[Duncan]

Hi
Your ideas about running a generator to increase mileage are just plain wrong (unfortunately)

A car engine is MORE efficient than a generator engine
And then you come to the efficiency of the conversion
Chemical energy - work (engine)
Work - electricity - (generator)
electricity - work (motor)

Every time you convert energy the gods of engineering take a cut!
And your generator system has two extra steps

A hybrid (like a Prius) is only more efficient because it can run a super efficient engine cycle and regenerate braking energy
And on a long run (highway) a Prius is not actually more efficient than an ordinary car

The reason that your emergency generator will run for a while is that you are not using anything like the power that your car will use

Rough figures - a house uses about 20Kwhrs/day
(with everything running - not in emergency mode)
That will take a car about 60 miles

 

[bdd72]

Okay, what the Chevy dealer told me about the Volt makes sense now. He said that it gets around 40 mpg when running on its generator, which sounded very low to me considering my Metro gets 45. So powering the car directly from a generator is out. What about using a generator to increase range? Have it set up to where when the batteries drop below, let's say 50% hypothetically, the generator fires up and charges the batteries until it reaches 100% then shuts off again. Or would the motor moving the car at 70 mph use power faster than the charger can put it back?

 

[bdd72]

A hybrid (like a Prius) is only more efficient because it can run a super efficient engine cycle and regenerate braking energy
And on a long run (highway) a Prius is not actually more efficient than an ordinary car

I delivered pizzas for a while. A coworker had a Metro but once in a while he drove a Prius hybrid. He said his wife took the Metro on business trips because it got better mileage on the highway than the Prius.

 

[Duncan]

Hi
Depends on the car but think about 20 to 30 Kw to maintain 70mph, so you would need a 30Kw generator to stay level and more if you want to charge the batteries

That is a big generator!

Effectively the Volt has a 63Kw generator

 

[Karter2]

I delivered pizzas for a while. A coworker had a Metro but once in a while he drove a Prius hybrid. He said his wife took the Metro on business trips because it got better mileage on the highway than the Prius.

I dont think you can ever justify a Hybrid or EV on fuel savings costs...even if you use Solar for charging.
You may think you are paying less for fuel, but you have to do a lot of mileage to recover the cost of conversion or the extra initial cost of the vehicle, and the costs of the Solar system you use
Even Tesla, where you can have free recharges, in reality you have simply paid up front for the fuel cost in the price of the vehicle.
No, ELectric drive is justified on other outcomes.

 

[Moltenmetal]

Karter is right- until there is another pricing strategy being used for fuel.

If and when a massive fossil carbon tax is put in place, so that IC engine cars can stop using the atmosphere as a limitless free public sewer, then battery EVs will become the cheapest transportation. Right now in my locale (Ontario, Canada), EV sales are so poor that the government has taken to offering massive (up to $14,000) subsidies on the purchase price of OEM battery EVs in order to try to make the economics work out for owners. That's not a sustainable pricing strategy for the government going forward, even though they do see the tremendous benefit of operating battery EVs off our amazing 40 g CO2/kWh electrical grid. Regrettably, purchase prices of new battery EVs are inflated here as a result, with all the border state dealerships being given direction that they will lose their dealerships if they sell to Canadian clients. The OEMs see the incentives as partially a reward for them, rather than for their clients.

If you can buy a used Leaf for peanuts (they're being sold very cheap in the US) and you can recharge off-peak, your operating cost would be very low indeed. In that case, the cost of capital for the battery EV components and R&D has been discounted rather dramatically.

As to the efficiency of hybrids: Duncan is right. But my 2013 Prius C, which is closer in size to the Metro than the mid-size Prius base model, gets 4.5 L/100 km (51 mi/US gallon) consistently (has done for over 40,000 miles so far) in real-world driving, doing a commute that combines free highway driving at ~65 mph (38 miles in the morning) and mixed highway/stop and go driving (38 miles in the afternoon- always busy traffic). Unless you're a hypermiler or like to drive 45 mph, you'd have a tough time matching that with an IC engine Metro. And don't forget, the Prius is an ultra-low emissions vehicle which also gets great gas mileage- the Metro doesn't have the same quality of emissions controls on it that the Prius does.

 

[bdd72]

Hmmm... I'm starting to get a little discouraged here. I was really hoping to find some way to extend the range of a DIY EV. By no means am I in the market to buy a manufactured EV like a Leaf, nor would I want to. Maybe it is foolish pride, but I'd love to cruise several hundred miles at a time in something I built myself, even if I had a lot of help doing it.

