# Planning '79-'93 Ford Mustang conversion



## Bullockracing (May 6, 2008)

I have not yet purchased the project car, however, an earlier ('79-'81) would be preferrable due to weight. I picked the Mustang, since I am familiar with it (I currently drive a '99 GT convertible that gets around 27 mpg - good for a Mustang, but still not good enough) and the availability of aftermarket parts.

I plan to execute this more as an engineering exercise than a quickie conversion. This would entail cutting the floor pans, trunk floor, and building an integral belly pan, which would also make room for batteries and lower the center of gravity. The firewall will also be lowered to hug the motor(s) and drivetrain. I also plan to add subframe connectors, a tubular K-member to increase strength as well as improve handling. The body will make use of a fiberglass flip-nose kit, sealed up for aerodynamics, and use of lightweight body components all around. The interior will be bare-bones - think race car-type seating and lack of interior panels. These could be added later. Wheels and tires will be ultra-light drag-race type, with skinnies on the front and moderate wheels on the back (but still small). Base weight without BEV equipment should be around 2000 lbs.

I have limited hands-on experience, but a lot of automotive concept and theory (I have a mechanical and civil engineering background)
I have a 75-mile round trip commute, so I need a good margin over that, say around 100 miles (?)
I need to get good performance - even taking the slow roads, it's mostly 55 mph two-lane, with limited passing. A jam car would be most unwelcome...
I am currently spending $4K annually in gas costs, and this is likely to skyrocket with the gas prices headed the way they are. My actual budget is a shoestring, since I'm stuck with a separate daily driver payment and my wife's truck payment (we won't even discuss her mileage).
I'm a performance car fanatic, so I've looked at the Warp motors, but they are cost-prohibitive, so possibly a pair of cheaper motors hooked together could work, but I would settle for a little less performance as long as I had the range. Unfortunately, I know next to nothing about the controllers and such. I'm working out the details in my head as far as construction goes.


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## mattW (Sep 14, 2007)

Ok just to whet your appetite before you read anything else take a look at the Ronaele 300e...


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## Bullockracing (May 6, 2008)

Yeah, and the 600E is totally awesome as well, but I think I could do better with a lighter car, plus the $80K conversion kit is a little over the top...

You're dead on though - that's the car that got me started on the thought process that led me here!


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## ngrimm (Oct 19, 2007)

I really like the Mustang foxbody platform. My only caution after having built an 82 for drag racing would be using a lot of care in cutting the belly pan etc. Since like most cars after the 70's it has a unibody instead of a separate frame the floor boards already have a tendency to crack behind the front seat from normal torque and twisting. It can be strengthened by welding in subframe connectors but I don't know how that would work once you started cutting. Btw the Thunderbirds are very similar in this respect. I wonder if a total tubular frame would be easier in the long run. Just my $02.


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## mattW (Sep 14, 2007)

So we're making a dream EV with great performance and 100 mile range with a shoe string budget... Do you have some wiggle room somewhere? Here's how I'd do your specs on the cheapest budget possible. At 250Wh/mile were talking a 25kWh battery pack which would have to be Lithium for size and weight restrictions... 40 3.2V 200Ah packs would do it @$400 each that $16000 for the battery pack (4 years of gas for 8 years of batteries but you've got to pick up a BMS to go with them). Buying two smaller motors might not actually be cheaper than one big one. I'd go with a kit like this one for a 144V system @$3500 + the adapter and battery racks etc. Lets set aside $5000 for the conversion + donor car + $17000 for the batteries. That would give you exactly what you asked for performance wise I would think. If you wanted a flat 75 mile range you could save $4000 or if you could recharge at work you and get away with a 50 mile range it would be $8000 for lithium but it would also be starting to be doable with Lead acid (much cheaper).


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## Bullockracing (May 6, 2008)

For the tube frame question - I've considered that - I have a guy that builds IMCA chassis who's going to assist me. The subframes will be tied prior to the floors being cut out for sure. 

I have some wiggle room on the budget, but I am definitely locked in on the range. I won't have access to plug in where I work (Uncle Sam), and my house isn't moving, so... I would be okay with a car that topped out around 50 - 55 mph, but probably not slower than that, since I have to go out of my way already if I want to dodge the 65 and 70 mph areas, which would increase the travel distance.

I've got a line on a donor car for less than $500, less transmission. I plan on going with a manual 4-speed (got a line on that too) or a C4 auto trans to reduce rotating mass, but am open to suggestions (direct drive and a numerically high rear end would have a couple hundred less pounds, and less rotating mass, but would it be cheaper?).

Could this be done with lead acid at all? I was looking at the Dyna Batt from Performance Distributors or possibly the deep-cycle Optimas... How do I get the Wh/mile spec estimate and the battery output to line up - I don't know either? The Dyna Batts are only 13.5 lb each, with a 16a/Hr reserve, but I don't think that tells me what I need to know... Can anyone assist me with that? 

