[Farther Faster Cleaner]

Hi, I am a full time student at a local college. I have always wanted to build an electric car, but never had the need until now. My daily drive is 30 miles to school and then 30 back, creating a total of 60 miles. I am in need of advice on what would be the best motor and pack combination for this distance, but also at the cheapest price possible, and as to what would make a good donor car. Seeing as I am a full time student, I don't exactly have a lot of money to spend, so the cheaper the better . I can post a video of the drive if that helps. I also happen to live in the boonies, with a lot of hills, think that may help with the advice.

P.s. As for the donor car I am thinking of a 83' porsche 944, good or no?

Thank you in advance, F.F.C.

 

[dtbaker]

regardless of donor chassis, you will need Li batteries to get reliable 60 miles... which takes you out the 'cheap' class right off the bat. In fact you are looking at a 120v or more pack of 160ah or more minimum.... figure at least $1.30/ah cells by the time you get them to your door. If you go over 120v you get better performance, but a whole new level of expense with motor/controller and everything else.

With hills, you almost have to consider AC to get regen braking, but not absolutely.... AC raises the bar considerably in price.

You are looking at $12-15k in parts to do it anywhere near right with that range requirement.

 

[Farther Faster Cleaner]

I was afraid of that, didn't know if there had been any advances in lead acid batteries that would allow for that kind of range. That's no good for the budget then.. Just have to wait a little longer than. seeing as the original budget was 8k including the donor car cost...

For the voltage, that will be determined by the motor... I think

As for the motor, I am a relative noob when it comes to motors of any type and battery discharge abilities. So why does a ac motor make more regen than a dc? And where would I go about buying a used one or will that cost more in the end? And and if I were to create a car with maximum regen capabilities, would a hevyish/aerodynamic car be better idea?

Sorry for so many questions, i really want to do this

 

[Amberwolf]

If you can carry your charger in the car, maybe you can ask about recharging at school. If they can supply enough power, and your charger can do it and batteries can take it, maybe you could add to the range that way, so you have enough to get back home after the day is over.

 

[sjc]

Hi, I am a full time student at a local college. I have always wanted to build an electric car, but never had the need until now. My daily drive is 30 miles to school and then 30 back, creating a total of 60 miles.

Can you charge at school? How long are you there? The only way I think you'll come close to your desired price point is if you can find a way to cut your needed range in half, especially taking in to account the hilly nature of your drive.

What speed do you need to attain?

P.s. As for the donor car I am thinking of a 83' porsche 944, good or no?

I'm converting an' 86 911 Targa, so I can't complain about the manufacturer you chose, but, at just under 3,000 pounds, it's not the lightest conversion. If your goal is to maximize range, you might consider a lighter car like an older VW bug with a curb weight of 2200 pounds. There lots of conversions of those around, and even complete kits for the bug that you can buy at modest cost.

As the old saying goes: Fast, good, cheap: choose two. If you can find a plug at school, you might see if a 96V conversion of a VW beetle would give you the range you want if you went with 200Ah 6V batteries. It won't go highway speed, but it should get you there (I won't say "and back" .

 

[Farther Faster Cleaner]

Point noted about chargeing at school, i will look into that, but some days I am only there for about 2-3 hours. But the more i think about the 60 mile range, it would allow me to go to the other big town near me, on one charge. So if it cost a little more, than i think i can stand the wait.

The speed that i need to "maintain" would be 60, it's mostly highway between my house and anywhere I would drive, which will make for a high kWh requirement i think.

The 944, the thought there was that i could basicly gut it, remove all the unneeded items, and cut the weight down, then add in all the ev componets to bring it back up to the original curb weight. Mainly because i want to keep the handling of the original 944.

None the less a bug is a choice... Won't quite looks as cool.. ;P

 

[dtbaker]

...60 mile range, it would allow me to go to the other big town near me, on one charge.

The speed that i need to "maintain" would be 60, it's mostly highway between my house and anywhere I would drive

The 944 is kinda heavy, but cool for sure. The thing about highway speed is that you need a fairly big draw 'continuous', which means you probably need to go for 160ah or 180ah and 120v or 144v total pack so that you aren't too hard on the pack.

I would say you are going to be happiest with a 144v or 156v worth of 160ah cells, and a 9" DC in a 944 if you have a line on a donor.... with a 500amp (minimum) controller, but don't go overboard or you will kill your cells. Otherwise, look for something a little lighter and you might get by with 120v worth of 180ah, whic would save you some $$,

 

[sjc]

The speed that i need to "maintain" would be 60, it's mostly highway between my house and anywhere I would drive, which will make for a high kWh requirement i think.

