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Discussion Starter #1
Hey all,

Just got home from work and noticed my lights suddenly go dim in the car. Thought it odd so got a multimeter and took readings.

The car drops to 12.6v at idle (battery voltage) and even reving it does not produce 14.x volts. It's only when you drop it back to idle from say 2000 rpm that it charges for a few seconds and then drops off again.

Blipping the throttle produces charge for a few seconds and then again, back to 12.6v

I've taken a video to show the dealers on Tuesday but does anyone have any pointers as to whether its likely to be the alternator?


https://www.dropbox.com/s/frq13xq0lvq4q18/Video 17-01-2014 17 01 53.mov

Thanks :)
 

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Bye bye Honda...
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5,892 Posts
I don't think you can draw conclusions from the battery terminal voltage at idle... you need to get it up to at least 1500 RPM and check you have around 14.4V even with the heated rear window, blower and headlights all turned on. Otherwise it's either the alternator or a duff connection somewhere.
 

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Premium Member
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533 Posts
Discussion Starter #3
You can hold it at 1500 rpm with no load and it still sits at battery voltage. You have to put lights, heated rear window on to get it to go up to 14.4 volts. Failing that, if you drop back to idle it'll charge for a few seconds and then cut out.

My problem is this : I drive to work with just the stereo on, and unless you drop throttle it doesn't seem to charge at all.

Edit : It certainly shouldn't be showing battery voltage at idle... I've restarted it four or five times to check if it behaves the same so the battery certainly wanted charge.
 

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1,212 Posts
sounds like alternator brushes are on their way out i had a very similar problem with an alternator a while back that was behaving similar

it's a 10 quid DIY fix if you can get the alternator off the car i don't know how much a garage would charge they tend to recondition / replace and charge accordingly

the switching lights on etc.. to get the alternator to produce 14.4 volts throws me a bit usually when the brushes are worn switching lights on etc.. tends to make the situation worse but it still might be the culprit
 

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Premium Member
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533 Posts
Discussion Starter #5
Its under warranty thankfully so I'll let Honda sort it out. It needs load to make voltage for some reason! I don't understand it, and I figured it probably wouldn't behave the same at the dealership so I video'd it for them and the knowledgeable forum to see ;)
 

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Premium Member
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533 Posts
Discussion Starter #6
Well they say its a feature of the ECU to tell the alternator to stop charging...... heres hoping that's true as its a pig to start sometimes.

I give up!
 
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