# Smallest pack that can output 2000A at 144V?



## dcb (Dec 5, 2009)

I *think* the NEDRA guys use kokam or a123 cells, but I don't have specifics. I'm sure they are costly though. Would like to know myself.

edit per wikipedia
https://en.wikipedia.org/wiki/Electric_drag_racing
Derek Barger and Rae Ciciora at High Tech Systems LLC comes up a few times in the top runners, from colorado

http://www.hightechsystemsllc.com/pt_Batterypacks.html

This pic is looking a little 18650-ish









edit: there are a crapton of good pics on that hitech site.

edit2: guessing ANR26650 cells? [email protected]?!?


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## dcb (Dec 5, 2009)

did some more figuring
http://www.a123systems.com/Collateral/Documents/English-US/A123 Systems ANR26650 Data Sheet.pdf

http://www.a123batteries.com/product-p/anr26650m1-b.htm

so a 10 second 100kw capable 500 cell pack (my purposes) looks like, not including assembly, $1 per wh, and about $4250 in cells (4125wh) and about 84 lbs in cells (500 cell pricing).

you would need 2.88x500 cells basically. I'm just doing a whole lot of guessing here, no promises.

and of course this stuff is changing all the time.


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## major (Apr 4, 2008)

Check out John Metric (member here) and his LoneStar EV racing team, or company, or website, or facepage, or whatever he calls it.


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## spaceballs3000 (Jun 22, 2012)

joetemus said:


> I am trying to find the cheapest way to get 2000A at 144V. I have experience building BMS systems, but on smaller packs. With some 30A 18650 cells I would need over 2,650 cells, which seems like an excessive amount.
> 
> Any tips?


How far are you moving the vehicle? i.e. how many Watt Seconds do you need at 2000A?


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## joetemus (Jun 29, 2016)

spaceballs3000 said:


> How far are you moving the vehicle? i.e. how many Watt Seconds do you need at 2000A?


My plan is to autocross it, so only for a max of say 1 minute, but it will more likely 2000A for 5 seconds a few times throughout the run.


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## joetemus (Jun 29, 2016)

dcb said:


> did some more figuring
> http://www.a123systems.com/Collateral/Documents/English-US/A123 Systems ANR26650 Data Sheet.pdf
> 
> http://www.a123batteries.com/product-p/anr26650m1-b.htm
> ...



I really like the look of those cells! 120A for 10 seconds should be more than enough! I would need 17 in parallel, and with a nominal voltage of 3.3, I would need 43 to 44 cells. I am not sure what the max voltage is, but I doubt it would be enough to destroy the motor when fully charged. 

Quick math with those prices leads me to think it would cost somewhere around $6500, which is about $1500 more than I was hoping, but its not bad!


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## WolfTronix (Feb 8, 2016)

Perhaps design the pack for your typical discharge current...
And then use a bank of capacitors to augment the battery pack, such that it can handle the 2000A bursts.


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## joetemus (Jun 29, 2016)

WolfTronix said:


> Perhaps design the pack for your typical discharge current...
> And then use a bank of capacitors to augment the battery pack, such that it can handle the 2000A bursts.


Honestly banks of capacitors scare the crap out of me. Ive "played" with a super capacitor when looking into them for the solar car team, and we accidentally welded a screwdriver to it. I would prefer not to use them if I don't have to. I will need to go to something like that if I add two more motors to the front wheels though.


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## bigmotherwhale (Apr 15, 2011)

capacitors scare you but extremely high discharge batteries dont?

what power level are you aiming for? 
can you increse the system voltage and lower the amps? 
are you planing on running two controllers and two motors?


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## joetemus (Jun 29, 2016)

bigmotherwhale said:


> capacitors scare you but extremely high discharge batteries dont?
> 
> what power level are you aiming for?
> can you increse the system voltage and lower the amps?
> are you planing on running two controllers and two motors?



Extremely high discharge batteries do as well, but not as much just because I havent had a lot of experience around them.

I am planning on running 2 warp 9 motors, one to each rear wheel and using two 1000amp controllers. I am basically looking to max out the two warp 9s.


