# stuck on my build need help with BLDC setup 10kw on my buggy urgent!



## falshami (Jan 13, 2017)

Ive been building an Electric buggy for myself to daily drive. most of it is complete, charging system works lovely. sound system, lights, everything is fine. However I am and have been stuck on the drive train. I have 35 inch tires. attached to a drive train that is realistically around 2:1 . the whole machine weighs about 900 pounds? I started with a 5kw BLDC motor. it didnt really do the trick. SO i upgraded to a 48v 10kw GM BLDC with a VEC500 controller and now we are moving at least. we got up to 30-40 mph. however acceleration is absolute dog crap i mean from a dead stop she struggles. also it seems the battery never gets taxed for the full 10kw. at peak amperage draw i saw maybe 160, when she should be able to do 200a draw. the controller is rated for 10kw continuous as well as 20kw peak for short bursts, i am no where near that, and with my gearing i should be able to get 60 mph . so what gives? why cant i squeeze all the power from my equipment? also motor hardly gets even slightly warm. controller a bit but since i adjusted a few settings its much better. thoughts? i need to finish this project asap!


----------



## Karter2 (Nov 17, 2011)

A 2:1 drive reduction is not going to get the motor rpm much above 1200 rpm at 60 mph with those 35" tyres.
You probably need something like 8:1 or more to get the power out of that motor.


----------



## falshami (Jan 13, 2017)

so are you saying that i should be reducing my motor or gearing it up? currently its 2 spins to ever one axle turn, and it just feels so slow and 30ish isnt cutting it. the motor is rated at 6000 rpm and maybe 4500 under load? so you are saying i should do a much smaller gear on my motor? and maybe by reducing the load the rpms will spin up higher? or is this a controller issue?


----------



## Karter2 (Nov 17, 2011)

Yes, smaller gear on the motor.
Calculate the axle rpm at 60 mph.....about 600rpm ?
So if you want besr acceleration with a 60 mph max speed, the you should aim for max motor speed at 60 mph....about 8:1 gearing needed.
That would give you 4 time as much torque at the wheels than your current torque.


----------



## falshami (Jan 13, 2017)

This is so obvious i feel like a moron. This is true. So currently with my 18 to 32 it is a bad combo. the smallest tooth gear i could find is a 10 tooth to 32 which should get us closer. to where we want to be. the next step is increasing the size of the axle gear but the issue there is that not much more will fit i don't believe much more will fit as it will hit the CV boot. but perhaps a 40 may fit and get us to 4:1. where as we will be at a 3:1 now. this should at least put me in a better position correct? and drop my amp usage at the same time?


----------



## Karter2 (Nov 17, 2011)

If you cannot get suitable gearing to fit, you may have to build in an intermediate "jackshaft" to get enough reduction.


----------



## nucleus (May 18, 2012)

Karter2 said:


> A 2:1 drive reduction is not going to get the motor rpm much above 1200 rpm at 60 mph with those 35" tyres.
> You probably need something like 8:1 or more to get the power out of that motor.


But there's more torque at lower RPM, and everyone knows that torque is more important than horsepower.
















Not.


----------



## falshami (Jan 13, 2017)

well we do want plenty of torque and we will most likely end up playing with jack shafts. my confusion with jack shafts is ratios , ive been researching and i dont quite get them... so if i start with a 10t sprocket and have an ending sprocket of 32 or 35, what do i need the two gears on the jack shaft to get me close to an 8:1 ratio?


----------



## Karter2 (Nov 17, 2011)

10T on the motor, driving a 40T on the Jackshaft (4:1 ratio) 
Then a 16 T on the jackshaft , driving to a 32 T on the axle (2:1 ratio)
That will give you 8:1 total reduction.
But a 10T motor sprocket is not ideal from a wear or chain life aspect !
What type of chain are you using ?
Can you run 219 pitch chain to get better sprocket sizing ? At least from the motor to the jackshaft.


