300hp single seat off road buggy project

Thanks mate.

Note sure of actual torque figures. Theoretically it is around 160ft/lbs but that is on paper based on 600amps. I am pushing 1000amps through mine (for short periods).

The 0-100 is about 4.5 seconds.

The battery pack is about 60kg, 1m long 0.4 m wide and 0.5 high. Cost is difficult but as per any battery figure on about $1000 per Kwh for new or about $300 per Kwh second hand. The figure of 7c springs to mind but it has been a few years since I was doing the research. But keep in mind you can run more cells in parrallel to increase the C rating (so long as they are the same cells and the consistant number in series).

Motor choice is quite difficult. There are so many choices and variables. Price, Power, weight, regen, AC/DC, availability, compatibility with controllers, voltage, current are the factors you need to consider. Warp9 is a solid choice but I am not sure it would stack up against your original goals. I would be glad to hear if you have diluted those requirements though. I think they were a tad optimistic on that budget and probably overkill for the result you are seeking. To put it another way the figures you were quoting don't seem to align with the results you describe in your last post. If you want great acceleration like mine and just achieve slightly more than 100kmph then you only need 90kw and 1000amps like mine. I'm not saying you shouldn't aim higher but in EVs the cost curve is exponential. The more power and the more weight you deal with the more it will cost you. Also keep in mind when I say 90Kw that is a peak power figure. Most motors are specified as continuous which is roughly a 3rd.

I hope this helps. I am happy to answer more questions if you have any.
 
Here's what 65Kw can do in a 1240 lb vehicle:
https://www.youtube.com/watch?v=W7qHHbTEPa0

That's scary enough winding out 2nd gear doing over 80 mph on the highway.

I can't imagine having 300 Kw of electric in a smaller frame.
 
Thanks for the replies guys... very much.
Galerdi, I sure can be over optimistic at times and need to know where my facts got skewed.... getting things skewed gets annoying for those trying to help! So please let me know
Jayls5, that rig looks sorta quick. What would it do on the quarter do you think?
In the interim I've acquired some parts for the drive line.
A friend sold me his elec car, 1981 Datsun Ute running a transwarp9, netgain warpdrive classic and a 19kwr leaf battery pack, also comes with a zilla 2k and hairball. The Ute's road registered, in great order and runs fine...ish. At 155v and 1000a it has the potential for 155kw but has battery sag under full throttle as the leaf packs are who knows how old or how many cycles etc to cut a long story short. It runs well though, will fry and is great fun, but could be a lot more.
The plan is to strip the car of the driveline and sell it as a roller, the warp9, zilla, busbars and all other elec wares will go in the buggy. The battery pack will be used elsewhere in my life.

I'm at the risk of sounding like a wanker so here goes....400hp/500ftlbsish can be achieved through a warp9 and zilla 2k, it can be done but only for a few seconds with the right battery, but that's not necessary....it'd be ridiculous, but nice. 300hp can be had for 15 second bursts which would do. The buggy would be usable at 200hp which where it would spend most of it's driving life most likely.
My point of seeming like a wanker is there isn't really ever 'too much' power is this kind of 'fun' application. I don't really care about range, longevity or practicality, it just has to smoke tyres, break axles, wheelstand and be generally off it's hinges.
It may well not produce 400hp but I'll sure squeeze what I can. Jonescg can build a battery that'll deliver 2000a @155v I'm pretty sure.... there's a start.
Sorry for being a wanker but I'm just a horsepower tragic...but need help ;)
 
It all depends on your appetite for risk and the length of run time. You can run those massive current figures for a short time so long as the heat does not have time to build. Volts are a different story. When you start increasing volts every little detail becomes important and as a result every individual motor may give different results. Just because a conductor might sit 1mm closer to the case or something and as a result may arc at a slightly lower voltage than another motor. I hope this makes sense. I know in my case I can't afford to be replacing motors or other major components all the time. So I am hesitant to push the boundaries too much.
 
