Well I figured i'd start a thread of my own about a project i've talked about before in other threads. I'm going to convert a mid bike from gas to electric, which im intending on drag racing and taking the 48 volt record of 9.5 sec. at 60-70 mph if i remember correctly. Currently i am in the testing phases of finding the optimum battery. I'm not looking into any lead acid battery, mostly nicad at this point.
I've come across some 1/2 D size nicad batteries from a local surplus store that I'm testing at high amp loads, 100 amps plus. The plan is to make 40 cell packs in series, and then parallel 6-10 of these packs in parallel. I'm thinking 48 volts 600+ amps as a starting point, about 30 kw, or around 30 hp.
I assembled a 6 cell pack, 7.2 volts, all batts read about .07 volts, so they must of been sitting for a while, but are brand new so thats a plus. After 5 cycles they came back to full capacity and are working great. I assembled a test for them, using 5 feet of 12 gauge insulated copper wire. I tested one cell so far and measured the voltage drop when shorting the cell with the 5 feet length of wire, im only guessing this is about 100 amps from the chart i looked at and what others have told me. The results were good however, 1.3 resting voltage, with the cell shorted the voltage dropped to .85 and .8 after 3 seconds.
So as a rough estimate thats 80 watts per battery cell, 30 kw will be about 375 cells. I'll post more updates as they come about.
wow insane project you got there!!! i dont think those batteries are going to last long being discharged at that rate... are you sure you can fit all those batteries in the frame? anyway good luck and show the progress on the beast please XD
Honestly I think i will be able to fit the batteries in the frame, but im not so sure about the motor . If i make each pack 40 cells, ill make them in a 8 by 5 configuration, with these cells that measures to 6.25 in. x 10 in. x 1.5 in. I'll need about 8 packs like this for the amount of amperage i'm after, which is about 75 lbs of batts.
As for the motor i was looking into a 3 motor setup using surplus lawnmower motors, but now it appears like this wouldn't be good for efficiency reasons i've been told. So i'm currently planning on using a forklift motor, while heavy it will give the performance i need, and you can get them for about 50 dollars used on ebay, plus shipping. Between the motor weight and batteries, im adding about 125 pounds to the bike, once its been stripped of the gas motor and all other gas components.
I'm thinking i'll cut the existing shock off the rear swing arm, and mount two shocks as to carry the additional load and abuse the bike will be subject to.
I've attached some pictures of what the motor looks like i'm considering using , and what my idea of this drag bike should resemble when completed.
i've remenber of other thing if the voltage on your batteries drop from 1.3 to .85 under load you would need to take that in acount when projecting your batterie pack, otherwise instead off a 48V pack you would have a 30 ish pack...
very nice john.... why not use a golfcart motor, you can got them @ surplus sites you can pick a new one up for 200 2.7hp and it's only 50lbs. but i guess if this is your first attempt the your choice is better just incase something goes wrong then it won't be a costly boo boo...... what buget you got for this drag bike...i too want to build an electric drag bike but i will be patient and keep looking for what i want.... when i find everything i'll have a frame custom made to fit all in there btw the one i'm talking about is a full size is the one you are doing is full or pocket bike size???????
i've remenber of other thing if the voltage on your batteries drop from 1.3 to .85 under load you would need to take that in acount when projecting your batterie pack, otherwise instead off a 48V pack you would have a 30 ish pack...
Yes you are correct, voltage drop is my main concern right now, and the biggest reason im testing a few different batts out, trying to find the most cost effective battery. There are many batts out on the market, like A123 cells, and other nimh cells that will give me the performance im after and avoid all the testing trouble, but for a college student on a budget its not reasonable. An A123 pack would cost 2000 usd or more, and even high quality hobby sub c nimh cells wouldn't be much less. With the batteries i am looking to use, i can make a 48 volt 20 amp hour pack and still get the same performance for 300 usd.
The motor will not be much more than 50 usd either, so for the two im looking at 400 usd for the batteries and motor (50 usd shipping cost) total. That may seem like a lot perhaps, but try and find a battery that will give you similar performance that wont weigh any more or be any larger in size, its not easy, i've tried.
The batteries im testing now are the 1/2 D cells like i mentioned before, and they seem to be performing very well. I still have to pick up an ammeter to measure the current so i can get an exact value on the cells, but each battery will put out 80 watts at 100 amps. Multiply that by 375 batts and thats 30000 watts, or 40.2 hp, but after efficiency losses, closer to 30 hp.
you must be one of the guys with the most tigth budged for one of the most ambitious projects lol what i mean is: GO FOR IT XD
what controler are you tinking use? on off switch?
you must be one of the guys with the most tigth budged for one of the most ambitious projects lol what i mean is: GO FOR IT XD
what controler are you tinking use? on off switch?
Well that might be true, but if i made the bike and it costed 5000 usd, then everyone would say yea well electric bikes are fast if you dump tons of money into them. So basically I'm looking to show/prove that anybody can make a relatively cheap fast electric bike on a budget if you know where to look for the right deals.
