DIY Electric Car Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
I am looking at building a truck. I have not made any purchases yet. Completely open to any ideas, thoughts so far are of either a casual driver, a dragster or a rock crawler.

This is my first project so I am thinking the casual driver project is best suited to start with. So far I am looking at a small truck conversion Toyota Tacoma with a standard transmission etc.

Main thing right now is I have batteries... 12v 500W 100lbs each, basically as many as i want to use.

I would like to be able to drive 200km per day approx and reach speeds of 90-110km/h for highway driving.

I haven't looked much at the details of the motor size or other equipment as I dont know weight to power ratios or power to distance ratios etc.

I would love to hear some opinions. Or just a point in the right direction would do.
 

·
Registered
Joined
·
511 Posts
If you haven't got the donor car yet, you might look for a Chevy S-10. They're a fairly popular truck to convert, which gives you a lot of other people's experience to pull from, as well as things like ready-made couplers.

Given that it's a truck, the 100 lb batteries do not over concern me, but you will most likely have to split the pack between the front and the back. It makes the wiring setup a bit more work at first, and you'll have to make a weatherproofed enclosure for the back ones, but nothing insurmountable. The wiki is highly recommend as a starting point, as MJM pointed out.
 

·
Registered
Joined
·
511 Posts
The battery specs...
http://www.cdstandbypower.com/product/battery/vrla/pdf/12_475.pdf

Thanks for the replies, I will be checking out all options over the next couple months.
That's a really detailed spec sheet. I thoroughly confused myself doing a lot of math before realizing I was being an idiot. :p In any case, a 16.08 kWh pack is pretty decent sized. Figuring 350 Wh/mi (300 is a more generic number; I'm being a bit pessimistic for an un-aerodynamic truck, weight distribution, etc), you're looking at 10.2 kWh usable (20% off each for DoD and Puekert), gives a range of 29 miles. If you use a more optomistic 300 Wh/mi, you get 34 miles. Not bad at all.

Edit: but unfortunately nowhere near 200km. Just reread the OP. That's only 54km, so you'd need at least 4x the batteries. At 100lb each that'd be almost 5,000 lbs of batteries. You could probably get a realistic 100km with PbA, but higher than that and you're looking into Lithium range for weight reasons, and just like PatricioIN said, large money.
 

·
Registered
Joined
·
894 Posts
look at other truck conversions in the garage section or on www.evalbum.com

Sorry, but no way you'll get anywhere near 120 mile range out of lead acid batteries, no matter how many you put in the truck. You could look at VERY high Ah lithiums, and it's possible with say 156v of 260Ah batts if you could keep your Wh/m down to 300. However, open your wallet! That would mean many thousands of dollars for batts alone - in the neighborhood of $16k.

There's a reason the Leaf/Volt/Tesla vehicles are so expensive. Range = Cash!

Keep your expectations realistic and you'll be very happy with an EV.
 

·
Registered
Joined
·
714 Posts
If you can get your garage to corral a VW pickup,this would be a real builder!
These VW pickups are getting very scarce.They are lightweight and have a small frontal area.
Put some other examples,too.
Regards,
John
 

Attachments

·
Registered
Joined
·
4 Posts
Discussion Starter · #8 ·
Ok so I have read the wiki. Got some great info. Comes down to two or three possibilities for me...

Option 1
I have a miata, front and rear bumpers smashed up but engine/drive train works still. Could bolt electic to the standard transmission.

Option 2
I always wanted an early 90's rx7 for the style. Again bolt to trasmission.

Option 3
Truck, but with this one I would go all out. AC system, VFD and motor to rear axle. Removing engine and transmission. Doesnt matter what truck i use in my eyes lighter is better I assume. VW might be fun if I can find one.. I have a friend thats a VW guru so he might be able to find me something. If I build an AC EV Truck, it will be for demonstration and advertising.

I like all three options and I have some descisions to make. Depends on what I can find around cheap vs if I can get sponsors.

That being said... I have a question for PatricioIN.

In response to...
"Sorry, but no way you'll get anywhere near 120 mile range out of lead acid batteries, no matter how many you put in the truck"

Do you have a graph to back up that statement?? I have been looking for curves to estimate from.

Thats pretty much what I was looking for soon as I found out I was getting these batteries.. (mass vs distance, mass vs power) I was looking for a breaking point in batteries where it is no longer worth carrying the extra weight. Your statement tells me you know this.

What I take from what your saying is 50 batteries at 100 lbs each will go approximately the same distance as 10 or 20 because of the weight vs power. Can you explain in more detail?? Or am just confused?

If distance is the main issue with 'ev vs price' I can over come it by making two evs... one for driving around town and one for my 40km commute each way on rough highway. ;) One charging while ones being used.
 

·
Registered
Joined
·
714 Posts
You may want to build an all-aluminum reverse-trike ev with the total weight under 1,000lbs.The secret is in the low weight and small frontal area for long commutes with minimal battery packs.The battery packs become less expensive,too.K.I.S.S .Keep it small silly!
The reverse-trike (motorcycle) is easier to license and gets you in the fast commuter diamond lane without any ev applications.
http://reversetrike.proboards.com/index.cgi?board=designs
Regards,
John
 

·
Registered
Joined
·
511 Posts
Ok so I have read the wiki. Got some great info. Comes down to two or three possibilities for me...