Another concept I've daydreamed about is using a small pickup like a Dodge D50 or an older Toyota or Nissan, you know, the genuinely small trucks. I fully understand that a completely self-regenerating vehicle is a pipe dream, but wouldn't a generator (or 2) mounted in the bed that is driven by a belt from the driveshaft or a pto type mechanism rather than an engine put enough electricity back into the batteries to extend the range by a significant amount? Or am I missing some basic principal of electricity and motion again?

I may end up driving myself crazy before it's over, but I feel there has got to be a way.

 

[bdd72]

I just looked up the range of a Nissan Leaf. The highest figure I saw was 117 miles. That is 18 miles short of my round trip work commute with no detours. And no, I wouldn't be able to charge it at work. And at around $10,000 for a 2013, the price is well out of my league. Tesla has the range, but I don't even want to consider what they cost.

 

[dougingraham]

Hmmm... I'm starting to get a little discouraged here. I was really hoping to find some way to extend the range of a DIY EV. By no means am I in the market to buy a manufactured EV like a Leaf, nor would I want to. Maybe it is foolish pride, but I'd love to cruise several hundred miles at a time in something I built myself, even if I had a lot of help doing it.

My conversion is fantastic as a short range commuter ~60 miles or 100 km. Exceeding that just costs more in batteries up to a point. On this car it would probably be about 120 miles. That would be about $16000 in new LiFeP04 cells or $4000 in salvage Leaf or Volt batteries. There is no easy way to range extend. The additional cost in weight and space of the ICE/Genset kills you. Hybrids from the OEMs are barely better than the pure ICE counterparts and they have spent huge amounts of money getting them to that point. I figured that with a 60 mile range battery and a 20 kw generator set on a trailer I could pretty much drive as long as I wanted. Road trips were about the only thing my conversion was not capable of (without unbelievable patience and planning). So I got a Tesla. Now the two or three road trips I enjoy doing every year are simple and the fuel is all prepaid.

Another concept I've daydreamed about is using a small pickup like a Dodge D50 or an older Toyota or Nissan, you know, the genuinely small trucks. I fully understand that a completely self-regenerating vehicle is a pipe dream, but wouldn't a generator (or 2) mounted in the bed that is driven by a belt from the driveshaft or a pto type mechanism rather than an engine put enough electricity back into the batteries to extend the range by a significant amount? Or am I missing some basic principal of electricity and motion again?

In a word, No! If you do the best possible implementation of a generator driven off the drive shaft or PTO you will only REDUCE your range by 10%. What most people overlook is that the motor moving the vehicle is going to have to put out additional energy to turn the generator and then extra beyond that for the loss in efficiency. Assume you are moving down the highway at 60 mph and this takes 20kw out of your battery. If you turn on the generator and set it to recharge the battery at 20kw the motor now has to draw ~44 kw from the battery (the original 20 plus the 20 the load from the generator adds plus the 4kw in additional heat generated in the motor, generator and charging electronics). 10% losses in this situation would be considered pretty good. If you spent a big bucket of money you could get the losses down to maybe 5%. Think in the $100k range for just motor and generator.

Regen braking for recapturing kinetic energy and storing it back in the battery can in simulations increase your range by up to 25% in stop and go traffic situations. In the real world you get between 5 and 10% under those conditions and almost nothing on a highway.

The least expensive vehicle for an overall cost to own is probably a used Nissan Leaf. About $10000 out of pocket and if you drive it 15000 miles per year your electricity costs to fuel it would be about $360 per year. This is based on 200 wh/mile and 12 cents per kwh. If you can plug in at work and your office gets the commercial rate for electricity of 6.5 cents per kwh then your fuel cost would be $195 per year. A Prius at 40 mpg doing 15000 miles with a cost of $250 per gallon would be $938 or at least 2.6 times more money. Add in the cost of five $30 oil changes and that goes to over three time more per year. At the cheaper commercial electricity rate this is 5.6 times more expensive per year. And you will be hard pressed to find a $10k used Prius in the same condition.

In your situation I would look for a used Volt and find some way to plug it in at each end of the commute. That way you get close to 80 miles per day all electric but you have the ICE as a range extender. Otherwise your only choice today would be a Tesla. A Bolt at the end of the year as a new car would work but it cant be used for road trips longer than 200 miles.

I don't want to discourage anyone from a DIY EV project but you need to have realistic expectations.

Best Wishes!

