Kona as a backup battery for home power outage?

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Thanks. With this knowledge I'm going to buy a 1200 Watt pure sine wave inverter, attach it to the battery if we get a power failure here in central CT,
and plug in my electric blanket.
 
hobbit said:
For completeness, here's another Goal Zero link. Nice product line,
but has a few issues on integration. It is possible to charge at 350 watts
via the mini-Anderson connection, as long as the source is north of 13.5
volts or so. The Kona with its ridiculously high 12V rail has no problem
with that...
_H*
Click to expand...
https://techcrunch.com/2019/09/29/k...delta-battery-generator-is-not-what-it-seems/

Hey what do you think of this unit? It claims to be able to charge 1300Wh in under two hours, wow, so it can take most everything the Kona 12V can throw at it. Feels like it can be an ideal backup scenario for us.

Fastnf said:
A simpler approach would be to have a transfer box installed and connect it to a 1000 watt inverter connected directly to the Kona battery. This would be more efficient than running the power trough Goal zero battery and charger.
Click to expand...

Thanks for breaking things down for me. Other than much lower continuous/peak output than something like the EcoFlow Delta linked above, are there more disadvantages to the inverter-only setup you suggest?

Also thanks for letting me know about the Vue. I bought one and can't wait to play with it.

eastpole said:
Milesian, can you tell us more? Are you heating with electrical resistance? Running a heat pump? Or just sparking up a gas boiler and circulating some hot water? Different heating systems have vastly different electrical draws...
eastpole
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Everything is gas for me in the winter, both water and heat, and no pumps or anything. So you're right, for emergencies I can likely get by even on the Kona 12V alone. That said, maybe something more powerful like the above 1800W/3300W EcoFlow is still a prudent choice, especially if it can really be recharged by the Kona at the rate that it alleges. Penny for everyone's thoughts.
 
milesian said:
Hey what do you think of this unit? It claims to be able to charge 1300Wh in under two hours, wow, so it can take most everything the Kona 12V can throw at it. Feels like it can be an ideal backup scenario for us.
Click to expand...

So the ecoflow is basically a 100 amp hour lithium battery connected to an inverter/charger. It has a 1800 watt output so it makes about 5 amps more than connecting an inverter straight to the Kona battery. Not sure its worth a grand for that. Also eventually you will reach a steady-state where what your putting in from the Kona is what you getting out of the ECOFlow. The only real advantage is the surge capacity. For that I would just buy a couple of deep cycle batteries to connect in parallel with the Kona battery and hook the inverter to the deep cycle batteries. This will cut the draw from any one battery including the Kona and its charger while providing short term surge capacity for running things such as running the furnace and the refrigerator simultaneously then when the surge settles the Kona will bring the charge back up on all the batteries.
 
Jgood said:
I saw this yesterday. https://electrek.co/2020/01/06/wallbox-quasar-tesla-nissan/ This is a fantastic idea. I really hope Hyundai gets on board with this. Of course we'd all have to buy new Kona's that support bi-directional current flow. Somehow I think Hyundai wouldn't mind that...
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Yeah I don't think I would be too excited about using a battery pack that currently has a $30K+ replacement cost + $4K for an bidirectional EVSE, while a much cheaper ICE generator or even a couple of dedicated Powerwalls will do it with much less financial risk. I could also see Hyundai not exited about this from a warranty perspective.
 
Apparently Nissan already has a certification program in place for companies that want to build products that utilize their battery pack. I'm willing to bet that every car BEV manufacturer will have something like this in less than 5 years. Especially since this is an emergency back up. We're not talking about people running their daily lives off their car's battery pack. This is more like an ice storm power outage that lets people keep the lights on or their furnace operating. A household of frozen and broken pipes could do far more than $30K of damage. Plus the inverter in this thing only allows 7.4 kwh in EITHER direction. It's not likely to damage the battery if the power flow OUT is no greater than a level 2 charger IN. Hooking your car up to a DC charger is going to be far more stressful on your battery pack than running your refrigerator. As someone who lives in the northeast and deals with many potential storm related power outages each year, I'd buy-in a heartbeat.
 
