# Planning Chevy Impala conversion



## madderscience (Jun 28, 2008)

Hi xaerios-

GVW and weight carrying capacity is certainly a good thing in a conversion candidate. But bigger isn't always better in a conversion candidate.

Given your budget and anticipated plan, I hope you are planning a short range car. I say this because 600lbs for a lead acid battery (the only one you could afford in that budget range) isn't going to give you more than maybe 10-15 miles of range in a large car, and the batteries probably won't last that long. The only battery configuration that comes close to that weight that might work would be twelve 6V golf cart batteries which will weigh around 720lbs and give you 72V. That would allow you an around town car (no freeways, top speed maybe 40mph) with maybe 20 miles of useful range. 

The usual rule of thumb with lead acid conversions is you want at least 1/3 of the total weight of the car after conversion to be batteries. So if the entire car weighs 3000lbs, at least 1000lbs of that should be batteries. If everything except the batteries weighs in at 3000lbs, (your expected case) then the battery should weigh about 1500lbs.

Midsize pickups like the S-10 and ranger are pretty common conversions, and are in a similar weight class to the impala / crown vic. They usually end up weighing in around 4000 - 4500lbs after conversion depending on their battery configuration, and it is easy to beef up their suspension.

Not saying it can't be done, but I'd shoot either for a midsize pickup if you want something larger (easy conversion, kits are available if you want them), plan a bigger battery, or find a smaller car. A 600lbs battery in a small geo (and everything else EV related basically the same) would be about double the usable range vs. the impala, not to mention giving much better performance.

For what it is worth, my MR2 weighs about 3400lbs, of which 1250lbs is batteries. I have the same advanced DC 9" motor you are considering. Of course the toyota MR2 is a two seater with a tiny trunk. Maybe you need more.

Good Luck.


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## david85 (Nov 12, 2007)

Is the impala available with a manual transmission for that year? You want to avoid automatic, although it you really want it you can keep it at a reduced efficiency.


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## Uncle Joseph (May 7, 2008)

To give you an idea of price/range, I've estimated my Jetta conversion (lighter than your Impala) to be between $10k-$12k for a 120V, 50-60 mile range at mixed speeds. I came up with this price using EV America's prices, and factoring in a suspension upgrade with a paint job for the car (about $800 after I do all the prep work). 

With your budget, you're either going to get a very low range, low speed car, or you'll only get it about 2/3 done. The resounding advice almost anyone will give you is "Lighter is better" almost always, or a small truck with a large battery pack.


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## xaerios (Jan 22, 2009)

Okay, back to square one.

Speculatively:

1) What's the ideal budget for

a) 300km range
b) 100 km range
c) how much range for $7500

I'm thinking of spreading this out over two years, my absolute maximum is around $18000, is that realistic?

2) In your opinion, is lithium worth it right now, or should I just wait?

Yeah, I think I'll take the "lighter is better" approach. I know I have a lot of questions, but I guess we're all n00bs at one point... at least I didn't start out with a free energy question. 

thanks,
xaerios


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## Uncle Joseph (May 7, 2008)

xaerios said:


> Okay, back to square one.
> 
> Speculatively:
> 
> ...


Unless you want to spend $30k on lithium batteries, 300km range is out of the question. 100 km range is very possible even on lead, although it will depend on your pack voltage, battery choice, desired speed and donor car weight (there are many more variables, but those are the big ones).

If you have a fantastic ability to scrounge used parts and/or modify existing stuff to suit your need, $7500 using lead acid batteries could get you 60-100km range. Price depends on a lot of things. For example, I spent $1100 on my donor car, invested another $800 or so in upgraded brake components (it needed a full brake job, including calipers, when I bought it), and it needs some body work and a paint job...hard to come by pristine, cheap cars here in Michigan.

The minimum cost for a reasonably sized lithium pack is still going to run $13k-$18k, unless the prices have come WAY down since I last looked.

You really need to define what your design criteria will be. These may be dependent on your budget. However, you can build a very nice conversion on $18,000 over the course of 2 years.

You need to know what range you absolutely must have. So what are you using the car for? Commuting to work? Drag racing? You also need to know what speeds you will need out of the car. Do you need to travel on the freeway? If so, what's the maximum vehicle speed you can live with, and how far do you need to go at this speed? How hilly is the area you'll be driving in?

With your $18k budget, flooded lead-acid batteries, or perhaps AGM batteries would suit you. FLA give the best bang for the buck, but they're heavy. With a $7500 budget, you're going to have to get creative...I suggest checking out http://www.forkenswift.com/ for ideas on an inexpensive conversion.

If you want all new components, you'll spend $7500 or more just on the donor car and systems, before batteries.

Top speed, acceleration and range will start determining your pack voltage. Once you have an idea of how much voltage you need, you can start sizing and pricing components. For example, you might be able to get away with a 72-volt conversion if you only need an around town type of car (say max speed of 40KPH). However, if you need freeway speeds (100KPH+), then you'll likely need at least a 120-volt conversion, with 144-volts being more desirable.