As noted in other posts, highway speed for that kind of distance translates into a much bigger pack. You want to up your voltage so the motor doesn't have to work as hard, and you want to up your AH to get range.

The 944, the thought there was that i could basicly gut it, remove all the unneeded items, and cut the weight down, then add in all the ev componets to bring it back up to the original curb weight. Mainly because i want to keep the handling of the original 944.

You'll face two challenges here. Challenge 1: overall weight. To get the kind of range/speed you're talking about, you're going to need a lot of lead. You'll end up higher than the original curb weight if going with lead, and given the amount you'd need, you'd probably have to beef up the suspension (read: $). For my 911 conversion, I'm going with a 144v 160Ah Lithium pack, and that weighs in at 550#. For lead, you'd want at least a 200Ah pack, and for 144V for 6V batteries comes in at a whopping 1700 # (or roughly 3x the weight of my lithium pack). Now we're running up against GVWR, if we haven't already passed it. Challenge 2: weight distribution. It can be tricky to keep the balance between the front and rear axles from the original ICE car. The original 911 has much more of the weight over the rear axle, but I'm going to want to put batteries in the cargo compartment (in the front). That's going to change the handling.

None the less a bug is a choice... Won't quite looks as cool.. ;P

Everybody loves a bug.

 

[cruisin]

I am doing a 911 also and am wandering where you got the adapter plate? Are you going to use a clutch? I do not use a clutch on my VW conversion and it works very well.

 

[JRP3]

I don't think a bug is a good choice since it's aerodynamics are poor, and aero counts more at speed than weight. Since you have hills to deal with weight is also an issue. Lead batteries are not an option with your range needs. I'll disagree a bit on the voltage issue. Sure higher is better, but I'm running a 115V nominal pack of lithium in my Fiero and I can usually drive pulling less than 200 amps from my SE 100 cells, less than 100 on the flat.

 

[sjc]

I am doing a 911 also and am wandering where you got the adapter plate? Are you going to use a clutch? I do not use a clutch on my VW conversion and it works very well.

Yes, I will be using the clutch. I don't yet have an adapter plate; I have the names of two folks who've done 911 conversions in upstate NY, and I'll be getting in touch with them to see what they did.

I'm just in the process of purchasing a transmission (I bought a glider w/o ICE or tranny). I have the cables, batteries, and motor here, but the implosion at EVC means I'm back to looking for a controller and charger.

 

[tomofreno]

Mainly because i want to keep the handling of the original 944.

That, and the 60 mile range eliminate lead acid batteries. I don't know the weight or drag coeff of the 944, but I would guess it would use about 270 Wh/mile or so at 60 mph (energy from the cells, not from the wall outlet). If you use 70% discharge to get better cell life, you need about a 270*60/0.7 ~ 23kWh pack. Maybe 20% more than that, or 27.6 kWh, if you live where it gets very cold in winter so you need to run a heater at about 3kW. A pack of 48 180Ah Sky Energy cells would be 154V nominal, giving good acceleration, about 27.6kWh energy, about 590 lb weight, and cost around $11.5k delivered. Or, if you want to save more weight, you could use Kokam lithium polymer cells, for maybe 3 or 4 times that cost. I think the only way you could hope to make that range with lead acid would be a small pickup truck loaded up with 250 Ah flooded lead acid cells.

 

[cruisin]

I disagree with your statement about a bug being a poor choice. Of all the cars I have done, the bug is the best. Easy to add/remove VW and EV motor, builtin heat tubes for all wiring to inside and to front of car, good storage space for batteries in rear, parcel shelf and in front. Car is light and most EV's dont drive a long way on the freeway and shouldnt. This car gets more looks than all my other conversions put together. Voltage is another issue. Keep the volts around 120vdc which will give you more speed than you will need, but go with at least 200mah Li-ion batteries for power and distance. I have tried all variations and this works best.

 

[Farther Faster Cleaner]

I don't think a bug is a good choice since it's aerodynamics are poor, and aero counts more at speed than weight. Since you have hills to deal with weight is also an issue. Lead batteries are not an option with your range needs. I'll disagree a bit on the voltage issue. Sure higher is better, but I'm running a 115V nominal pack of lithium in my Fiero and I can usually drive pulling less than 200 amps from my SE 100 cells, less than 100 on the flat.

That was what I thought to be the problem with a vw bug, and i am not a fan of them in general, lol oh well.

So for hills weight is the most important value, and then aero is the most important value for speed?

