Prius as backup generator with midnight classic as voltage converter possible?

[travissand]

After messing around with the wind graph settings & maximum amp limit in the charge menu I still have the resting cycling problem. Since this is never a problem in the absorb phase of charging I'm thinking I'd like to have two classics that way I'm capable of pulling 4000 Watts out of the Prius and It will be less likely to enter into the bulk phase. Keep in mind that when it's in the absorb phase it's not really at the true absorb voltage recommended by the house battery manufacturer. I have turned it down to about float voltage because the batteries are already full and I'm not trying to charge them at this point I'm just trying to let the power pass from the Prius through the classic to the inverter to power the house without draining the house batteries.

[travissand]

I'm almost thinking since batteries are so dang expensive it might be a good idea to use a supercapacitor bank in the place of the house batteries (or a small but high amperage ability house battery bank) and leave the Prius on indefinitely. During the daytime most of power will come from the sun and every once in awhile maybe the Prius will give a boost. Then at night all the power would come from the Prius instead of draining the house batteries. Sure then you're paying for gasoline but that might be cheaper than paying for a new large house battery Bank every 5 to 10 years.

It's all quite complicated and thinking with a large enough lithium house battery Bank the Prius / generator wouldn't be needed at all and there'd be no complicating anything. That's looking like an attractive option even though it's expensive.

[travissand]

I played with the U-set mode and I don't like it. I set the mppt sweep interval to 0 so it'll only do a sweep the first time it turns on. I set the sweep parameters to stay within 3% of voltage open circuit. The problem is as the Prius battery drains down it's voltage beyond the 3% the classic will simply switch to rest mode and stop helping. When this happens since there's no load anymore on the Prius battery the voltage rises a bit and then when the classic sees that it's back within range it turns back on and initiates another sweep so it finds the best mppt from that new sweep point and starts pulling the correct amount of power out of the Prius again. Then the Prius battery voltage starts to drop and the cycle repeats itself.

If I stood there and push the enter button to force a sweep every few seconds it works pretty good.

so I went back to the sweep interval adjustment and it's only adjustable in 1 minute increments. so the lowest increment of sweeping every one minute is not often enough to avoid the problem. also with the one minute sweep interval it's annoying because the kids will turn on the microwave in the house and the classic is resting so all the power comes from the house batteries. Then the batteries charge rapidly after the classic turns itself back on at some point and does a new MPP sweep. This is just needlessly cycling the house batteries.

I like the wind setting better because it never does a sweep and you can set the cut in voltage so it will also never draw the Prius battery down below what you specify.

[travissand]

I want to focus the Prius on charging the batteries and I’d like to use a Classic 250 to do this. It seems simple and efficient. I’ll order the 250 and start to collect some smaller items needed. Thanks for the code reader / app recommendation.

The classics tech support guys said that the classic will no longer get any substantial update and definitely never get new mode options because they're coming out with new hardware soon. He said their new hardware would never get a mode like this either.

I'm wondering what other brand manufacturers might have for us.

the frustrating thing about using the classic right now is that when someone turns on a heavy load in the house when it's dark out and they're drawing from both the Prius and the house batteries that will bring the house batteries voltage down too far and trigger the cycling back and forth into resting problem.

Another another frustrating aspect is that depending onbattery voltage when you decide to start the Prius you might have to adjust the battery voltage in order to keep the classic in the absorb stage to avoid the cycling.

I'm starting to think the classics solar mode might work.

[travissand]

Trying the solar mode is sketchy though because tech support said it would burn the fets. I was reading through the different mode descriptions in the classics manual and it didn't necessarily say it would do a sweep clear down to battery voltage like it does in the hydro description. If it tried to drag the Prius high voltage battery down that far it would be bad but it's output is amp limited according to my set point. So wouldn't it just get to the maximum output ability and hold there? Tech support guys don't seem to know for sure so of course I tried it.

I'm the guinea pig with this I suppose. so in solar mode when the kids were turning on and off the microwave for me in the house and the toaster oven at the same time I did get some cycling into resting mode. And I also could hear the sweep and it sounded a bit more strenuous.
Once the display showed "solar shading" and the classics output was zero. I keyword search the manual and Google and I couldn't find anything probably because I should have been looking for PV shading instead. Does anyone know what this means? UPDATE PV Shading – This indicates the Maximum power point voltage is less than half the open circuit voltage... That's scary so does that mean that the midnight pulled the Prius battery voltage down 50% from open circuit? It must have happened fast because I was watching the voltage display of the incoming and it didn't move that much. I've got 25ft of 10 gauge wire connecting the Prius to the midnight according to the voltage drop calculator I'll only lose 1% with that run. Maybe I'll double it up anyway.