For speed control I was thinking a dimmer switch, it adds some variable throttle to the bike. Seriously though, i've come across a company online that remanufactures existing controllers and then sells them to the public for cheap. If they can come through for me i can get a 72 volt 1000 amp controller for about 400-500 usd, maybe cheaper.
very nice john.... why not use a golfcart motor, you can got them @ surplus sites you can pick a new one up for 200 2.7hp and it's only 50lbs. but i guess if this is your first attempt the your choice is better just incase something goes wrong then it won't be a costly boo boo...... what buget you got for this drag bike...i too want to build an electric drag bike but i will be patient and keep looking for what i want.... when i find everything i'll have a frame custom made to fit all in there btw the one i'm talking about is a full size is the one you are doing is full or pocket bike size???????
Well golfcart motors would work, but they sometimes dont have an end plate, so i would have to machine my own. The one you mentioned i have seen at a surplus site and i would have to make a face plate for it. For 200 dollars i would like to have a complete motor, lol.
As far as budget, I am thinking about 1000 usd, besides the cost of the bike, I figure the batteries will cost about 350, the motor will cost 50, and the controller, im guessing 400-500. That 1000 budget seems to get used up fast, but thats what i would like to have spent when its finished.
This bike im doing will probably be a converted X7, at least thats the bike i'd like to convert since the style appeals to me. If this bike gets the results im looking for, i might consider making a full size drag bike, with the right amount of funds. Heres something i'd like to make, the fastest electric bike in the world. http://www.electrifyingtimes.com/a123/KillaCycle.html
yeah the killacycle rules but if have that kind of money i would rather do something with 4 wheels... something like the white zombie or the current eliminator, but in small size, in my dream it would have: one warp 11 motor 80 kokam batteries (making a 144V - 1000A), a 1000A zilla controller, it would weigth about 1200lbs, have a top speed of 125mph, 0-62 in 5.6s and 0-125 in 16.5s
i just wish someday after i take my degree and all that shi* i have the money and the skills to build my projects...
As a short update i'm still determining what battery im going to use, its an aggravating process. I have found several that would work well but still dont quite know which would work the best.
I found some 14 a/h and 24 a/h flooded sintered nicad cells for $5 and $7 each. These can be discharged at 20C continous, or 280 amps continous and 480 amps continous, with peak rates of around 50C+.
I can't seem to find any information on them though, besides that they were used for starting jet aircraft and are surplus. My main concern is finding out how low the voltage of the battery will drop at different amp draws, once i know that info i'll be able to determind if i will use these or not.
I found out the 20C continous ratings on a pdf file i was able to locate on them, but it basically explained how to service them and charge, no technical info that im after.
The other battery im looking at is the surplus gp 1.6 a/h nicad sub c cells. A pack of 10 cells in series is going for $4.95 on a surplus site, but the cost of assembling this many cells might cost as much as the batteries themselves.
Each pack I need to disassemble and take off the existing tabs on the batteries, then reassemble the packs into 60 cell blocks. 100 battery bars from my local hobby shop goes for about 40 dollars, i need about 650, so thats about 300 dollars for battery bars alone, plus shrink wrap, glue, solder etc.
After some delay the project is back in motion, and I'm buying all the parts. I went with the 1/2 D nicad cells, and they turned out to be some high quality saft cells. I ended up buying 350 of the batteries which was a little pricy, but hopefully it's worth it. For now I'm planning on using the c40-300 mag motor, unless i find a forklift type motor on ebay for cheap. Here's some pics for now. Anybody got a location for an X7 type frame?
I located a controller, brand new 36-48 volts that will do 700 amps continous, and even higher for the peak rating. I'll be putting in the order today or tomorrow.
I located a controller, brand new 36-48 volts that will do 700 amps continous, and even higher for the peak rating. I'll be putting in the order today or tomorrow.
john i'm no expert but i think your going to melt that motor or blow it up(and i do mean blow it up not just fry it) if you use that motor and controller setup.. you may want to go to visforvoltage.org and ask those guys what they think... and the setup you want to use.......cause i see 1 or 2 gauge wire in your future...which means you need to change the lead wires on the motor...
john i'm no expert but i think your going to melt that motor or blow it up(and i do mean blow it up not just fry it) if you use that motor and controller setup.. you may want to go to visforvoltage.org and ask those guys what they think... and the setup you want to use.......cause i see 1 or 2 gauge wire in your future...which means you need to change the lead wires on the motor...
I've been looking for a forklift type motor on ebay, but recently there hasn't been many listed at all.
I've been looking for a forklift type motor on ebay, but recently there hasn't been many listed at all.
Look for a 5000-8000rpm range motor...PM me if you need help finding one, I have some people in mind that may be able to help you out
the motor you posted looks good and should not "Blow Up" if you keep the load down and not use the full 1000amps of powere your cells and controller may deliver keep it about 6/1 to 4/1 ratio and you should be safe
look at wired temp meters and put one probe in each pack, that way you can watch the temp so you dont pop any in the pack(the gas that come out when they pop is very hot! can start fires)
I ordered a forklift motor off ebay today, it seems to be what im looking for. A bit heavy though at about 70 lbs, it should give good performance and i can run it pretty hard and not worry about it over heating. It's used so i'll need to take it apart and clean it up a bit, seat some new brushes, clean up the comm and what not.
