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power draw

Posted: Wed Dec 27, 2006 12:54 am
by KU40
Does anybody have some guesstimates on how much amperage the braking system uses when engaged as well as the power steering system while turning?

Posted: Wed Dec 27, 2006 1:01 am
by Atomic Fusion
KU40 wrote:Does anybody have some guesstimates on how much amperage the braking system uses when engaged as well as the power steering system while turning?


Virtually none from my knowledge of vehicles... Both are hydraulic systems... Steering using mechanical force of the steering wheel assisted by hydraulics, which are driven by the power steering pump.

Some cars do use electric motors to assist steering rather than hydraulics, but they are not very common and are usually only featured on smaller and somewhat more exotic cars, like the Acura NSX. Their current draw is a maximum of about 80 amps.

The brake system is also hydraulic, with the master cylinder at the brake pedal operating the cylinders on all four wheel braking mechanisms.

There may be some incidental/indirect power draw, perhaps from brake lights being turned on... But I wouldn't say this is more than a few amps. There is virtually no electrical load presented by either of these systems from the best of my knowledge.

Adam

Posted: Wed Dec 27, 2006 8:31 am
by KU40
that makes sense, thanks. my car is just being weird and the engine seems to bog down a tad when I do those things and my voltage drops a couple tenths. but I suppose the voltage drop may be a consequence of the former rather than vice versa.

Posted: Wed Dec 27, 2006 2:16 pm
by Big Mack
Keep in mind that many vehicles are now using ABS and the speed sensors and related computers do draw power. In addition, depending on the car, they do have drive by wire, which is another computer. They're getting more complicated, so it is very real that you may draw power when you hit the brakes and turn.

Let's also keep in mind that when you brake, your transmission is electronically controlled and has to interact with the TPS and the rest of the systems in the car, which ABSOLUTELY will draw power. Your engine isn't so much bogging down as it is slowing down. The downside of many of these systems is that they are designed for the "what if" factor, as opposed to trying to be as efficient as possible in all situations. Typically the "what if" factor is "what if the driver is trying to avoid an accident", not "what if the driver is trying to take the corner at speed". That's why the VSC defeats are nice in some cars (vehicle skid/slide control). Turn it off, and you can really get a car with some chutzpah loose around a corner. But I wouldn't know anything about that ;)

Big Mack