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Newbie looking to be a bit more efficient

1224 Views 23 Replies 6 Participants Last post by  travellersall
Hello. I found this place while looking for a way to DIY a small single-seat EV for just my daily commute, since my truck (A necessity for my ranch unfortunately) is terrible for gas mileage, and I have a pretty good 30 mile commute each way.

I've been doing small-scale EV stuff in the form of RC cars for about 15 years, and am familiar with motors and motor controllers, as well as manual PWM controllers and servomotors, and large battery packs (Up to 48VDC 10Ah LiPo) but I haven't done anything rideable, or anything street legal or highway capable.
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There are some EV motorcycles and trikes that you might look at.

Many of the NEV (neighborhood electric vehicles) will be too small for you. Look at their speeds. They may not be safe on your roads, and possibly not legal. Driving 60+ miles at 30 MPH will be a long commute.

If you are driving to a place you stop all day, then look into recharging at the destination. Minimum of about 220V, 30A if you have a large battery.

My Transit Connect minivan has about a 28 kWh battery pack which is good for about 80 miles range. However, I wouldn't be comfortable doing 60+ miles regularly. Any side trips? Unless I could reliably recharge in the middle.

Your battery pack is about 48VDC x 10Ah = 480 Wh, or about 0.5 kWh.

So, say you targeted 50 kWh, you'd be 100 times as large. Perhaps a little smaller if you keep the car small. But, you still run into the range/weight/performance tradeoff.
Generally I'm trying to avoid the motorcycle thing for both local licensing (Very strict and expensive training required to get Motorcycle licensed), and safety (Too many bad drivers to go out without a cage).

Recharging at work isn't really an option, as a contractor I'm not allowed to use the employee chargers, so I have to carry the full 60 miles plus power for the heater in the winter.

As far as side trips, the grocery store is walking distance, and I'm at work 12 hours a day so I don't have time for side trips during the week, so that same 60 miles should cover any weekend trips.

As far as size, all it really needs to carry is me and my work bag. So weight shouldn't be a huge issue. I'm looking at a total weight of under 1000lbs. (And I can easily get my hands on 5Ah LiPo packs up to 48V, since that's what my RC buggy uses. That's about 4lbs of battery. 10Ah would only be 8lbs. There's more than enough slack to throw 80lbs of battery in for longer runs, but charging the pack would be more problematic. It takes 2 hours to charge my buggy batteries as is.)

Potentially I could get a larger charger, since I have 1000w available in the garage (120V) which could charge everything overnight.

And then if I really need payload capacity, I have the gas-burner. The car/trike is solely for the commute.
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Closed passenger cabin


Buy one.

Leafs are cheaper than anything you can build that's reliable enough not to get you fired because it died ten miles from the house and nobody will tow it.

Gas mileage is not a reason to build a car - you will never come out whole on the spend.
That is fair. I'm not necessarily building it for the mileage (If I was, I'd shove a motorcycle engine in the back instead of $5000 in batteries). I'm building it because I hate gas stations in Oregon because we're not allowed to fill our own tank, and I'd rather plug in in the garage.

As far as a closed cabin...That's not actually necessary for the heat...A 40W 12V heated snow-suit actually would be more effective than any heated cabin at this size. The most 'enclosure' I need is the aero-shell front to keep me from getting soaked by puddles, and a canopy piece for rain.

I'll look at the Leaf as well, but personally I think those are ugly.
I'm not sure hobby lipos are a geat choice. I've done plenty of RC as well (including drones/planes, Losi 8e, 5T, and some boats that draw insane amperage) and I'd be worried about heat and longevity. I think I've puffed enough of them to be a bit scared to spend that much money on packs stuffed into a car.

Better bet is to grab a used hybrid car pack. Chevy Volt packs for example have a nice built in water cooling jacket, and are 96s2p (or 3p on earlier ones). The 2018 model had 18.4 kwh worth of capacity (they rate them in kWh instead of mAh like on RC stuff) and the Chevy Volt had a range of 59 miles. If you put them into something lighter and at least as aerodynamic, you might stand a decent chance at hitting your target.

Oh, and don't forget, just like lipos, ev batteries do worse in the cold, so that's worth factoring in. Heck, maybe just hit up autotempest and see what a chevy volt is going for in your area?
Oh, I've pillowed enough RC lipos. Most likely I'd either order a custom pack or get some Battleborn Li-ion boxes to avoid that.

But yeah, I'm gonna look at EVs at the junkyard that have been in rear-end collisions to nab a drivetrain from one.
Gas station pump jockey -> job -> pays taxes -> lowers everyone's taxes
See, I understand that part. I'm just not a fan of the dirty looks they give me when my truck rolls in with a 50 gallon tank mounted in the bed that they have to climb up the wheel to get to.
It's not like they're using a hand pump, lol. Most of the guys & girls I run into seem happy doing it.

Is this a fabbed aux tank in the bed, or factory? A simple billet or even sheet metal nozzle retainer in the filler would let it fill unattended, if the former...

