GroupN

One for the more informed members I feel

Running 8 x PIAA Super White bulbs (55w input - 110w effective output each)
2 x headlights + 6 x spotlights)
normal side lights, rear lights, engine management etc

What capacity battery and alternator is required to support this amount of power requirement or is there a calculation to achieve the desired figures?

Present set up = Battery 62Ah, Alternator 70amp

All the headlight / spotlights lights work but go dull after about 3 minutes of operation....

Its all wired in correctly via relays fusebox etc so any solutions or suggestions would be appreciated

Cheers

alcazar

iTrader: (2)

They go DULL?

You AREN'T running them without having the engine on, are you?

AFAICS: you have 8 PIAA bulbs at 55W (probably two of which are 60w anyway), so if we take:

6 x 55 = 330w, and
2 x 60 = 120w, and add them together, we get
450w.

Now your alternator is rated at 70 A, and since Amps x Volts will give Watts,

12 x 70 =840w.

Even allowing for HRW, engine, fuel pump sidelights etc etc, you have 39w to play with before you start discharging your battery, so you ought to be OK.

BTW: when you switch them ALL on, does your car "recoil" backwards from all the light going out the front?

Alcazar

DubaiNeil

Does the alternator not only provide 70A at a set (or higher) revs though? IIRC this is about 3000rpm (i.e. driving!) rather than at tick-over where there may be a trickle of charge from the alternator, but not sufficient to support a supernova lighting system!

alcazar

iTrader: (2)

Nope: that was the problem with the older "Dynamos", which alternetors replaced.

A modern alternator will produce 90% of it's output at 1000rpm.

Alcazar