----------



## falshami (Jan 13, 2017)

I can run any chain you recommend! im currently running a size 50 chain, will other chains and small toothed sprockets wear incredibly fast compared to others?


----------



## dain254 (Oct 8, 2015)

With a vehicle like you describe.. 60mph is going to be a challenge with 10kw continuous. If you are running lead acid batteries... you are probably looking at a 15 mile range maximum. 8:1 final that was recommended towards the top is definitely more in the ballpark than the 2:1 you are using. My guess is even with ideal gearing you may only see 40-45mph since you don't have the continuous power to pull past bad aerodynamics of a buggy

If you are making a jackshaft, on your first reduction you could probably get by with quality 40 chain, like a 15T and a 60T to the jackshaft, then reuse your 50p parts to get the 8:1. The 60T gives you some range to drop gearing if you decide you aren't gaining on top end but want to accelerate faster by dropping to 12T for a total reduction of 10:1. Pictures????


----------



## falshami (Jan 13, 2017)

i should have mentioned we are using lithium batteries from a chevy volt. we have three 48v modules at 47ah each or 6kwh total. so batteries are only about 110-120 pounds. here are some photos. 

we dont need to hold 60mph for long periods but we do need it for quick passes etc. 


http://imgur.com/tS4YJjK

http://imgur.com/QzRd8Hf

http://imgur.com/6ehZT3X

http://imgur.com/jELj9Hc

http://imgur.com/BgkIb3f


original concept drive train with CVT

http://imgur.com/82hPtZb


----------



## falshami (Jan 13, 2017)

i have done some work on aero dynamics, by having the air flow above the buggy and below, also the front end will be sealed up, and the bottom will be sealed up so its smooth. ive also added 240w of solar on the roof for a kind trickle charging

my calculators said that we should have a range of 45 to 50 miles of course its not at full bore, though motors are most efficient at full pull am i right? well BLDC at least

also shouldnt a 10kw motor be able to push a 900 pound machine with good gearing to 60 mph ? i mean it just seems about right?


----------



## dain254 (Oct 8, 2015)

Pictures are worth 1000 words! Your tires are nowhere near 35" in diameter, my guess would be closer to 25". This will make quite a big difference on your ratios and is likely the reason you were even able to make the vehicle move with a 2:1. 

If you don't want to use a jackshaft, you could probably get away with a 12t and 60t rear for a 5:1 reduction. I genuinely hate using more than a single roller chain in a driveline... so a gearbox would be your next best option. With 5:1 your acceleration won't be amazing, but it will get you moving... 4500rpm would give you 900rpm axle speed which is about 60mph on a 25" OD tire. You are in better shape than I thought with the Volt modules, I have my current vehicle rigged up with just 4kwh in series... it rips and I can get 25 miles out of it if I'm somewhat careful on the throttle. I assume you have them tied in parallel, but did you also tie the balance ports in parallel to your BMS? This is important to not ruin the batteries! Looks like a fun machine!


----------



## falshami (Jan 13, 2017)

these are the tires on her with 15 inch rims 
215/70-15 SENTURY TOURING 70R R15 TIRE 29216

acceleration curently with a 10 tooth to a 32 tooth was not awful actually, theres no room for a transmission and jackshafts are the only way to go, so we need to aim for a 4:1 or 5:1 ratio in your opinion? the volt modules were my favorite part and yes we have the BMS wires in parallel so all is good! i may add a 4th battery sometime soon but i do hope to get a 60mph speed possible and roughly 60 mile range. what is your vehicle? any more recommendations? what gearing with jack shafts would i need?


