Kona as a backup battery for home power outage?

[milesian]

I'm a little embarrassed to share my schematic, but maybe it's not as bad as I think. See attached.

https://www.renogy.com/dcc50s-12v-50a-dc-dc-on-board-battery-charger-with-mppt/

The DC-DC charger route appealed to me because I wanted to electrically isolate the Kona from everything else. I bought 2x of this 50A charger because I'm greedy and wanted 100A out of the Kona. No 100A DC-DC device seems to exist, but YouTube (and a Renogy FAQ) told me two 50A chargers should work together to give me 100A. We shall soon see... I plan to hook it up this weekend. Gulp.

Another reason I bought this DC-DC model was because it only calls for a connection to the starter battery, not direct to an alternator (can we even do that?) Its ability to work with SLA->LFP was another reason, though now I'm worried I made the wrong choice. Apparently LFP batteries cannot charge under 32F, so unless I figure out how to keep it warm in my garage during a winter outage, it'll be drained and useless in no time. Any advice?

As for solar, this charger can indeed accept 660W at 24V. This probably means I'll get to try my first solar panel ever. Look forward to that, though got to figure out something to actually power. Maybe my new 600W water distiller? Hmm intriguing.

https://www.sigineer.com/wp-content...ower-Combi-Inverter-Charger-Owners-Manual.pdf

My 3kW split-phase inverter is the Sigineer model you found years back, Fastnf. Still haven't tested it yet but already worried I made the wrong choice. Initially I thought, hey, 3000W inverter means I can send 25A (pre-losses) to my house, nice, that's more than I need. But for a split-phase inverter, doesn't that mean each hot line only carries half of 25A, meaning I can only send 12.5A (pre-losses) to either side of my panel bus bars? Real bummer if so...

 

[Fastnf]

I'm a little embarrassed to share my schematic, but maybe it's not as bad as I think. See attached.

https://www.renogy.com/dcc50s-12v-50a-dc-dc-on-board-battery-charger-with-mppt/

The DC-DC charger route appealed to me because I wanted to electrically isolate the Kona from everything else. I bought 2x of this 50A charger because I'm greedy and wanted 100A out of the Kona. No 100A DC-DC device seems to exist, but YouTube (and a Renogy FAQ) told me two 50A chargers should work together to give me 100A. We shall soon see... I plan to hook it up this weekend. Gulp.

Another reason I bought this DC-DC model was because it only calls for a connection to the starter battery, not direct to an alternator (can we even do that?) Its ability to work with SLA->LFP was another reason, though now I'm worried I made the wrong choice. Apparently LFP batteries cannot charge under 32F, so unless I figure out how to keep it warm in my garage during a winter outage, it'll be drained and useless in no time. Any advice?

As for solar, this charger can indeed accept 660W at 24V. This probably means I'll get to try my first solar panel ever. Look forward to that, though got to figure out something to actually power. Maybe my new 600W water distiller? Hmm intriguing.

https://www.sigineer.com/wp-content...ower-Combi-Inverter-Charger-Owners-Manual.pdf

My 3kW split-phase inverter is the Sigineer model you found years back, Fastnf. Still haven't tested it yet but already worried I made the wrong choice. Initially I thought, hey, 3000W inverter means I can send 25A (pre-losses) to my house, nice, that's more than I need. But for a split-phase inverter, doesn't that mean each hot line only carries half of 25A, meaning I can only send 12.5A (pre-losses) to either side of my panel bus bars? Real bummer if so...View attachment 11419

First don't be embarrassed about your schematic. Peer review is what makes us better. My biggest complaint as an engineer is lack of decent peer review. I want to know what my mistakes are so I can correct them, grow and be better.

The only question I have on the schematics is: Is the 70 amp breaker in the A line on the A1 side or the A2 side of the leg. It should be on the A2 leg. Wire size all look good.

You will get 3kw at the house. It will just be 1.5 kw on each 120 volt leg. or 3kw on 240 volts. or some combination of 240v and 120v with a total of 3kw I would make a load chart of the items you want to run and the evenly distribute them between the two 120 v legs and if any 240 volt. The total should come to 3kw or less.