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## dcb (Dec 5, 2009)

caps are a bit too experimental yet, and need bucking/boosting in a separate string (to the tune of 1/4 megawatt in this case for 10 seconds) with its own bms and etc. expensive and bulky if there are already batteries that can do it and will not drop their voltage linearly.

The price and likelyhood that it won't do a bit of good after lots of experimenting is enough to scare me.


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## joetemus (Jun 29, 2016)

dcb said:


> caps are a bit too experimental yet, and need bucking/boosting in a separate string (to the tune of 1/4 megawatt in this case for 10 seconds) with its own bms and etc. expensive and bulky if there are already batteries that can do it and will not drop their voltage linearly.
> 
> The price and likelyhood that it won't do a bit of good after lots of experimenting is enough to scare me.


Exactly. I don't want this car to be overly complicated either. I've dealt with overly complicated electric vehicles and you are always chasing gremlins...


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## major (Apr 4, 2008)

http://www.ampahaulic.com

John says his are the highest kW/kg and lowest $/kW.


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## major (Apr 4, 2008)

You may want to read up on power density and specific power. A member (Davide, who hasn't posted lately) wrote an excellent article on the subject a few years ago. http://elithion.com/wp_short_discharge_time.php


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## dcb (Dec 5, 2009)

ampahaulic.com is definitely a good tip!


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## spaceballs3000 (Jun 22, 2012)

joetemus said:


> Honestly banks of capacitors scare the crap out of me. Ive "played" with a super capacitor when looking into them for the solar car team, and we accidentally welded a screwdriver to it. I would prefer not to use them if I don't have to. I will need to go to something like that if I add two more motors to the front wheels though.


If you messing with batteries that have super high current, then you better have the same respect with them as the same as the super caps because they are affectedly the same when it comes to shorting them out with wrench/tools.

Like others have posted your best bet is racing lipos or ultra caps, hybrid approach isn't simple unless you know what your doing.


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## spaceballs3000 (Jun 22, 2012)

dcb said:


> caps are a bit too experimental yet, and need bucking/boosting in a separate string (to the tune of 1/4 megawatt in this case for 10 seconds) with its own bms and etc. expensive and bulky if there are already batteries that can do it and will not drop their voltage linearly.
> 
> The price and likelyhood that it won't do a bit of good after lots of experimenting is enough to scare me.


There is no existing small form factor bucking/boosting device that meets the needs of what you mention. the simplest solution is have enough caps in series to cover the energy needed.


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## bigmotherwhale (Apr 15, 2011)

I wouldn't usually or normally recommend hobby stuff because its mostly crap, but the turnigy graphene batteries are performing amazingly well under high discharge and according to people running tests, are for the first time true to ratings.

They apparently hold their voltage under high discharge very well at low SOC and remain cold due to very low internal resistance. 

You can get them as high as 90C discharge rate. 

It might be worth getting some sample cells and doing some testing


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## joetemus (Jun 29, 2016)

bigmotherwhale said:


> I wouldn't usually or normally recommend hobby stuff because its mostly crap, but the turnigy graphene batteries are performing amazingly well under high discharge and according to people running tests, are for the first time true to ratings.
> 
> They apparently hold their voltage under high discharge very well at low SOC and remain cold due to very low internal resistance.
> 
> ...


I actually run those in my racing quadcopter. Quite amazing little batteries. I'll try to count up how many I would need and see if its worth while.


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## dcb (Dec 5, 2009)

I'm not one of the people suggesting supercaps FYI, but i.e. ~115 16000 farad supercaps in series (that can support 2000A for 10 seconds) would put you in the ballpark, charged to 288v, and after 10 seconds @ 2000A is at 144v. if you figure on the motor/controller bucking that 288v reasonably efficiently, then the "average" current is 1500A so maybe 12000 farad * 115. You *could* also account for starting at 0 motor rpm, but if night rider taught me anything it is that you are already in motion when you hit the boost button before the ramp...

edit: http://www.mouser.com/ProductDetail...GAEpiMZZMuDCPMZUZ%2bYl45oKYEsy2zXBoyjx4taiX8=

so: $300 for a 4k farad (no hint at current rating in datasheet), *3 * 115 , thats a mere $100,000 experiment 

edit2: and it weighs 800 grams, so * 3 * 115 = ~ 600lbs...

an equivalent power, pre-assembled from ampahaulic or hightec would be ~ $5000 and ~70 lbs, and have a whole lot more amp hours. I think supercaps are a bust.


