Best E-bike Drag Racing battery

[Doctorbass]

I am considering building a battery for drag racing ebikes yes..guys .Another :wink: !

A typical run should be about 16 second on the 1/4 mile in the best hopes.. (I remember i did in the low 19sec with a single X5)

So the battery dont need to have alot POWER and it only need to last about 16 sec full power and 30 sec for the return.
I estimate that the battery current would have to be about 300A for the 16 sec if i use 2WD with dual MAX-E controller ( about 28kW)
I know Luke like these Nano-tech and i'm considering using these... but if some similar performance lipo exist that would be great too..
For the Noan-Tech, i know that they have regular and the A-Spec. i am not sure of the power density if very different and that's what i want to know.

That battery need to be lightweight and have JUST THE RIGHT AMOUNT OF ENERGY for one run and the return ( let say 16 sec at 300A + 30 sec at 30A witch correspond to about 1.33Ah + 0.25Ah = 1.58Ah. That mean if i take only the only required capacity it would have to be 1.58Ah and capable to deliver 300A (about 200C)

The nano tech are 65-130C so for a drag racing " burst" the rated 130C could be ok... so 300A at 130C mean a capacity of 2.3Ah for the C rate but the run would take 1.58Ah witch leave a margin of 0.72Ah witch wold be the discharge state at the end that would remain untouched... to not fall at too low voltage when the Ri raise at the end.
That would be a 22s 300A burst battery for two Max-E Adaptto controller. (24.4kW) and an estimation of 24hp total at the two wheels

Some of will ask why saving wieight when it's only a fractino of the total weight of the bike and me... well i would say .. 1kg less to push to the bike to the finish line is still 1kg less... lol it remove fractin of second during the first 0-60ft witch is also important...

But even if these cells are really capable of 130C.. I have a doubt about how the soldered 10Awg wire are capable of not unsolder from the battery terminal at so high current... and how the battery heat increase lol

So i also wonder f driving it to lower C rate and using higher capacity would be best... It's all a question of power to weight ratio so the voltage sag also is important.
Doubling the battery capacity mean doubling the weight.... but also reduce the voltage sag.. witch mean more power... but is the added power worth the addeed weight to cary on the bike... I know there is an optimum point that can be calculated.. just like i did in 2009 for my A123 cells on the speed record bike...

I have never used yet any Nano tech.. A spec or not... and if you guys have some recommandation i will really appreciate.

 

[Doctorbass]

Well.. it appear that i was a bit pessimistic about the ET for the quater mile..

I have used this websike and it estimate that with a total weight of 250 pounds and 24hp at the wheel i shoudl get about 12.7 sec! 8)

I doubt i could acheive that as well.. but if it's between 12.7 and 16 second i wodl be really happy !

With a high KV motor of 18 and the OVS feature on the bike make the wheel no load speed over 200km/h.

Usually my thumb rule to know the max speed of an ebike is that the real speed is 2/3 of the max speed at no load witch mean about 132km/h.

Now is it possible to get in the 13-16 sec on the 1/4 mile with only 132kmh max?..

The Ebikecalc vers 17 simulator is estimating about 14 sec for the 1320ft and 92mph top speed. ( with dual 5302 on 26" and 92V and 800A phase and 300A batt for 250 pounds ebike)

Doc

 

[Ohbse]

It's certainly possible to get under 16 seconds, however that's going to be largely down to your ability to accelerate (without flipping) in the first ~100 metres. To get quick times will require full throttle as soon as possible, something that's very difficult with a short wheelbase, high CG (relative to length) 'bicycle'. Look at Deathbike in its latest iteration - long, low. It is possible to calculate your maximum torque at the tire that can be delivered without flipping if you have a model of the bike and the location of all the variable mass.

The calculator that you looked at is applying established 'rule of thumb' for ICE vehicles, EV's are dramatically different in their power/torque delivery and so the result is perhaps not so useful.

2wd will not really help you much here except for perhaps moving your weight bias forward somewhat (and up increasing weight in general). If you're limited by the physics of your wheelbase and CG and peak acceleration is with zero weight on the front wheel then a front a hub is really not going to provide much assistance until your torque at the rear drops enough to again put weight on the front tire. You really want one motor that can power the rear wheel with all of the power. See my thread in motor tech that nobody has replied to about powering a single motor with dual controllers for this exact reason!

