Keep forgetting to bring this phenom. up....

I noticed when I turn the wheel, the lights dim, both headlights and dash lights. To me this means two things: one, the motor isn't turning the alternator fast enough (noticed it most when standing still); and two, the power requirement involved in actually allowing the lights to dim means something is using lots of power.

My previous wonderings in automotive audio had produced very similar results with high output stereo systems using high wattage amps and speakers. More than once I caught my battery dead after thumping to Kris Kross. I know the fix for this in the audio world is caps (capacitors) linked somewheres inline with the battery, amp, install (not sure where, I never used them.)

As I see more threads exploring hotter ignitions, I begin to wonder where the extra power is being taken from. I know there is much more involved than that, but...

Anyone?

 

goin440--

What kind of lights do you have? I've got the Xenons, and haven't noticed this...

 

If you're talking about low speed or at idle, its not surprising that the lights may dim slightly. Mini's have electric power steering and without rolling the tires or just around the parking lot, the power steering pump gets taxed quite a bit more than if you're up to speed. That's why MINI tells you that a little pump whine at idle is normal. You also have to take into account that the alternator really doesn't pump out a lot of amperage at idle, so it just sounds like the system is taxed to the limits.
I've never noticed the lights dimming, but I don't spend much time in the car at slow speeds either.

 

Regular, with optioned driving lights. I've noticed this in a friends regular-lighted, no DL MCS too.

 

Sounds like the power to the electric power steering is causing this. That's my guess anyway. Of course, it doesn't seem that this should be case. Is your idle speed too slow?


R.E.

 

I apologize in advance for this....

I just drive straight - turning affects my 0-60 times in the turtle like Cooper...

In any case, I notice that depending on the turning direction, I feel a loss of power. I have yet to see the lights dim though.

 

I know the PS is causing a major drain but I'm not asking for a fix. I meant the thread to explore ideas about electrical performance. Our MINIs use lots of power... The steering is electro-assist, the throttle is electro, the computer uses elec, the ignition uses elec.... radio, lights, air/heat, D/C jack... all use elec. Combinations of above all drain the power and load the Alt, requiring the motor to use more force to spin it---wasting force that other words could be used for power.

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-goin440 IB/IB MC

 

The alternator used on the MINI is a Denso 105 amp unit, one of the most efficient units out there in terms of horsepower usage versus electrical output. There is no doubt these cars use a considerable amount of electrical power, but they have been engineered to do so efficiently. For example, the interior accessory and gauge lighting is done with LEDs, drawing a fraction of current that the equivalent conventional bulbs would use.

As for the steering, it's fairly unique as far as it's power usage goes. In low-effort or straight ahead conditions, it's 'throttled down' using a fairly small amount of current, and increases speed when you need a greater assist. You can watch this in action while standing still. First, 'stall' your engine by letting out the clutch with your foot on the brake. The steering will still be running, you'll hear it. Turn on your interior lights or headlights. Now, slowly turn the wheel to one side. You will hear the pump slow a bit at first, then it will 'kick in' and go faster, and it's pitch will increase. You will see the lights dim a bit when it accelerates. release the wheel and it will drop back down.

There isnt much you can do to kill off all the load on the alternator, but being that it pulls probably 2hp at most at maximum output, I wouldnt worry too much. It's not like the old days where racers would underdrive their alternators with a huge pulley on it to pick up a few horsepower. Those old alternators would often pull 5 or more horsepower and put out only half of what the ones in the MINI do.

 

>>There isnt much you can do to kill off all the load on the alternator,

I found it helpful on my ol'd trusty samurai to replace all the battery/alternator/starter cables with high quality oversized replacements made from car audio cabling (welding cables work too). Maybe it made no power difference (who cares it was a samurai) but it sure made a difference in how quickly it started up!

I never understood why the positive lead was bigger than the negative lead... I guess thats why I have a ME degree and not an EE


--
Cheese

 

The negative lead is usually shorter, so it can often be of a smaller gauge wire and not be a problem.

The MCS in particular has a rather cool electrical setup. Not one, but two large positive cables come from the rear mounted battery, a larger one (appears to be 2 gauge, approx) goes directly from the positive terminal to the starter, running under the car. A second one around 4 gauge heads to the front fuse/relay box, this is run inside the car. This powers everything else. This feed is fused near the battery with a 200 amp fuse for safety. This setup keeps the heavy draw of the starter motor from creating a large voltage drop that would affect the accessories and ignition/ECU when starting the car. Very sound automotive electrical design indeed!

Oh, the negative cable is smaller than the rest, but it's only about a foot long.
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"Earl Grey" - '03 MCS, DS over DS, 17" R85s, NAV, DSC (often turned off!), Packs #1 and #3, Rally lights, etc, etc. Perf Mods by the boatload, on the way! Fulton, MD. FRS 7-21
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