# What is Total Cost DIY EV ?



## favguy (May 2, 2008)

Hi,

Short answer, NO! 

You might want to try looking at evalbum.com for ideas on builds. Also read up on the wiki on here, look at the garage section.

Ball park battery cost alone to get your range at 70mph is $15k if you have a really aerodynamic lighter car, more like $20k realistically. Total build cost doing all your own labour will come in at about $30k plus the cost of the donor car.

You might just build an EV for $4500, with a used forklift motor, DIY or used controller, scrounged used parts and lead batteries and get a range of about 20 miles at 50 MPH or so, but it will be tight to do.


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## mizlplix (May 1, 2011)

Just an example:

My car=2,000 Lbs.
Range is a comfortable 55 miles @45-50 MPH.
Cost to convert(I already had the car) was $12,500

Miz


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## ga2500ev (Apr 20, 2008)

ATL-David said:


> Hello,
> 
> Im trying to plan ahead and determine the total cost of building an EV with the capability of 90 miles at 70mph. I havent decided if I want to convert a 5 spd car or truck, but I am looking for a something cheap on craigslist (Less than $700).
> Im still reading the beginner info on this forum, but I havent run across potential ranges in cost.
> ...


That's a tough nut to crack. High speed, long distance, small budget. Be aware that the Nissan Leaf cannot meet these requirements, and that vehicle cost about $25K.

As always it starts with the battery pack. The cost is measured in $/AHr (Amp Hour). For that range and speed, Lithium is the only option. Current prices run about $1.20/AHr give or take 15%.

So how many AHr do you need? We start with energy consumption which is measured in WHr/mile. This number is dependent on aerodynamics, speed, and weight of the vehicle. Very light efficient small cars can get it under 200 WHr/mile @ 70 M/Hh. Heavier, bigger, and blockier vehicles (Such as a truck), would be along the lines of 750-800 Wh/M or more at those speeds. Let's be conservative and give a budget of 600 WH/mile.

It gets pretty simple at this point. 600 WH/mile * 90 miles = 54000 Wh. You need some reserve because you cannot empty the batteries each time you use them so add 25%. 54000 *1.25 = 67500 Wh.

Now fortunately WHr takes into account both the voltage and the Ahr capacity of the pack. So we get to divide that 67500 Wh total by the voltage to get the number of Ahrs we need. Note that the speed of the motor is directly related to the voltage of the pack. In addition, the lighter the current draw on a pack, the less stress you put on it. In short, a higher voltage is better.

For the sake of argument let's put together a 144V pack which should be adequate for the task. So the total number of AHrs required is:

67500 WHrs/144V = 468.75 AHr.

Note that lithium cells come in standard Ahr sizes (40,60,90,100,160,180,200 Ahrs are typical). You could get away with 3 160 Ahr cells in parallel giving 480 Ahrs, which will oversize a bit. Each cell is nominally 3.2V so to get 144V you would need to string 144V/3.2V = 45 of the 3 cell groups together. So you'd need 45*3 = 135 160 Ah cells to build your pack.

Taking a quick look on electric car parts company CALB 160 Ahr cells are running $200 apiece in those quantities. Note this is in the original ballpark of $1.20/Ahr as these cost $1.25/Ah. So you have 135 cells at $200 each. That's $27,000 for the pack.
BTW that's without cables, charger, controller, motor, or vehicle. Just the raw batteries.

I hope this helps you to see why something like the Leaf is actually a great value. There's no way to have a long distance, fast, car cheap. You're going to have to give up the range, or the speed, or the weight if you're going to get it done.

My handle is the price point I'm trying to reach. I started with a $200 shell, a $600 Advanced DC 4001A motor, a DIY controller and charger, and planned to use refurb 12V 35AH U1 AGM batteries that I can get off the pallet for $25 a piece. Looking at a top speed of 55 Mph and range of about 30 miles. It's been slow going.

Your only hope for a vehicle with that speed and range is a cycle or trike. You may have to pull a trailer of batteries though.

Hope this helps,

ga2500ev


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## jeremyjs (Sep 22, 2010)

You're being a little pessimistic. 600 w/h a mile equals, approximately, a 6000lb finished vehicle. Short of a small to mid sized truck that's unlikely. You could go with a lightish car with descent aerodynamics and be half of those numbers or a really lightweight car with excellent aerodynamics and be nearly 1/3 of those numbers. Still well over the proposed budget, but nowhere near your truck numbers. 

Generally you need about 1 w/h per 10 lbs of vehicle, in good working order, to go 1 mile.