My track record with most projects (home improvement, building a computer, getting my pilot's license, etc), is that you will spend twice what you plan to. So if you say your budget is going to be $8k, you'll probably spend closer to $14k-$16k by the time you're done. There are so many things that you'll run into, or forget to consider, that you'll almost always go over budget. If you plan properly, and get tons of advice from the right places, you can minimize overruns...but you will still likely have some.

The easiest way to enter the arena for a known cost is to duplicate what someone else has done, when they have documented all the expenses. Even a kit from the major suppliers yields a lot of price unkowns, such as how much you pay for your donor car, how much local labor/materials cost for things like the battery trays, sealed boxes, pack heaters, insulation, etc...


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## Qer (May 7, 2008)

Uncle Joseph said:


> The minimum cost for a reasonably sized lithium pack is still going to run $13k-$18k, unless the prices have come WAY down since I last looked.


3 Volt 100 Ah LiFePO4 (top current 300 Ampere since LiFePO4 can "only" handle 3C) seems to weight in at about $300 including balancer from, for example, lionev, 200 Ah is about $520.

Personally I'm aiming at starting with a pack of 30 100 Ah batteries, which means $9000, and later upgrade it to either 45 or 60 depending on the performance with 90 Volt. If 100 Ah and 90 Volt is "reasonably" is probably very depending on the situation, like curb weight...



Uncle Joseph said:


> My track record with most projects (home improvement, building a computer, getting my pilot's license, etc), is that you will spend twice what you plan to.


We did a budget for our last home improvement project and doubled the result because we have the same experience. We still ended up spending approximately twice even that sum.


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## xaerios (Jan 22, 2009)

I've noticed the 2x budget phenomenon myself in other projects to, hehh... I think it might be best to start off small, maybe an e-bike or something, then take it from there.

Realistically, I'm not going to _need_ a lot of range, but of course I'd want it. For me it would be mostly for city driving, but I'm in a big city, so going on highways to get somewhere in the city is normal.

I know you'd get a huge efficiency loss, but is it possible to use a DC/DC step-up converter for highway speeds? I can't see myself using it on a highway every day, but once in a while I'd like to be able to go down an expressway for short distances, 100km/h for 10-20km (or 60mph for 7-13 miles) Because I wouldn't be primarily using it for highway speeds, I think I could get away with a lower voltage system with some sort of power boosting setup for when I need it.

My other question is if it would be possible to use an array of capacitors on a generator, so that it would be able to provide enough power if necessary. I know it's probably been asked before, but I've never seen someone propose using caps. This way if you're going up a hill or something, then the generator would be able to provide enough power. I imagine that's how the volt does it, with capacitors to provide a lot of "peak" power from the generator if needed?

Would you recommend the Jetta? I'm looking for a domestic/european donor car, if you have any suggestions

thanks
xaerios


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## david85 (Nov 12, 2007)

Qer said:


> 3 Volt 100 Ah LiFePO4 (top current 300 Ampere since LiFePO4 can "only" handle 3C) seems to weight in at about $300 including balancer from, for example, lionev, 200 Ah is about $520.
> 
> Personally I'm aiming at starting with a pack of 30 100 Ah batteries, which means $9000, and later upgrade it to either 45 or 60 depending on the performance with 90 Volt. If 100 Ah and 90 Volt is "reasonably" is probably very depending on the situation, like curb weight...


Your pricing and performance data on LiFePO4 are out of date.

5C peak is the norm now. I paid $298 per 200Ah cell before BMS and charger. Don't buy from LionEV either.....many have been burned.


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## Qer (May 7, 2008)

xaerios said:


> I know you'd get a huge efficiency loss, but is it possible to use a DC/DC step-up converter for highway speeds?


Possible? Sure. Practical? No way.

It's better to go for higher pack voltage and switch the Voltage down than even consider switching the Voltage up since it will make an already demanding amount of current increase to even higher levels. So instead of using, say, 72 Volt and 200 Ah you should go for 144 Volt and 100 Ah since the amount of kW (and thus range) will be the same.



david85 said:


> 5C peak is the norm now. I paid $298 per 200Ah cell before BMS and charger. Don't buy from LionEV either.....many have been burned.


Ah. Even better. Well, not the part about LionEV of course. Gonna avoid those guys then...


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## Uncle Joseph (May 7, 2008)

xaerios said:


> Would you recommend the Jetta? I'm looking for a domestic/european donor car, if you have any suggestions


I am only in the beginning stages of planning my Jetta conversion, so it's hard for me to speculate on its suitability. However, plenty of people have converted Jettas, and it seems to be a fairly successful platform for an EV. I won't even begin taking the ICE out until mid to late spring (April or so). That being said, I'm very in to familiarizing myself with the layout and wiring diagrams during these colder months. And I must say, that the Jetta is an elegantly simple car. Everything is easy to reach and work on compared to some other cars I've owned. The more I read about it and look over the factory manual, the more satisified I am with having bought it for my donor.

That being said, there are plenty of other excellent candidates out there. My Jetta tips the scales at 2660 pounds...not light, but not heavy either. I just got my calculations from EV America and now I just have to decide on 120V or 144V.


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