight climate control without the gas engine turning on. And 74 inches of sleeping space without modification. (One can do slightly better - a PHEV RAV4, Tucson, etc - for probably about $10,000 more in this market [complicated by differing tax credits.])

For anyone following along here is a huge dive into how these systems work on a Prius:
 

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Discussion Starter · #15 · (Edited)
Interesting. So if you click left and right on the pages here you can learn a lot about the DC to DC convertor. Most interesting for this conversation is that it appears the converter can provide a maximum of 1800 watts to the 12 volt battery. So that makes me even more confident that 1000 watts continuous is manageable - particularly with no other significant loads. Further confirmation of what @91cavgt had proven already.


By the way, through the OBD the Car Scanner app offers me the voltage of the auxiliary battery. It also notes two additional sensors related to the 12v auxiliary battery:
[VMCU] AUX amps LDC
[VMCU] Auxiliary Battery Current var.2

The first sensor would, I think, tell us how many amps the DC converter is sending the 12 volt. The second likely how many amps are being drawn from the 12 volt. But these two sensors are the only two, in the 100 or so sensors, for which Car Scanner does not return data.

That said there does seem to be hope. It appears to be possible to input a custom PID to obtain the data. I’ve reached out to @davidtm who might know more…

Here is the discussion: Tracking the 12v Battery with OBD2 @Watchdog.

And just to put everything in one place here is this:Custom sensors (PIDs) – Car Scanner ELM OBD2. Using Car Scanner primarily because I’m on an iPhone.
 
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