DIY Electric Car Forums banner

1 - 9 of 9 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter · #1 · (Edited)
I own a 1980 Dodge D50 that has already been modified:

197? Toyota Corolla 2TC Engine / Transmission (came this way, with an unregulated alternator which cooked some of the electrical)
199? GM Alternator (I custom fabricated this one in personally)
1980 Dodge Chassis / Electrical

Modified to add auxillary lighting (Also done by me)
  • I'm not the greatest with mechanics and fabrication (just not enough experience) but I have access to a quality machine shop with skilled staff
  • I'm hoping to get at least 100 miles on a charge (this will be a 'garbage' truck, and the transfer station is about 40 miles away)
    • I can use a ICE genny to charge it in transit or at destination if absolutely necessary
  • I will be hauling no more than 1000 lbs in a vehicle with a curb weight of about 2500 lbs, and speed is not of the essence
  • My budget is very very limited, but I can be resourceful in other ways
    • $10k kits are out of the question
    • A parts list with custom fab is very possible
  • I'd like to go with a setup that allows charging while braking, which I read somewhere requires an 'AC' setup (could be misinformed though)
Edit:

Also on my agenda, if at all possible, is an AWD or FWD conversion.
 

·
Registered
Joined
·
511 Posts
AC does, in fact, offer better regen ability, but is fairly expensive. You're looking at > 10k for a decent motor/inverter combo. You can do regen with some DC, like sepex motors. Regen is not my forte so I'll let someone else comment further.

100 miles for a heavy vehicle will be extremely difficult to do on any sort of budget. Figuring something large, like 500 wh/mi when loaded, you're looking at 500 wh/mi x 100 mi = 50,000 kwh. At a DC voltage of 156 (one of the largest DC voltages commonly used), you're looking at 320 Ah batteries. I can't find anything in this range, so you're looking at making a large pack larger by putting it in parallel. Even using something cheap like FLA, you're looking at ~ $300 per 150 ah battery, and to get 156v you need 13 of them. Multiple by 2 to put them in parallel and you get 26 $300 batteries for about ~$7.8k. And, these weight about 100 lbs each, meaning you just put in 2,600 lbs of batteries, meaning you probably don't have the weight left over to put anything in the truck.

You can overcome the weight with Lithium batteries, but then your price goes up dramatically. You're talking ~ $1.20 per Ah, so $360 per battery (if they made 300 Ah lithium cells available, which I am not aware of right now. You're back to putting sets in parallel, but since the cost is per Ah, it doesn't really matter). However, these are only 3.4v each, so you'll need 45 of them. 45 x 360 = ~$16k. (this would probably be something more like 130 100 Ah cells but the price, again, is given per Ah so for our math it doesn't matter).

The 100 miles is really the sticking point. It is very hard to get 100 mi on a light car with what's available to DIYers. When you make it a 3,500 lbs vehicle, that just isn't realistic on anything short of a fantastic budget.

The axium is, you can have range, low cost, and speed. Pick two. If you were to run this like the space shuttle crawler, where it moves at .3 miles an hour, you could maybe do it on a budget, but it would be a lot of work still, and still very tough.
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #3 · (Edited)
Understood a pure battery range of 100 mi is a bit over the top (considering available capital). Is there such thing as a diybrid (diy hybrid) or similar model, and is this forum the right zone to try to develop such a thing?

My initial idea was to get an electric powertrain in the vehicle (FWD if possible), and provide the energy needed to propel it through batteries or a mix of batteries and an alternate power source, most likely ICE. A 3kw gasoline powered generator would cost me less than $1k.

Acceleration isn't a huge concern. 0-55 in 45 seconds is plenty fast enough for me. As long as it can get up to highway speeds (55mph) eventually. The common load would only be about 250-300 lbs, but that still puts you at 2800 lbs with the current configuration. I'd be interested in lightening the load (fiber / plexy hood, etc) and I'll be removing the clunky current engine, even though it is likely less than 200lbs.

