Battery not charging continuously

[jonathansp]

Hi to all,

I'm a new Honda Accord 7th gen owner so please bare with me if I may ask some silly questions.

After a month I got the car, I noticed that it kept blowing the dim bulbs. I even put an HID slim kit on it and seems like it also blew the ballast. So I went to local electrician and diagnosed that there is a charging issue with the alternator. So we pulled out the alternator (having dismantled half of the engine to take out the alternator, is it necessary?) and he found that one of the diodes on the rectifier was blown. So we just changed the rectifier and all seems fine then. It was charging at a voltage of 14.1-14.2V.

Two days after the reinstallment of the alternator, one of the bulbs blew again (becoming blue-purple around the metal), but the filament was still intact. Then I connected a multimeter to the battery and noticed the charging. With the lights on the alternator was charging at 14.2V but everything was off after a while, it seemed like the alternator stopped charging after all, and the battery decreased to a voltage of about 12.3V. When starting the lights again, the alternator started recharging again at 14.2V. Is this normal? Is there some kind of relay or something that stops the charging process when the battery is fully charged maybe?

Thanks
JS

 

[Jon_G]

There's no relay (like there was on older dynamo systems. The alternator should produce a constant voltage (above tick-over, at least) and as the battery charges it's terminal voltage rises... this results in the voltage differential diminishing, resulting in the charge current falling towards the 'float' level (where the battery only has a trickle of current passing through it). If you are noticing this voltage 'stepping' (as described) when not at tickover, then I think it may indicate a problem - try again but holding the revs to at least a constant 1500 RPM and see if the same fault happens.

I'm guessing that your previous alternator problem weakened (or prematurely aged) some/all of your cars lamps, so maybe you'll have a few more failures?

 

[Jon_G]

Welcome to TA, btw.

When you get a few minutes, introduce yourself here... http://typeaccord.co.uk/forum/forum/9-newbies/ and tell us a bit about you and your car!

 

[jonathansp]

Thanks for the reply. Up till now I only had to change the dim lights and no other bulb has blown. The driver's side (right) blew 3 times and the (left) passenger blew once.

So the voltage drop from 14.2 to 12.6 V after a while with no lights and accessories on is normal?