Then I tried the mode called dynamic p&o. And it's doing the best out of all the modes. I was able to cycle the microwave and toaster oven on and draw all battery voltage is down. I saw the bulk charge and it was in its Max output with amp limit mode light on. I forced a few sweeps and tested those wile the Prius was charging and discharging. I saw the Prius voltage get down to 199v while the microwave and toaster oven was on right at that moment the Prius started its internal combustion engine and I saw the voltage dip down like 190 or something but the engine started right up and the voltage climbs quickly and there was no relay clicking no resting it seems to be working.

So far the fire extinguisher hasn't been needed but I am worried about the long-term longevity of the classic when used with the Prius. I'll be running the Prius as a generator 16 hours every night for a month or two until my new lithium setup is in place. And I'll keep you updated with its fuel consumption versus time and KWH.

[travissand]

I can get about 2,200 maybe 2400 Watts out of the classic with the output amp limit setting lowered to 45 amps. but if I start pulling additional even in the legacy mode it eventually start cycling to rest and repeat. Tech support said you can't feed two classics from the same source but I'm thinking that's because the classic can normally more easily manipulate the source voltage with their own muscle as part of their algorithms. In this case the Prius out muscles the classic and would probably eventually burn it up. I don't think the classic is going to throw the Prius voltage around so I don't think the two classics together would be messing with each other as much as if it were hooked to a traditional wind hydro or solar. I think it's worth a try hooking up 2 classics to 1 Prius.

I'm currently using a 48 volt system with all this experimenting. And I would think that's the bare minimum to have this system be usable otherwise you wouldn't be able to turn on the microwave without overloading 1 classic. So maybe 4 classics on a 24 volt system or 2 classics on a 48 volt system would be good.

How's it's working now assuming it doesn't burn up shortly I'm comfortable with setting the voltage output of the classic low enough to keep it in the absorbe stage and if I want to charge the batteries further I'll occasionally raise the absorbing voltage set point.

Also if I had two classics I would switch back to the wind mode because it doesn't do any sweeps and that makes me feel better for reasons previously described.

[travissand]

Some preliminary testing my of generator fuel rate / run time / hours per tank. OBD2 scanner shows the
Prius 0.107 average gallons per hour delivering 570w to the house inverter.

Compared to my Honda eu2000i at 0.138 gallons per hour.

This would only save me $0.73 per 16hr night but in reality if I forget to turn the generator off I get punished a lot compared to forgetting to turn the Prius off. Using the Prius will likely save me over $1 per day in fuel savings.

I'll do more testing at different loads later. And I'll verify the OBD2 scanners information by hooking the fuel line up to a small 1 gallon container of fuel for exact real world data.

[travissand]

Here's a side note to myself of things I should try to stop it from cycling. Number one I've seen in several places that if the battery bank is too small that could cause it. My bank is definitely small. AGM 230 amp hours. Only rated to absorb 50 amps and it's old and worn out so it probably could only handle 30 amps at this point. Although the other two classics work together when the sun is out and they don't have any problem putting more than 30 amps in.

1. Larger battery Bank
2. Heavier gauge wires to the Prius.
3. Add another classic hooked to the Prius.
4. Add another cell raise the battery voltage.
5. Disable LoMax in the tweaks menu.
6. Put a resistor on the input to soften the source?
7. Ask tech support if there is an address in the hidden tweaks menu that could be altered in order to stop it from dragging the Prius voltage down below 200 volts.

[Carmat76]

Based on your reports of experience with the Classic 250 so far, I’m wondering if I should switch my approach and feed my Conext SW 4048 AC input from an inverter. I have found a Canadian source ($500CAD) for the Sunny Boy 3000US which is in the DC input range required. Here’s a link to the spec sheet if I could get confirmation from the group that this is appropriate.

https://www.solarelectricsupply.com/fileuploader/download/download/?d=0&file=custom%2Fupload%2Fsunny_boy-SB3000US_4000US-spec.pdf

[Carmat76]

I have discovered a local seller with an APC Smart UPS 6000 RT ($600CAD). It’s battery voltage is listed at 210vdc. Seems like a good match for the Prius. The unit is rated for continuous 4.2kW and doing a little research Schneider guarantees 105% operation or ~4.4kW indefinitely... seems like a perfect ‘generator’ for me to control and feed into my SW4048. Any thoughts ?

[travissand]

Based on your reports of experience with the Classic 250 so far, I’m wondering if I should switch my approach and feed my Conext SW 4048 AC input from an inverter. I have found a Canadian source ($500CAD) for the Sunny Boy 3000US which is in the DC input range required. Here’s a link to the spec sheet if I could get confirmation from the group that this is appropriate.

https://www.solarelectricsupply.com/...000US-spec.pdf

The short answer is no that Inverter should not be used for what you were trying to do.

