Made a way to take energy out of my car

[electricCowboy]

I'm going to try and do it with my Energica motorcycle as well. I decided to make a very very silly video to show things working. I have posted others on Facebook and youtube which explained what was happening, but people seemed to miss the forest for the trees when I did that, so this time I went super simple.

I think this sort of thing could be really useful in California where the power outages are all happening.

https://www.youtube.com/watch?v=UqPOQzQoCZQ

 

[Nubo]

What's it cost? You can already power reasonable loads inexpensively by hooking an inverter to the 12V system.

 

[LeftieBiker]

It's a good idea to use the Chademo port, and has been done by Chinese manufacturers. It's all in the implementation and, as Nubo notes, the cost. It also has to be safe. The splices on that transfer switch look pretty dodgy...

 

[jjeff]

I was just holding my breath doing a crosscut on something as large as a 2x4 without a miter pusher thing :shock: much better to use a radial arm or miter box for crosscuts

 

[electricCowboy]

Thanks for the feedback guys. I don't have a price just yet, we have only made 4 of them to test for now. So far it's going quite well. What do you guys think would be a reasonable cost for something like this?

Right now we limited one unit to 7kw out, 1 to 20kw out, and one, with much larger wires to the vehicles maximum output.

We are going to test a ridiculous idea... charge at free public stations each night and power the shop off of the car all day this way for a month and see how much juice we shuttle around.

 

[LeftieBiker]

7kw would probably serve most needs, but a 10kw limit would probably make more people happier. 20kw is too much strain on a Leaf battery for regular use, I think. They tend to heat up.

 

[Oilpan4]

I sprung for a new, only dropped once forklift battery and an 2kw outback inverter.
It's only 5 to 6kwh depending on discharge rate.

 

[estomax]

that is neat, my take on price, for about 200 bucks you can set up a ~1 kw setup through the DC system of your car to power emergency needs. For a normal house, a 7-10kw system will be viable. If a 20KW system doesn't cost much more, then you can pretty much use this on any house without worrying about timing your loads. My house very rarely goes above 10kw (water heater and clothes dryer on max for example), and i could manually make sure it never does if i had to.

This would be a semi-alternative to a tesla powerwall, which are in the 10+ grand range, but come with the battery obviously. Personally i don't have enough power outages to justify something that steep, but for someone that loses power often, if it was priced only a bit more than a similar output generator, i could see this being viable. That would put it in the 2-5k range, depending on how well it is packaged/integrates with the house.

Marko

 

[HerdingElectrons]

I'm very intrigued & a 10-20K seems like it would be great for a power outage for typical household power maintenance needs.

 

[HerdingElectrons]

7kw would probably serve most needs, but a 10kw limit would probably make more people happier. 20kw is too much strain on a Leaf battery for regular use, I think. They tend to heat up.

Typical freeway cruising is 20-40Kw with 70-90Kw draws for hill climbs not counting initial acceleration. A 20Kw option would allow for something like a A/C to power up but the actual constant load would be much lower like 5-10Kw for a house load with is nothing is terms of C discharge rate any of the leaf packs.

Sustained 30-40Kw will heat up the packs faster than heat can dissipate quite readily which a 20-30min QC session which is around 30-40Kw of energy transfer will readily demonstrate

 

[LeftieBiker]

7kw would probably serve most needs, but a 10kw limit would probably make more people happier. 20kw is too much strain on a Leaf battery for regular use, I think. They tend to heat up.

Typical freeway cruising is 20-40Kw with 70-90Kw draws for hill climbs not counting initial acceleration. A 20Kw option would allow for something like a A/C to power up but the actual constant load would be much lower like 5-10Kw for a house load with is nothing is terms of C discharge rate any of the leaf packs.

Sustained 30-40Kw will heat up the packs faster than heat can dissipate quite readily which a 20-30min QC session which is around 30-40Kw of energy transfer will readily demonstrate

I realize that brief loads can be much higher than 10kw, but the system should be designed with the understanding that some people will max it out, and sustained loads above 10kw are going to heat up the batteries too much. Imagine cruising on the freeway with zero airflow over the car.

 

[powersurge]

I don't see what benefit there is for this compared to a 12 volt inverter or having a gas generator?

It's nice to say that it can be done, but is it solving an unsolved problem?

 

[HerdingElectrons]

The whole freeway airflow cooling IMO is over rated. I have a car lift & have been under my car doing tire rotations & once you realize how much plastic is keeping the airflow away from the car for aerodynamics that air flow really isn't doing jack to meaningfully cool the pack.

It's literally mass heat sinking & time that's doing all the thermal transfer work here. That's why 30-50Kw charging & high speed sustained driving above 25-30Kw discharge results in such high battery temps. This design was engineered around local city car use patterns & not typical American 70-85mph freeway driving.

 

[LeftieBiker]

The 24kwh packs do cool significantly from airflow on the highway - this is known. What is less clear is how much cooling occurs with the 40kwh packs, which essentially fill up the little bit of space on top of the pack that used to be used for air cooling. It has also been observed that people using Leaf2Home in Japan have seen increased degradation, and I believe that it's from lack of cooling airflow with the cars parked.

 

[electricCowboy]

Wow, thanks for all the feedback guys.

So far I only saw one suggestion for price, which was retail between 2k and 5k. I think that that price range could be met if we got parts made in a reasonable quantity. It was similar to what I was thinking for home use as well.

As for the high discharge data, I suppose getting that info which would be exceptionally difficult outside of powering entire strip malls etc. So perhaps using the leaf as a portable charging station for other EVs would be one of the few ways I could imagine allowing us to do really high sustained load on the battery and see how it deals with it.

Best,

Brandon

 

[Oilpan4]

If this is going to succeed it has to be competitively priced against small gasoline generators with similar output ratings.

I would do all 4. My gasoline generators, forklift batt with outback, sunnyboy SPS inverter that can make 120v power straight off the panels and add a leaf inverter that puts out 120, maybe 240v 60hz.

 

[estomax]

Brandon,

Would this also charge the car at 10-20kw? That could be another selling point, at home fast charger.

Marko

 

[Rodriguez]

I don't see what benefit there is for this compared to a 12 volt inverter or having a gas generator?

It's nice to say that it can be done, but is it solving an unsolved problem?

A 12V invert is less efficient, you're first tapping juice from the main battery to put it in the 12V battery and then you make AC out of it, wasting power at every step. While good enough to run a few lights, the 12V battery and dc-dc charger aren't made for this and the power output is limited. Of course you can pull more if you want for a short time but at some point the car's 12V charger can't keep up and you flatten the 12V battery. Using the chademo port is not only more efficient but you can run way more stuff on it, because the Leaf and Chademo standard have been designed to be able to V2G. This is something you can hook up to a main panel and run a whole house from it, ideal for brown-outs and off-grid locations like remote worksites or cabins, campsites etc etc.

For the generator, there is a reason some people get a Leaf, because the don't want to drive around in a car that is powered by a highly tuned rube goldbermachine with thousands of moving parts that is powered by liquid dinojuice, so getting a generator while they have access to a powerwall on wheels would be silly.

 

[Oilpan4]

Remember the leaf draws around 2 amps of main battery power just to keep the DC to DC power supply and inverter powered up.
So just sitting there with nothing on ithe car is using around 700 watts.

Having an electric car and no backup generator is silly. So when the power goes out the battery powered car is 1 or 2 days away from being dead. For me when I get home from work my car is getting pretty low, it won't make it to work and back 2 days in a row with out a charge.