Bad Alternator?


#1

I have a 2004 Honda CR-V LX, 2.4l engine, automatic, with 152,000 miles on it. On July 27, my battery went dead. I had it replaced at the local Honda dealer. They tested the charging system and said it was fine. Today after having a faulty compressor replaced at a private shop (I only had them do it because it was under warranty- they replaced it 5 weeks ago), they told me that they tested the charging system because the car was difficult to start and found that it tested at 12.59 volts and that it should be at 13.5 volts; therefore, the alternator was going bad. Do these numbers make sense? Also, could or is it likely that the alternator would start going bad just a couple of weeks after the charging system tested ok?


#2

It could happen, but I suggest you get it checked at a third place. Not all meters are accurate. The correct charging voltage should be between 13.2 and 14.2 volts.


#3

Thanks Keith. The third check showed 13.98 volts. Other than a meter that is not accurate, can the test be done incorrectly somehow and show lower volts?


#4

The voltage could be different at idle and at running speed, about 2,500 rpm. If one shop provided a reading at idle speed and the other rev’d the car up to running speed (2K to 2.5K) to take the reading that could account for the difference.

When your car is idling, with the lights on, the AC blower running, and the radio on the battery isn’t getting much of a charge. This is pretty common with any car. Perhaps your battery could use a good road trip or some time on a charger.


#5

Thanks UncleTurbo. The battery is new (July 27), installed by the local Honda dealer and this previous weekend we had a 5 hour round-trip roadtrip (2.5 hours Friday night and 2.5 hours Sunday back home). The 13.98 V test was at idle with no accessories on.


#6

you’re talking about load testing the battery at start I think. before you start it in the morning, check the voltage at the battery. should be around 12.6-12.8 with everything off. If it’s dying in the night, but the alternators working correctly, i would check to see if there’s a parasitic load (something grounding out or shorting). basically you put an ammeter on the battery and then start pulling fuses and wait to see a drop. also, it should go without saying but make sure that nothing is staying on that shouldn’t (trunk light etc.) you said you’re battery went dead, what happened before? were you driving it recently, or had it been sitting for a day or week? was it Really hot out? the garage said they had trouble starting it, did they say what it was or wasn’t doing? how’s your belt? if it’s slipping, you should be able to hear it but…


#7

Thanks for the input Blaineyb. Check out another thread about the hard starting at http://community.cartalk.com/discussion/2219201/2004-cr-v-with-possible-hot-start-problem#Item_5

That problem started when the shop replaced the fuel pump. In reference to the battery going out, I had just driven 5 minutes, just after noon (temp approximately 102 degrees), had the car off for about 5 minutes, then tried to start. With the start I had nothing but a very weak/sick sounding seatbelt warning beep then with the key turned all the way to start there was nothing but a rapid clicking from under the dash.

So, yes, I am still trying to find out why the hard start happens…


#8

it might still be worth trying a battery test, but probably not a load issue if you were just driving it. sounds to me like it’s more of a fuel issue. probably related to the other post and you just had a couple of bad or incorrect readings on the meter. good luck man