# Lightest 50-55 HP motor?



## somanywelps (Jan 25, 2012)

When you reduce weight, you reduce overload capability.


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## frodus (Apr 12, 2008)

Focus on the batteries first, before you do anything with the motor. Those 40Ah CALB cells you have on your website *will not* put out 37kw (50hp) at 72V.... that's over 500A (12C). You will kiss those batteries goodbye in a matter of races. Seriously. Especially considering the voltage with sag, you're going to put out a lot less than 37kw.

Focus on finding a battery pack that can *OUTPUT* that 50hp. Just because the motor will do it, doesn't mean the batteries will. While 50hp might not be that hard, but finding a small, lightweight pack that can do 50hp with even a little range is going to be hard.

Start considering Lithium Polymer, A123, or increase the size of the pack to 100Ah cells.


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## ruckus (Apr 15, 2009)

somanywelps said:


> When you reduce weight, you reduce overload capability.


For amps, yes. For volts, no.

Increasing volts is the single best way to increase the hp/lb of an electric motor.

Do you want to win? or just build something?

If you want to win, seek out the highest voltage motor. 240v 360v 540v 640v. etc. 640v is exactly 200 lithium cells. A nice round number. Just be aware that you will be charging to 720 or so... 

96v is lame tech. no offense. ( I built a 96v car and was Underwhelmed by the performance).


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## frodus (Apr 12, 2008)

At 10C, you're going to get to ~2.5V per cell VERY quickly and probably lower, which would yeild about ~65V, and ~400A. The manufacturer spec is <10 seconds for that burst, but even then, the power output at that level maybe 26kw, or maybe 35hp. 

Anything over 10C and you're asking for trouble and you may find cells smouldering/melting/etc after a run.


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## ruckus (Apr 15, 2009)

frodus said:


> At 10C, you're going to get to ~2.5V per cell VERY quickly and probably lower, which would yeild about ~65V, and ~400A. The manufacturer spec is <10 seconds for that burst, but even then, the power output at that level maybe 26kw, or maybe 35hp.
> 
> Anything over 10C and you're asking for trouble and you may find cells smouldering/melting/etc after a run.


Yep. I would calculate on 3c. If you get more, consider it a bonus. As Frodus points out, voltage drop is very related to C-rate. So you might get 10C, but at 1/2 the voltage of 5C. So you really gain nothing in terms of watts. 

Unlike Frodus, I would suggest you pick your motor/controller first. The pack can always be scaled to amperage and voltage. It really comes down to motor choice where you are limited. As I said before, go for high voltage as that is key to hp/lb. THEN, spec a battery that can drive the chosen motor.


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## frodus (Apr 12, 2008)

There's different methods, in the end they need to be matched before you buy stuff. What I find myself doing though, is specifying them at about the same time, and going back and forth until I get a good match. 

I personally think those 40Ah batteries at 72V are the weak link, but they will be much better at 144V and 40Ah. But seriously reconsider if you are going to run at 4C continuous... they may not last long (they'll do it though). Even then you're looking at what, 160A (might sag from 153.6V to 2.9-3V a cell or 139.2-144V, and 160A..... which is ~22-23kw or about 30hp.

Winzeracer, Did you already buy stuff? According to your website you already got an Advanced DC A89-4001 motor, Alltrax Axe 7245 and 26 CALB 40Ah batteries.


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## ruckus (Apr 15, 2009)

If he already bought the stuff then why is he asking us?

Hook the crap up and see what it does. 

I completely agree that components must be balanced. but if he decided to go with a 320V motor then 100ah batts would not work. Too much weight. Motor voltage must be picked first. Then a batt to feed the necessary amps.

My opinion is his volts are way too low.


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## somanywelps (Jan 25, 2012)

AC-20 motor(54lbs) with something like a 1238-7601 controller? 

7500rpm lets you gear down harder.


