im working on various ideas of building an EV of my own… i was thinking of ordering the plans to the XR-3, possible convert it to a 4 wheel version… anyway, im hoping to go all electric, but if i cant get the range i want, i might install a small, light, diesel generator for backup power… anyway, i was thinking of using aerogel ultracapacitors in place of batteries, with a pulse electric motor… i would like to find people who know more about these technologies and could discuss it with me further, im not too sure how much the aerogel capacitors will cost, and im not too sure about how much power and range increase i will have, if any, over lead acid batteries in a battery pack of the same physical size…
If you only need two seats, it would be hard to beat three wheels. It is lighter, less rolling resistance, and more aerodynamic. With the two wheels in front, one in rear, there is just as much stability, as four wheels, and three is actually quicker in left to right slalom.
The advantages really start to add up, if you want to go with direct drive (no transmission) No differential, and it’s weight. simpler suspension. Chain drive is the most efficient method of power transfer, but toothed belts are close. Gears in a transmission are heavy, and more parasitic loss.
Can you tell I am building a three wheeler? I did not like the idea at first, but after learning about it, I am sold on the idea! Just my two cents, Eric
did you see the XR-3? its a 3 wheelers you get plans for, and the plans include instructions on building a tunnel frame, and the mould for the body you can then make out of any material you want… carbon fiber, fiberglass, i might go with kevlar, or fiberglass, depending on what i want to pay… but my thought would be to use plate steel over the a frames, over the top, and around behind the seat to give it more strength, and make it a ton safer in a roll, without adding too much weight… anyway, im not sure what im going to use for power, all the best stuff isnt out on the market, some company in texas making ultracapacitors thatll put any modern battery to shame, firefly making batteries thatll put all current battery technology to shame… im just not sure what im going to do for now, any ideas? id like to use an ultracapacitor to be used for acceleration and to take the charge of regenerative braking to be used on another short acceleration burst (mostly the ultracapacitor giving off the charge under acceleration, and getting a lot back under regenerative braking) and then use the batteries to pretty much top off the ultracapacitors as i drive along… and also use the batteries for a longer sustained highway cruising… anyway, id like to fit all this behind the seat of the XR-3…and maybe a small diesel generator in the front for backup until i can get the cutting edge stuff when available… for your 3 wheeler, what are the specs on your battery pack? lead acid? lithium? how many, what charge, etc? and whats your calculated performance?.. also, what do you think of having a small solar panel built into the roof so when its parked in the sun on a hot day, itll run a small A/C, parked in the sun on a cold day itll run a small heater, so when you get in your car in the morning, its nice and warm on a cold day, or nice and cool on a hot one?
Hi Burnt,I did take a look at the XR-3. I’ve seen it before , and like the layout. I’m just getting started with my build as well. I have the wheels, tires, brakes, rack, and pinion steering, hubs, and spindles, and a bunch of misc. pieces. I have most of the aluminum for the frame. I am using rectangle box, and sheet, for kind of a hybrid tube/monocoque frame.
As for batteries, that will be my last purchase. I have to save for quite a while to be able to buy them. I also figure that I don’t want to lock in on any one brand, or type as in the year it will take for me to save enough, things can change alot in prices, and technology. It doesn’t help that the US dollar is falling like a rock right now. A week ago the batteries I was looking at were $8,000, this week $10,000!
At this time, I am looking to Lion ev http://www.lionev.com/Battery_Pricing.html for their gold pack 44v 200AH each. For the AH this is the best deal I have found. I am also considering the Thunder Sky large format Lithium http://www.thunder-sky.com/products_en.asp?fid=66&fid2=70 they offer a 3.2v 90AH pack for about $180-230 each. I am planning for a 156volt pack, so this would require about 49 of these packs.
I am thinking the same for my car, as far as a generator for extended range. I am figuring on about a 75mi. range with the Thunder sky pack, and about 165mi. with the Lion pack. In the times I need to go farther (rarely) I could fire up the series hybrid, and do it. I am looking at a honda 4 stroke motor called an IGX it is a 15hp single cylinder, that uses a computer to turn on, and off based on the voltage you input, using a computer. I am hoping to run it off propane.