 

[Doctorbass]

It's certainly possible to get under 16 seconds, however that's going to be largely down to your ability to accelerate (without flipping) in the first ~100 metres. To get quick times will require full throttle as soon as possible, something that's very difficult with a short wheelbase, high CG (relative to length) 'bicycle'. Look at Deathbike in its latest iteration - long, low. It is possible to calculate your maximum torque at the tire that can be delivered without flipping if you have a model of the bike and the location of all the variable mass.

The calculator that you looked at is applying established 'rule of thumb' for ICE vehicles, EV's are dramatically different in their power/torque delivery and so the result is perhaps not so useful.

2wd will not really help you much here except for perhaps moving your weight bias forward somewhat (and up increasing weight in general). If you're limited by the physics of your wheelbase and CG and peak acceleration is with zero weight on the front wheel then a front a hub is really not going to provide much assistance until your torque at the rear drops enough to again put weight on the front tire. You really want one motor that can power the rear wheel with all of the power. See my thread in motor tech that nobody has replied to about powering a single motor with dual controllers for this exact reason!

Thanks for sharing your experience Ohbse.
I know that puting so much power on the front wheel is not the best way to do... but as you said i guess that the torque on the front would be better if applied at a given speed.. or only if there is significant force between the front wheel and the ground and that the CG have something to do in the equation. Finding a 24kW motor for the rear wheel that is not too large and too heavy is more difficult.. the hub monster from John mighht be something interesting in thts case but that motor us ugly !! :lol: I would need a kv of 18-20 minimum plus the flux weakening active too. otherwise i woudl not get enough speed...

But I might try the dual 5302 anyway.. for fun... 8)

Doc

 

[gogo]

Just curious why the 1/4 mile?

I had a 40 HP motorcycle that needed a wheelie bar for a 12 second 100 MPH 1/4 mile. It was mostly finished with accelerating after 1/8 mi. because air resistance matched power available. I'd think the same thing will happen for you and concentrating on 1/8 mi. might be more fun. I made my wheelie bar from two straight pieces of electrical conduit, steel wire, turnbuckles, and wire clamps. A long wheelbase might be easier and better for a narrow-frame bicycle.

 

[hydro-one]

i have 6 pack of 5s a-spec nano packs. i dont recoommend these due to the cheap way they are put together. no pcb inbetween the cell tabs, they are just bent together and soldered with foam and paper in between. i just lost two packs to galvanic corrosion, the cell tabs just disintergrated because of a small amount of moisture ingress into the foam between the cell tabs. there is no way to fix this cause the tab is basically gone off the cells. alot of money for cells and they go and do that...i almost cried. i wouldnt use them. even though they are rock hard still at more than 150cycles,


good cell, shit pack construction

 

[Doctorbass]

i have 6 pack of 5s a-spec nano packs. i dont recoommend these due to the cheap way they are put together. no pcb inbetween the cell tabs, they are just bent together and soldered with foam and paper in between. i just lost two packs to galvanic corrosion, the cell tabs just disintergrated because of a small amount of moisture ingress into the foam between the cell tabs. there is no way to fix this cause the tab is basically gone off the cells. alot of money for cells and they go and do that...i almost cried. i wouldnt use them. even though they are rock hard still at more than 150cycles,


good cell, shit pack construction

Thanks for sharing your experience with these A-spec Hydro-one. I guess that it is possible to get somewhere the cells only ?.. I have to search for that... maybe John Wayland from the white zombie know how...

Doc

 

[Hillhater]

i have 6 pack of 5s a-spec nano packs. i dont recoommend these due to the cheap way they are put together. no pcb inbetween the cell tabs, they are just bent together and soldered with foam and paper in between. i just lost two packs to galvanic corrosion, the cell tabs just disintergrated because of a small amount of moisture ingress into the foam between the cell tabs. there is no way to fix this cause the tab is basically gone off the cells. alot of money for cells and they go and do that...i almost cried. i wouldnt use them. even though they are rock hard still at more than 150cycles,
good cell, shit pack construction

If you are building a drag bike, it's likely that much of it is custom built for the purpose.
..So why not apply the same thinking to the battery pack and rebuild those "good" cells into a better pack construction and configuration from new , ....rather than risk failure from shoddy Chinese pack assembly ?
You would probably want better primary cabling and connectors anyway.