The next thing I would suggest is rather than hook every thing up at once do component testing first. This will help in both verification and trouble shouting of components. I would recommend the following test and order.

First test the inverter and LFP battery together but not connected to the house or the car. Connect loads directly to the inverter. This will verify that the inverter is working properly

Second disconnect the inverter from the LFP and connect the LFP to the DC-DC charger and the charger to the starter battery and turn on the car. The LFP should be in a low start of charge in order to properly test the charging: This verifies that the DC-DC chargers are working

Third if the LFP charges properly in step 2 connect the inverter and loads and test the system with the inverter operating and connected to LFP charger and car but not the house.

Fourth disconnect the LFP from the charger and car. Then connect the inverter to the house with no loads applied then connect the LFP to the inverter still no loads applied. Then start adding small loads and evaluate the system while connected to the house. Be aware that some inexpensive inverters have a floating neural and aren't happy having neutral and ground tied together as in a typical house system.

Fifth when all of the bugs have been worked out of the first 4 steps and every thing is working properly, disconnect the loads and connect the charger and car back up to the LFP and see if the LFP charges properly. Still connected to the house with no loads applied

Finally add loads to the set up from step five and test the entire system.

Also verify the continuous load of the inverter. I have a 3kw inverter but its only rated at that for 15 minuets. Its continuous rating turns out to be 2.2 kw. Found that information buried in the manual. Mine also has a one minute surge of 6kw for motor starting and the like.

Also Keep in mind you are experimenting with you house and your car and are doing so at your own risk.

 

[Lars]

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

I agree with Fastnf, we need more details. Not sure what are you trying to achieve. A wiring diagram for start would be nice.

 

[milesian]

A wiring diagram for start would be nice.

Hi Lars, I attached a diagram to my post before Fastnf's masterful work plan above yours. Would be glad to hear your commentary.

Thank you kindly for the work plan, Fastnf. That helps me more than you know, though probably you do know. You're right about not being afraid to show my work. It's more about my rookie confidence level rather than embarrassment, you know how that goes.

https://www.amazon.com/gp/product/B000CQBNJ4/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

I got a burning question before replying to your post: I found an adapter on Amazon (link above) that I plan to screw onto the Kona's positive terminal stud each time I want to tap into it. While it does fit, I can only turn it like 3 or 4 times before it gets stuck, so the adapter is barely halfway screwed onto the stud. Do you think that's sufficient contact from the standpoint of safe/stable power transfer? And in general, do I have to worry about this adapter overheating/melting like I do when sizing wires?

You will get 3kw at the house. It will just be 1.5 kw on each 120 volt leg.

Does this mean if I try to power a 1.6kW+ 120V appliance, the inverter is going to trip?

make a load chart of the items you want to run and the evenly distribute them between the two 120 v legs

"Evenly distributing my loads" means I'd have to rearrange my panel breakers between the main bus bars according to my load audit, right?

Be aware that some inexpensive inverters have a floating neural and aren't happy having neutral and ground tied together as in a typical house system.

I thought a "floating neutral" inverter means that the ground would need to be provided by the panel? So I emailed Sigineer about this and they said "our AC output neutral can be bonded to the ground or separated." I have no idea what that means, so I told them that I'm hardwiring the inverter into my main panel which has a single neutral+ground bar. They said yes just wire the neutral and ground wires together just like everything else is wired in my panel. I'm counting on it...

 

[Fastnf]

T

Hi Lars, I attached a diagram to my post before Fastnf's masterful work plan above yours. Would be glad to hear your commentary.

Thank you kindly for the work plan, Fastnf. That helps me more than you know, though probably you do know. You're right about not being afraid to show my work. It's more about my rookie confidence level rather than embarrassment, you know how that goes.

https://www.amazon.com/gp/product/B000CQBNJ4/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

I got a burning question before replying to your post: I found an adapter on Amazon (link above) that I plan to screw onto the Kona's positive terminal stud each time I want to tap into it. While it does fit, I can only turn it like 3 or 4 times before it gets stuck, so the adapter is barely halfway screwed onto the stud. Do you think that's sufficient contact from the standpoint of safe/stable power transfer? And in general, do I have to worry about this adapter overheating/melting like I do when sizing wires?