I have a line on some electric motors as well, but they're from oil field pumps (how ironic) and I don't know if they are DC or AC, which could make them impractical for me. Obviously speed costs money, even in electric cars. Would any of the forklift motors work?

I did stumble on one that would be a couple thousand horsepower - it was about 4' long and 3' diameter - absolutely monstrous! I have no idea what it was used for, but it's just sitting in the oil field yard - but obvious not for an EV.


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## Bullockracing (May 6, 2008)

So I've narrowed it down - to meet the budget, the build is going to start slow, and pick up momentum later. I'll start with the donor, sell off parts, and pick up non-perishable parts (controller, etc) with the proceeds, and continue from there. 

I need someone to verify my math:

I am overestimating MattW's 250 Wh/m to 300, so 300 Wh/m x 100m range gives me a requirement of 30,000kWh total onboard available energy. The higher voltage systems are more efficient, so 30,000 kWh / 144V = ~208.33 Ah. Adding in the DoD requirement for lead acid gives me ~260.42 Ah. Adding the discharge rate into the equation gives me a requirement of ~585.95. Is this right? 

Nominally, I need 12 12V batteries to make a 144V system. I seriously doubt that I can find a battery with a Ah rating of 590. Do I need to divide the 585.95 by 12 to get the rating of the batteries I need? That would give me a battery requirement of 48.83Ah per battery, but I'm not sure you can just divide your total Ah battery pack by the total number of batteries, can you?


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## Bullockracing (May 6, 2008)

Assuming the Optima D31T/A would have the proper Ah rating, 12 of those batteries (59.8 lbs each) would weigh 717.6 lbs. The Dyna Batts would only be 162 lbs, but the reserve capacity is only 16Ah. I don't think the rating I need is related to MCA or reserve capacity. Even then, it would take 54 Dyna Batt batteries to outweigh the Optimas, giving me a 850 Ah rating for the battery pack, assuming the math is right (16Ah reserve x 54 batteries=850.49). The Optima battery pack would have a total Ah rating of 1860, again, assuming my math is correct...

Anyone have another take on this?


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## ngrimm (Oct 19, 2007)

I think you've got the idea. The Optimas you listed are 75 ah so times 12 volts equals .9 kw or just under 1 kw each right? Since you have estimated needing 30 kw total it would take roughly 30 of them. Being they are lead acid you would probably need extra so maybe 36 to give you three groups of 12 batteries. So 36 batteries at 60 lbs each equals 2160 lbs. I think the only drag racing will be your rear end dragging on the ground. I think you will find that it takes a certain amount of lead to for a given ah so which brand or model of battery won't change that very much. Btw you would want to use the "m" series of Optimas since that is a true deep cycle. The "a" you mentioned is a combination starter/deep cycle so I have been told they won't stand up to discharging as well. Good luck.


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## MrCrabs (Mar 7, 2008)

Bullockracing said:


> I need someone to verify my math:
> 
> I am overestimating MattW's 250 Wh/m to 300, so 300 Wh/m x 100m range gives me a requirement of 30,000kWh total onboard available energy. The higher voltage systems are more efficient, so 30,000 kWh / 144V = ~208.33 Ah. Adding in the DoD requirement for lead acid gives me ~260.42 Ah. Adding the discharge rate into the equation gives me a requirement of ~585.95. Is this right?
> 
> Nominally, I need 12 12V batteries to make a 144V system. I seriously doubt that I can find a battery with a Ah rating of 590. Do I need to divide the 585.95 by 12 to get the rating of the batteries I need? That would give me a battery requirement of 48.83Ah per battery, but I'm not sure you can just divide your total Ah battery pack by the total number of batteries, can you?


No, you don't take the total Ah needed and divide by the number of batteries in series.
When you stack batteries in series, the voltage increases, but the current that flows through them is the same, and the capacity in Ah is the same as if you only had 1 battery.
So if you stack 12 12v 60Ah batteries in series, you have a 144 v 60 Ah battery pack.
If you put batteries in parallel the voltage stays the same, but the current adds up.
So you figure out how many batteries in series you need to get your voltage, then you figure out how many packs you need in parallel to get the Ah capacity.

I don't think your going to be able to get 100 miles with lead acid in a mustang.

http://www.evalbum.com/733
http://www.evalbum.com/98
http://www.evalbum.com/273.html


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## Bullockracing (May 6, 2008)

MrCrabs said:


> I don't think your going to be able to get 100 miles with lead acid in a mustang.


Yeah, it's not looking good, is it? Thanks for the assist on the math - I'll have to work it some more...


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## Bullockracing (May 6, 2008)

Bullockracing said:


> Assuming the Optima D31T/A would have the proper Ah rating, 12 of those batteries (59.8 lbs each) would weigh 717.6 lbs. The Dyna Batts would only be 162 lbs, but the reserve capacity is only 16Ah. Even then, it would take 54 Dyna Batt batteries to outweigh the Optimas.


Assuming that the Optimas are "only" 75Ah, I would need 7 packs (at 717.6 lbs), so those are out, since the battery pack would be 5023.2 lbs(!).

