i am going to pick up a 200 amp alternator today. when i spoke to the guy i asked him if i needed to up my battery fuse. he told me that if i get the 200 amp alternator i am going to bypass that fuse and run it straight to the battery with 1 or 2 gauge wire. is this correct? don't want my battery to blow up

 

Current is drawn as needed, not forced by the alternator. Your battery is not going to draw any more current than it did with your present alternator. The higher current alternator is going to give you more reserve for those times when you were previously draining your battery.

 

Battery and charging system are not very well understood by most.
1. Battery is there mainly for starting and a supply when the engine is not running.
2. After starting, the difference between the batt voltage and the alternator regulator intenal reference, causes the alternator to raise "voltage" output which forces current into the battery to recover to it's previous state of charge and remain floating until the next time current has to be drawn from the battery.
3. At all other times, the alternator supplies the vehichle's operating loads and not the battery.
4. The fuse and lead size is designed to cover the peak "normal' charge events with safety and reliability.


Upgrading the alternator only provides more reserve running power to the truck.
It won't recharge the battery any faster if at all. Reason is the internal voltage reference still controls the recharge action, same as stated above.
A larger alternator output will provide for more peak current draw before system voltages begin to drop as it's capacity is approched.
An alternator rating is peak for short periods of time without over heating and not a continious output rating.
As for the lead size, if you check the current capacity of any lead size used in a vehichle it is not large enough to carry the full alternator output for very long without beginning to over heat. (look at the starter cable sizes) The smaller size is based on the normal time it should take a good battery to become re-charged 'at a much lower current level' and taper off to a low floating charge level. This time interval with a known good battery is usually less than 15 min running time at raised engine rpm, after a start has occurred.
The fuse is more of a safety and libaility issue in event of accident and blows the fuse or fuse link so shorts does not cause a fire or the fuel pump dosent keep putting gas on a fire and such events as well as the fuel pump crash sensor.
As for battery capacity, the larger the battery the lower it's internal voltage drop (dc impedence) to the starter, the faster the starter will crank the engine up to a limit.
In addition the battery acts as a large storage reserve in those cases with large audio peak draws that are usually after market application driven.

Adding large current draw lighting has many issues to consider.
A. At high enough engine rpm the alternator should supply the demand unless it goes over the alternator capacity then the battery begins to discharge into the load as well. Not a good situation.
B. The alternator begins to heat up at the higher loading.
C. Lead current carrying capacity becomes an issue.

Using a larger 'charge' lead with an upgrade is fine. It offers lower voltage drop to recharge the battery sleightly faster and with less heating.
Many volage regulators in modern vehichles are temperature compensated such that high charge rates are prevented in cold weather to protect the alternator and the battery for over stress since a cold battery does not discharge or take a re-charge as fast as at higher temps. After the battery has been heated by the engine bay, restarts' charging changes as a result.
The whole system is relitivly simple but you must understand the electric theroy behind all parts of the operation.

 

just found a 200 amp alternator, but nor sure if it will fit my truck? anyone know if it will?http://store.summitracing.com/partde...5&autoview=sku

 

not sure if it will fit yours... But like Bluegrass said, the alternator will only put out as much power that is needed. A 200amp alternator is a good thing to have it you have added anything aftermarket that draws current.

 

Yeah I know about the alternator only putting out what is needed, but I'm in the process of upgrading my sound system to ~2750watts and would like a little insurance.

 

Oh yeah, I would too, I wish I could afford a 200amp alternator, at night with the radio up and the lights on, im sure its straining!

 

That's a high price... Look on ebay or call around at local shops that rebuild alternators. You can use the same alternator the crown vic police car used. I was quoted by 2 local shops one gave me a price of $180 w core exchange and the other was $210 and didn't mention anything about the core. The more expensive place of course will warranty the alternator. Like i said if you are going to do it, shop around first.

 

I plan on shopping around, that is just the first one I saw.