Also Dr, there may not be much to learn from the larger drag bike racers, since the top guys (Killacycle etc) use 18650 or 26650 cells in their packs to maximise the kWhr/kg ratio with the bigger packs

 

[flathill]

You need to calculate the energy you need to get down the track once and then find the optimal specific energy : specific power ratio you need considering the total system mass (including the rider)

Frome there we can select the cell.

For a ultralight bike maybe even a lithium ion capacitor will work of you can your hands on one from eastern europe. Extremly high specific power but relatively low specific energy

 

[Doctorbass]

For a ultralight bike maybe even a lithium ion capacitor will work of you can your hands on one from eastern europe. Extremly high specific power but relatively low specific energy

Flathill, Are you talking about the SAFT cells?

 

[Doctorbass]

Just curious why the 1/4 mile?

I had a 40 HP motorcycle that needed a wheelie bar for a 12 second 100 MPH 1/4 mile. It was mostly finished with accelerating after 1/8 mi. because air resistance matched power available. I'd think the same thing will happen for you and concentrating on 1/8 mi. might be more fun. I made my wheelie bar from two straight pieces of electrical conduit, steel wire, turnbuckles, and wire clamps. A long wheelbase might be easier and better for a narrow-frame bicycle.

According to the ebikecald simulatin i made the bike still accelerate at 1100ft distance... maybe i'll test both 1/8 and 1/4...

DOc

 

[DanGT86]

John Metric over at Diyelectriccar.com uses lipo in his drag car that runs mid 8sec 1/4 miles. He is affiliated with lonestar ev who is a Lipo importer and sells the same drag race lipo packs that he uses in the race car. Sounds like they do custom packs. These may be re-labled hobby Lipo packs but I would imagine they have found a pretty good source with good quality control considering the size of their packs without bad cells. I also like the fact that they are advertising the specs off of the real world performance they get from them at over 600kw

http://www.lifegeode.com/ampahaulic_products.html

They have the following specs as measured and documented during races:
Specific Data - Actual(DCP)
>=5.9 HP/lb peak power
>=4.4 HP/lb continuous rating

>=9.7 kw/kg peak power
>=14.5 kw/liter peak power

 

[Ohbse]

While it is cool to think about power density of the batteries, for your specific application (your NYX bike I assume) it really won't make an appreciable difference.

I'm going to assume your bike works out to be around the same as mine - ~47KG with the 22s Zero battery. I'm going to guess the battery weighs something like 10KG? I guess you weigh around 75KG wearing your safety gear with a helmet. So system weight with Zero battery is 122KG.

Lets say you come up with a battery in line with the same power density specifications that John Metric mentions - 9.7kw/kg or 2.5kg for 24kw output. That's going to improve the total system weight by 7.5kg or about 6%. Unfortunately that weight subtracted is coming from forward and below of CG, reducing the deliverable thrust (while keeping the front wheel on the ground). This will likely *increase* your ET.

The other thing to consider is at the quoted power density level the sag will be very substantial. Given the limitations of the controller, you want to be maximizing load voltage in order to deliver highest power and highest trap speed. If you've traded 7.5KG for a 10v drop in pack voltage you will definitely go slower!

To go quick you need to make the most of the electric drivetrains inherent strength - peak torque from low RPM. To deliver this you need a vehicle that looks nothing like a bicycle due to inescapable laws of physics. Or use wheelie bars.

If you want to more accurately predict how quick you are really able to go you can measure your bikes weight distribution. Get two sets of scales, preferably accurate but it's not that critical as you can swap them, re measure and account for innaccuracy. Get somebody to assist while you mount the bike with a tire on each scale and get into a realistic riding position. Once you obtain your static weight distribution you can determine the longitudinal position of centre of gravity.

