How to get more juice out of my alternator

[SKID]

How to get more juice out of my alternator.
My problem is if I let my truck sit for a week or two, the battery drains. I have a lot of gadgets and accessories and an alarm running, I charged the batter to full about a week ago and took it for a night run with some mates, and after about 5 hours driving with the spotties etc on, my volt meter was running at about 8V, I could tell during the night that the battery was slowly discharging and that the alternator was'nt keeping up, By the end of the night unless my revs were right up, my HID's wold flicker and go out. Would putting a dual battery system in help? or what can I do to get the alternator to keep up. I don't want to have to take the alarm and accessories out of my truck if I can get away with it.

Any Advice or suggestions appreicated

[threedogs]

how many watts are all your lights and what size alternator are you running ATM

[Winnie]

Dual battery won't really help.... you need a bigger alternator. Cheaper than fitting a second battery too!

[SKID]

How do I calculate the amount of watts? its a standard 50 amp alternator.

[Winnie]

For example you said you had HIDs. Are they 55W? Higher? Lower? Just add them all together.

[BigRAWesty]

For example you said you had HIDs. Are they 55W? Higher? Lower? Just add them all together.

Then once all added together, divide by 12 (12v system) = Amps.

I'm gunna take a stab and say your alternator is shot..
You can have them re kitted fir a little over $100

Or you can fit a bigger alternator

[SKID]

I've just called a local parts wholsaler, I can get a 70Amp alternater which replaces my current 50 amp exactly via the part number, or I've seen some advertised on ebay for around the 200 dollar mark rated at 100AMPs. I know a new 50amp would mae a difference as this one is probably as old as my car "89 model" and a 70 amp wpould obviously make a difference as its pushing out an extra 20 Amps. Does anyone advise going to the 90-100amp models?

I've added up my lights and with out knowing what my alarm is pulling the lights alone add up to 30, not including my radio, my uhf and what the engine draws to run using the formular given above all added together, divide by 12 (12v system) = Amps.

[BigRAWesty]

What motor and age of the car do you drive?

[SKID]

What motor and age of the car do you drive?

Its an 89 GQ TB42S Carbie model

[threedogs]

if you intend doing a lot of night driving I would fit a 100 amp alternator.
not fun stuck in the bush at night with a flat battery, the noises oh the noises lol.
As Winnie points out an AUX battery wont help your cause,
but if camping is part of your weekend then a second battery is great for running a fridge and camp lights

headlights are say 50/90 watt x 2 =100/180 watts
2 x say 55 watt HID driving lights = 110 watts
So we are nearly 300 watts divided by 12 = 25 amps
One of two things could be wrong either the battery cant hold its charge
or the Alternator is on the way out,
check the back of the alternator with a multi meter see what it reads at 1200 revs