I also have a Mitsubishi Mirage (2000 lbs curb weight, no weight reduction modifications in place) that I plan on doing a similar conversion to; the pickup is the 'alpha version'.

Edit:

Looking at the math, 500 wh/mi means at 60 mi/h, I'd need a 30kw genny, not a 3kw genny... am I reading that right?
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #4 ·
The trip is 21.9 miles from my place to the transfer station. Not 40 miles... that significantly reduces the necessary range of my vehicle. 50 mile range is about it. It is a 40 minute trip one-way though, so average speed of 30 miles per hour, peak speed of 55 miles per hour. Thank Google Maps for refining my accuracy. Given that information, is my project more do-able?

And what is the charge-time necessary using your 'average charger' to make the 50 mile trip (or half of it)?

500wh/mi * 50 mi = 25kwh...
25kwh / 3300 wh/h (@ 30 amps, 110 volts) = 7.5 hrs.

Just trying to figure out if I have the math right on all this (as obviously I can't figure out how to read a map).
 

·
Registered
Joined
·
290 Posts
100 miles for a heavy vehicle will be extremely difficult to do on any sort of budget. Figuring something large, like 500 wh/mi when loaded, you're looking at 500 wh/mi x 100 mi = 50,000 kwh. At a DC voltage of 156 (one of the largest DC voltages commonly used), you're looking at 320 Ah batteries. I can't find anything in this range, so you're looking at making a large pack larger by putting it in parallel. Even using something cheap like FLA, you're looking at ~ $300 per 150 ah battery, and to get 156v you need 13 of them. Multiple by 2 to put them in parallel and you get 26 $300 batteries for about ~$7.8k. And, these weight about 100 lbs each, meaning you just put in 2,600 lbs of batteries, meaning you probably don't have the weight left over to put anything in the truck.
Out of interest, where are you getting the "500Wh/Mile" figure from? Here are some figures liberated from elsewhere on the internet:
Ford Ranger (Production) 400 WH/Miles, AC, 4,750 lbs, 312V
Toyota Rav4 (production) 250 WH/Miles, DC, 3,500 lbs, 288V
Small truck (4wd) 366 WH/Miles, DC 9", 4,060, 192V
Small truck (eff. 2wd) 300 WH/Miles, AC, 4,880, 312V
Medium Sedan 345 WH/Miles, DC 9", 3,650, 228V
Micro car 133 WH/Miles, DC, 1,750, 120V
Small Car 250 WH/Miles, DC 8", 3,280, 114V
Aerodynamic Small car 180 WH/Miles, DC 9", 2,725, 240V
Small SUV 200 WH/Miles, AC, 1,650, 600V
From the looks of the D50, it'd probably come in somewhere between a "Small Truck" and the Ford Ranger, which puts the power requirements at between 300 and 400 W h/Mile, probably closer to 300 than 400.
This helps your range calculations considerably, making a 100 Mile range needing between 30 and 40KW h of power, and meaning using a 156v pack you'd have to have (40000/156) 256Ah. This is easily achievable using Thunder Sky 260Ah cells (http://www.thunder-sky.com/products_en.asp?fid=&fid2=&page=3), which can be purchased from any number of dealers. If you wanted Floodies, that might be a little more difficult, and certainly heavier.

As for a generator to power the vehicle as it's moving, you'd need approx a 40KW generator (40KW generated constantly for 1 hour = 40KW h). This would be more than enough to power the vehicle entirely without a battery pack, but it will end up being less efficient then the ICE that's already in there. It may be possible to make your own generator using the engine you pull out of the truck, hooked up to a similar sized electric motor as your traction motor, perhaps on a trailer, for long distance runs.
 

