Using PIP As A Generator

Wouldn't that depend on different variables? I was just thinking .... I was just thinking - if you're not putting ANY kind of load on your PriUPS (maybe 500 watt hr's over the night), the parasitic loss to the Prius traction pack will require the ICE to periodically fire up to recharge from 20% to 80% iirc. And again ..... and again .... and again .... etc. You could effectively regen 20kWh during the night, just to run your night stand clock.
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That's very impressive if the hydrogen could be separated from the gas economically. I think the future of energy for the human race lies with hydrogen, but as long as petroleum is still the cheapest energy source, we're probably stuck with it for a long time.

 

Yes, it will cycle periodically since the Prius itself is using about 200 watts, plus another 100-200 for the UPS. I make sure to turn off the screen, A/C, radio, and turn the speedometer down which helps with this parasitic load somewhat. I looked over old posts I made at the link in my signature, and I estimated about 8 cycles per hour under a half load (which is far more than I use in the evening when we are awake) and about 4 cycles per hour under the minimal overnight loads off about 200 watts. One of the very first tests I ran with my old UPS, with about a 1500 watt load (excluding overhead) I got accurate on/off times: "on for around 2 minutes 40 seconds, then off for 4 minutes 50". Which is where my 8 cycles per hour under load estimate came from. The 4 cycles per hour estimate with a low load might be high since I don't think I tested that accurately.

Remember the Prius does not recharge the battery to 80% SOC from the engine - on the road or while parked. It goes from 20% to roughly 30% from the engine, just enough to get a light charge on it. The rest comes from regen braking. You'll experience this after you've been in heavy traffic on flat roads for a while and the A/C is fighting 90+ degree outside temps. The battery will run down to 20% and the engine will come on, turn off, but almost immediately turn on again. This will happen over and over until you hit a hill or traffic gets moving again.

 

Don't you also get a lot of CO2 from the CH4+2H2O->4H2+CO2 reaction which is used to produce the hydrogen from the methane (natural gas)?

 

Not nearly as much as a diesel generator. Remember this only a backup system.

 

I think that may be the typical average ratio, but I'm sure it depends largely on driving patterns. If you are light on the pedal, and don't deplete the EV partition too much by hard-driving, the amount of charge coming directly from burning fuel may be much less. Personally, I get my best mileage when I'm not in a hurry to get to work.

I love saving a buck on fuel as much as anyone, but not enough to drive without A/C in hot weather, or without heat in cold weather.

 

Yes, there are certainly parasitic loads on the PriUPS system but it's alot more efficient than running your generator at full speed to power your alarm clock. Obviously the alternative would be to just turn off the electricity in both cases assuming you're not worried about the fridge getting warm or watching TV late at night.

 

have you used any external fuses between the inverter and 12V battery?
thanks!

 

ok - this is definitely a zombie thread - other than this post & the one prior. But since the OP 1st posted - lo and behold look what came along;

Now you don't have to worry about a generator running at high RPMs all night - or the priUPS having to cycle the Prius dozens of times per night. With the power wall, you can capture excess solar output during the day that would otherwise go back to the grid - you can use your own power all night long, without having to pay the higher utility rates. Boy, that's really going to mess up the utility companies business model.
You gotta love all these lithium batteries - and their receding prices

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It is just another battery in a solar system. In fact it isn't the most cost effective battery for a solar system. Lithium batteries solve weight and space issues - both problems for cars, but not home solar systems. You want the cheapest battery per kW supplied, and flooded lead-acid is still the winner there. The Tesla battery is just a marketing gimmick, no utility is worried about it.

Any system that has a battery as the power source can not compete with the cost of a utility connection. An off-grid system costs many multiples of what utility power costs, which is why the most cost-effective, quickest payback solar system (excluding solar thermal) is a grid-tied system. All of the energy that is produced gets used, after inverter inefficiency (most are about 95% efficient). Either by you or by your neighbors, and you get the credit for all of it. Most of the potential energy on an off-grid system is wasted because it is either not used at all (system goes to float charge), or is lost in charging inefficiency, or inverter inefficiency, etc. The rule of thumb is only 50% of the DC energy potential of the PV panels is even available for possible use as AC power - and some to most of that available energy isn't used. Then add in the great expense of the batteries that need to be replaced every 5-10 years and that is why it is so much more expensive.