Thanks mate and your reply made perfect sense.
I'm not particularly interested in frying zilla 2k's and warp9's on a daily basis don't get me wrong!
Run times can be super short...down to a couple of minutes.
As has been mentioned before by others as well, super duper amounts of torque and horsepower need only be had for a few seconds at a time anyway.
Am as much interested in what the motor will take and what the 'feel' of what that level of torque and hp will be like.
This all an experiment and of course a side by side comparison to similar ICE numbers.
I've never been in a 300+hp lightweight elec vehicle so keen to find out.
Thanks again and will be picking up the car with all the components, minus battery, in the next few days so will post some picks.
Cheers
 
The controller should be ok. They will have limits set to avoid any damage. Motors on the other hand don't have the smarts in them to limit the power. Add 5 more amps = ok, add 5 more amps = ok, add 5 more amps = ok, add 5 more amps = ok, add 5 more amps = BANG!!! More like fizzzz actually as the conductors melt, bang is more of a voltage reaction. Its very hard to predict where the limit is when you are dicing with the edge and then it's too late. It's similar to turbos in ICS cars. Build a motor that can theoretically take a certain boost but can it take another 5% you don't know until it either works or goes bang.

I am looking forward to hearing the results.
 
Yes this is exactly what I figured on the not exactly knowing how far to push it business.
Will be cautious in the amps area, obviously gathering as much pre info first and will talk with others who've pushed these motors hard.
One tempting thought is to run it through a powerglide or some other gusty 2 speed which would help with heavy amp overload at low take off speeds. Much to resolve yet....
 
And I've also become pretty good at leaving out the efficiency losses....88% efficiency tops for the motor.....heat losses in cabling and busbars, whatever for the controller....is 75-80% efficiency about realistic then?
 
Nice plan. Power glide style gearboxes seem to do a good job for those chasing straight line speed.

If money were no object a bespoke dual clutch setup would be awesome too. But I suspect that is out of range for almost anyone. I think for quoting power anything around 75% is fair. And it also makes in head calculations easier :)

If your setup has built in heat sensors make sure to set them up. And get an infared thermometer. You can keep tabs on the heat generated in the carious components/conductors. This is a good guide that will act as a warning if you are heading towards the current limit. In my car the super high current draw is only momentary and quickly falls as the speed rises. There really isn't much time for the heat to build to problematic levels. But if you were doing repeated standing launches without a pause, or if you had a heavier vehicle it would be a different story.

Voltage and arcing are different though. There is no warning until it is too late. In mine I could hear the arcing but I am not sure that is a reliable warning. You can get away with a second or so of arcing but after that components start to dissolve!!
 
Hi again,
So picked up the Datsun on the weekend, she's in pretty good order and took it for a short run down to the front gate n back. Runs well but needed a charge.
I'm fairly fixed on starting with the warp9 coupled straight to the IRS diff. A primary concern with the likely 29" tyres I'll be running is needing a diff ratio in the regions of 5.5:1...where 4.11:1 is the most commonly had low gearing.
May have to set up some type of reduction between the motor and diff.
Anyone know of any super low geared IRS diffs that may work?
So.. very excited about all this... she's onScreenshot_20190514-201124.png
 
Nice,

Just an idea, but maybe keep that diff and run a 4x4 low/high range transfer case. That way you get to choose the ratio depending on the purpose at the time?

Otherwise you could de-couple the driveshaft from the motor and recouple them through a belt or chain drive setup. Then you can adjust for the ratio using different sized cogs.
 
Yes that's certainly and option, I've been rattling about 6 gazillion alternatives through my head over the last week.
The main issue, as is no doubt obvious, is that I don't really know what the machine needs.
Perhaps a 4.11:1 direct driven diff will be fine.... I just don't know, so starting off with the simplest configuration and working it from there is probably the go.
I did find out how to shorten a powerglide to about 350mm which would be nearly perfect with the 1.82:1/1:1 option...minus the extra weight, length and complexity of course!. Powerglide's have very little drag apparently and are classically bullet proof so yep... ANOTHER option to break down.
Thanks mate I certainly appreciate your help here
 
Why would you want a gearbox in your buggy? And a very inefficient slush box even?
Just use sprockets and a (double) chain to get the right gearing. You don't need the top speed that 300hp is capable of (160mph?) so just gear the motor to the maximum speed you desire. For an off road single seat buggy I think 100mph would be enough? That gives so much torque that no gearbox will be needed. You do know an electric motor can deliver a huge amount of torque from 1rpm right? So where a gearbox is used in an ICE application it is needed because a combustion engine has a lousy torque curve compared to an electric motor. Tesla (and most EV car manufacturers) only uses a single reduction stage to get serious acceleration and a very decent top speed for their cars.
 