·
Registered
Joined
·
511 Posts
Out of interest, where are you getting the "500Wh/Mile" figure from? Here are some figures liberated from elsewhere on the internet:
It's just a number I threw out. But consider you're saying 400 wh/mi with an unladen light-truck, and he's talking about putting 2-300 lbs, up to 1,000 lbs, of weight in it. But even for the sake of argument, let's say 400. I'd probably want to take the ICE and do a coast test with a load to try and see what the rough Ah needed really would be.

The math I did before was just shoot-from-the-hip to show that 100 mi was pretty tough. I didn't take into account Puekert or safe Depth of Discharge (DoD).

With only 50 mi, 50 mi x 400 wh/mi = 20,000 wh. Increase by 50% for Peukert (an effect that lowers the energy available because it is being pulled out faster than the 20 hour Amp-hour rating on the battery). Increase again by 20% for a safe depth of discharge, means 20k + 10k = 30k + 6k = 36kwh when it's all said and done. Easier to reach but still hard. That's using flooded lead-acid batteries. At 156v, that's 230 Ah batteries. Unfortunately, these are ~ 166lbs each and ~ $600 ea, so you're still looking around 8k for a pack and around 2100 lbs.

AGM batteries are cheaper than lithium, and provide a better Peukert effect than FLA, but may not last as long. If you use AGM, you're looking at 20k + 4k + 4.8k = 28.8wh. At 156v, that's 185 Ah batteries. These are ~ 106lbs each and ~ $260 ea, so you're looking around 3.4k for a pack and around 1,400 lbs.

Lithium becomes much more affordable, about 12.5k. Same basic math as before applies.

Cutting the range in half makes the trip much more doable. You can put 1,400 lbs of lead-acid batteries in a truck and get the range you want. I don't know if you'll have the capacity to put 2-300 lbs more in it or not, depends on the axle weight ratings, bed weight rating, etc. This is a much more doable project though.

As for the hybrid, yes, some people do look to do that, and people have asked questions and gotten help here. This is not very often tried, however, and the engineering/manufacturing needed is beyond your average DIYer's ability and/or patience, so you probably won't get as many responses on the hybrid bits as you do the strictly EV bits. But we try to help where we can anyway and some of the folks here are pretty handy with that sort of thing. :)
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #7 ·
Thank you all for the valuable input. It will take a bit to digest the additional math, but I can work through it. I won't be using a 40kw generator, that's for sure. Maybe I can figure out how to balance the load. Mechanically doing so would take fabrication of custom transmission-like components, which if done hydrostatically may not be beyond my range. Doing so electrically would be, as you said, less efficient, but also less effort. A 5 kw generator could still lighten the burden on the batteries, as well as allow one to avoid needing a tow if it can park for a day.
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #8 · (Edited)
...making a 100 Mile range needing between 30 and 40KW h of power...
...As for a generator to power the vehicle as it's moving, you'd need approx a 40KW generator (40KW generated constantly for 1 hour = 40KW h). This would be more than enough to power the vehicle entirely without a battery pack...
I would need a 40KW generator if I was planning to travel at 100 mi/hr.

I would need less power at lower speed. 60 miles per hour, for example, would only require 60% of the power to generate the necessary KWh/h. A 24 KW generator would suffice. (Still bigger than I plan to get, as they run about $10k and weigh about 900 Lbs)

The formula as I take it would be Eff (kwh/mi) * Spd (mi/hr) = Demand (kwh/hr).

(Which of course allows you to reduce units to kw, as kwh/h = kw)
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #9 ·
A guy and his Fiero just inspired me to try to find salvage parts. Apparently a forklift motor might do the trick.

So back to the math involved.... The vehicle currently has a 2TC engine in it. Modified 2TC engines can get up to 200+hp, and 150 ft-lbs of torque... but mine's pretty much bone stock or worse. 88 at 6,000 rpm 91 at 3,800 rpm 8.5 1970–1979 << from Wikipedia http://en.wikipedia.org/wiki/Toyota_T_engine

So what's the minimum motor size, in part specifications, that I could get away with?

Do I need a 100kW motor?
 
1 - 9 of 9 Posts
Top