Does this mean if I try to power a 1.6kW+ 120V appliance, the inverter is going to trip?

"Evenly distributing my loads" means I'd have to rearrange my panel breakers between the main bus bars according to my load audit, right?

I thought a "floating neutral" inverter means that the ground would need to be provided by the panel? So I emailed Sigineer about this and they said "our AC output neutral can be bonded to the ground or separated." I have no idea what that means, so I told them that I'm hardwiring the inverter into my main panel which has a single neutral+ground bar. They said yes just wire the neutral and ground wires together just like everything else is wired in my panel. I'm counting on it...

In answer to your question

1: it depends on the 1.6 kw appliance. If it is some thing like a heater 1.6 kw heater where operate continuously at 1.6kw it will work but tend to over heat the inverter if run for long periods. If the appliance if some thing like a refrigerator or a/c with at motor. It is rated at the starting (max) kw but drops to a lower kw (continuous running load ) once started, there will be no issues as long as the continuous load of the appliance is with in the rating of the continuous load of the inverter.

To evenly distribute the load you don't have to move breakers but you could. The easy way is just figure out which plugs are on different bus bars and plug the appliances into the plugs that evenly distribute the load between bus bars.

So according to Sigineer your fine to connect the ground to the house panel with a bounded neutral so your good on that point.

Finally rather than hard wiring your unit to the house panel I would recommend using a generator power inlet. That way you can plug in when you want to and the rest of the time leave the system disconnected. It also allows you to use a generator if you want to. The generator power inlets are code approved and can be permitted. I have one on my box and use it for either my generator or an inverter. Below are links to two types, an add on box and one that can be installed in an existing box.

https://smile.amazon.com/X-Haibei-G...30+amp+generator+inlet&qid=1617978302&sr=8-16

https://smile.amazon.com/Generators...jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==
.
Here are a couple of shots of my power in let

 

[Lars]

T


In answer to your question

1: it depends on the 1.6 kw appliance. If it is some thing like a heater 1.6 kw heater where operate continuously at 1.6kw it will work but tend to over heat the inverter if run for long periods. If the appliance if some thing like a refrigerator or a/c with at motor. It is rated at the starting (max) kw but drops to a lower kw (continuous running load ) once started, there will be no issues as long as the continuous load of the appliance is with in the rating of the continuous load of the inverter.

To evenly distribute the load you don't have to move breakers but you could. The easy way is just figure out which plugs are on different bus bars and plug the appliances into the plugs that evenly distribute the load between bus bars.

So according to Sigineer your fine to connect the ground to the house panel with a bounded neutral so your good on that point.

Finally rather than hard wiring your unit to the house panel I would recommend using a generator power inlet. That way you can plug in when you want to and the rest of the time leave the system disconnected. It also allows you to use a generator if you want to. The generator power inlets are code approved and can be permitted. I have one on my box and use it for either my generator or an inverter. Below are links to two types, an add on box and one that can be installed in an existing box.

https://smile.amazon.com/X-Haibei-G...30+amp+generator+inlet&qid=1617978302&sr=8-16

https://smile.amazon.com/Generators...jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==
.
Here are a couple of shots of my power in let

View attachment 11442 View attachment 11443

This project is beyond my comfort zone. I am not up on generator connections, never needed one. I only know that you have to make sure that you disconnect the the house from the hydro before connecting any power source to your home wiring. You also have to be careful about how you handle the NEURAL connection. It is true that it it is ultimately connected to (frame/earth) ground. But this connection should only be made at a single point - usually at the main electrical box. Having multiple locations can result in "phantom currents" on the neutral lines.
The bottom line is I would consult a licensed electrician in your area for advice.

 

[Fastnf]

I agree with you completely. If you have any concerns get a professional to help. In my case I always get a permit form the county and have my work in inspected and approved. Like I said earlier I appreciate good peer review.