I was just reviewing some of the earlier posts/discussion. I think in summary your estimate of 450KG and 300HP is a somewhat challenging combination and I suspect you came up with the 450KG without understanding the battery constraints? My car is 450KG and includes a 7Kwh portion of a Volt battery weighing approximately 65KG. This battery realistically limits power to around 100HP. So to increase the limit you will need a combination of more efficient batteries (able to provide more current) plus more of them either in parallel or series. Lets say hypothetically you choose a battery which provides 50% more current than the volt batteries. You would still need to double my pack to achieve 300HP. It is possible but will make your build more expensive and challenging. My experience is that in a 450kg buggy 1000amps is sufficient off the line. Any more than that and you'll need F1 tyres to stop from spinning. But of course my experience is based on 1st gear launches. So if you do skip the gearbox you would need to compensate with more torque to achieve similar results off the line.
 
SlowCo said:
Why would you want a gearbox in your buggy? And a very inefficient slush box even?
Just use sprockets and a (double) chain to get the right gearing. You don't need the top speed that 300hp is capable of (160mph?) so just gear the motor to the maximum speed you desire. For an off road single seat buggy I think 100mph would be enough? That gives so much torque that no gearbox will be needed. You do know an electric motor can deliver a huge amount of torque from 1rpm right? So where a gearbox is used in an ICE application it is needed because a combustion engine has a lousy torque curve compared to an electric motor. Tesla (and most EV car manufacturers) only uses a single reduction stage to get serious acceleration and a very decent top speed for their cars.
Click to expand...


Hi there, most certainly understand that elec motors produce torque from 1 rpm and bags of it... I built an elec downhill bike some years ago.
As I mentioned I'm still investigating all alternatives and a gearbox may not be the way to go.
A direct drive is certainly preferable but a powerglide, according to many who've used them in EV's, have worked out pretty well and also have very little drag. Tesla run a very high rpm AC motors and gear down to 9:1 this way they achieve good pick up and top end, not to mention their motors are properly cooled.
My DC warp9 will spin to 5500rpm but torque drops off radically after about 3200rpm which why I'm looking at a 2 speed in efforts to keep the motor a tad cooler and keep it in its torque band.
 
galderdi said:
I was just reviewing some of the earlier posts/discussion. I think in summary your estimate of 450KG and 300HP is a somewhat challenging combination and I suspect you came up with the 450KG without understanding the battery constraints? My car is 450KG and includes a 7Kwh portion of a Volt battery weighing approximately 65KG. This battery realistically limits power to around 100HP. So to increase the limit you will need a combination of more efficient batteries (able to provide more current) plus more of them either in parallel or series. Lets say hypothetically you choose a battery which provides 50% more current than the volt batteries. You would still need to double my pack to achieve 300HP. It is possible but will make your build more expensive and challenging. My experience is that in a 450kg buggy 1000amps is sufficient off the line. Any more than that and you'll need F1 tyres to stop from spinning. But of course my experience is based on 1st gear launches. So if you do skip the gearbox you would need to compensate with more torque to achieve similar results off the line.
Click to expand...

Mate I come up with all kinds of ideas without understanding the constraints! Hahaha!. Seriously though...the battery is by far going to be the biggest concern. I've saved a lot of money by buying the Datsun which has everything I need bar the battery so that leaves me with monetary room to get it right.
Also finding concrete answers on what warp9 will handle is very difficult.
A 10kWr 155v 45c lipo battery pack weighs in the regions of 70kg and should by rights deliver 300hp.
If I get one built would be about 12k...this I've factored into the budget.
On the gearbox business...1000 wheel rpm with 29" wheels equates to 137 kph, this would be enough for me but I am concerned about motor heat at take off.
My place is quite hilly but with longish straights also and the track will be a mixture of this.
To be able to divide that wheel rpm by 1.82 (as in using 1st) to reduce need for massive take off amps makes sense to me. Your gearbox is obviously very handy for this reason even though, as you've mentioned, that you definitely don't need all 5 gears!
If 1000amps is all I can use than so be it but I don't want the battery to be the limiting factor.
The Datsun runs a 19kWr leaf pack and netgain classic (comes with a 2k zilla) to the warp9 direct driven through a 4.11:1 diff to 22" wheels and the batteries drop out when tromped off the line. These batteries aren't in brand new super good shape though.
The 450kg estimate is about right with a 70kg battery, it maybe a tad more but should easily come in at under 500kg.
This all just takes research, loads of it. A properly cooled (I've seen some water cooling attempts on a warp9) motor, helwig brushes and variable timing (also hard to get definitive answers on) may negate a gearbox.
Thanks for all inputs very much appreciated.
 