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## winzeracer (Apr 3, 2012)

frodus said:


> Focus on the batteries first, before you do anything with the motor. Those 40Ah CALB cells you have on your website *will not* put out 37kw (50hp) at 72V.... that's over 500A (12C). You will kiss those batteries goodbye in a matter of races. Seriously. Especially considering the voltage with sag, you're going to put out a lot less than 37kw.
> 
> Focus on finding a battery pack that can *OUTPUT* that 50hp. Just because the motor will do it, doesn't mean the batteries will. While 50hp might not be that hard, but finding a small, lightweight pack that can do 50hp with even a little range is going to be hard.
> 
> Start considering Lithium Polymer, A123, or increase the size of the pack to 100Ah cells.


Frodus,

Thank you for your input, I realize that voltage sag will be Very Significant I actually am running 83.2v to make up for some of that but will still be at 12c for hard acceleration. But I get that prismatic will not work for race applications. I think I will end up building this kart with the parts I have [ ADC- A89-4001, Alltrax AXE-7245, and 26 Calb 40 ah] and limit it to 10C max. And on my next kart or car do a lipo pouch or cylindrical, battery setup, for high C rates.

So with the setup I have( ADC, Alltrax and CALB 40ah) 10C draw would be 2.5v*26cells*400 amps= 26kw just like you said. 

Do you think pack will last at least 250 cycles with a max 10C draw and 3C continous? ( with a decent algorithm style charger)

Ruckus,

Voltage is low b/c this is a ~400lb kart with prismatic cells. If I could go HV I would but not an option on such a small platform. When I get to build a full size race car I will definatly shoot for ~500v.

Somany,

I like where your head is at with the AC-20 that is a good idea but cant quite see spending nearly $8k on a shifter kart.

Thank You all for your input I guess I will just have put it together with what I have and see what happens. For my second EV I will be sure to make more considerations before purchasing parts.



Brock
www.winzeracer.com


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## somanywelps (Jan 25, 2012)

winzeracer said:


> Do you think pack will last at least 250 cycles with a max 10C draw and 3C continous? ( with a decent algorithm style charger)


It's the heat that kills the cells, not the draw....


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## frodus (Apr 12, 2008)

Keep that 10C draw less than 10 seconds and keep the continuous as low as possible. Try not to stay in the 3-10C range a lot.

I think you could get 250 cycles out of them, but it sounds like you might be wanting to hammer them hard.

Put it together, try it out, and dial the controller to about 200A to start, then slowly go up. Invest in a clamp on current meter (or a shunt meter) with a PEAK HOLD function so you can see what you hit while riding.

What do you intend to use to charge 26 cells?


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## winzeracer (Apr 3, 2012)

frodus said:


> Keep that 10C draw less than 10 seconds and keep the continuous as low as possible. Try not to stay in the 3-10C range a lot.
> 
> I think you could get 250 cycles out of them, but it sounds like you might be wanting to hammer them hard.
> 
> ...


I would like to find a diy charger kit, or use a elcon pfc-5000 so I could charge quickly( .5-.7C). I know that you are very knowledgeable in this area. Is this ok to do in your opinion?

Thanks,
Brock
Www.winzeracer.com


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## frodus (Apr 12, 2008)

But realize a PFC running full bore on a discharged pack at 5000W is going to be charging those cells at almost 1.5-2C. A bit much for those cells if you want to keep them healthy. Also, 5000W won't work out of a normal 120VAC outlet, it'll blow the fuse. I'd suggest getting a 1500W version.

DIY charger kits could be done (not sure what you're considering), but I think you'd spend more and put more time in assembly than is worth for a smaller project like this.

Consider getting something like an Elcon/TCCharger (from me) or DeltaQ from here: http://www.diyelectriccar.com/forums/showthread.php?t=73247&highlight=deltaq
I can reprogram the DeltaQ for your voltage.


