The Prelude charging system and battery questions!

BMCC · Post by **BMCC** » Thu Mar 13, 2014 5:29 pm

wurlycorner wrote: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.

I think this was because the because the battery had just been charged. I'll recheck it in the morning before I head to work and see what it is saying. Could always be the trusty multi-meter that's knackered..................

Post by **RattyMcClelland** » Thu Mar 13, 2014 8:28 pm

How do i test voltage across the alt?

Post by **Merlin** » Thu Mar 13, 2014 8:32 pm

Put the positive of your multimeter on the big nut under the alternators rubber protector.

Post by **RattyMcClelland** » Thu Mar 13, 2014 9:11 pm

Merlin wrote:Put the positive of your multimeter on the big nut under the alternators rubber protector.

Do i put the ground on the left falangee?

Post by **Merlin** » Thu Mar 13, 2014 9:13 pm

Earth it on the battery.

Post by **RattyMcClelland** » Thu Mar 13, 2014 9:22 pm

Merlin wrote:Earth it on the battery.

It will have to be earth on the chassis since the alt in in the front and battery is in the back and the cable isnt long enough.

Post by **cebul** » Fri Mar 14, 2014 11:03 am

Scott, I have 2 altwrnators layed in my garage, if you will have any work to do in my area or you want to travel to my place you can have them for test and you will see is taht alternator playing up or something else

Post by **RattyMcClelland** » Tue Mar 18, 2014 6:17 pm

So i finally got the car running to test the alternator.

On the cold start i tested voltage at the battery.
Its was 13.5v on the fast idle.
I tested at the Alt and its 13.5v on fast idle.

Drove the car. Noticed the fast window wipers are very slow well as slow as the normal speed.

Got back onto the drive and test voltage again.

Lights on and wipers
11.5v at the battery
12ish at the alt.
Revving the car doesnt change much.

The alt was uber hot. My Hytech does touch the alt despite the primary been heat wrapped.

I test voltage on the 4 pin terminals and its 11.5v/11.5v/4.85v and 0.06v on the wires so within tolerence i think.
Any thoughts?

mercutio · Post by **mercutio** » Tue Mar 18, 2014 6:19 pm

should be more voltage than that I think

Post by **indigolemon** » Tue Mar 18, 2014 6:20 pm

I'd expect 14.4ish volts from the alt myself. I don't think it's doing much atm

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The Prelude charging system and battery questions!

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