You are correct about disconnecting from power. I have an interlock on my generator inlet and you cannot turn on the generator breaker without first shutting off the main. Hence the name interlock. The two breaker are interlocked so that one must be off for the other to be on. Below is a picture of my interlock (the sliding silver plate) This is a UL approved and code permitted interlock. Note that the generator 30 amp breaker cannot be turned on because of the silver tab keeping it in the off position. To turn it on you must turn off the main breaker slide the silver plate up. When you do this the main breaker is held in the off position and the silver tab is held up by the on generator circuit breaker . To turn on the main beaker you have to turn off the generator breaker and slide the silver plate down.

 

[Fastnf]

I got a burning question before replying to your post: I found an adapter on Amazon (link above) that I plan to screw onto the Kona's positive terminal stud each time I want to tap into it. While it does fit, I can only turn it like 3 or 4 times before it gets stuck, so the adapter is barely halfway screwed onto the stud. Do you think that's sufficient contact from the standpoint of safe/stable power transfer? And in general, do I have to worry about this adapter overheating/melting like I do when sizing wires?

Well melting probably isn't an issue as its brass on steel. I am guessing it is bottoming out in the threads so it probably has a fairly good connection. During you initial testing when your charging the LFP keep an eye on it and see if it gets warm or hot. If so find a different connection method

I just used a piece of copper pipe that I flattened and bent in to an L bracket which I bolt to the top of the battery clamp.

 

[electriceddy]

I agree with you completely. If you have any concerns get a professional to help. In my case I always get a permit form the county and have my work in inspected and approved. Like I said earlier I appreciate good peer review.

You are correct about disconnecting from power. I have an interlock on my generator inlet and you cannot turn on the generator breaker without first shutting off the main. Hence the name interlock. The two breaker are interlocked so that one must be off for the other to be on. Below is a picture of my interlock (the sliding silver plate) This is a UL approved and code permitted interlock. Note that the generator 30 amp breaker cannot be turned on because of the silver tab keeping it in the off position. To turn it on you must turn off the main breaker slide the silver plate up. When you do this the main breaker is held in the off position and the silver tab is held up by the on generator circuit breaker . To turn on the main beaker you have to turn off the generator breaker and slide the silver plate down.

View attachment 11445

Those interlock kits are the cheapest way to go, I have installed quite a few over the years on various electrical panels. Much more cost effective (and labor savings) than a generator panel installation, although you do have to be careful not to put too much load on the generator... ie leave written instructions to just keep certain breakers on such as freezer, water pump, lighting circuit, and a couple of receptacles- load calculated to match running wattage of generator. I typically use a solid bonded neutral connection (neutral bonded solid to the panels neutral bar which is bonded to ground at the service side) with a separate bonding conductor run to the generator.
BTW kits are available at any electrical wholesaler.

 

[milesian]

Checking back in after my tests this past weekend. All is working as hoped between Kona and inverter. The two DC-DC chargers are very efficient, each asking just ~55A from the Kona to output 50A. Best part is they limit the current drawn from the Kona to a safe ~110A and allows my LFP house battery to carry the remaining load. Case in point, the Kona LDC output (per hobbit's Torque PID) never rose above 115A and kept the Kona at a stable 13.4V on a 1650W test load. Splendid.

On a side note, the Kona seems to keep itself at 14.6V a lot less than it used to, almost like it knows to float the starter battery. Is it just me or did the LDC have smart-ish charging logic all along?

If it is some thing like a heater 1.6 kw heater where operate continuously at 1.6kw it will work but tend to over heat the inverter if run for long periods.

You called it. A constant 1650W test load (hair dryer) on the AC receptacle immediately flashed overload warnings on the inverter, though the load didn't run long enough to trip it. I guess this same "50% of rated-capacity per leg" limitation will also apply to the inverter's AC terminal block. Wish I had understood this before buying into this setup.

To evenly distribute the load you don't have to move breakers but you could. The easy way is just figure out which plugs are on different bus bars and plug the appliances into the plugs that evenly distribute the load between bus bars.

See attached photo of my tiny load center. It's also full up after adding the backfeed breaker, and with so many tandem breakers already in play, I'm not sure any amount of fooling around can evenly distribute my loads.

During you initial testing when your charging the LFP keep an eye on it and see if it gets warm or hot. If so find a different connection method

A constant 100A load did cause the adapter to feel not-cold, as in slightly warm. The 9" cables from it to the breakers (A1 and B1 in my diagram above) also felt slightly warm. Is this a cause for concern? How long should I stress-test it to be sure?

