newby motor question

cooney? said:

i have an boat engine with a dyno start which mean it starts the engine, then when it it running it becomes the charger is there any motor out there which could do the same in regards to regen breaking ????
i'm just wondering if this is possible

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Hi coone,

Welcome.

All motors can generate and all generators can motor, if properly excited. Here, "excited" means the type of field winding in the dynamo (which is an electric machine (motor or generator)) and the controller between the dynamo and load and/or source. So, one dynamo can function both as a starter motor and generator for battery charging and auxiliary system power.

But in the real world, a starter motor needs high current for high torque to crank the engine and a generator runs at relatively low current for battery charging and headlamps and stuff. So using a single machine (dynamo) for both functions is a compromise. It can be done, obviously. But such are usually only used on smaller engines not requiring large cranking torque. And then the generator efficiency suffers. But the good news is that it cost less to attach a single dynamo to your engine than both a cranking motor and an alternator.

And yes, this "dynamo" can be made larger and designed differently so it starts the engine, can actually propel the vehicle to some degree and charge the battery, either from the engine power or from regeneration. See the Honda hybrid system for an example.

2nd question
whats a gd voltage and ampage to start at for a 100mile range car with a warp9 engine on a light weight sports car

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Pick one 144V A lot depends on the particulars. Hang around and read a lot and then ask some reasonable questions and you can figure it out. No one answer fits all.

Regards,

major

ps...please call it a motor (or dynamo ), not an engine.

warp9 engine

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Your current and voltage values will depend on your power output requirements. Neglecting drivetrain losses and mechanical/electrical loss, power(watts) = volts x amps, and one horsepower is 746 electrical watts. As a very rough approximation that covers some of the losses, you could say 1 kilowatt gives you one horsepower. Therefore, a car that requires (let's say) 15 horsepower to maintain some given speed will require about 15 kilowatts of electrical power. At 100V system voltage, that would be 150 amps.

Another aspect that helps to determine system voltage is power loss in wiring. Power loss (watts) = Resistance (ohms) x (current (amps) squared). So, because increasing the system voltage reduces the current requirement, you will lose less power. However, higher system voltage typically means you need more batteries in series and it therefore has a higher cost to get going at first, although in the long run it will be more efficient.

Best system design matches the battery, controller, and motor so that none are substantially more capable than the other (unless you want to leave room for upgrades without replacing all three), but usually it comes down to budget.