I hope to start posting a few pictures in the next few weeks, as it progresses. Eric
i still have a lot of specifics to work out before i even start mine… maybe fireflys new batteries will be out by then, if not, ill go with cheaper 6 volt batteries till they do… but the supercapacitor idea i think im going to use, itll be a batter/capacitor hybrid, use the battery only for cruising, and the capacitor for short bursts of large energy for acceleration, and since the capacitors recharge as fast as they discharge, i should regain most of what i lost under acceleration during braking on city street stop and go driving using regenerative breaking, using only a steady flow from the batteries to top off the charge in the capacitors, so i should have one hell of a range in city, and im hoping to get 100+ on highway… anyway, how many batteries of how many volts and Ah do you think i would need to get a 1300lb 3-wheeled car to 60-80mph, and a range of 100+ miles?
My best guess would be, 120v as a minimum 144-156 would be optimal, especially if direct drive. 100mi. for this car, 150AH as a minimum would seem about right. So, 10-13 12volt batteries, at 150ah each. Just my best guess, but I think pretty close, Eric
Well, unless this is going to be an NEV (neighborhood electric vehicle… less than 25mph) you won’t he able to legally put 4 wheels on it without passing side impact requirements. Thats why most go 3 wheel or 2, because they are a motorcycle, and exempt. If you throw another wheel on, no insurance company will insure you, you won’t get it registered, and if you go over 25, and you get a ticket, its not going to be cheap, or easy to explain to a judge.
Next, supercapacitors… in order to do what you want (replace batteries) you need high voltage, high capacity caps, and as the caps discharge, the voltage drops. So you have to design a controller that will operate at high voltage, and have the same efficiency at lower voltages (while its discharging). Thats going to be pretty hard. If you just want a cap to smooth out the regen and fast acceleration, you only really need a cap thats rated for your battery pack voltage, as well as have some current carrying capacity. I’d recomend this, because batteries don’t like short fast discharges… so the cap would take that, they also don’t like short fast charges. But I don’t know if you need a super cap.
3 wheels are nice though, because you can get past the legality of side impact and highway requirements, and still keep the speed and style of a car.
Good luck though.
well, i dont want it to be unsafe either, one hit in that thing at almost any speed against any other car and youre as good as dead, i will keep the rear wheel, but im going to use a really wide one so the rear wheel surface area would be the same as on a regular car… lots of traction, the supercapacitor i will use for acceleration, and with as well as they brake regeneratively i should be able to get great city fuel economy… id like to do something that could allow the car batteries to discharge at a regular rate no matter what the rate of power change in the vehicle… which these capacitors should do nicely for, as far as the three wheel car goes, since it is so light weight as it is, what i was thinking of doing is with the body, bending and welding some plate steel (or rectangular tube steel) around a roll cage pattern of the body (around the windows, over the top, down around the door, etc) that should end up as an integrated, unnoticed part of the body thatll increase safetly to what youd expect for any car
also… to be more enivronmentally friendly… im thinking for the rest of the body parts, non steel, and the interior panels, to use some sort of recycled materials if i can, but im not sure what would be best suited for this… maybe recycled fiberglass for the exterior body, recycled polymer for the dash, and panels… what do you guys think?.. and im probably going to have to go with a plastic windshield to save weight as well as the cost of a custom windshield being made… i could get some UV-safe clear shatter resistant acryllic sheats for the windshield and windows
so what supercaps are you looking at? I know that you can use large caps in a cap bank to use as you think, but they don’t need to be supercaps. THey’re just going to act as a buffer. Supercaps are meant to store large amounts of energy. What you explain (using them for acceleration) is basically only using them for regen and heavy drain (accel). You don’t need supercaps. Just a cap bank. Not a bad idea… In fact, I was going to use one for my motorcycle…
Do you realize that most controllers use a cap bank for the DC bus? All you’re doing is extending that.
