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12 volt Battery signal check

Discussion in 'Gen 2 Prius Technical Discussion' started by e*l*o, Jan 28, 2009.

  1. e*l*o

    e*l*o New Member

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    I have looked at several post but can't find what I am looking for. I read in a previous post last year that mentioned something about checking the voltage of the 12 volt battery using the screens signal check (not started but in accessory mode). I have a 2002 and I'm pretty sure its the original battery. It is measuring 11.9V and 11.0 with the lights on. Is this enough?
     
    #1 e*l*o, Jan 28, 2009
  2. e*l*o

    e*l*o New Member

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    [FONT=arial, helvetica]Well, no reply from anyone so went to another site and finally found this. Just posting it for someone who might also want this information.


    With no electrical accessories on including lights the voltage should be fluctuate between 12.2 and 11.9. The lower the voltage, the less of a charge your battery currently has. If the voltage is low do not proceed as the load test might totally discharge your battery. (If you see a voltage around 13.5-13.8 you are seeing voltage from the high voltage battery being converted to around 13.5-13.8 in an attempt to recharge your battery. This normally does not occur till after you start the engine but might occur earlier if the battery is very drained.)
    You can also test the battery by turning on the headlights, rear window heater and the heater fan. For a new battery the voltage would be around 11.3. If the voltage drops below 10.2 it should definitely be replaced. For voltages in between the lower the voltage, the lower current charge of your battery.
    Note: If in doubt disconnect the 12 volt battery completely (start with the negative post to avoid shorting the battery) and hook it up to a battery tester.
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    #2 e*l*o, Jan 28, 2009
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Yes, it sounds like your current battery is OK. It is not in as-new condition, but is good enough for another year or two of service, if you drive your car frequently so the battery can remain charged-up, and don't leave a door or the trunk open inadvertently.
     
    #3 Patrick Wong, Jan 29, 2009
  4. KD6HDX

    KD6HDX New Member

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    If I was you, I would just replace the battery now. Why wait until you actually NEED to? Assuming the battery is from 2002, you are running on luck. I replaced mine at the 2 year mark just because. I still have the original 12 volt aux battery on a float charger in the garage. It has remained in good shape, and I use it here and there for all kinds of little jobs from ham radio to powering my tank-less water heater hooked up to a 300 watt radio shack DC/AC inverter.

    Just do it! :mod:
     
    #4 KD6HDX, Jan 29, 2009
  5. richard schumacher

    richard schumacher shortbus driver

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    Seven years is awfully old for a small lead-acid car battery. What is the voltage with all accessories and lights off? If it's less than 12.0V the end is near.
     
    #5 richard schumacher, Jan 29, 2009
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