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## ga2500ev (Apr 20, 2008)

jeremyjs said:


> You're being a little pessimistic. 600 w/h a mile equals, approximately, a 6000lb finished vehicle. Short of a small to mid sized truck that's unlikely. You could go with a lightish car with descent aerodynamics and be half of those numbers or a really lightweight car with excellent aerodynamics and be nearly 1/3 of those numbers. Still well over the proposed budget, but nowhere near your truck numbers.
> 
> Generally you need about 1 w/h per 10 lbs of vehicle, in good working order, to go 1 mile.


I said this was a truck. I also said that a lightweight aerodynamic car would be under 200 Wh/mile too. The other reason I inflated the figure is that the OP specifically stated he wanted the 90 mile range at 70 MPH. We all know the power consumption goes up significantly when maintaining high speeds.

None of this negates the point that there's no lithium at the $4500 price point that can support that range, and that to get that range in lead, it in fact will be a 6000 lbs vehicle.

Let's start with the fact that the OP will need something like 144V to support the speeds which he wants to travel. That means 45 cells, even if they are singles. In addition the OP will have to have cells that support the power needs of the vehicle. With most cells operating in the 2C-3C range, that means that 40 Ahr cells simply won't cut it. Trust me, I've asked here multiple times. 90-100 Ahr cells are a more likely bet.

45 90-Ahr cells eats the entire $4500 budget and then some. Also those 45 cells gives and WHr budget of 144V*90AHr = 12960 Whrs total. Even at the margins only 80% of the capacity is usable as total drainage is a really bad idea. That gives 10368 Whrs capacity. For 90 miles that leaves 115 Wh/mile.

By your numbers that means the the total vehicle weight needs to be less than 1200 lbs or so. And you need 225 (45 cells * 2.3 kg/cell * 2.2 lbs/kg) for the battery pack and likely another 75-100 for the motor. At least another 200-300 for driver and passenger/cargo. Seems about right? So 225+75+200 = 500 lbs, leaving only about 700 lbs for the vehicle. That's an ultralightweight.

Design and budget starts with the battery pack. I hope these examples shows the OP how to compute range, weight, and cost for a given pack. It looks like a pack of 90-100 Ahr cells would be able to do 40-50 miles with a small car. 90 miles at that price point is a tough challenge.

ga2500ev


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## jeremyjs (Sep 22, 2010)

Sorry I missed the bit about the vehicle potentially being a truck. In that case you numbers are spot on or even a little conservative, depending on the size and aerodynamics of it.


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## ga2500ev (Apr 20, 2008)

The bottom line is the battery pack ends up replacing the gas in cost. The problem is that in general it's a capital cost that must be paid up front. Once you have the pack, the electricity to fill it is on the order of $2 a day if that. A well maintained pack can last 5 years or more. When you amortize the cost, it's a good deal. But when looking at it from the beginning, it can be a bit daunting.

ga2500ev


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## puddleglum (Oct 22, 2008)

ga2500ev said:


> My handle is the price point I'm trying to reach. I started with a $200 shell, a $600 Advanced DC 4001A motor, a DIY controller and charger, and planned to use refurb 12V 35AH U1 AGM batteries that I can get off the pallet for $25 a piece. Looking at a top speed of 55 Mph and range of about 30 miles. It's been slow going.
> 
> ga2500ev


I'm wondering what pack size you think you will need for your mileage parameters. I want a similar top speed and range with an avg. speed of 25-30 and a cruising speed of 40 in say a 3000lb car. I'm guessing I will need about a 9.6kw lithium pack at 80% dod. Does that sound about right?


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## ATL-David (Jul 14, 2013)

Batteries are expensive..

I found a site that sells 24V EV Rechargeable Li-ion battery Pack 600Ah for $300-1000/pack. Could i put 6 of these in series for 144V 600AH and call it a day?

http://www.alibaba.com/product-gs/1051732023/24V_EV_Rechargeable_Li_ion_battery.html


Or am I missing something?


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## ga2500ev (Apr 20, 2008)

ATL-David said:


> Batteries are expensive..


Yes. Yes they are. They are the primary cost center of any EV conversion.


> I found a site that sells 24V EV Rechargeable Li-ion battery Pack 600Ah for $300-1000/pack. Could i put 6 of these in series for 144V 600AH and call it a day?
> 
> http://www.alibaba.com/product-gs/1051732023/24V_EV_Rechargeable_Li_ion_battery.html
> 
> ...