I would have concerns about using the connector that I use for occasional rapid charging getting the wear and tear of everyday charging.
I can also see car makers being very wary of allowing (via providing software support in the BMS) this type of use due to the possible bad consequences of the full battery supply being available in a domestic environment. A damaged cable could be a major arc-flash fire and injury risk.
 
Jgood said:
Apparently Nissan already has a certification program in place for companies that want to build products that utilize their battery pack. I'm willing to bet that every car BEV manufacturer will have something like this in less than 5 years. Especially since this is an emergency back up. We're not talking about people running their daily lives off their car's battery pack. This is more like an ice storm power outage that lets people keep the lights on or their furnace operating. A household of frozen and broken pipes could do far more than $30K of damage. Plus the inverter in this thing only allows 7.4 kwh in EITHER direction. It's not likely to damage the battery if the power flow OUT is no greater than a level 2 charger IN. Hooking your car up to a DC charger is going to be far more stressful on your battery pack than running your refrigerator. As someone who lives in the northeast and deals with many potential storm related power outages each year, I'd buy-in a heartbeat.
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The economics make no sense when you can buy a energy efficient Honda inverter generator for under $1000 to do exactly the same thing. Sorry I don't see it taking off at $4K but I could be wrong, wouldn't be the first time.
 
apu said:
The economics make no sense when you can buy a energy efficient Honda inverter generator for under $1000 to do exactly the same thing. Sorry I don't see it taking off at $4K but I could be wrong, wouldn't be the first time.
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Until the carbon monoxide fumes; frequent refueling, and; noise has to be dealt with. Add to that the failures to start because it was not run for several years. Then there is the cost per kilowatt hour.

Pay me now or pay me later.

Bob Wilson
 
apu said:
The economics make no sense when you can buy a energy efficient Honda inverter generator for under $1000 to do exactly the same thing. Sorry I don't see it taking off at $4K but I could be wrong, wouldn't be the first time.
Click to expand...

I would buy it. First it puts out 7 kw that's lot more than a Honda inverter generator. A 4 kw Honda inverter generator is around $4k. I have a 5.5 kw generator and it is noisy but livable. I have it running on propane off of a 250 gallon tank so it can run all day. I don't run it at night. I use it may be twice a year.

With this product I could use it in conjunction with my solar and run indefinitely with no fuel costs, oil changes, emissions or noise. As far as the affect on the battery it uses about the same energy as cursing at about 50mph. I don't drive a lot of miles so using it for a back up for me would not cycle the battery any more than most on the site are with there normal driving.

It may not work for everyone but it would for me.
 
Of some relevance, this article and photo appeared on the FB group, frustratingly with no details.

81895454_10157803302288164_8038052812250152960_n.jpg
 
I'll bet that it's much easier to do this with CHAdeMO than CCS, for starters, just from
the complexity of control protocols. On the other hand, this is what ISO-15118 is
supposed to be for. Except that there are lots of vehicles already on the road
that can't natively participate in this, so either they're hosed or Wallbox has come
up with some clever workaround to convince DC-chargeable cars to at least
turn on the big DC contacts and then not worry about current flowing in the
"wrong direction". I'm going to try and get a question to the company as far
as their expectations on vehicle compatibility. And what they do about
islanding, transfer switches, etc.

That output to "the grid" had better be real split-phase 240 with a proper
neutral and ground, too, as it's going to see unbalanced loads and stuff
that also needs 240 to work [like my heat pump]. There are quite a few
ancillary things to think about for a real-life installation.

_H*
 
hobbit said:
That output to "the grid" had better be real split-phase 240 with a proper
neutral and ground, too, as it's going to see unbalanced loads and stuff
that also needs 240 to work [like my heat pump]. There are quite a few
ancillary things to think about for a real-life installation.
Click to expand...