----------



## Duncan (Dec 8, 2008)

Hi falshami

This is my car 
http://www.diyelectriccar.com/forum...dubious-device-44370p15.html?highlight=duncan

I think it's quite similar to what you are trying to do -
I have a 10Kw 48v motor - 17 inch wheels a 4.1:1 final drive and I can spin the tires

- bit tongue in cheek - the motor is rated as 10Kw - but I am actually feeding it a lot more voltage and current


----------



## falshami (Jan 13, 2017)

what setup do you have going? what are your top speeeds Duncan? whats the controller?whats the motor type? i want details buddy! i want power like this!!! haha


----------



## Duncan (Dec 8, 2008)

Hi
The details are on my thread 

The Device has a Hitachi 11 inch diameter forklift motor rated at 10Kw and 48v
I'm using a beta test version of the Paul & Sabrina 1400amp controller - set to 1200amps
and most of a Chevy volt pack (2 x 1Kwhr + 6 x 2Kwhr) - 340v

It's driving through a Subaru Limited slip diff - 4.1:1
215 x 45 x 17 tires

Total weight 805Kg - 900 Kg with me in it 55% on the rear tires

I hit 87mph and 4700rpm at the end of the 1/8th mile - which is 200rpm higher than I ever intended to go
And it was still building acceleration when I lifted felt like the acceleration was increasing

Did the 1/8th in 9.2 seconds - which is faster than most of the V8's - would have been faster but it spun the rear tires and frightened me

I'm using some dashboard switches to limit power - I normally drive at 48% power - 100% is too dodgy around town

Doing some grass events great fun - but fastest with the power cut down to 30%
Did one tarmac event - tried at 100% - I'm now sure it would have been faster at 80% 

Great fun machine - yours should be fun as well


----------



## falshami (Jan 13, 2017)

that is an impressive set up. so tell me does this mean you are running 58kw of power? if that is the case how is that motor not frying to death? also your 58kw make my 10kw system sound like childs play! its a brushed motor i take it? do you run a cycle analyst for your live settings ? im learning alot from you guys!


----------



## Duncan (Dec 8, 2008)

Hi
As your speed increases the amount of power you draw increases

I take off at 1200amps - and maybe 15v (motor) - 18Kw
As my revs rise the required voltage rises -
Before the end of the 1/8th I am at 300v and 1200amps - 360Kw

The motor survives because its only for a couple of seconds - one day It won't and I will have to get another motor!

I do have a Cycle analyst - modified for the higher voltage
This works fine normally
But when I do a full power run it takes the huff and gives stupid answers for a couple of minutes - like 300kph on my run down
After a couple of minutes it gives sensible answers

With the Volt pack there is a useful voltage/charge relationship

I charge to 340v - and discharge to 295v


----------



## Karter2 (Nov 17, 2011)

if you want to see what good data instrumentation can show you , take a look at this typical record of a 10 sec run from John Metrics DC Plasma EV racer...
Note how the motor voltage increases as the battery voltage sags to peak output


----------



## falshami (Jan 13, 2017)

are any of you familliar with the vec500 by golden motors do you know if a cycle analyst can hook up to it? maybe this will help? also does it seem that a higher voltage is what may be needed?


----------



## falshami (Jan 13, 2017)

so latest update.. i put in a jack shaft, i got a gear ratio from 10 teeth to 21 , attached to a 10 tooth to a 31, so roughly a 5:1 ratio, and now she does 24 mph... also the power wont go past 6 or 7 kw, i am quite confused. any ideas guys? i was really sure that with my size wheels at 5:1 i would have at least 50 mph?


----------



## Killzilla (Aug 19, 2016)

Any updates? Running into a similar problem.