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## Hollie Maea (Dec 9, 2009)

dcb said:


> edit2: and it weighs 800 grams, so * 3 * 115 = ~ 600lbs...


This is a great illustration why at the moment supercaps are not the way to go--even for power intense applications.

Using Samsung INR18650-25R cells, the same performance could be achieved with a 40S50P pack. These cells would only weigh 200 lbs. And would have the added benefit of holding more than an order of magnitude more energy and a much flatter voltage curve. And would cost less than a tenth.

The ability to discharge all of its energy in a couple of seconds is not by itself an advantage. C rate is only a useful metric for power when used in conjunction with energy density.

Edit: And various LiPos could get the power with even less weight, with a modest sacrifice of energy. Looks like John Metric's cells could do it for about 60 lbs.


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## bigmotherwhale (Apr 15, 2011)

I agree.
ultracaps seem to be suited to hybrids as they are lighter and only have to be big enough to accept the energy of regen from full speed, not sustain the vehicle for long duration (which the ice is best suited to) and also the charge discharge / efficiency is very high and the cycle life too. 

these plugin hybrids have to carry a big weight penalty in having as large traction pack and all the ICE stuff too its no surprise they aren't all that much more efficient, i wonder if any of the manufacturers of hybrids have considered a capacitor approach?


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## dcb (Dec 5, 2009)

bigmotherwhale said:


> I agree.
> ultracaps seem to be suited to hybrids


I have no idea what that statement would be based on. ultimately it is about energy density as creating 1/4 megawatt for a microsecond is about useless.

edit: just from the example in my previous post, they look like they are at least an order of magnitude worse at energy density per g than available batteries (and an order of magnitude more expensive)


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## bigmotherwhale (Apr 15, 2011)

I thought it was pretty self explanatory, but studies have been done, a quick google.

"The fuel economy improvement with the ultracapacitors is 10%-15% higher than with the same weight of batteries due to the higher efficiency of the ultracapacitors"

http://ieeexplore.ieee.org/xpl/logi.../iel5/5/4168011/04168012.pdf?arnumber=4168012


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## dcb (Dec 5, 2009)

bigmotherwhale said:


> http://ieeexplore.ieee.org/xpl/logi.../iel5/5/4168011/04168012.pdf?arnumber=4168012


Lol, aside from half-assed paywall, when you dig into it this explains the gains as much as anything
" and will be concerned primarily with the fuel economy gains that can
be achieved utilizing a sawtooth control strategy that optimizes the efficiency of the
engine"

i.e. pulse and glide... apples and oranges.

DO SOME SOME OF YOUR OWN GODDAMN RESEARCH!


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## Hollie Maea (Dec 9, 2009)

bigmotherwhale said:


> ultracaps seem to be suited to hybrids as they are lighter and only have to be big enough to accept the energy of regen from full speed


I disagree. While ultracaps have extremely high C rate, the energy density is so low that batteries actually can match or exceed them in power density. So I would assert that there is NO traction application for which caps are currently better.

If you're really worried about cycle life in a hybrid application, use LTO cells. They'll last as long as caps.


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## bigmotherwhale (Apr 15, 2011)

I dont have the money to spend doing research or i might possibly do some, there is plenty of studies already, enough you can see where they outperform batteries and where they do not. 

Regenerative braking is where ultracapacitor technology clearly outperforms battery storage. 

Whats the point of having a large storage capacity in a car with an engine? 
you would be better off trying to store braking energy more efficiently, and reducing the weight to an absolute minimum.

these plugin hybrids are either running on electric power and hauling an ICE running on ICE and lugging a battery. In my opinion each would be better off on its own.

the power density of an ultracapacitor means it can be very small and still cope with high currents of regenerative braking, and the charge / discharge efficiency is more than any battery I know of. 