You can determine its height by using the following


You can then calculate the acceleration possible while weight on front wheel is still >0 by using this:


You can then use this acceleration to determine the upper limit for wheel thrust that's possible and use the ebikecalc application to determine how much power that will require as input. You can limit your wheel torque with phase amps to dial in the highest possible acceleration within the physical possibility of your bike. The ebikecalc will also give you reasonable accuracy for a 400m distance calculation, you just need to make sure the data you're putting in is accurate (by using physics!)

 

[Joe90]

My experience flying RC helicopter is that the lipo that have the lowest internat resistance are the best.
easy for that. now finding information about this is more difficult.
The best results I had is with Gen's ace 25C not 50 or 100C
the C rating is just a selling label now.
They are difficult to find but there is rebranding like Glaciers that look like the same tihing.
I bout 2 of them last summer and performed extremely well.
1.5mOhms/cell in ''cold'' state
0.9 to 1.2 mOhms/cell warmed after first filght
This is for 5.3Ah cell 25C rated Glacier.

Write dowm each aspect that improve performance, work on all those aspect while building.
if you are using only best practice everywhere instead of state of the art you will get amazing results.
University of Sherbrooke blew the door of the competition with evolve just using easy best practice and working on ALL point that would get them to their goal.
Even having a light driver and trained as well make a difference.

Here some of my ideas
Light rim + tires
I would use not more that 25C out of the lipo. only the best are able to whitstand this ''without damage''
light frame
smallest possible diameter wheel (you know that)
strive for off the line performance this is where it counts. just think of the P85D
Fairing is not hat important for now I believe.
I am not too sure about 2 wheel drive. It's a good way to have 2 controllers and more motors but it will require a long wheelbase to keep front loaded.
Maybe 6 phases motor to have 2 controller on it.
Hub monster ?
Mid drive ?
zero drive train around a custom frame ?

Just brainstorming

 

[jansevr]

very interested to see where this thread goes =) best of luck to you building your drag racing bike!

if it was me i would just use LiPo. probably 4s hardcases because thats what ive had the most experience and success with. ive only had a few dud cells (within the first few cycles or less) and around 20,000 miles in about 20 of the 4s packs and about 1/2 are still running fairly strong at 80-90% capacity after 1,000s of miles!

we both know lipo gets a bad rep from some but if you are familiar with it and comfortable using it i think this is the main thing. that being said, lipo is probably the easiest for the biggest and highest power available in a small package especially for drag racing. maybe even look into the multistar batteries? it will require less soldering to make a large battery pack that should be able to handle a 3-400 amps no problem.

he might not use them anymore but for a while luke was using turnigy lipo on his deathbike. farfle also has used them on some of his high powered bikes and motorcycles. can't find the pictures now but john metric has built some pretty fast drag cars with huge lipo packs. not sure if his miata runs lipo now or not but i did see a video of it running 8.9s in the 1/4 mile at 140+mph and around 700kw

[youtube]hgxSThg3-VU[/youtube]


edit* - i found one of the pictures of john metric's fiero

90s 6p 800hp LiPo pack

 

[Doctorbass]

I have contacted John Metric to get a quote for 4x 6s packs rated 100C. These are 120$ each, not bad. The A-Spec Nanotech are impossible to get in Canada now and i would trust more a EV racing legent like John than HK!

4.5 Ah 6S 22.2V nominal 25V charged with large 8AWG cables and 8mm bullet connectors are $120 each

Doc

 

[Ohbse]

Why 6s packs? Seems like a poor match for the Adaptto controllers. Did you ever work out what your potential ET could be with the dual drive NYX?

 

[Doctorbass]

Why 6s packs? Seems like a poor match for the Adaptto controllers. Did you ever work out what your potential ET could be with the dual drive NYX?

I woul dbe satisfied if i could pass a TESLA S on the 1/8 mile! due to my better power to weight ratio.. all depend on the torque i will get with max traction possible.

I just ordered 4x 6s pack from the LONESTAR cells from John Metric. These are ultra high quality Lipo cells also used in the military but now unclasified.

Both of my Adaptto MAX-E should draw about 160A each for a total of 320A at 20 or 22s voltage during less than 10 sec for the 1/8 and less than 16 sec for the 1/4 mile.

These are 4.5Ah capable of 100C tested for 10 sec by John on his Miata. This mean about 450A for 10 sec so i bet that 320A for 16 sec shold be OK and should be prety close to the same amount of energy in heat produced and dissipated by the cells..

