We seem to be having a little trouble with the voltage regulator, which I think has been there along time, as we only race 25 minutes its not been a problem, with the 24hr race adding lights etc etc, don't seem to be getting a good battery reading, even though now I have wired the big terminal of the alternator straight to the battery, I do think its something to do with the wiring of the voltage regulator

Simon,
check the voltage at the battery with the engine running above 2,000 rpm, when you should see 14.4 volts or thereabouts.

Voltage regulators are either electro-mechanical ( big ones) or electronic (smaller box of trickery), with just 3 wires in the connector plug.
Those wires are '12 volts in', then 'earth' and lastly 'regulating voltage out to alternator'...

You can check the function of the alternator by connecting a flying lead to apply 12 volts directly to the spade connector on the alternator.
Be very careful with this, as the voltage will rise towards 18 volts ( or beyond) if the alternator is working correctly, so bring it up off tick over slowly whilst watching the voltmeter.

If that's found to be working OK, the fault will be with the regulator or its connections...

ken

( edit: the battery isn't 'tired', is it?
More than a few 24 hour teams have been caught out by using those small motorcycle batteries, many of which have been left standing idle during the off season. ;o( )

Hi Ken I think that the biggest problem I have is I am not sure when I wired the car up originally I wired it up correctly, the + feed from the voltage regulator - was never sure where it should go or what it should feed

Simon,
the pins/blades on the underside of the regulator look like this...

I _ I

Pin at the right is '12 volts in to the regualator',
pin at the left is the 'regulating feed out to the alternator'
and the one at the bottom is the earth for the regulator.

ken

I take it you've done the maths to make sure your lights etc are not drawing more current than your alternator can provide?

Watts = amps x volts

Therefore if you're using the standard 30 amp alternator which is rated at 30 amps@14 volts you have an absolute maximum of 420 Watts to play with. The alternator won't deliver it's peak output all the time. If for instance the car is crawling along at low revs with all the lights on you'll be consuming more than the alternator is delivering, hence you need a decent battery. Because doing that drains the battery you want some excess capacity in the charging system, otherwise even when at full output the battery won't be getting recharged. The smaller the battery, the less time you'll have to run the car at less than full alternator output. You can't run a battery empty, much below 50% discharge and it's useless.

Now list out what lights you're running.

Standard headlight bulb 55 watts (are you running the dipped and main filaments at the same time?) 110 watt minimum

2 Big spot lights @100 watts each 200 Watts

2 Tail lights @ 5 Watts each 10 Watts

2 Brake lights @ 21 Watts each 42 Watts

Wiper motor 20? Watts

Just that is 380 Watts and I've not included instrument lights, indicators, front side lights ..........

Don't the racers tend to use HID kits? If so, they're usually only 35w each. Some H4s, otoh, are up to 100w each.

There's also the door number illumination, roof id lights etc - however LED bulbs would pull all those tail/brake etc bulbs way down from 5w/21w to virtually nothing.

brake lights x 3 63w

door lights x2 10w

id lights? another 10w

lumi?
fat coil?
head temp sensors?
lambda sensor?
etc

from hour 6 its usual to be bump starting the cars up the pitlane

We used to have a switch to interupt the alternator, there was always way of an excess available to power all, if it's running out after hour 6 then the alternator is simply non functional!