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A couple questions....brakes, a noise and a new 12v

Discussion in 'Gen 2 Prius Main Forum' started by jayhawker88, Mar 20, 2013.

  1. jayhawker88

    jayhawker88 Junior Member

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    Just had a couple questions, if any of you might be able to lend a little advice and/or insight. The first one is in regards to the brakes on my '09. I've read that the brakes themselves don't actually kick in until you are going 7 mph or less. Anyways, when I am coming to a stop it is not necessarily smooth. I try my best to apply even pressure to the brake, but I basically come to a jerky stop. Is this common in a Prius? I bought my car certified pre-owned last month and I know the brakes were one of the checklist items.

    Secondly, I always hear a noise when I am starting up my car. It is coming from the rear, back towards the HV and 12v batteries. It just sounds like a "click, click, click." I never hear anything else from that area....just when it starts.

    My third question is related to my 12v that I just replaced yesterday. I ordered the Optima Yellow Top last week and got it in a matter of days. However, I didn't have a 10mm socket and my 3/8" wouldn't quite fit. So, my plan was to leave work yesterday and head straight to the hardware store. Unfortunately the old one decided to die...yet again. So, after purchasing a speed charger and getting the car up and running again, I headed to the store. When I got home I figured I might as well put the charger on the Yellow Top, just to ensure it was fully charged before I installed it. I set it to charge an AGM battery at 8A and the battery percentage initially showed 70%. It quickly rose from there and right before I took it off the charger, it said 98%. After getting everything installed, I tested the battery via the MDF and it read 12.8V. After putting it under load, it dropped to 12.3v and then to 11.9v with the headlights on. Today I checked again and got 12.3v to start with and then 11.8v under load and 11.1 with the headlights. Is this normal for a new battery? A sticker on the top stated "2/13," so I would assume it was manufactured last month....I purchased it from Advance Auto Parts.

    Thanks in advance for any and all help!
     
    #1 jayhawker88, Mar 20, 2013
  2. nh7o

    nh7o Off grid since 1980

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    1. The Prius brakes need to get cleaned of rust, as they get used so little. The way recommended on PC is to get the car up to speed, shift to N (neutral) and brake to a stop a few times. This forces the car to use friction braking and cleans the discs.

    2. The clicking in the back is the HV battery relays being energized. The battery is disconnected at all other times for safety reasons.

    3. I don't have the Optima, but there are reports of varying quality. However, deep cycle batteries will develop more capacity after some initial discharge/charge cycles. It is probably OK. If you really want to find the true voltage, use a voltmeter at the battery terminals, as that eliminates the uncertainty in the car's measurement.
     
    #2 nh7o, Mar 20, 2013
  3. Britprius

    Britprius Senior Member

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    I would keep a very close check on this battery.

    According to Optima's own specifications for the Yellow top batteries they do not pack (box) batteries with a voltage below 13.2 volts, so I would expect a minimum of 13 volts after a few weeks of standing. Did you check the battery voltage out of the box? Self discharge should be lower than 3% a month.

    With a reading of only 12.8 after being charged and dropping to 11.1 under load is poor performance for a battery only manufactured a few weeks ago.

    To be fair Iwould check the battery with a volt meter at the battery to confirm the MFD is reading correctly "not always the case".

    John (Britprius)
     
    #3 Britprius, Mar 20, 2013
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