There's quite a few problems with trying to use that inverter. The first obvious problem is it's a grid-tie inverterso it's only going to take power from the DC input but it's never going to send the power back. The next problem is it will synchronize with your Schneider AC wave form accept it will alter it's en wave slightly in order to force Power into the Schneider.

I have not tried this with my Schneider yet though I suspect it will work just like it does with my other inverters it actually back feeds through my inverter and into my house batteries.
I think for this backfeed thing to work it probably has to be a heavy inverter like with the large copper transformer that you're Schneider does have. Problem is the charge is completely unregulated. The only thing I could do to slow it down to a reasonable amount amount of charge was to use a light-duty very long extension cord between the two inverters. It was a great work around and good way for me to hook my Honda generator to directly and efficiently feed my house while also charge my batteries when I had no battery charger and my inverter didn't have a battery charger either. The shorter the cord the faster the charge.

Keep in mind this was connecting the output of my Honda eu2000 directly to the output of my inverter.
That's a little different than what you'd be doing the same thing but with a grid-tie inverter instead and I'm not sure how the grid tie inverters Works compared to my generator but I think that they'll be a little more aggressive since their sole purpose is to pump power into an existing grid.

The next problem is this inverter is also a mppt sweeping input so it will try and pull power from the Prius in a similar way that the classic does and so it'll have similar problems.

[travissand]

I have discovered a local seller with an APC Smart UPS 6000 RT ($600CAD). It’s battery voltage is listed at 210vdc. Seems like a good match for the Prius. The unit is rated for continuous 4.2kW and doing a little research Schneider guarantees 105% operation or ~4.4kW indefinitely... seems like a perfect ‘generator’ for me to control and feed into my SW4048. Any thoughts ?

Yes this sounds a lot better. Does it have a cold start option? I've seen some people having to modify to get UPS units to cold start. One guy simply started up his generator and then turn on the UPS in standby mode and then he would unplug the generator. The UPS thought The power went out so it would start up it's AC output at that time. He called it the generator dance and said it was a pain in the ass.

It seems though that a lot of these UPS's put out the wrong voltage. The voltage can be altered with an additional purchase of a transformer but I'm not sure if you can get 240 volts. The snyders output is much more capable when you have 240 volt input. If you run 120 volts into the Schneider its output is crippled and its ability to charge the battery is greatly lessened. And I'm not sure if it requires a center tap on its input. in other words if your UPS is putting out 230 volts with no center tap does anyone know if you can put that straight into the Snyder's 240 volt input?

[Carmat76]

I missed out on the UPS... someone beat me to it. At this point I’m wondering about using the 12 volt side of the Prius output. 100 amps available and this seems to provide 1500W of power. Maybe I could start really simple and pick up 4 cheap charge controllers and charge my 48v bank in 4 sections. I’m running Rolls 1860 which are 1440 Ah (20h) 2v cells. It would be a start and somewhat helpful. This is just an experiment on the side. I have a regular backup generator and 7250 watts of solar for primary charging.

[travissand]

I missed out on the UPS... someone beat me to it. At this point I’m wondering about using the 12 volt side of the Prius output. 100 amps available and this seems to provide 1500W of power. Maybe I could start really simple and pick up 4 cheap charge controllers and charge my 48v bank in 4 sections. I’m running Rolls 1860 which are 1440 Ah (20h) 2v cells. It would be a start and somewhat helpful. This is just an experiment on the side. I have a regular backup generator and 7250 watts of solar for primary charging.

I thought about doing that as well but with all of the conversion it's not going to be very inefficient compared to using the high-voltage battery. The thing is the Prius generator does not make 12 volts. It makes high voltage for charging the HV traction battery and then there's a dc-to-dc converter bring it down to 12 and then your inverter would bring it back up again. You would be taxing the 12 volt converter a lot with what you're planning. people who are using a 12 volt inverter are not drawing the maximum continuously like you would be for charging your house battery Bank. You would be the guinea pig risking damage to your Prius.

With multiple small cheap controllers and all the wires and all the fuss you'll be better off to find a UPS and do it that way instead. Considering everything we've discussed if I were you I would use the UPS.

If you can't find one soon enough use a classic. If you find a UPS later you could sell the classic and get probably 100% of your money back from it. I see the 250cp selling for more elsewhere.

[travissand]

And one more thing with cheap charge controllers you won't have the level of control that you have with a classic. And definitely do not try a pwm charge controller because it will get fried. And don't be fooled by cheap mppt charge controllers that are actually functioning like a pwm. A lot of these have mppt in the name as in that's the name of it not that's how it functions. Chinese trickery.