A hybrids means for increasing efficiency is not to do with storage capacity, its to do with how much braking energy you can effectively capture and use again.

PHEVS rely on short journeys and cheap electricity.

Anyhow, i dont want to hijack this thread, i know this is not about capacitors.


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## sunworksco (Sep 8, 2008)

Graphene batteries and super capacitors are scaling up for production, soon....


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## dcb (Dec 5, 2009)

I think the supercapacitor speculation belongs in the overunity thread.


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## joetemus (Jun 29, 2016)

What do you guys think of these graphene packs?

http://www.hobbyking.com/hobbyking/...h_2S2P_Hardcase_Lipo_Pack_ROAR_APPROVED_.html

Would only need a 19S3P pack! Only $4400 will get me over 144v charged and 2025 amps output!


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## Duncan (Dec 8, 2008)

dcb said:


> I think the supercapacitor speculation belongs in the overunity thread.


Disagree - it's not a question of loonies - just an issue about maths

I suggest Bigmotherwhale does the calculations 
Assume a 1500Kg car and the amount of batteries or supercaps to absorb a single stop from 70mph - then compare weights/costs


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## dcb (Dec 5, 2009)

joetemus said:


> What do you guys think of these graphene packs?[/url]
> 
> Would only need a 19S3P pack! Only $4400 will get me over 144v charged and 2025 amps output!




looking at the ampahaulic page, I think you are going to need more like 23s to account for sag.

which is $5300 and still lots of assembly and about 105 pounds.

I'm sure the dragster guys have experimented with 'em.


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## joetemus (Jun 29, 2016)

dcb said:


> looking at the ampahaulic page, I think you are going to need more like 23s to account for sag.
> 
> which is $5300 and still lots of assembly and about 105 pounds.
> 
> I'm sure the dragster guys have experimented with 'em.



For sag is it a better idea to go for more cells in parallel or in series? To me it would make sense to put another pack in parallel to take some of the amp load.


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## dcb (Dec 5, 2009)

the motor/controller should buck the extra voltage into motor current, and as the current drops off on the high end a higher voltage pack will allow more rpm.

so for a given motor current the higher voltage pack has more dynamic range 

but brushes can complicate that of course.

and I am just arm-chairing it too. (edit, but the packs/graphs on the ampahaulic site seem to go with more voltage than more parallel, i.e. 100C is assumed and 2.78 cell volts @ full sag is assumed)


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## dcb (Dec 5, 2009)

fyi, now that I'm understanding the ampahaulic graphs better, I'm going to up my guesstimate on those hobbyking batteries to 26s(3p).

(a 72s pack is listed as 200v fyi under full sag, which is 266v nominal)

edit: and there is about a 100% chance that hobby king is full of shit, that "graphene" is a marketing term.
http://www.quaddiction.club/the-reality-of-turnigys-graphene-lipo-batteries/


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## bigmotherwhale (Apr 15, 2011)

The first thing would to buy a few and test them to the limit. see how well they hold capacity, voltage, temp, IR ect and go from there. 

BTW the previous generation "nanotech" batteries are absolute shite as per all the reveiws. These graphene ones always seem to be in favour, peoples tests have shown them to be true to rating which is a good sign.


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## dcb (Dec 5, 2009)

bigmotherwhale said:


> The first thing would to buy a few and test them to the limit. see how well they hold capacity, voltage, temp, IR ect and go from there.


first thing would be to ignore that suggestion and go with people who have already tested their products. It already looks heavier and more costly so I don't know why you are still on about it.

if they can't provide useful data, screw 'em.


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## joetemus (Jun 29, 2016)

dcb said:


> first thing would be to ignore that suggestion and go with people who have already tested their products. It already looks heavier and more costly so I don't know why you are still on about it.
> 
> if they can't provide useful data, screw 'em.