As a thought experiment, I wonder if you could find a Leaf in a junkyard, and take the battery, inverter, and Chademo charging circuitry to make your own powerwall? What could possibly go wrong?

We have a surprising number of 240V circuits in the house, but none that I would contemplate trying to run from a Kona battery. We have a gas fireplace that we use from time to time (the only gas appliance in the house). It doesn't throw off a huge amount of heat, but it would do if there were a power outage.
 
Really happy to see this thread bumped. I've taken everything I learned here (special credit to Fastnf and Kiwime) and very slowly pieced together a solution over the years, or so I hope. No electrician would help me plan, nevermind do the whole project for me so I decided to try it myself. Would you guys mind gut-checking my rookie outing?

Starter battery -> 70A fuse -> 50A DC-DC charger with total 3 feet of 4 AWG wire

I got a second identical 50A DC-DC charger, same as above.

2x DC-DC chargers -> 70A breakers -> 100Ah LFP battery with total 3 feet each of 4 AWG wire

LFP battery -> 250A breaker -> 3kW split-phase inverter with 1.5 feet of 0 AWG wire

Inverter -> 30A house panel breaker (interlocked with mains breaker) with 30 feet of 10-3 Romex wire, ground to neutral bus bar

The two DC-DC chargers supposedly have mid-90% efficiency, so the Kona should survive even a 2x 50A draw for some time. Downstream from there, the LFP battery can discharge at 100A, so altogether this setup can send 200A to the split phase inverter. I'd like for this setup to power a 700W to 1300W sustained and 2000W peak AC house load.

Voltage drops average around 1%. Different wire size charts gave me different answers, but I feel pretty comfortable with the setup. Or, should I not?

Penny for any and all you guys' thoughts and advice, as always.

Sent from my ONEPLUS A5000 using Tapatalk
 
milesian said:
Really happy to see this thread bumped. I've taken everything I learned here (special credit to Fastnf and Kiwime) and very slowly pieced together a solution over the years, or so I hope. No electrician would help me plan, nevermind do the whole project for me so I decided to try it myself. Would you guys mind gut-checking my rookie outing?

Starter battery -> 70A fuse -> 50A DC-DC charger with total 3 feet of 4 AWG wire

I got a second identical 50A DC-DC charger, same as above.

2x DC-DC chargers -> 70A breakers -> 100Ah LFP battery with total 3 feet each of 4 AWG wire

LFP battery -> 250A breaker -> 3kW split-phase inverter with 1.5 feet of 0 AWG wire

Inverter -> 30A house panel breaker (interlocked with mains breaker) with 30 feet of 10-3 Romex wire, ground to neutral bus bar

The two DC-DC chargers supposedly have mid-90% efficiency, so the Kona should survive even a 2x 50A draw for some time. Downstream from there, the LFP battery can discharge at 100A, so altogether this setup can send 200A to the split phase inverter. I'd like for this setup to power a 700W to 1300W sustained and 2000W peak AC house load.

Voltage drops average around 1%. Different wire size charts gave me different answers, but I feel pretty comfortable with the setup. Or, should I not?

Penny for any and all you guys' thoughts and advice, as always.

Sent from my ONEPLUS A5000 using Tapatalk
Click to expand...

The wiring sizes look correct. And the main breaker interlock is definitely required A wiring schematic would be helpful to see how you have this set up. (or a written description of how the system is connected to the various components). As I understand it the DC to DC charger typically can charge both the starter battery and the deep cycle battery from either a solar panel or an alternator. Are you using the cars high voltage dc to low voltage dc converter as your alternator replacement. Can you clarify the need for the second DC-DC charger. Is it because of the different battery types? LFP versus lead acid. Are you also using solar or just the high voltage battery through the cars dc-dc charger. Also what brand of inverter and DC-DC chargers are you using?
 
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