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## winzeracer (Apr 3, 2012)

frodus said:


> But realize a PFC running full bore on a discharged pack at 5000W is going to be charging those cells at almost 1.5-2C. A bit much for those cells if you want to keep them healthy. Also, 5000W won't work out of a normal 120VAC outlet, it'll blow the fuse. I'd suggest getting a 1500W version.
> 
> DIY charger kits could be done (not sure what you're considering), but I think you'd spend more and put more time in assembly than is worth for a smaller project like this.
> 
> ...


I am ok with 220V input, I would like to be able to quick charge at the track in ~2hrs. Any recomendation?

Brock


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## frodus (Apr 12, 2008)

I'd aproach it in reverse. The datasheets for CALB 40Ah cells say 12A recommended charge. I wouldn't charge over that, so do a 0.3C charge. So 12A on a 72V pack is about 7-900W. So just about anything over 800W. 

I wouldn't try to quickly charge these cells, especially without a BMS. One cell can (and will) charge quicker and overvoltage.... if it does that, while the others are slowly charging, the cell WILL go thermal. These cells are meant for low current charge and a 3-4C discharge continuous. Don't go outside of those specs or you'll really risk losing cells, either all at once, or one at a time. Keep it at 0.3C or close to it. No need to go 220V input, just get a 120V 1000-1500W charger and call it good. I've got several models available if you want, both 120/240V (they autoswitch) programmed for your pack.


If you go the other way around, and want a full charge in 2 hours, you need to put about 3328Watts (approx size of your 26s1p 40Ah pack) into the pack if you discharge to 100%, which you shouldn't. At that much energy, you'd want to do about 1600W per hour. But the first hour needs to be more because as the voltage increases, the current decreases once you hit CV. So I'd size to something like a 2000W charger. Now, 2000W at ~72V lets say, is going to be about 28A, or about 0.7C, over twice the recommended charge current. 

Risky, but it's all your decision. I'd keep it under 1000W. You underdesigned your system, I wouldn't push it!


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## winzeracer (Apr 3, 2012)

frodus said:


> I'd aproach it in reverse. The datasheets for CALB 40Ah cells say 12A recommended charge. I wouldn't charge over that, so do a 0.3C charge. So 12A on a 72V pack is about 7-900W. So just about anything over 800W.
> 
> I wouldn't try to quickly charge these cells, especially without a BMS. One cell can (and will) charge quicker and overvoltage.... if it does that, while the others are slowly charging, the cell WILL go thermal. These cells are meant for low current charge and a 3-4C discharge continuous. Don't go outside of those specs or you'll really risk losing cells, either all at once, or one at a time. Keep it at 0.3C or close to it. No need to go 220V input, just get a 120V 1000-1500W charger and call it good. I've got several models available if you want, both 120/240V (they autoswitch) programmed for your pack.
> 
> ...


Frodus,

I realize now that I totally under designed this. I work with people in my line of work that want to push the specs too. It is a pain so I appolgize for all the hypothetical questions. And realize that this is not a great way to design a system. But now that I am locked into what I already bought I kinda need to reach a bit. So I will heed all warnings and not go too extreme.

Can you get me a price on a 1500 watt Elcon or Delta-Q, programed for 26 cells to charge at 16 amps? In compromise for the .4C charge I will run a Mini-BMS, unless you have another option I should look into?

Again, thanks for all you help,

Brock
www.winzeracer.com


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## frodus (Apr 12, 2008)

I'm not saying you can't get it working, sorry if I came off abrasive. Just wanted to make sure you had all the data first so you can decide if you want a pack to last 1500 cycles, or if 10 was ok 

I'll PM you


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## winzeracer (Apr 3, 2012)

Hey all please see new post here 
http://www.diyelectriccar.com/forums/showthread.php/d-d-es-31b-and-solution-74588.html 

Thanks,
Brock


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## winzeracer (Apr 3, 2012)

Yabert found this motor only 26lbs and 50kw Agni 111rdr
http://endless-sphere.com/forums/viewtopic.php?f=30&t=33440&hilit=agnI

Brock
Www.winzeracer.com


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