Brakes Pulsating / Shuddering When SOC ~ 100%, '09 FEH
 

I noticed for the 2nd time now when coming down out of the mountains the brakes were pulsating / shuddering when the charge of the battery was at 100%. The car was stopping but the feeling on the brake pedal was not normal. As soon as the charge meter was off of 100% the brakes felt normal. I don't typically drive in the mountains so I have not noticed this except for one other time a couple of weeks ago, also in the mountains.

Does this sound like normal brake wear, I am at 26K miles?

Re: Brakes Pulsating / Shuddering When SOC ~ 100%, '09 FEH
 

This is not normal. First, regen will stop at 60% and your brake pads should take 100% of braking. In other words, unless you're having a HV battery recalibration that will allow a charge above 60%, something is wrong. I've heard people post about a regen battery charge above 60% while going down hill but the system is not designed to do that.

This sounds like a bad rotor and/or rear drum and pad defect or even ABS fault. The '09 FEH also was the first FEH to get RSC (roll stability control) and that may be involved. At any rate, how did you determine your HV battery was at 100% SoC? More than likely you were reading 60% Max on the Nav Sys.

If you had no warning lights of the ABS or RSC, you must have a defective brake part or bad rust on them.

GaryG

Re: Brakes Pulsating / Shuddering When SOC ~ 100%, '09 FEH
 

Gary,
Thanks for your reply.
I did not have any warning lights and yes I was looking at the NAV system. The charge / assist needle on the dash was not moving any more so I assumed it was 100% charged.

I will be inspecting the brakes tonight and most likely contacting the dealer first thing tomorrow.

Dale

Re: Brakes Pulsating / Shuddering When SOC ~ 100%, '09 FEH
 

Probably NOT a major problem, but good to get it checked out.
My #1 bet is just warped rotors.

Usually, most of your braking, most of the time comes from your electric motor.... aka "regen" brake. You don't feel the "wobble" since your pads are not being used most of the time. ( I went in for a check up at 120,000 miles and mechanic says my brake pads look like new. )

Above 60% charge regen is not disabled or anything, but it turns off for about 15 seconds to give the battery a "rest" and measure resting voltage, then comes back on at a reduced rate ( about 25% of full regen ) for another 15 seconds, and cycles like that. ( In Colorado I have some very long hills to test and record this stuff... :angel: )

If you were feeling pulses every 15 seconds, that could be it.
If you were feeling pulses many times per second, probably warped rotors.
If the warp is slight, you don't need to replace anything... you can live with it. :shade: John

Re: Brakes Pulsating / Shuddering When SOC ~ 100%, '09 FEH
 

Might be normal, either EBD, or maybe even ABS activation. EBD on my '01 F/awd RX300 often feels like you describe going downhill with light (frictional) braking.