----------



## falshami (Jan 13, 2017)

so i did have an update. a 5:1 ratio with a wheel of around 21 inches tall , did not work out, good acceleration but she got to a top speed of 24 which wasn't what we wanted. i next tried a ratio of 18 teeth to 31 and that worked for a top speed of almost 40 ish mph. take off power was abysmal it would struggle to start up any hill. i then dropped to a 14 tooth to 31 and got spectacular results, up to 47 mph depending on the grade of the road. take off power is still weak but not as bad. i am moving to a 12 tooth to 31 which i think should be my magic numbers i may lose a couple miles per hour but im hoping i can make up for it with better acceleration . next issue is it draws a lot of amps. i had originally planned my buggy to have a range of nearly 60 miles, she does around 20 now with this gearing, which is problematic, since the final 7 or 8 miles arent as usable as the first 12 especially with the said lack of power on take off. i have raised the starting phase amps to help to 350, but that isnt sustainable. I am going to activate regen soon and have added 240w of solar to the roof to help a bit. maybe this may add an extra mile of usable range.. unsure still. i have calculated that my vehicle uses 7.5ah per mile or roughly 360 watts per mile, which is atrocious efficiency. i think that part of this is due to poor aero dynamics, since this is the realistic range at higher speeds. also the fact that the gearing is set so high, i am thinking that when i drop to 12 teeth my draw should drop a bit. if i could get the draw to around 240w per mile id be in much better shape, although that's still quite inefficient. but it would up my range to about 30 miles which would work for my commute needs. any ideas to bring my efficiency up would be wonderful!


----------



## Killzilla (Aug 19, 2016)

Have you played around with the controller settings? I had a 3 KW motor from golden motors, initially it was terrible, played around with the settings a bit and it improved. Not dramatically, but it did improve. The 3 KW motor takes 3840 W of power for us (48 V x 80 A) so we are maxing it out almost. We also used a 5 KW motor and got quite a decent range. We were drawing 1 Amp/hr per Km so approx 48 Wh/km. Only issue was gradeability and top speed. All this was on a flat road though (the range test).
Only difference between our vehicles is I have a three wheeler (reverse trike), and probably thinner or less wider tires than you. But that shouldn't give such a dramatic difference in numbers. 

Vehicle Weight = 500 kgs
Drive wheel radius = 24 inches
Motor = 3 and 5 KW. 
Transmission = CVT
3 KW gave us top speed of 35 kmph, and lousy to OK acceleration. 
We wanted to go ahead and buy a 10 KW and hook it up with a gearing of 4:1 or 5:1 (similar to yours) and hope to get to at least 50 mph. However a little underwhelmed after hearing your situation.


----------



## falshami (Jan 13, 2017)

I am simply astounded that you got such an efficient run out of the vehicle, although at 35kmh i only draw about 80 to 110 amps as well so we are about as efficient as each other there. and my vehicle weighs about 400kgs. roughly. i can no longer dead lift the rear end my self, it originally weighed around 650 but motors and batteries add up. im thinking i simply need more volts which is unfortunate. sicne that means upgrading my controller and battery setup which will confuse me quite a bit, my suggestion is sell your 48v stuff and use 96v. thats what i should have done. from my experience a 10kw motor will not get you to 50 mph especially at a 4:1 ratio or 5:1. that actually got me speeds of only around 18 to 22 mph, it ripped though, it really hauled! i have settled on a gear ratio of 2.58 to 1 that should net me a top speed at full voltage of around 43 to 45 mph with one occupant. and hopefully give me a range of hopefully 24 miles? thats at 150ah. i tried a cvt at first to no avail. it was incredibly loud , unreliable and just didnt work , especially with reverse. a cvt would have been a dream. i have messed with that controller a ton as well, i have it damn near maxed out on settings. starting amps are at 350, peaks at 350 battery amps . again this was using a 3:1 ratio . my 2.58 to 1 should be my golidlocks gear or a 12 teeth to 31 . what i need to do is drop my amps consumption and maintain speeds of around 40 to 45 mph. im hoping my new gear will arrive soon. also adding another battery will really help . i sometimes push betwen 9600 and 12600 watts . my biggest accomplishment so far is keeping my controller super cool! i only wish i could improve the take off torque. it concerns me since it may not be able to get up inclines with two passengers. its only funny since while moving it accelerates just fine. so i am bewildered.


----------



## falshami (Jan 13, 2017)

one big thing i am doing is trying to see if there is a way to add a 2 speed or 3 speed transmission to my vehicle.


