Kona as a backup battery for home power outage?

So, I might be jumping ship to Kona EV if I pursue buyback w/GM for my '19 Bolt and the offer is good (more details at https://www.vwidtalk.com/threads/inverter-on-12v-bus-to-power-devices-during-extended-power-outage.3073/).

Does the Kona Electric have any sort of timeout where it shuts itself off after being in READY mode for 1+ hours? Is there a workaround? Bolt had a relatively easy workaround that for me in 2 over 24 hour https://www.pge.com/en_US/residential/outages/public-safety-power-shuttoff/learn-about-psps.page that happened in 2019. I wouldn't be surprised if we have more in the next few years.

 

Bolt allowed hvac to stay on indefinitely while you're not in it ,as long as there's a charge which the Kona electric doesn't offer.

 

Wouldn't that be "Utility mode"?

 

So, for you PV nerds: Is there a smallish string inverter that can accept pretty much anywhere between 330
and 420 or so volts DC? Such a thing could likely run straight from a typical 96S or 98S EV pack. I'm still
thinking that Utility mode and a little relay skulduggery to bring the rapid-charge contacts hot could make
a perfectly usable "plug-out". I'm more interested in this now that the Prius has been put out to pasture
and my old plug-out is sitting unloved and unpowered in the basement. It can only
deal with up to maybe 260V or so.

_H*

 

I've looked into this - it certainly is doable, The coils of the contactors in the HV junction box connect directly to the connector on the front of the HVJB, so would be possible to actuate them to connect the battery to the CCS connector pins. (I.e. there is no CANbus or other intelligence inside the HVJB) As far as I can tell, there is no monitoring of the charger-side HV connections ( i.e. the car wouldn't think the contactors have welded) .
I suspect there might be some monitoring of the contactor coils, as there are seperate + and - connections to each contactor coil and none appear to connect directly to ground or +12V. If there is any monitoring, this could be worked around. Unfortunately I think these connect to the BMS in the battery so hard to access to see what the they connect to.
You can buy DC-input inverters that should work - I bought this one to look at :
https://www.aliexpress.com/item/1005001704095436.html?spm=a2g0s.9042311.0.0.48bf4c4dRALLGm
I'm not too impressed with the build quality, and there is no protection to speak of.
I've also sketched out an idea for how an external CCS plug could signal to some added circuitry to control the contactors to turn them on when my "special" plug is inserted.

However the one thing that prevents me moving forward is that the inverter output is this :
That inverter (and another solar unit I looked at) is not galvanically isolated from the input.
And I don't know that if "something" triggers the car's HV isolation test, which will probably lock out the HV system, whether it can be reset without access to the manufacturer's diagnostic tools.
If I was sure that I could recover from this I would definitely investigate further.

As regards doing it without any mods to the car, I know (first hand from someone who has done it) that on at least one car (ID3 or 4, don't recall which but likely both), it is possible for something that pretends to be a CCS charger to initiate a charge session but not supply any current, and draw current from the CCS pins, without any errors or timeout from the car. I would think this is very implementation-dependent, so may or may not be feasible on other cars.

 

No,for utility mode to remain on,you'd need to leave your door unlocked with your fob inside while you're not in the vehicle.

 

I just tried that and I could walk away with the fob and it stayed in utility mode. Locking the doors was harder but seemed possible.

 

Just got to use the clandestine key inside the fob to look the door once you're out. This is how I kept my Kona alive while waiting a week for dealer to replace my very dead 12v battery under warranty.

Sent from my ONEPLUS A5000 using Tapatalk

 

We had a storm here today, and power was out for 4 hours. I have several salt water aquariums with coral and fish that are very sensitive to lack of water flow and temperature changes. So I attached my inverter to the 12V battery and ran an extension cord from the car in the garage to my pumps. Kept my aquariums going, and only used up 2 kms of range. So really didn't take much power.

First time I had to do this, so wasn't exactly sure how Utility mode worked. I turned it on, but had to keep the car in the On position to keep it active. Reading the manual later, I found that is how it works. So I also had to shut off my auto lights so I wouldn't waste extra power there. But it made me wonder what is the benefit of Utility mode if you have to leave your car On with the fob inside it? I thought if the car was On it was always charging the 12V battery anyway? So why use Utility mode?

I did check SOC on my 12 battery while the inverter was on, and the voltage was a steady 14.65V, so obviously was being vigorously charged. Any thoughts about this?

 

Why do you think you need to leave the key inside ?
I think the thing about utility mode is that you can't put the car into drive or reverse. Not tried it but I'd expect you can lock the door and take the key away.
While utility mode is on, the HV system is active, so the DC/DC converter is supplying regulated voltage to the 12V system

 

Oh, I thought if the car had to be left in the On position, it would get upset and beep if I walked away with the fob.

But again, why do you even need Utility mode if the 12V is always being charged anyway when the car is left On? Is there any benefit by also turning on Utility mode? I did turn off radio, climate and lights.

 

Utility mode seems to function as an anti-theft feature. If you leave the car ON (even without the key fob), someone could drive off with it.

 

It beeps, but stops after a few seconds.
As above, it stops the car being driven. It's possible that it may shut down some systems to save power.

 

Well, it is in my garage, so no worry about theft. But was just surprised the car had to left in the On position when using Utility mode. If you can leave it that way and walk away with the fob, I guess that is OK then.

 

I'm gonna have to get a half decent inverter. Last winter our power went out for almost 12 hrs overnight and the wife had a horrible sleep as she couldn't use her cpap machine. A few other times, power went out in the neighborhood and it would be nice to have some juice to power a few things.

 

Don't get a cheap one! Shop around a bit. Mine is only a 1500W unit with 'True Sine Wave' output. I only used it once connected to my Prius. In that case I had to leave the car outside, because the engine worked on and off as needed to charge the 8kW battery. This is a non issue with EVs.

1500W is not much but kept our LED lights on. Ours was the only house with lights in the hood! I am quite sure it would be enough to run the furnace with a couple of LED bulbs in the house but never tried.

IMPORTANT NOTE! If you decide to feed power back into the house SHOT OFF the Main Breaker BEFORE you connect the inverter. And disconnect the inverter before turning the Main Breaker back on.

 

Better yet if you decide to feed the house from the inverter use a proper interlock circuit. They are not expensive only about $50. They interlock with the main breaker with the inverter feed breaker so that the main circuit breaker cannot be on at the same time as the inverter feed circuit breaker so it either the main or the inverter is on not both. In addition if you are going to feed the house with an inverter make sure that it is compatible with a bonded neutral other wise you will have problems. Only the more expensive inverters are designed for and comparable with bonded neutral.

 

^^^^^ Thanks Lars for the tips.
Yeah when I read about it before, I did read about getting a true sine wave one.

 

Also, I think there is a limit how many watts can be fed from your 12V, so as not to overtax charging from your traction battery. I would just use extension cords to various appliances. Fridges and freezers only have to be on for short while at a time to retain their cooling. And we have a couple of nat gas fireplaces in the house we can turn on to keep warm. Stove, oven, and hot water are gas. Plus we have a few LED lanterns, so can do without house lights. I even ran my computer and wifi internet with my UPS from time to time. So I can last for quite a while without power if need be.