Sunday, Oct 26, 2014 at 01:08
I trust you mean, "my battery isn't being charged"?
Have you run a multimeter over your alternator and battery to see what the voltages are?
The alternator should be putting out around 13.8V at a little over an idle, if it's working properly.
Your battery should be holding around 12.2V to 12.8V if it's in satisfactory condition, and being charged properly.
I worked on a Camry the other day where the engine was refusing to start.
I was suspicious that it could have been a dud battery - although the battery was near new, and a top quality Exide.
I ran the multimeter over the battery, and it read 10.8V - way too low, and indicative of a flat battery or an internally shorted battery.
I jump started the car and checked the alternator output and it was 11.1V, when it should have been 13.8V at least.
So, the problem was a faulty alternator that wasn't charging the battery properly.
However, even with the battery getting down to around 10.8V, the Camry had been running just fine, until it refused to start because of inadequate battery charging.
I replaced the alternator, charged the battery, started the car, and the alternator was putting out 13.8V, and the battery was then holding 12.8V.
The engine computer isn't reliant on the alternator charging to perform satisfactorily - but it is dependent on a supply of electrical current, of a voltage range that is set at the factory. I can't tell you what those voltage parameters are, but usually they are reasonably wide - generally in the range of 10V to near 15V.
If the battery was failing to supply enough current to meet the computers lower voltage parameter, then you wouldn't be able to start the engine, because of that excessively low voltage and lack of current-producing ability.
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