That's great to hear. It's one thing to set goals but it can be heart breaking and demotivating if they become impractical to reach. So keep it flexible/realistic/achievable. One of the reasons you will find it difficult to find a definitive quote on what any motor will handle is because there are too many variables. Don't quote me on the following, I am just talking hypothetically. That Warp 9 might handle 2000amps...….for 5 seconds, then you ease off for a moment and give it another 2 second burst and bang. Because the heat builds up. Heat plus prolonged high current don't mix. When the motor is cold it will handle a little more current because it will take more before the conductors melt. It is a little like high revs or high boost in a combustion motor. You won't know what the motor can handle until you've taken it too far and then it is too late. Make sure you have built in temp sensors in your setup so you can monitor how it is travelling and Invest in a laser thermometer so you can point it specifically at key components like conductors immediately after heavy load. You'll soon get an idea what you are comfortable with. In my case every course I have run has been under 2 minutes usually more like 1 minute. The system draws 1000amps for a second and then reduces the current gradually over 10 seconds to something like 500amps until I accelerate out of the next corner. But then after my run it sits and cools for 10-60minutes. So the motor might peak at around 60-70 degrees but cools slowly before the next run. At 450-500KG you have the advantage as you can use my car as a benchmark. Take a look at my latest videos from Mt Cotton. Those inclines are fairly steep. I found my car handled it best in 2nd gear (including the launch). It did launch better in 1st gear but it put me in a bind for the first corner having to brake and change gears for the 1st corner. My system peaks at around 90KW and it suffers a bit from 85KPH and above. It definitely goes quicker (I've had it up to 130KPH in 4th gear) but the acceleration is noticeably slower above 85KPH. But this is based on the brush timing being approximately 10 degrees advanced. This setup is great for flatter courses requiring less torque and where high revs are expected and could cause arcing. But I now introduced an intermediate brush setting so I can have it at approximately 5 degrees. Not so great if high revs are expected but it will produce noticeably better torque which will be great for hill climbs. I will just get it in a higher gear and leave it there. I can't wait to compare this setup at Noosa to my previous attempts. I think in my case I am also suffering from my voltage (172v) limiting my upper revs. But short of wholesale component replacement there isn't much I can do about that.
 
I've looked at this sort of thing before and I ran into the 'powerglide solution'.

Powerglide can be ran without a torque converter. You can use a pump to provide the hydraulic pressure necessary to operate the internal clutch packs. I don't know the details on how to do this, though. No real clue. I do know, however, this was a popular solution for circle track racers with lightweight cars and high output motors. Some classes, apparently, required automatics and this approach allowed them to use an automatic without the interference of the torque converter. Supposedly with a converter-less configuration it can possibly offer higher efficiencies than similar manual gearboxes that can handle those big V-8 torque levels.

edit: There are 2-speed manual racing transmissions for circle track that will handle a powerful DC motor, but I expect they are going to use straight-cut gears and be noisy as hell.

The main advantage I see with this approach is here isn't really that you have multiple gears.. But that powerglide is cheap, strong, and lightweight transmission with a crap-ton of after market support and racing history you can get off the shelf that will provide a good amount of gear reduction.

The deal here is that a Warp9 motor or something like that will want to spin thousands of RPMs when the desired wheel speed is in the hundreds. And a differential alone can really only do 4:1 or 5:1-ish ratios. At least OEM ones that I am aware of. And using the powerglide can probably save you the engineering and expense necessary to design a custom gear reduction.


Although for a buggy I would probably look at the Nissan Leaf motor. Everything you need is one convenient hunk of metal, very compact, it's cheap and can handle high output. Water cooling will give you robust cooling performance when you need it. You just then have to get stub shafts fabricated to adapt the diff output to CVs that will work with your wheel hubs.
 
Hillhater said:
They use a battery that can deliver 400 kW of power from 100kWh of capacity ..iE its 4+C capable.
Click to expand...

You can buy 4C batteries can't you? lithium ion is not a secret technology the problem is that chinese factories use low cost materials i.e. thin graphite foil, badly pyrolyzed lifepo4, cheap electrolyte blah blah, I'm sure the oven curing time steps are proprietary for some manufacturers but that's about it.
 
Good to see the thread is still kicking. There hasn't been massive amounts of movement on the buggy build other than, for the time being, I'll stick with the Nissan leaf battery pack. A 45c lipo power plant would be ideal but in order to just get the buggy up and running sooner it makes sense to use the gear I have.
Shocks, axles, diff and a fair number of other things are yet to fitted up. So that's that for now...def big thanks to the help thus far too guys...far from finished with me yet!
 
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