 

[PStechPaul]

Depending on how long you stay at work, a genset might give you just enough extra range to make it work. A 4 kW genset provides 32 kWh over an 8 hour span, and an EV with 300 wH/mile would obtain over 90 miles of range. You might even find a genset with a "clean diesel" or biofuel ICE to make it a bit more environmentally friendly. Propane or methane fuel is another option. Ideally you would only run the genset once the battery pack is mostly depleted, but then you would have to stop and let it run an hour to go another 12 miles or so.

 

[Karter2]

Its always cheaper in the long run to invest in more battery than haul gensets around.
Gensets cost money, use fuel, and add extra weight, noise, maintenance, etc
As Doug says, unless you can find a cheap used Volt, or a Leaf, just ensure you have enough battery for your needs.

 

[bdd72]

Thanks for all the input and information. It appears that my best bet for my 130 mile work commute is to stay with my 45mpg Geo. Maybe if I find a job closer to home or move closer to work, I will take another look at building an EV. As for my son's Civic... I may still do something with it and take comfort in the knowledge that range limitation will cut down on joy rides. LOL!

 

[bdd72]

Depending on how long you stay at work, a genset might give you just enough extra range to make it work. A 4 kW genset provides 32 kWh over an 8 hour span, and an EV with 300 wH/mile would obtain over 90 miles of range. You might even find a genset with a "clean diesel" or biofuel ICE to make it a bit more environmentally friendly. Propane or methane fuel is another option. Ideally you would only run the genset once the battery pack is mostly depleted, but then you would have to stop and let it run an hour to go another 12 miles or so.

My work days range anywhere from 8 to 14 hours. A 90 mile range would be plenty for one way but fall 40 miles or so short for a round trip. If I could plug in at work, there would be no need for a generator. In all honesty, my boss would probably be okay with me hooking my car right up to our electric forklift charger,eliminating the need for me to mount the charger on board which would save some weight. It's my petty coworkers who would gripe and whine that I'm "stealing" electricity from the company.

 

[Duncan]

Hi bdd72

With a 130 mile commute you are losing another 2 hours a day 10 hours a week - 40 hours a month - like unpaid overtime -

Moving closer would give you those hours back

 

[bdd72]

Hi bdd72

With a 130 mile commute you are losing another 2 hours a day 10 hours a week - 40 hours a month - like unpaid overtime -

Moving closer would give you those hours back

Moving closer isn't a realistic option. My wife and I own our home. No rent, no mortgage, just taxes and utilities. Moving closer to work would add a housing expense (rent or mortgage) we don't have, not to mention higher taxes. That justifies the commute for me and I don't mind the drive since it is very low traffic, particularly in the morning. I would take a little less per hour for a comparable closer job, but that just doesn't exist where I live. Plus... I'm a country boy. I couldn't live in a city very long.

 

[Moltenmetal]

Plug in at work- for 40 miles of extra range, a level 1 120 V outlet will recharge you fully before you go home. My drive to work is 38 miles each way and I recharge fully in about 6-7 hours. Forget the forklift charger- just plug into a landscaping outlet like I do. If you look hard enough there's always one around. Of course if you do have access to 240 VAC you can recharge more, faster, and reduce your required battery capacity onboard. That will save serious cash.

 

[galderdi]

I dont think you can ever justify a Hybrid or EV on fuel savings costs...even if you use Solar for charging.
You may think you are paying less for fuel, but you have to do a lot of mileage to recover the cost of conversion or the extra initial cost of the vehicle, and the costs of the Solar system you use
Even Tesla, where you can have free recharges, in reality you have simply paid up front for the fuel cost in the price of the vehicle.
No, ELectric drive is justified on other outcomes.

He could move to Australia. Our fuel cost is $4.54 per gallon. Therefore the switch to electric is justifiable. However his round trip just jumped from 140 miles to 14,000miles.

 

[tomofreno]

... In all honesty, my boss would probably be okay with me hooking my car right up to our electric forklift charger,eliminating the need for me to mount the charger on board which would save some weight. It's my petty coworkers who would gripe and whine that I'm "stealing" electricity from the company.

That's easy to avoid if your boss owns the company. Just pay your boss the electric cost plus say a a 40% margin. A civic would likely use around 1/4 kWh/mile on the highway, so if you add 50 miles range at work that's around 13kWh. At 12 cents per kWh that's about $1.56, and $2.18 with 40% margin. Then you can tell your friends how much you are paying for "gas" even with a 40% markup.