Honestly, you are missing so much that it's difficult to know where to start. First off that price means that it's $300 each if you purchase 1000 packs. Next these are Chinese packs. This means you have to get them shipped. Also, there is suspect quality control which you will not have a chance to inspect until you receive your shipment months from now. Finally most firms of this type has a "You bought it, you bought it." mentality.

Do some research on this site and on Endless Sphere on companies such as Victpower. You will find this is a path that is fraught with danger.

ga2500ev


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## frodus (Apr 12, 2008)

Those 24V 600Ah batteries are NOT $300-1000 a pack. There's an error somewhere. Normal pricing for LiFePo4 is around $1.25/ah... lets say $1/ah direct (for sake of simplicity). Lets say 24V 600Ah costs $1000. 24V = 8 cells in series, so $125 per 600Ah cell. That's $0.20/Ah, which is going to be pretty much impossible.....

Using NORMAL China Lifepo4 prices, each 600Ah cell would cost $600 and have 1920Wh. For 24V, you'd need 8-cells, so $4800 for just one 24V 600Ah pack (15360Wh for a single pack). To get 144V, you'd need 6 (like you said), which would give you 92160. It's going to weigh almost 1000kg (just over a ton in just batteries) and cost $28,800.


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## EVEngineeer (Apr 11, 2012)

http://evolveelectrics.com/CALB.html here are some prices for batteries. The total cost for you will have to be above 20K, because batteries alone will cost 15k+. Now go buy the car, the parts, and the labor and it will cost you 5k+. A pickup truck is good for holding the batteries without having an issue on weight distribution. A car may not have enough room for all of the batteries. Just drop the ground clearance on he truck to give it better aerodynamics.


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## Duncan (Dec 8, 2008)

ATL-David said:


> Batteries are expensive..
> 
> I found a site that sells 24V EV Rechargeable Li-ion battery Pack 600Ah for $300-1000/pack. Could i put 6 of these in series for 144V 600AH and call it a day?
> 
> ...


"Continuous Discharge Current: 55A"


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## ga2500ev (Apr 20, 2008)

ATLDavid,

I know the replies that you have been getting are a bit frustrating and discouraging. There really isn't a viable way to get to your original parameters at the $4500 price point you seek.

My suggestion is that you dial back the range requirement significantly and start working from there. The only difference between an EV that has a range of 5 miles and one that has a range of 100 miles is the $20,000 battery pack. The vehicle, motor, controller, charger, wiring harness, and the like are the same. An EV that can get up to 70 MPH and has a range of 5 miles is doable on the cheap. So instead of focusing on the monumental task of trying to get a battery pack that can give you the range you seek, instead focus on everything else you need to get done and just be range limited for the time being.

One thread that has been of real interest to me here is the Lithium/Floodie Hybrid Pack thread the ZiggytheWiz has been working on. One of the toughest problems with Lithium only packs is that they need to have enough Ahrs to provide peak power. That's the reason why EVs are not built with 40 Ah packs. they cannot deliver enough current to accelerate the vehicle properly.

Ziggy's lithium booster straps lithium side by side with a lead pack. Lead is cheap and heavy. However it will happily provide the required amps at a cost of total energy. The lithium booster can supply more energy without overamping. So you can add lithium slowly instead of having to buy it all at once.

My goal was to start with a 6S2P lead pack of 12V 35 AH U1 wheelchair batteries. 96V*70Ahr = 6720 Wh of which about half is usable. 3360 Wh with an expected cost of 300 Wh/mile would give me about a 10 mile range. Not every useful. But this battery pack only cost $320 to build with refurbs. Call it a test pack. You can ride on the cheap and build and test everything with an EV without having to break the bank on batteries.

Now the booster. For example CALB cells seem to be running between $55 and $60 each for 40 Ahr cells. Let's call it $60 each. for 96V you need 30 of them. So a 96V, 40 Ah pack cost $1800 or so and adds 3840 Whr of energy to the mix. Unlike the 12 23 lbs U1s which clock in at nearly 300 lbs, the booster will be a shade less than 100 lbs more, while doubling the range of the vehicle.

The way I see it, it's possible to cobble together a long range pack in bits and pieces instead of having to come up with $15-20K all at once.

So don't give up. Your ultimate goal isn't achievable at the $4500 price point. But there are ways to get there without having to break the bank.

ga2500ev


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## AndyGaryLee (Jul 21, 2013)

I agree with ga2500ev that building an electric motorcycle would be your best bet, although trying to do it under $4500 will be pretty difficult. 
Here's a good place to look: http://www.instructables.com/tag/type-id/?sort=none&q=electric+motorcycle


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