----------



## Killzilla (Aug 19, 2016)

Maybe my vehicle is slightly more efficient as I only have three wheels! And one driven wheel. So with my current set up being useless, I am probably going to buy a 10 kW motor from GM and use a final drive ratio somewhat similar to yours (3:1). However I cannot use a 72V system as my budget is stretched to the limit. So I am stuck with 48V. Also acceleration is not a top priority if I can reach around 40-45 mph. Do you think such an effort is even worth it? Would said 10 KW motor be able to reach the requisite speed even if I sacrifice acceleration instead?


----------



## Duncan (Dec 8, 2008)

Why not buy a Forklift motor and a Paul & Sabrina controller

75Kw!

I paid $100NZ for the motor and $600US for the controller

You will also need more volts with only 130 I struggled to reach 100Kph

NOTE pay no attention to the nameplate power on the motor - mine is 10K
But I'm putting about 300Kw into it


----------



## falshami (Jan 13, 2017)

killzilla, you are probably more efficient , but you do weigh more. realistically both of our vehicles to compete with every day cars require a minimum of 20kw motors, i arrived to this number because we weigh about 4 times less than a Nissan leaf which has an 80kw motor. (of course high voltage BUT BESIDES THE POINT) I think a 10kw motor running at a higher voltage would be fine. i am in between selling my 10kw motor and buying a 20kw motor, or just selling my controller and buying a 96v controller to run on my 10kw motor. i think that acceleration isnt the issue as once it starts to move it will scoot along just fine. its initial take off uumph that is concerning. my motor on an uphill feels like it wants to stall but doesnt. hasnt yet at least. but once going like ive mentioned ive hit 47 to 48 mph with my little monster and maintained 45 mph. a 3:1 final drive ratio netted me around 36 mph to 38 mph, which should be sufficient for you and still gave me some start up issue , but after getting that initial wheel rolling she pulled pretty hard. you could feel it in the butt dyno, and might even be a bitt too aggressive for me so im going to back it down to a 2.583 to one ratio. the gm 10kw version will do what you ask, use more volts if you can however, your amperage will thank you. 

Duncan, i went with a GM brush-less for size weight and efficiency. the setup you recommend sounds awesome though and i want to look into it


----------



## Killzilla (Aug 19, 2016)

Yesterday I did another trial run, used the 5 KW motor I had in stock and was able to get to 50-55 kmph on a flat road. The gearing was 8:1 and was able to accelerate at a fairly lousy rate of 0-40 kmph in 12 seconds. Which is alright as I know the 5 KW isn't doing much. Hopefully things improve with the 10 KW motor, may try different sets of gearing and see what gives me the best acceleration vs speed. Still stuck with 48 V though.


----------



## falshami (Jan 13, 2017)

you may want to consider a dual 5 kw setup if you can, it would give you some great cooling better than that of the 10kw model. dual controllers. and of course you might be able to push each motor to maybe 8 kws? that might be an awesome bet, i considered this had i had the space for it. im going to push alot out of my motor but my 10kw cooling isnt as good and i know this. which also means i have to sadly sell my 5 kw motor and controller. 

here are some photos!

http://imgur.com/a/vyPrS


----------



## falshami (Jan 13, 2017)

alot has happened so far, i have two threads on this, but as of lately, my vehicle now has floor boards so she is totally sealed underneath from whatever could come up. i am working on aerodynamics and lowering my watt hour consumption per mile which seems to hover around 220. this needs to come down so that i can get a better range which now seems tob e around 30 miles, but only around 18 miles of effective range ,meaning sustaining good speeds. does anyone know if i can use a 96v system and limit to output up to 60v and get more speed out of my 48v motor and eliminate my voltage speed drop?


----------



## Killzilla (Aug 19, 2016)

Hi Falshami,

How's your vehicle coming along? What modifications have you made and did you achieve your desired speed and range?

Would be great to hear back from you.