Doc

 

[Wheazel]

Intresting project
Whats the reasoning for choosing adaptto controllers? I know they are powerful, but arent there other choices that makes more sense for a dragbike?

 

[Doctorbass]

Intresting project
Whats the reasoning for choosing adaptto controllers? I know they are powerful, but arent there other choices that makes more sense for a dragbike?

Maybe.. but as you probably know i love to keep all y components availlable for future projects!. the Adaptto are very powerfull and very tunable.. even they have traction control WITCH IS A KEY FEATURE FOR DRAG RACING! :wink:

Doc

 

[MrDude_1]

So is this going to be an "electric bicycle" or a electric dragrace motorcycle ? or the latter, but with pedals?

Personally, I want to build a sportbike with at LEAST 130kw of power.. since I dont want too much less than my old ICE power.... but then comes the old "we cant hold that much energy in batteries and have it fit on your bike" problem... and if you fix that theres the "your bike is huge and weighs twice as much as the ICE version" problem.


I am 100% behind this idea of yours though. I would set 11sec (11.99) as a 1/4 mile goal, but.... 99% of drag racing is the first 60ft. first work on making it use as much power as possible launching. aim for 1.2 sec 60ft times.. the rest is just you sitting there with the throttle pinned, waiting for the finish line.
I could do 1.2 sec times on a old honda hawk with less than 50hp peak. I am sure you can do better since you have all 24.4 kw right there at the start... all you have to do is put it to the ground in a controllable fashion.

 

[Hillhater]

.
.....I would set 11sec (11.99) as a 1/4 mile goal, but.... 99% of drag racing is the first 60ft. first work on making it use as much power as possible launching. aim for 1.2 sec 60ft times.. the rest is just you sitting there with the throttle pinned, waiting for the finish line.
I could do 1.2 sec times on a old honda hawk with less than 50hp peak. I am sure you can do better since you have all 24.4 kw right there at the start... all you have to do is put it to the ground in a controllable fashion.

A 60 ft time is a good indicator but only if you are geared and set up for the full 1/4.
There are several EVs that can do that sort of 60ft time ( 0-60 mph in 1.4 secs ) but then they are stuffed on low gearing and would not break a 15 sec 1/4 mile.

 

[Doctorbass]

.
.....I would set 11sec (11.99) as a 1/4 mile goal, but.... 99% of drag racing is the first 60ft. first work on making it use as much power as possible launching. aim for 1.2 sec 60ft times.. the rest is just you sitting there with the throttle pinned, waiting for the finish line.
I could do 1.2 sec times on a old honda hawk with less than 50hp peak. I am sure you can do better since you have all 24.4 kw right there at the start... all you have to do is put it to the ground in a controllable fashion.

A 60 ft time is a good indicator but only if you are geared and set up for the full 1/4.
There are several EVs that can do that sort of 60ft time ( 0-60 mph in 1.4 secs ) but then they are stuffed on low gearing and would not break a 15 sec 1/4 mile.

Did some test today with only the actual 5403 rear motor with one of the quater mile Android apps that seem accurate enough but not for ther 0-60ft:

60': 2.997s @24km/h
330' 5.973s @89km/h
1/8mi: 10.01s @102km/h
1000': 12.986s @106.5km/h
1/4 mi: 15.987s @109km/h

0-20km/h: 2.997
0-60km/h: 4.967
0-100km/h: 10.002

12.4kW recorded and 143A batt constant at 88V

Doc

 

[DanGT86]

Why don't you believe the 60ft measurement? It seems reasonable with the other measurements. 15-16sec is quick enough to beat or hang with average cars on the road. Its not sports car territory yet but I bet it would give drivers a shock to see you next to them over a whole quarter mile!

Glad to see you building with John Metric's lipo cells. I have always been amazed that he builds packs that big from what looks like RC Lipo. Its worth the extra price for sure if the quality and the C rate are very consistent. Looking forward to seeing how fast you can go with this.

 

[Doctorbass]

The apps is not very accurate and was using the GPS for the 0-60ft witch is not accurate my average 0-60ft is actually about 2.5 sec and it shold decrease below 2sec once i installed the controller on the front motor =)

Doc