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Whizzy Brake Current Draw?


MarkAZ

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The other day while sitting at a stop light at idle I noticed that when I applied the brakes the engine slowed down by about 100 rpm. The bike (04 R1150RT, 26k miles) idles at about 1100 rpm (about a needle's width above 1000), the battery is less than a year old & always on a tender when garaged and AFAIK the charging system works fine. How much power do those whizzy brakes draw, anyway?

 

No big deal, I was just a bit surprised.

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*Lots* of amps -- can't remember the number off the top of my head, but enough that:

 

(i) the system has a voltage sensor and will shut off the ABS (and throw a dash warning) if it doesn't think there's enough juice to operate, and

 

(ii) -- I believe I'm remembering this correctly -- during a BMW press intro in Spain a few years ago, after multiple immediate back-to-back ABS demonstration passes (10? 20?) without enough battery recharge time (in other words, many battery-draining high current-draw braking operations), a press member was killed when the Integral ABS system unexpectedly failed to operate.

 

BTW, the 100 rpm drop at idle is normal -- my 1150 does it at any stop light that I'm holding the brake lever.

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Morning Mark

 

Your ABS servo pumps are powered directly off the back of the alternator (no fuse) as they do draw a sizable amount of current.

 

Under some stopped conditions that will lower the engine RPM enough the be noticeable to the rider.

 

Your 2004 1150 is a late enough build to have the version 9 software in the ABS controller so the rear servo pump should shut down as a power saving measure (only at stand still & at engine idle) & only once a certain rear pressure is reached & the rear brake pedal only is used to hold bike.

 

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BTW, the 100 rpm drop at idle is normal -- my 1150 does it at any stop light that I'm holding the brake lever.

 

+1. Mine too. Maybe not quite a 100rpm.

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