You'll face two challenges here. Challenge 1: overall weight. To get the kind of range/speed you're talking about, you're going to need a lot of lead. You'll likely end up higher than the original curb weight if going with lead. For my 911 conversion, I'm going with a 144v 160Ah Lithium pack, and that weighs in at 550#. For lead, you'd want a 200Ah pack, and for 144V for 6V batteries comes in at a whopping 1700 # (or roughly 3x the weight of my lithium pack). Challenge 2: weight distribution. It can be tricky to keep the balance between the front and rear axles from the original ICE car. The original 911 has much more of the weight over the rear axle, but I'm going to want to put batteries in the cargo compartment (in the front). That's going to change the handling.

Ok... that makes sense, has anyone ever actually made a parallel circuit using lithium batteries? Would that help with my range requirements?

 

[cruisin]

That was what I thought to be the problem with a vw bug, and i am not a fan of them in general, lol oh well.

So for hills weight is the most important value, and then aero is the most important value for speed?



Ok... that makes sense, has anyone ever actually made a parallel circuit using lithium batteries? Would that help with my range requirements?

I work with inividual cells and build them in parallel for the ah I want and then in series for the voltage I want. You dont have to run complete string to the controller, just between pacs works well. I have a range of about 100 miles with 220ah under good conditions.

 

[JRP3]

I disagree with your statement about a bug being a poor choice. Of all the cars I have done, the bug is the best. Easy to add/remove VW and EV motor, builtin heat tubes for all wiring to inside and to front of car, good storage space for batteries in rear, parcel shelf and in front. Car is light and most EV's dont drive a long way on the freeway and shouldnt. This car gets more looks than all my other conversions put together.

Since this poster is specifically needing long range and 60mph speeds none of what you mentioned is relevant. Aero matters most at speed, then weight. The most aerodynamic vehicle he can find will give him the most range with the smallest pack, that's what he needs.

 

[JRP3]

So for hills weight is the most important value, and then aero is the most important value for speed?

That's about it.

Ok... that makes sense, has anyone ever actually made a parallel circuit using lithium batteries? Would that help with my range requirements?

Sure people parallel smaller cells to get a larger amp hour rating but you're better off just buying a larger amp hour cell. One 100Ah cell is better than two 50Ah cells paralleled since you have few connections. What matters most is total kilowatt hours, Tom laid out what you probably need.

 

[Farther Faster Cleaner]

Sure people parallel smaller cells to get a larger amp hour rating but you're better off just buying a larger amp hour cell. One 100Ah cell is better than two 50Ah cells paralleled since you have few connections...

Is that only because of the added resistance of the addition of wire to the whole system?

That, and the 60 mile range eliminate lead acid batteries. I don't know the weight or drag coeff of the 944, but I would guess it would use about 270 Wh/mile or so at 60 mph (energy from the cells, not from the wall outlet). If you use 70% discharge to get better cell life, you need about a 270*60/0.7 ~ 23kWh pack. Maybe 20% more than that, or 27.6 kWh, if you live where it gets very cold in winter so you need to run a heater at about 3kW. A pack of 48 180Ah Sky Energy cells would be 154V nominal, giving good acceleration, about 27.6kWh energy, about 590 lb weight, and cost around $11.5k delivered. Or, if you want to save more weight, you could use Kokam lithium polymer cells, for maybe 3 or 4 times that cost. I think the only way you could hope to make that range with lead acid would be a small pickup truck loaded up with 250 Ah flooded lead acid cells.

Alright that helps a lot, really lays out the price point for the packs nicely, as for the location part, I live in the midwest, Indiana to be more specific, so summers of 80f and winters of 20f or less. In an effort to be smart, how would I prepare this car for year round driving?

As for the pack, with your math i would need 27.6 kWh, so say i rounded to 30 kWh pack, that should compensate for the heater during the winter, but will it also help the acceleration times of the 944?

Maybe a better question is what does it take for a car to have say, sub 8 sec 0-60 time? J/w

 

[JRP3]

Is that only because of the added resistance of the addition of wire to the whole system?

Any extra connection has the potential to introduce resistance and another point of failure. Of course it can be managed, Tesla uses 6831 cells quite successfully, but why make it twice as complex as you need? Unless you have some specific space issues where two smaller cells would work better than one larger.

Alright that helps a lot, really lays out the price point for the packs nicely, as for the location part, I live in the midwest, Indiana to be more specific, so summers of 80f and winters of 20f or less. In an effort to be smart, how would I prepare this car for year round driving?

Insulated and heated battery packs.

Maybe a better question is what does it take for a car to have say, sub 8 sec 0-60 time? J/w

Probably more money than you want to spend