Also, when you turn the car off, the bank is fully charged, so be safe.
Not trying to shoot you down or anything, but I’m trying to understand what you’re thinking, where you got this idea, and how you plan on incorporating it.
im just going to use it for acceleration, and to take advantage of the regenerative braking, so i wont need more much than what the batteries total output will be… but, if these are efficient enough in stop and go driving (most of what i do) i might be able to get away with smaller batteries as they would only be needed to top off the capacitors charge as the regenerative braking recharges them most, so if i go with 144 volts, i could use a 144 volt bank that should be able to accelerate me up to top cruising speed and then the batteries could hold it… but as i said, stop and go mostly what theyd be used for… and for such a capacitor or supercapacitor bank, how much weight would i be looking at added?.. if i could remove batteries all together i would, but i doubt id get the range i needed for the size required
well, first off, what supercaps are you talking about?
If you want to put supercaps in there, go ahead, you’ll be one of the first to do it. There’s a reason people don’t use supercaps. Cost, size and high voltage requirements.
Lets say you get some 144V supercaps. They start discharging at 144V. Unfortunately, the curve for them is steep and a constant load will make them drop in voltage. So in 15 min, you may only be at 72V. Your controller is built for efficiency at certain voltages, which is why there are several voltage options available (curtis, alltrax). There are 36, 48, 72, 84, 144 and even higher. The issue being, one controller might not be able to WORK at 72V after 15 min, and shut off. Another thing, even if the controller DOES work, its going to have less efficiency at lower voltages if its made to work at higher voltages.
Go look at some curves for supercaps, and then compare then to a battery. A battery is more flat, and drops off after a long time. They work for their Ah capacity and then start to degrade. But most people use them to 80% DOD, and thats enough to get their 20-30 miles.
Also, why 144V? What chassis are you using that is going to house 144V, even if you DO use lithium, they’re not tiny…
My 2 cents, is that you should stop trying to design a system you don’t know a ton about. Go out, get a book and read it. Search on www.evalbum.com for others that have similar weight setups. Use what is proven, unless you are prepared to spend time, money and resources to design a controller and this supercap idea.
If its your first EV (this is my first as well), keep it simple. You can always upgrade a controller, motor and batteries. I’d concentrate on calculating the requirements of the vehicle:
Then chose a motor and battery pack to suit the requirements you need. Then get a controller that is available for that voltage. Add the bells and whistles, and you’re good to go. Then you can test ideas with supercaps. go search the EVDL (EV discussion list) archives, and look at people’s comments on supercaps. DO NOT JUST POST… read a little bit, it’l save you time.
As i said, I’m not trying to shoot you down, but don’t plan on it being bleeding edge. Controllers are not meant to run on supercaps.
144 volts is on the higher end of what i need, 96v at about 200ah is what i need to match the speed and range requirements i look for, so i would need 16 of these that are going to weigh about 1,000lbs total… ive been checking out capacitors, and they all seem to be able to supply the voltage needed, but im just not sure what kind of capacity i will need, or how many of them in a pack, if i could figure out what kind of capacitor ill be needing, and the price is good, then ill more than likely use them for acceleration, and regenerative braking.
well, good luck to you, keep everyone posted on your progress, calculations, cost and manhours.
what i think im going to do is cut the battery pack down… im still going to need 96 volts, but im going to cut down the capacity and size of the battery pack to closer to around 30 miles range, to save weight for the capacitor pack to be used for acceleration, and a small diesel generator for range, so during city driving the batteries should be able to assist the regenerative braking to keep the capacitor bank charged, and then when the voltage drops below a certain level on the batteries, the small diesel generator would kick in and extend my highway range (where the range is really most important) to about 1000 miles… (estimates on the size of the car, power of the generator, puts about 200 miles to a gallon when used to charge the batteries which will be used to drive the motor) with about a 5 gallon tank for biodiesel… any thoughts on this idea?
I was reading this post and was wondering if anyone had progressed a 3 wheel EV.