Thanks for the power inlet and interlock references and masterful advice, Fastnf and electriceddy. Will consider adding an inlet later when needed. About the interlock kit, I'm lost trying to find what'll fit my ancient Challenger panel (see attached photo) to interlock breakers opposite each other. Any guidance for me?

Interlock kit or no, this weekend will be the house hookup and load test. Here we go.

Quick question: my DC circuit breakers have 1/4" studs but my ring terminals are 5/16". Any safety concerns pairing them together? They do screw down nice and tight, for all I know.

 

[Fastnf]

A constant 100A load did cause the adapter to feel not-cold, as in slightly warm. The 9" cables from it to the breakers (A1 and B1 in my diagram above) also felt slightly warm. Is this a cause for concern? How long should I stress-test it to be sure?

Best way to test it would be to use an infrared thermometer to measure the temperature of the adapter. Run it long enough for the temperature to stabilize. 10-20 degrees above ambient is probably ok.

About the interlock kit, I'm lost trying to find what'll fit my ancient Challenger panel (see attached photo) to interlock breakers opposite each other. Any guidance for me?

Some Bryant circuit breakers fit challenger boxes so perhaps this link to a Bryant interlock will work. Maybe contact the seller and verify dimensions and interchangeability

https://www.amazon.com/BRY-200A-Bry...sprefix=challenger+interlock,tools,813&sr=1-5

The 5/16 ring terminals should work if they are tight. if your concerned keep an eye on the temperature.

Also challenger breakers are not known for their reliability so if you change them out use a reputable brand like Bryant, Cutler-hammer or Eaton.

So to load balance make a list of all the loads you plan on running on the system continuously. Then list the intermittent loads like microwave and hair dryer. Remember you only have a max of 30 amps total and 15 per legs so your not going to be running a lot of things. Probably Heater-fan, Refrigerator, Lights, computer/wifi and TV. Figure out which circuit runs which load. Simply turn off the circuit. If the devise stops its on that breaker. For outlets use a circuit tester to see if its off. A lamp will also work. If the device is hard wired like a heater-fan list those first. Then you can move plug in devices to different out lets to balance the load If you need to re-balance

 

[electriceddy]

Checking back in after my tests this past weekend. All is working as hoped between Kona and inverter. The two DC-DC chargers are very efficient, each asking just ~55A from the Kona to output 50A. Best part is they limit the current drawn from the Kona to a safe ~110A and allows my LFP house battery to carry the remaining load. Case in point, the Kona LDC output (per hobbit's Torque PID) never rose above 115A and kept the Kona at a stable 13.4V on a 1650W test load. Splendid.

On a side note, the Kona seems to keep itself at 14.6V a lot less than it used to, almost like it knows to float the starter battery. Is it just me or did the LDC have smart-ish charging logic all along?

You called it. A constant 1650W test load (hair dryer) on the AC receptacle immediately flashed overload warnings on the inverter, though the load didn't run long enough to trip it. I guess this same "50% of rated-capacity per leg" limitation will also apply to the inverter's AC terminal block. Wish I had understood this before buying into this setup.

See attached photo of my tiny load center. It's also full up after adding the backfeed breaker, and with so many tandem breakers already in play, I'm not sure any amount of fooling around can evenly distribute my loads.

A constant 100A load did cause the adapter to feel not-cold, as in slightly warm. The 9" cables from it to the breakers (A1 and B1 in my diagram above) also felt slightly warm. Is this a cause for concern? How long should I stress-test it to be sure?

Thanks for the power inlet and interlock references and masterful advice, Fastnf and electriceddy. Will consider adding an inlet later when needed. About the interlock kit, I'm lost trying to find what'll fit my ancient Challenger panel (see attached photo) to interlock breakers opposite each other. Any guidance for me?

Interlock kit or no, this weekend will be the house hookup and load test. Here we go.

