# little bit faster



## diamond (Feb 23, 2014)

How can I make my car 10 km or 15 km speed up the drive motor is a Leroy Somer series. 2850 rpm max 4000 85V 150 Amp 11pkw.
Curtis controller 1221C (this is now broken)
If I buy a heavier controller (1231C) runs the car(1200kg) than faster?
or wil it damage the engine?


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## dougingraham (Jul 26, 2011)

The answer depends on what is the limiting factor and you don't have sufficient information in your query to tell this.

When you reach your max speed you are going to be limited by either maximum motor rpm or by motor output power or by battery output power or by motor controller.

At your max speed, knowing your battery voltage and current, your motor voltage and current and rpm will go a long way towards answering this question.

But your motor having a max voltage of 85 and a max current of 150 amps gives us a maximum motor input power of 12750 watts which is equivalent to 17HP. Your wheel horse power might be as low as 12 to 13 HP.


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## diamond (Feb 23, 2014)

Thank you for answer
I only have some inf. from the manual in French

Dc moteur série
Puissance nominale :12,76 kw
Puissance maxi :18,9 kw
Régime nominal :2850 tr/mn
Régime maxi : 5000 tr/mn
Couple maxi : 5,96 mdaN

Connect with Trojan T105 225 Amp C5 185 Amp totaal car 1200kg
transmission 4 gears max speed 73 km (45,4 mph)
I prefer 85 km (52,8 mph)


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## dougingraham (Jul 26, 2011)

My best guess is that you simply don't have enough power to go any faster and it should probably be considered a motor limit. It takes about 18kw to maintain 100kph (depends on the aerodynamics and rolling resistance of the vehicle) in a smallish two place sports car and you have at most about 12kw. A larger controller that can do more amps will probably get you there for a while but it could also damage the motor. You could also be running into a limit on the batteries but I doubt that unless they are old or it is cold.

One thing to remember is that electric motors do not generate energy, they merely convert it from electrical to mechanical. There are no hard limits except for RPM where the armature will fly apart or an absolute current where the copper wire will melt. At some point the motor will not be able to get rid of the waste heat that occurs during the conversion and this will cause an assortment of various failures. In the case of permanent magnet motors excessive heat or power levels can affect the magnets and they can be demagnetized making them useless. Also you can sometimes reach power levels that will deform the output shaft. So what I am saying is that if you increase the voltage the motor sees it will try to turn faster and because of that it will try to draw more current. If your motor controller will provide that it will increase output and you can do this until something bad happens.

Best Wishes!


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## diamond (Feb 23, 2014)

I only now their is a smal fan with a clixon 130 *C linked to the motor
I think a red stop light one the dash for overheating
I did measured once max 53 mph (Tomtom) with good weather 
The batteries are 6 months old.
wil it run faster with a 5 gear? or is the motor to weak


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## dougingraham (Jul 26, 2011)

diamond said:


> wil it run faster with a 5 gear? or is the motor to weak


You might get a little more speed with a slightly different top gear. But it might also make no difference at all or slow you down. We don't have enough information to do more than guess.

Your best shot at going a little faster is going to be increasing the battery voltage. This will increase overall power from the motor. But before you do this I would run it up to top speed and measure the motor voltage and motor current and motor RPM. From this you can tell if a change in gear ratios will help or if you need to do something else.


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