Yea if I have to go with 4 in parallel it's not worth it. Still leaning towards a123 cells


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## ishiwgao (May 5, 2011)

dcb said:


> edit: and there is about a 100% chance that hobby king is full of shit, that "graphene" is a marketing term.
> http://www.quaddiction.club/the-reality-of-turnigys-graphene-lipo-batteries/


it may be a marketing term, but from the same website it shows under the updates at the bottom of the article that some tests had been done and the batteries work well too. so maybe it isn't all that shit.


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## dcb (Dec 5, 2009)

I saw a lot of hype, but nothing spectacular. nothing that beats a123 published nano-phosphate specs.

oh, and the graphene explanation is buried in 2 seconds of comment in a video :/ https://youtu.be/38cqjpp2xJY?t=271

they added g10 graphene plates as armor... the batteries are probably the same and the fandom is imagining the rest (well a bit of compression is good BUT WE ALREADY KNEW THAT!!!)

edit: apparently g10 is fiberglass, and the cells say A123..
https://youtu.be/fBy4eoDVp_g?t=201


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## Yabert (Feb 7, 2010)

joetemus said:


> I am planning on running 2 warp 9 motors, one to each rear wheel and using two 1000amp controllers. I am basically looking to max out the two warp 9s.


If you are looking to this you will need more than 144v underload.
For peak performance, you will probably need 170v to 200v at 2000A. This imply an higher nominal voltage.

Just in case you don't know: 300v and 1000A battery can supply 150v and 2000A to motors.


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## joetemus (Jun 29, 2016)

Yabert said:


> If you are looking to this you will need more than 144v underload.
> For peak performance, you will probably need 170v to 200v at 2000A. This imply an higher nominal voltage.
> 
> Just in case you don't know: 300v and 1000A battery can supply 150v and 2000A to motors.


Do the controllers drop the voltage? My understanding was that they just used PWM to connect the batteries voltage to the motor?


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## dcb (Dec 5, 2009)

a motor is basically a large inductor and combined with a controller it is basically a buck converter, it can take higher voltage at lower amperage and convert it into lower voltage at higher amperage.

like this, only with the inductor connected straight to ground, and no load resistor or output cap. Just the switch and the diode (to maintain motor current when the switch is open) and the motor.

the conversion is based on duty cycle (100% means battery voltage=motor voltage, battery amps = motor amps). It is like an adjustable DC transformer in a way.


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## joetemus (Jun 29, 2016)

dcb said:


> a motor is basically a large inductor and combined with a controller it is basically a buck converter, it can take higher voltage at lower amperage and convert it into lower voltage at higher amperage.
> 
> like this, only with the inductor connected straight to ground, and no load resistor or output cap. Just the switch and the diode (to maintain motor current when the switch is open) and the motor.
> 
> the conversion is based on duty cycle (100% means battery voltage=motor voltage, battery amps = motor amps). It is like an adjustable DC transformer in a way.


So if I went 100% full throttle with a pack that has a voltage of 300V, wouldnt that damage it? I don't think I understand what you mean. The motor will drop the voltage when the duty cycle is low, but if its 100% that should be basically a direct connection?


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## dcb (Dec 5, 2009)

the controller controls motor current (i.e. torque), sort of like how your foot does in a regular car.

so when you wang open the throttle, it sets the duty cycle to limit the motor current. At low rpm the back emf is negligable so the duty cycle is low to limit the effective motor voltage, and the pack current draw is also relatively low. As the rpm comes up, the controller has to increase the duty cycle to counteract the back emf of the now faster turning motor (motors are generators), and more current is taken from the pack.


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## joetemus (Jun 29, 2016)

dcb said:


> the controller controls motor current (i.e. torque), sort of like how your foot does in a regular car.
> 
> so when you wang open the throttle, it sets the duty cycle to limit the motor current. At low rpm the back emf is negligable so the duty cycle is low to limit the effective motor voltage, and the pack current draw is also relatively low. As the rpm comes up, the controller has to increase the duty cycle to counteract the back emf of the now faster turning motor (motors are generators), and more current is taken from the pack.


Very interesting. So finding a super high current pack might not be the best way to go. More cells in series and less in parallel.


