How Much of an motor and Battery would this require?

Master of Cards · Post by **Master of Cards** » 2006-05-31 10:31am

An Cart that weighs in the range of 150 kilos getting up to 40 kmph in 7 seconds with 2 motors? and how big of a battery is needed for it to go for a hour

Master of Cards · Post by **Master of Cards** » 2006-05-31 10:33am

227 kilos not 150

Post by **Sea Skimmer** » 2006-05-31 06:03pm

How about you do your own math to figure out how much energy that requires, thus making it much less of a burden for peopel to help you figure out the required motor wattage and battery capacity.

aerius · Post by **aerius** » 2006-05-31 06:20pm

Impossible to calculate with given info. Go find some specs for motor & drivetrain efficiency, drag coefficient and frontal area, then go work it out yourself.

LaCroix · Post by **LaCroix** » 2006-06-01 04:05am

Also wheel size is crucial for calculating the gearbox needed. Which is crucial for getting the right motor and is the most important factor for getting lower wattage. The more the gear amplifies your torque, the less power your moters will need, thus saving battery weight, and therefore increase your wattage/pound even more.

In modelling, when we like too have scale speeds, we calculate the neded wheel rpm, and then find a motor/gear combo to get it with enough torque according to planned weight to still move it. Then add some 20% more torque to be able to go up hills without loosing too much top speed.

Datasheets (or tests) will then tell you the wattage of your motor at that given situation, so you can calculate the needed amp-hours.

Don't forget, you can't make an electromotor draw more energy. It will suck as much energy as it can get&handle, you can only make it suck less of it. Always remember the max voltage of the motors.

Master of Cards · Post by **Master of Cards** » 2006-06-01 09:42am

90,000 J I got for going 25

sketerpot · Post by **sketerpot** » 2006-06-01 06:21pm

Master of Cards wrote:90,000 J I got for going 25

Is that experimental or calculated?

Master of Cards · Post by **Master of Cards** » 2006-06-02 09:34am

sketerpot wrote:
Master of Cards wrote:90,000 J I got for going 25
Is that experimental or calculated?

25 mph with 227 kg

sketerpot · Post by **sketerpot** » 2006-06-02 02:27pm

Master of Cards wrote:
sketerpot wrote:
Master of Cards wrote:90,000 J I got for going 25
Is that experimental or calculated?
25 mph with 227 kg

WTF?

Sea Skimmer, aerius, and LaCroix were very helpful, but I think someone needs to shout at you:

If you want help, read what people wrote and show your figures and some attempted calculations. We can't read your mind.

Unless you communicate clearly, you're just wasting your time.