Quick question: my DC circuit breakers have 1/4" studs but my ring terminals are 5/16". Any safety concerns pairing them together? They do screw down nice and tight, for all I know.View attachment 11508

A straight on well lighted picture would help, but it looks to me as if all the identified conductors (neutrals) and bonding conductors (ground wires) are all tied onto the isolated neutral bar on the left side (and the right one as well?- I can't tell by the picture) if the bar on the right side is isolated as well or a properly bonded (to the can ) ground bar.
In any case it may be time for a panel change, to conform with neutral bonded to ground inside the service side of a combination type panel.(and the only location where that should happen). At least the feeder ground is bonding the neutral bar on the left side as it should be.
To repair best as possible using the existing panel, all the white conductors should be terminated to the isolated neutral bar and all the ground conductors should be tied onto a bar bolted to the panel. The ground wire from the ground electrode (if that's where it originates) should remain on the neutral bar (as it is) but in addition a separate (same size) ground wire should also be run to the box from the neutral bar or pass thru a ground lug bolted to the can before terminating to the neutral bar.
I hope this makes sense to you, normally there is a brass screw in the service compartments neutral connector to accomplish this.
Basically all whites to isolated neutral bar bonded to ground(with bonding screw or jumper) and all grounds to ground bar mounted to panel.
A grounding bushing couldn't hurt on the incoming feeder connector as well (if this was fed with ACWU or TECK cable there would be a bare ground as well)
Trying to install an interlock should be easy, think a turning circle with a space in one side to allow only the left or right breaker handle to be in the "on" position at one time, or even a square (movable side to side) piece of metal that would only allow one breaker to be on, mounted to the panel cover

 

[papab]

This is very nice. I've been wondering how I might do something like this with my future EV. I was thinking one would need to access the high voltage battery. It looks like the EV will keep the 12 V battery charged up with a pretty good load. Any idea how much capacity this circuit has? I understand your logic to use the DC-DC adapters & 100aH LFP for isolation, but it looks like all of that could be eliminated?

 

[Fastnf]

This is very nice. I've been wondering how I might do something like this with my future EV. I was thinking one would need to access the high voltage battery. It looks like the EV will keep the 12 V battery charged up with a pretty good load. Any idea how much capacity this circuit has? I understand your logic to use the DC-DC adapters & 100aH LFP for isolation, but it looks like all of that could be eliminated?

You can pull about 120 amps max out of the 12 volt battery with out blowing the battery fuse. I have a 3000watt pure sine wave inverter that I limit the input with a 100 amp dc circuit breaker so as not to over load the 12 volt battery circuit and have used it a number of times as a back up during power outages. It really nice at night when I don't want to listen to a generator running. It will run my refrigerator, tv, lights, and computer with no problems. Here is a link to that thread where I show that simple set up. https://www.insideevsforum.com/comm...-battery-backup-utility-mode.8589/#post-96554

 

[Recoil45]

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.

If you use an appropriate grid-tie inverter you can do exactly what you suggest. The concept was around and in use, way before Tesla power wall came out.


Sent from my iPhone using Tapatalk

 

[hobbit]

... Catching up ...

As with many such projects, it's somewhat unfortunate that you have to go down to 12V and back up.
I realize that's what we get off the shelf, but really, why doesn't someone make a decent self-starting
split phase inverter that accepts a wide range of DC input voltage? The "plugout" 3-kva unit I have for
the Prius runs from ~ 190V up to 250 or more, it wouldn"t be that much of a stretch to have a front end
that could handle up to somewhere north of 400. Heck, PC switching supplies start with something
like 350VDC derived from the wall. Proper topology would draw as much current as it needs at the
available voltage to drive the output. I think the "plugout" was derived from a PV string inverter but
it innards are pretty sketchy and of course there's no documentaton.

But it sounds like your 2 x 50 arrangement is being pretty efficient, and is producing around what the
plugout can do. If that thing sees >10A on either output leg it starts cycling annoyingly on and off.

There are main pack connections in that big "HV junction box" hung off the side of the charger/VCU
block,which I haven't dug into yet, and it seems like a bit of skulduggery with relay control could
even present pack voltage at the CCS connector.

_H*

 

[Recoil45]

Current grid tied inverters with battery backup are available in three voltage levels, 12, 24, 48.

It is wise for many reasons to use the 48v models. I have seen several installs using tesla packs which are around 48v. A 48v inverter will generally have a 40-64v input range.