 

agree - the grid is the best. Lithium though, isn't just the best backup because of its power to weight ratio, if you've seen many peoples garages there's just not room for lead acid batteries. LED isn't as robust either. Lithium can take way more charge / discharge cycles. And then there's that nasty issue of flammable off-gassing. I suppose you could always set up a ventilation system - more cost. Lithium can flame out also, but Tesla has that dialed in now with years of experience. Its called thermal management. Lead-acid also requires more maintenance. Grab your hydrometer / turkey baster and go check pH. Add water too. Yes, a battery backup is a huge expense for most, & the reason that we'll likely never have one. I just know if I had the spare cash, which way I go. YMMV.
Yes we get credit for our surplus but it's only at 2.9¢. The utility turn around & sells it to the neighbor for ¢40 & above. So the $7K cost for a powerwall pays for itself. Ok, it's 1,000's of hours of surplus ... and i can't find mt calculator

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Lead-acid can take up the same space as that Tesla battery, if you build your rack vertically. FLA does require a lot of maintenance, I agree. That is one of the reasons I used to have a 22 kw FLA battery bank and don't now (inverter-generators are a much better backup solution). But there are other chemistries like flooded NiCad that are still much cheaper than lithium, require less maintenance than FLA, and have a similar duty cycle and count as lithium.

Not all localities have rate schedules where you are credited so much less than market rate. Many states and other countries credit at parity and in some cases much more than market.

And again, no matter which battery chemistry you use - or your rate schedule - you will not earn/save as much as just sticking with a grid-tie system. See my point above about most of the potential energy of the PV panels either being absorbed by the system or just not used. Even if you go with a hybrid system you've still introduced charging and inverter losses into the equation (which cost you money), and the cost of the battery. You can minimize that loss a little by only using it for emergency backup, but then it is far, far, cheaper and easier to use an inverter-generator for emergency backup.

 

I'd bet money those Tesla powerwalls are just where Elon puts all the used batteries once they are no longer good for vehicles. It's a great concept but certainly not unique and they are running into issue with solar power now because people were able to get net metering in the past (ie power was bought sold at the same price) but due to the number of people now moving to solar the power companies are lobbying to pay less than retail for solar generated power.

 

I don't think so. I think they are made with the celks that doesn't meet specs for the cars.

Remember, Model S over 8,000 cells. I don't know the yield but there is potentially a large number of unusable cells for the BEVs.

 

Agree

 

Wouldn't those be rejected by the manufacturer of the cells? I believe Tesla isn't yet mining and manufacturing the lithium or cells.

 

My understanding is that Tesla would be the manufacturer in the Gigafactory. So, whatever that can't be used in the car would be sold in Powerwall. They probably could use it in laptops also. I think the size is the same.

 

actually the last i'd read was, besides buying batteries from Panasonic, their current supplier, Tesla is (in addition to starting up the gigafactory) , looking to possibly purchase cells from Samsung;
Samsung SDI, supply ‘18650’ battery sample to Tesla, Targeting for mass supply in October : teslamotors
The company is so successful it needs that many batteries - literally millions.
the unsubstantiated - no link to verify - that powerwalls are made out of rejects - is tantamount to someone saying, "well i'd heard that Toyota Mirai fuel cells were manufactured for industrial use - but they didn't quite cut it, quality wise" -
Really? we need to go there?
A reject fuel cell is a reject fuell cell .... and a reject battery is just that. It doesn't take a lot of thought to grasp that when a battery (for example) has too high a resistance or some other issue, that it may lead to additional issues. That's why it's a reject. You don't sell it, hoping it won't cause a fire and burn somebody's house down.
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I understand by out of tight specs for vehicular application not the same as "rejected" on lieu of defective.
These out of spec's could easily be repurposed to the power wall being that it is only a stationary power reserve of energy; and I'm good with that terminology