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## dcb (Dec 5, 2009)

joetemus said:


> Very interesting. So finding a super high current pack might not be the best way to go. More cells in series and less in parallel.


I think the drag race guys know what they are doing 

edit: typically the less you have to convert volts/amps the more efficient. As well a lot of controllers don't like high voltages. You want to finish the race at or near %100 duty cycle IMHO, and the controller still needs to handle the motor current, only now it has to handle higher voltage stresses as well.


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## joetemus (Jun 29, 2016)

dcb said:


> I think the drag race guys know what they are doing
> 
> edit: typically the less you have to convert volts/amps the more efficient. As well a lot of controllers don't like high voltages. You want to finish the race at or near %100 duty cycle IMHO, and the controller still needs to handle the motor current, only now it has to handle higher voltage stresses as well.


So in reality stick to as low of a voltage you can to get the voltage you want after it sags? I guess it doesn't really matter as the revolt motor controller I plan on building only accepts up to 144V...


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## Duncan (Dec 8, 2008)

Hi Joe
The OpenRevolt controller is great - I built one - but it is 150v and 500amps - why are you looking for 2000amps?

If you are going to redevelop the power stage to handle 2000amps then you should also increase the voltage capability


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## joetemus (Jun 29, 2016)

Duncan said:


> Hi Joe
> The OpenRevolt controller is great - I built one - but it is 150v and 500amps - why are you looking for 2000amps?
> 
> If you are going to redevelop the power stage to handle 2000amps then you should also increase the voltage capability


The wiki says they have a 500 and 1000 amp controllers. I was going to build two 1000 amps, one for each motor


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## Duncan (Dec 8, 2008)

Hi Joe

I have a beta version of the "1000amp" OpenRevolt controller

I will be using it at 325v - Paul thinks it should be OK for 400v
and I could turn the current up to 1400amps!!

Which motors are you using?


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## dcb (Dec 5, 2009)

he mentioned dual warp 9s, but unless they are physically coupled he is probably going to want dual controllers.

edit, is there a link to the 1000amp 500v jobbie? (edit, this one? http://www.diyelectriccar.com/forums/showthread.php?t=170938 igbt 6 pack style?)


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## joetemus (Jun 29, 2016)

Duncan said:


> Hi Joe
> 
> I have a beta version of the "1000amp" OpenRevolt controller
> 
> ...


Dual warp 9's. Do you have a link to the new controller? Id love to build and help "beta test" it.


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## Duncan (Dec 8, 2008)

Hi Joe

http://ecomodder.com/forum/showthre...cheap-diy-144v-motor-controller-6404-712.html

This is a LOOONG thread - the new controller - the "Dirty Diaper Controller" discussion is near the end


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## joetemus (Jun 29, 2016)

Duncan said:


> Hi Joe
> 
> http://ecomodder.com/forum/showthre...cheap-diy-144v-motor-controller-6404-712.html
> 
> This is a LOOONG thread - the new controller - the "Dirty Diaper Controller" discussion is near the end


Probably not a bad idea to read it anyways


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## joetemus (Jun 29, 2016)

Duncan said:


> Hi Joe
> 
> http://ecomodder.com/forum/showthre...cheap-diy-144v-motor-controller-6404-712.html
> 
> This is a LOOONG thread - the new controller - the "Dirty Diaper Controller" discussion is near the end


Is there actually files for that controller, or are there only a few people who are working on it right now?


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## Zimnismoboy34 (Sep 27, 2016)

have had a interesting read on there about this build .
Regarding the motors one attached to each wheel ? not sure if you know this but you will have equal power to each wheel, turning will be a nightmare as the inner wheel will need to slow down and the outer speed up, this will induce a heavy case of fighting the steering wheel. which is why most drag and track ev high performance cars use a strong diff and prop shaft with out a transmission .
The electronics to drive around corners with hub powered wheels with that much energy would be nothing short of insane, effectively you need steering input sensors, g force sensors and throttle position mapped out so that the hubs can operate as a matched pair, they have to talk to each other .
And know power out put proportionately .


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