But, AWS GMC gets 9mpg towing, so the wallet does gets awfully sore. With the 120MPGe Bolt EV, the truck sits most of the time and is used maybe once or twice a month.

Arabs are f'ing with the world economy having announced, this past weekend, a cutback in production next month (tell me how raising interest rates will fix that rise in CPI). Oil prices are already rising. That means any EVs out there will get scooped up quickly and EV prices will go up...
Fabbed side-saddle tank (Wraps around the wheel-well). Technically it CAN fill unattended, and back in AZ I do it that way. But they don't like that because they don't think it'll stay in at that angle. It's a top-fill though, and the cap is 5' off the ground.

I feel like I'll probably be doing something similar to you, use the EV as a daily and the truck when I need it. As far as building it myself, that's because I really don't like how ANY of the commercially available EVs look. The sedans are kinda ugly, the trucks are too big to justify having 2 vehicles, and the single-seater stuff just looks unstable at speed.

My goal is something similar to the Solo, but with a wider, lower stance for better stability and aerodynamics. (Also if I can make it fit between the saddle-tank and the saddle-toolbox, in the 4' bed space in between, then I don't need to worry about running out of battery because I can get my housemates to bring me my truck to rescue it)
One drunk or distracted (texting) driver can ruin your day. Get the ugly car.
Hence the crash cage. I do have a fair bit of fabrication experience with making things that can withstand 'car crash' level things. (Like being bounced off the bottom of a 300' cliff at speed...)

But even in a bigger car a drunk or distracted driver could ruin my day. I know. I've had it happen in other cars. (And based on the crash test results...I'd prefer something that gets pushed over something that gets crushed...)
The EV market seems to be moving in several directions.

NEV (Neighborhood Electric Vehicle). Good for short hops. 30 to 40 MPH or so.
Compact short range. Smart Car, Leaf, Fiat 500E, Chevy Spark, etc.
Mid sized. Chevy Bolt, etc.
Luxury. Many of the Tesla cars
Pickups. Ford Lightning, Hummer EV, Rivian, Chevy Silverado EV (coming soon), Tesla Pickup (coming soon).
Full sized electric vans. Ford E-Transit
Electric Mini-Van (Ford/Azure Transit Connect from 2011/2012), Canoo minivan (coming soon?)
Small electric trucks (Smith and others).

In your case, I'd first look at the compact class: Smart Car, Leaf, Fiat 500E, Chevy Spark, etc. Or you could use one as a donor vehicle for your build. If you can get about 100 to 120 mile range, you should be OK for your commute.

Ultimately one always wants whatever range one's car has plus a little bit.

When looking at the cars, look at the charging. The basic J1772 only charges at either 110V or 220V AC, and can be rather slow. Most of the newer cars are getting high speed DC charging, but they may be skipping some of the economy vehicles.
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The Chevy Spark is one that I've sort-of looked at. (I'm a Chevy girl, so I've also been following the Silverado EV). Even if I do get a Spark, odds are pretty high that I'd wind up stripping it for parts mostly, but as far as a Silverado EV, that's not really worth the money for me. It's the equivalent of a half-ton, and my ranch stuff is already nearly killing a 3/4-ton.

My house doesn't have a 220V line to the garage, so 110V slow-charge is probably the best I can expect, which is part of why I want as small and light as I can get away with.
I used my 120V 12A charger for the first two years. You can run >75 mile round trips weekdays and keep up.

"Slow" charging means absolutely nothing when the car is sitting in the driveway or garage for 15 hours a day. Slow only matters if you're too poor to have your own wall socket...some Tesla paupers drive a $130k car, but don't own a house.

A "fast" charging car makes sense if you live in an apartment or condo.
Unfortunately, at best I'll have 11 hours to charge during the weekdays. But I do have a garage with a 120V outlet to charge it off of. (Now, if I DIY, I also have no problem having 2 batteries so I can leave one at home charging while I use the other.)
You need to do the math over a full cycle - for most people, that's 7 days.

It's ok to "leak down" the SoC during the week if you can make it up on the weekend to being at Max SoC the morning of the start of the next weekday.

This is a key aspect many people miss - they calculate daily commutes, and expect full SoC every morning - the full capacity of the battery never gets used and they're hauling around the equivalent of two fatsos in the back seat all the time.

Expect a bit better than 3mi/kWh in winter, 4-4.2 in summer in a Bolt.
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Many of the NEV (neighborhood electric vehicles) will be too small for you. Look at their speeds. They may not be safe on your roads, and possibly not legal. Driving 60+ miles at 30 MPH will be a long commute.
True. It's unlikely that a 60-mile trip would be entirely on low-speed roads suitable (or legal) for an NEV.

NEV (Neighborhood Electric Vehicle). Good for short hops. 30 to 40 MPH or so.
Typically an NEV will have a top speed of only 25 MPH (40 km/h)... so very short trips.
Yeah, an NEV is a grocery-getter at best. Almost nowhere I go is not connected by highway. I've used them before as tour vehicles when I worked at a fairly large auto museum.
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