Well, first of all, let me tell you watch out on how many of these lights you use, b'coz the extra load is extra work exerted on your engine.
You see, the alternator is nothing but a generator, just like the power generators used to power the house up during cut-outs or to power the electric motors of submersible water drawing pumps. A higher load means the generator has to work harder, and so has the engine. The point is that a higher load on your vehicle means the engine has to work harder, and is lots of lights are put on at the same time while you are travelling, it could also mean that the engines fuel consumption goes up too.
Now, the battery is just a storage device, so if you use a lot of lights (load), without upgrading the alternator, soon enough the battery will drain out of energy, and the sole electricity source left is the alternator.
For Instance:-
You suppose a vehicle having a stock 50Amp alternator(almost the same power as the Gypsy's), and a battery that you have now upgraded to 100 amps/Hour, and the reason for which is the 5 pairs of extra lights,each having a single 100Watts Bulb Filament.
The total load, ignoring the energy consumed by the various normal and necessary components of any vehicles like headlights, brakelights, distributor,etc, is
5 lights in pairs(x2) of 100Watts(x100)=1000watts,
or since Watts/Voltage=Amps, Therefore zero'ed at 83Amps.
Since you only have a 50Amp output alternator, the rest 33Amps load left would be powered by the battery, which in this case is a big 100 Amps/Hour one. The specs of any battery, like 7 Amp/Hour, means that the battery can steadily provide that amount of current for 1 hour, and in this case 7 Amperes for one hour. Therefore a 33Amp load on a battery of 100Amps/Hour means that the battery, if not simultaniously being charged by the alternator (and in case its not being charged since all the current produced by the alternator is going to the extra lights), would exhaust all of its current in 100/33=3 Hours. It means that after 3 hours, you've got a dead battery, and excess load on the alternator that it cannot provide, causeing it to heat up very quickly, toasting it along with the light bulbs and would even take the wiring along with it. Also include the battery in that list since you know that is the current level on a normal Automobile goes below a certain value(which in this will), it would not come back to life no matter how much you try to recharge it. Ofcourse if Deep Cycle Automobile batteries are used, which are the same as those that are mostly used in inverters, although here in India ppl don't use these as widely since they are expensive, you can still manage to charge it and use it normally since this battery, going just by the nature of its design, can be recharged even if the last drop of charge is extracted from it. Batteries like Optima, are deep cycle batteries, but it cost 3-4 times as much for the same value of continuous current output for a normal automobile shallow cycle starting battery(although its advantage is that it can provide a heavy amount of current at short bursts, like when cranking the starter, that the deep cycle battery has difficulty in, but Optima states its battery has the best of both worlds, that is Deep cum Shallow cycle).
Now to upgrade the electric system in your vehicle, you need to concentrate more on using a bigger alternator than a bigger battery, although theres nothing better if both are. If the alternator is more powerful than the sum to all the electrical components of the vehicle, then the only time when you'll ever need a battery is when you'll crank start the vehicle, or when you're using components when the engine is not running. The bigger the battery you can use, and in your case the biggest that can fit inside the battery box (i think a 100amp battery costs around 3.5 Grands), the better, since you still have a better chance of saving your battery(from discharging to a value beyond recovering),if you forget to switch off the lights(i can happen sometimes). Also another advantage, especially when using a winch, of using a bigger battery is that you atleast stand a chance of extracting your vehicle using a winch, powered solely by the battery, like in emergencies where the engine is not running anymore, something that can quite commonly happen when offroading.
There are quite a few vehicles here that use big alternators, although the massive 300Amp/Hour alternators ain't available in India. Mahindra Scorpio and Tata Safari use alternators rated from 90Amps/Hour to 135Amps/Hour (the Safari uses the 135Amps alternator, while the Scorpio uses the smaller one, although i think after the CRDe Scorpio came out with the heavier load of the electronic engine, the company wallas surely might have shoved in a bigger alternator). Moresoever, there are other vehicles like Ford,etc, that too might be having the same alternator sizes.In petrol motor powered cars, the biggest i've seen is the one used in the Opel Astra. It has a Bosch 14.2-14.6volts 130Amp alternator, and second hand versions are easily available foraround 1500 bucks. Don't go for the alternator used in the diesel Astra, as it quickly finishes off the carbon points, and just a pair of those points can cost around 10 Grands.The problem with alternators used in a diesel motor is that they have an extra pump fixed to it that is used as a vacuum pump for the power brake booster. Not that it would render the alternator useless for petrol cars, but infact make the pump more expensive to buy. |