Option 1
I have a miata, front and rear bumpers smashed up but engine/drive train works still. Could bolt electic to the standard transmission.
I don't recommend this. There's a reason you haven't fixed it up yet. That reason apparently hasn't changed, or it would be fixed. Having to do a lot of body/restoration work on the car before you start doing the EV work is a bummer (first hand experience here). If you think you'd like to do this, then restore the car first, as it's own project. If you finish, you can EV it. If you don't, you won't have an EV that looks like it's been in a wreck.

Option 2
I always wanted an early 90's rx7 for the style. Again bolt to trasmission.
Curb weight seems to be around 2800 Lbs. That's a little heavy. Not too bad but getting up there, when you think about adding in 1200lbs of batteries. The GVWR is 3792m so a little over 900 lbs of weight you can add. As ICE bits you remove are ~450lbs + your weight, it'll work out, but that's getting a bit high. Sports vehicles are problematic because they often have a high weight-to-load ratio, because they're not designed to carry much load. It can be done, however:

http://www.evalbum.com/260.html

Option 3
Truck, but with this one I would go all out. AC system, VFD and motor to rear axle. Removing engine and transmission. Doesnt matter what truck i use in my eyes lighter is better I assume. VW might be fun if I can find one.. I have a friend thats a VW guru so he might be able to find me something. If I build an AC EV Truck, it will be for demonstration and advertising.

I like all three options and I have some descisions to make. Depends on what I can find around cheap vs if I can get sponsors.
Of course option number 3 is entirely dependent on your funds. AC is typically more expensive (less mass production working for it, more components, etc). AC is generally said to have the best performance.

That being said... I have a question for PatricioIN.

In response to...
"Sorry, but no way you'll get anywhere near 120 mile range out of lead acid batteries, no matter how many you put in the truck"

Do you have a graph to back up that statement?? I have been looking for curves to estimate from.

Thats pretty much what I was looking for soon as I found out I was getting these batteries.. (mass vs distance, mass vs power) I was looking for a breaking point in batteries where it is no longer worth carrying the extra weight. Your statement tells me you know this.

What I take from what your saying is 50 batteries at 100 lbs each will go approximately the same distance as 10 or 20 because of the weight vs power. Can you explain in more detail?? Or am just confused?
I don't think that's quite what he meant. The limit is how much the car can hold; at 100lbs a peice, you're probably pushing the GVWR of almost any street car at around 15. 15 x 12 = 180v x 134 Ah = 24,120 Wh. Puekert on FLA is 50%, on AGM it's around 20%. So if these are AGM batteries, you're looking at total usable pack size at 15,436 Wh (20% off for Puekert, 20% off to keep the depth of discharge safe). With FLA you're looking at 9,680 Wh.

At a safe estimate of 300 Wh/mi, that gives you 32 mi with FLA and 51.4 mi with AGM. The energy density of PbA is such that to get enough to move you that far, you have to have a much heavier, better built vehicle. Maybe if you were converting something like a heavy-duty pickup you could pull it off, but it would require some very specific numbers and some good math.

What he meant was just that you're not going to have the weight overhead available to put enough batteries in to go that distance. I'm sure there exists some number where the weight and energy balance out, but just in practical terms, a street car (or truck) isn't going to get there.
 

·
Registered
Joined
·
4,326 Posts
"Sorry, but no way you'll get anywhere near 120 mile range out of lead acid batteries, no matter how many you put in the truck"
without exhaustive formula to back up the statement, I would agree with Patricio on this. It seems that with Lead there is a diminishing return when attempting to get more than about 40 mile range. You end up hauling around so much weight in lead that it gives a diminishing return,and you'd have to make major suspension upgrades, and have a wy over-size motor to get it rolling.

The 'realistic' range limit for lead seems to be right around 40 miles, whereas you can get much closer to 100 miles with Li even with no regen and DC motor in a small car.
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #12 ·
Thanks guys I appreciate the help. I'm gonna do some more reading and start figuring out ratios.

The miata part was just an idea since I have it sitting there, I promised myself I would never get rid of that car. I'm thinking small scale for it. Its going to be a frankenstein project if I do it. Miata's owners know space is limited. So seing one with no trunk and a shortened front end would turn heads. The big advantage to going EV in this case is space.

I am probably just dreaming here but if I have the money I think I would try to make my miata look like an audi TT. No use other than as a new age classic cruiser.

I was thinking originally of a big truck. Reason being I have lots of batteries. But their weight makes it illogical to use too many. Reading posts made me think smaller is better. Which I would agree with, unless you have surplus of batteries!

If I find a bigger truck at a scrap yard, like an F350, That could make for a fun project. I'll try working out the numbers and then I will post it, you guys can tell me if I am doin it right after.
 
1 - 12 of 12 Posts
Top