----------



## falshami (Jan 13, 2017)

Hello there again, my apologies for not being around, life took its time on me and the summer in Arizona hit so i had to shelve the project for a few months as it is unbearable to be outside working on her in this heat. last i left off, she had reached a peak of 50 mph but was able to sustain this speed for many miles. i came to the conclusion that i needed more hp to go any faster and much better cooling for the controller. even water cooling this motor i dont think is enough but ive been told otherwise. the range was pretty good, somewhere around 30 miles, depending on how you drive it, but realistically in town 30 miles. which is pretty damn good! i figure with another battery 40 miles would be a sinch. the last issue i had the with the vehicle was the gears still. the chain was getting hot due to being slightly misaligned. so i am going to be working on realignment of the chain drive, my only issue is the gear is practically welded itself to the shaft of the motor . i ordered a pully puller, however the motor shaft spins as i try to turn the pulley puller spindle, i was going to put a slightly larger gear on it bring the top speed down to around 45- 47 mph, but create less heat from, the chain moving so much around a small gear. i am considering selling her as i being about to graduate college. will be needing a larger vehicle, so i do have her up for sale for 4100 bucks or what ever offer comes my way. though i may continue to drive her around, she did 200 miles in a few weeks with no issues. and i absolutely love driving her. range is perfect for me , especially living in a bigger city (tucson az) the only things she really needs done is me re doing one wire that was too small of a gauge, and putting the chain and gear back on. other than that she is perfect, she survived the Arizona scorching heat with no issues, even the monsoons season didnt harm the electrics which were well covered and the solar panels kept the batteries charged as i needed them! this little car is really a trooper. i may get back to work on it in the sense of upgrades such as bigger motor ect. unless she sells. i really do love this car. it helped me through alot emotionally and mentally i am a much more mature person for it. I am open to ideas on how to continue improving her though!! I do have plans to add an Air conditioner in the near future if she sticks around , i will be creating a canopy for her from fabric for convertible tops to keep the air inside nice and cool!


----------



## Killzilla (Aug 19, 2016)

That's great news and all the best for grad school.

What was your final configuration in terms of motor KW, battery pack, voltage and other things? Did you end up using dual motors or stuck with 10 KW and 96V system? And i presume you used lithium ion?


----------



## falshami (Jan 13, 2017)

Thank you, its my bachelors im about to finish with, but all the same thank you, i stuck with 3 batteries from a volt , at 48v . the motor and controller are still at the same 48v setup. i was never able to figure out if running 96v would be a good idea. and it is still a single motor setup. the multiple motor with transmission didnt pan out before the summer hit. it may still be an option however!


----------



## Killzilla (Aug 19, 2016)

What's the amp hour rating of the chevy volt pack that you used?


----------



## falshami (Jan 13, 2017)

im rust on my conversion from kwh to ah, but i am running about 6kwh of power at 48v. looking back... compared to a tesla its such a small amount, but it sure does pull for quite a while!


----------



## MalibuMan (Feb 28, 2015)

Thanks for all the details on your problems and possible solutions.

I am designing a very light (200 kg including driver) cyclekart with for street-legal moped laws reasons a 3 kW BLDC motor from Golden Motors, but my top speed only has to be 50 km/h. 

Plan is to drive past the morning traffic on the bicycle path ;-) On a busy morning my car commute is about 1 hour for 38 km, and my velomobile commute over the bicycle path takes me 1:02 hour but arriving drenched in sweat, without a shower possibility at work. So I figured the fastest way was an electric cart that was allowed on the bicycle path and would go the legal limit 45 + 10% = 49,5 km/h. Maximum engine power (continuous) is 4000W, but I could not find a light motor of 4000W so I will try 3000W.

I have already calculated my reduction gearing to go 49,5 km/h and hope that that will give me enough bottom-level torque to accelerate adequately from standstill.

I decided on 48V too, because it is the new voltage for cars like high-end Audi's so will give me availability of off-the-shelf parts, and also allow easy conversion to 12V should I need it. 

One question I have: Is that VEC200/48Vdc controller correct for my setup or do you or someone else advice a different controller?


----------



## falshami (Jan 13, 2017)

the biggest thing i learned is GO WITH MORE POWER, look for a 5kw motor and get more power , you will thank me later , i never had enough power on my build. so if you can get bigger than calculated its much better


----------