It's possible to create inverters with higher voltage inputs, but then you have a whole other range of safety issues to deal with that increase costs of the installation.

Checkout the outback inverter or Victron energy forums to read up on them. Many people there are doing it for off grid purposes, but the same applies for the gridtie models.


Sent from my iPhone using Tapatalk

 

[hobbit]

Forgot to mention before, as well: be careful how you try to "float" that LFP unit. Their top-of-charge
dynamics are, uh, quite different from lead-acid. Kinda like the Kona pack... I don't yet know of a LFP
that will gracefully disconnect or current-limit itself under continuous charging and then kick back on
to deliver full current as soon as there's demand.

_H*

 

[milesian]

Figure out which circuit runs which load. Simply turn off the circuit.

https://www.amazon.com/gp/product/B000LEBRNE/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I found a super cool gadget for this. After living here 25 years, I finally know where circuits tie together. I'll need this knowledge because those empty slots in my panel turned out to be phantoms... there are no bus stabs for a breaker to grab on to. That put a hard-stop to my tests last weekend. Luckily rearranging my breakers around two new tandem breakers should free up the two slots I need... fingers crossed that the existing wires are long enough.

BTW Fastnf, is it just me or do Sigineer inverters look just like AIMS models? Got to say, a lot of inverters are starting to look the same to me, and they well may be.

I hope this makes sense to you, normally there is a brass screw in the service compartments neutral connector to accomplish this.
Basically all whites to isolated neutral bar bonded to ground(with bonding screw or jumper) and all grounds to ground bar mounted to panel.

Thanks for your analysis, electriceddy. This panel hasn't been touched since day one back in the late 80's/early 90's, so no surprise it has not aged well. Though, likely not the worst you've seen?

I understand your logic to use the DC-DC adapters & 100aH LFP for isolation, but it looks like all of that could be eliminated?

Agreed that all this could be eliminated. Even the Ioniq 5 will do bi-directional charging out of the box, which to me is the promised land. In the meantime, I'm basically mimicking what "van life" people do with their RV's as seen on YouTube. I even want to try out solar panels with my setup.

But it sounds like your 2 x 50 arrangement is being pretty efficient, and is producing around what the
plugout can do. If that thing sees >10A on either output leg it starts cycling annoyingly on and off.

Is the on/off happening because there's no surge capacity in that setup? Otherwise it looks like our setups perform similarly, though mine can survive >10A bursts. Ugh, wish I had gotten a 4kW 12V unit like what I just found on Amazon:

https://www.amazon.com/dp/B07CH8RL4M/ref=twister_B085VWZH9D?_encoding=UTF8&psc=1

Anyway, our output characteristics may be similar, but your plug-out must be tons more efficient going straight to 120V/240V. I wonder by how much... Torque should tell us, right? Just compare the total battery discharge with the LDC output (the PID that you discovered) and subtract maybe 15A background draw?

There are main pack connections in that big "HV junction box" hung off the side of the charger/VCU block,which I haven't dug into yet, and it seems like a bit of skulduggery with relay control could even present pack voltage at the CCS connector.

This would be the hack of the century. I and many others support you, for what it's worth!

be careful how you try to "float" that LFP unit. Their top-of-charge
dynamics are, uh, quite different from lead-acid

Have a look at the attached table for the "LI" setting. I barely understand the in's and out's here, but it looks like my DC chargers do not supply a float voltage for LFP's, and will instead let it self-discharge to a certain point, I guess? What does all this mean, anyway?

Speaking of floating, how smart is the Kona in terms of charging the starter battery? Lately I've seen it at 14.6V a lot less and a lot more at 13.2V, which looks a lot like the attached table as far as a multistage charge profile. I should go read that huge 12V battery thread.

 

[Fastnf]

BTW Fastnf, is it just me or do Sigineer inverters look just like AIMS models? Got to say, a lot of inverters are starting to look the same to me, and they well may be.

h

I agree with you. They look identical to Aims even there manuals are identical. I am guessing there is one factory that makes all the inverters like this and supplies them to every one else who re-labels them. My guess is the factory that makes Sigineer is also making Aims and Sun power.