So checking the Dyna Batts, I would need 30 of those (assuming the reserve capacity is the Ah rating I am looking for) for a total weight of 4860 lbs. 

Crud...

I'm going to research the Dyna Batts some more before I move on...


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## mattW (Sep 14, 2007)

Bullockracing said:


> So I've narrowed it down - to meet the budget, the build is going to start slow, and pick up momentum later. I'll start with the donor, sell off parts, and pick up non-perishable parts (controller, etc) with the proceeds, and continue from there.
> 
> I need someone to verify my math:
> 
> ...


You were close, "_The third step in [wiki=12581]Sizing a battery pack[/wiki] is compensating for the characteristics of the batteries we choose, for Lead acid batteries this can be achieved by multiplying our Amp-hour rate from step 2 by 2.25."

208.33 time 2.25 = 469Ah, still a lot probably too much for Lead acid unless its a truck... You'd need 2 strings in parallel of 6V batteries and probably have to upgrade the tyres, suspension and possible the chassis depending on the car.

With lithiums the Peukerts effect is only about 0.95 not 0.55 so you get much more bang for your buck. You only have to multiply by 1.25 for DoD and 1.05 for lithiums peukerts meaning (in one step) multiplying by 1.32 not 2.25 so your pack would only be 275Ah worth of lithiums... Much lighter and much more doable (except for $$$).
_


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## Bullockracing (May 6, 2008)

So I checked and the Dyna Batts are only 16Ah - way too small...

So it's looking like a 3/4 ton truck frame would be required to haul the amount of lead acid batteries I would need. 

I'm going to research the next most economical battery choice - any recommendations?


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## Bullockracing (May 6, 2008)

mattW said:


> _208.33 time 2.25 = 469Ah, still a lot probably too much for Lead acid unless its a truck... You'd need 2 strings in parallel of 6V batteries..._


If I'm getting this, I need 469 Ah worth of juice, in strings of 144V. So that's 469 / 75 = 6.25 (round to 7) strings of Optimas, at 717.6 lbs per string would be 5023 lbs of lead.

Dyna Batts would be 469 / 16 = 29.31 (round to 30) strings, at 162 lbs per string would be 4860 lbs.

It looks like I did the math a little different, but the results are the same. That's a lot of extra weight just to get the range I need out of lead acid batteries.

What's the next most economical choice for batteries?


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## mattW (Sep 14, 2007)

I'd go with two strings of big Ah trojan 6V batteries if you want to go with Lead. Two strings of T105s would give 450Ah using 48 batteries. Check out Red Beastie for the biggest range of anything I have seen using Lead...


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## Bullockracing (May 6, 2008)

Using Trojan T105s, I would need 24 batteries to make a 144V string of batteries, at 62 lbs each for a total weight of 1488 lbs per string, two strings would be 450Ah, but weigh 2976 lbs.

Trojan T125s would still be 24 batteries, at a string weight of 1584 lbs, with a total weight of 3168 lbs. with 480 Ah.

T145s would be 24 batteries at a string weight of 1728, for a total of 3456 lbs, but with 520Ah.

Either way, I'm looking at a GVW of over 5000 lbs, which is extremely heavy for such a light vehicle frame. The hard part of this build is the planning, since my driving radius cannot change, and the vehicle speeds are high...

What's the next best choice for batteries, Li Poly or NiMH, etc...???


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## joseph3354 (Apr 2, 2008)

lithium iron phosphate appears tp be the next best thing right now.1/3 to 1/2 the weight of lead with deeper discharge capabilities.however,they are expensive.if your budget can handle it you might want to check them out.the company i have been dealing with would cost you about 22k for 300 amp hours at about 900lbs of lifepo.there are many different manufacturers out there.just do a google search for lifepo batteries.


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## Mastiff (Jan 11, 2008)

Basically you will need either Lithium Polymer or Lithium Iron Phosphate to achieve the range you require.

But here's the real question:
*What is your Budget?*

If your looking at saving money on your gasoline over time, an EV is a good investment, but if your looking for a cheap solution right away, you won't get it.


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## Bullockracing (May 6, 2008)

Would you believe I can't find the LiFePO batteries on Google? Anyone have any recommendations on a good manufacturer?


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## kcblkeeley (May 8, 2008)

try internationalbatteryinc.com .That's where I've been looking at. let me know if you see anyone else.


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## Bullockracing (May 6, 2008)

Meh - still no prices on anything...

Where can I buy these stinking things?

I may switch to a full-size pickup so I can haul all of these *&%^*(&^ing batteries...


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## joseph3354 (Apr 2, 2008)

mostly you have to look at chinese manufacturers for lifepo batteries.american manufacturers are either outrageously priced or not selling to the general public.international battery inc manufactures lifepo batteries under license from thundersky.they are currently charging $3.25/amp hour compared to a direct buy from thundersky at $2/amp hour.i spoke with a sales rep from international battery and commented on the price difference.he said "yeah,but try getting a warranty from thundersky".


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