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The Prelude charging system and battery questions!

Posted: Wed Mar 12, 2014 6:23 pm
by RattyMcClelland
I need someone to do a test please.

Im not sure how my charging system is coping.

Battery voltage is around 12-12.4 with engine off.

When i start the car battery voltage is around 12.4-12.5.

When i rev the car to around 3k and hold it a little it goes to around 13.8v.

This is all on a stone cold start.
Trid with the lights on and seems about the same.


Whats the verdict? Battery is relocated to the boot and everything seems wired up correctly.

How long will a lude with on battery power alone?

Posted: Wed Mar 12, 2014 6:39 pm
by batkosio
Approximately 50 km. The problem is in the diode rectifier block, replace it.
Image

Posted: Wed Mar 12, 2014 6:55 pm
by jjmartin349571
I'm just charging my 4g now to have a check of the voltage at idle. Coincidentally I measured my Accord and Golf's battery voltages at the weekend - both roughly 12v when turned off and just over 14v at idle.

Posted: Wed Mar 12, 2014 7:07 pm
by batkosio
jjmartin349571 wrote:just over 14v at idle
That means you`re fine :)

Posted: Wed Mar 12, 2014 7:13 pm
by RattyMcClelland
Need to check my alt ground 1st actually.

Posted: Thu Mar 13, 2014 8:26 am
by BMCC
I had a flat battery as the lude was sitting for a few weeks whikle I sorted the fuel line and power steering line. I left the boot open all night when fitting the coilovers a few yrs ago and it ain't been the same battery since. It was charged up over night.

Now when it was fully charged the volts were showing up as 15.2V with the battery out the car. In the car and charging at fast idle it was nearer 17V. At normal idle I would have thought closer to 14-15V. I was suprised to see 17V on fast idle though! I'll need to check that again :think:

Posted: Thu Mar 13, 2014 9:19 am
by RattyMcClelland
I need to try a new battery. But mine is a stinger spv44 deep cycle agm battery. Charging it on the wall is around 13.8 to 14. Charges fine off the wall.

Posted: Thu Mar 13, 2014 9:23 am
by Merlin
What does your alternator output?

Posted: Thu Mar 13, 2014 10:07 am
by wurlycorner
BMCC wrote: Now when it was fully charged the volts were showing up as 15.2V with the battery out the car. In the car and charging at fast idle it was nearer 17V. At normal idle I would have thought closer to 14-15V. I was suprised to see 17V on fast idle though!
Something not right there. You'll start burning things out at that voltage. 5v above nominal might not sound much, but it's actually nearly 50% increase! Cars should be around 12v on battery only and around 14v with engine running/charging and that should be stable throughout the rev range - increasing engine speed should make no difference.

Posted: Thu Mar 13, 2014 3:30 pm
by nucleustylzlude
That all sounds fine Scott. My battery (a little Odyssey PC680) holds 12.7V engine off and usual charging volts are usually 13-14V.