Alternator
Posting Guru
Joined: Nov 2004
Posts: 2,155
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From: sunny fla sometimes windy
You need to figure out your average draw either in amps or watts (figure 75watts=1amp) Then figure out how much your batt is good for(cca) and how long it would take of running to recharge what you took out of the battery(with current batt.
Then basically match the new alt with your current drain or higher. If you don't want to do all the math, Get the biggest you can fit and afford can't go wrong with more
power!!RRRRRRR!!
Then basically match the new alt with your current drain or higher. If you don't want to do all the math, Get the biggest you can fit and afford can't go wrong with more
power!!RRRRRRR!!
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Joined: Jan 2001
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From: Virginia
How are you using this equipment, and what has been happening that leads you to believe you need more power? How you have it wired and the size of the wiring can affect the performance too.
If these lights are 130w each, then that's only a little over 10 amps each. The 200w amp is probably around 20 amps, and that's only during music peaks. The new headlights, even though they are brighter, should stil be around 55 watts each, which is going to possibly be just a little bit more than stock. The stock headlight wiring and switch cannot take much more amperage without getting overloaded.
The smallest alt they put on the older trucks was about 63 amps. Most newer trucks have at least a 75-90 amp alternator stock.
If these lights are 130w each, then that's only a little over 10 amps each. The 200w amp is probably around 20 amps, and that's only during music peaks. The new headlights, even though they are brighter, should stil be around 55 watts each, which is going to possibly be just a little bit more than stock. The stock headlight wiring and switch cannot take much more amperage without getting overloaded.
The smallest alt they put on the older trucks was about 63 amps. Most newer trucks have at least a 75-90 amp alternator stock.
Last edited by Franklin2; Oct 13, 2007 at 08:46 PM.
Posting Guru
Joined: Nov 2004
Posts: 2,155
Likes: 1
From: sunny fla sometimes windy
It might be the problem is not enough drive time to recharge the battery!! Even with a upgraded alt. if the drive is not long enough to recharge the amps drawn during starting,lights, radio, running engine itself. Then it won't come close to topping off the amperage in the battery, It is a gradual thing say it takes 80 amps to start and run everything for your 15 minute drive, Well the alt. puts out 70 amps by the time you shut down. Multiply that by 5 days 2 times a day and you are now short 100 amps!!!
You could fix the problem by spending money on a bigger alt, Driving a bit longer everyday or taking it for a long drive on the weekend, or a small underhood charger that you could plug in overnight and it will keep the battery topped off Just a 1 amp charger on for 10 hours overnight would replace the gap the stock altenator is leaving and might be the cheapest, considering gas prices!!
You could fix the problem by spending money on a bigger alt, Driving a bit longer everyday or taking it for a long drive on the weekend, or a small underhood charger that you could plug in overnight and it will keep the battery topped off Just a 1 amp charger on for 10 hours overnight would replace the gap the stock altenator is leaving and might be the cheapest, considering gas prices!!
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Joined: Jan 2001
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From: Virginia
If you have a meter, put it on the battery with the engine idling. If you are around 14 volts, then your charging system is healthy. If it's around 13 volts, then you might have a blown diode in the alternator that is reducing it's output.
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how are the high beams at idle? I have an 83 F150 4x4 stock alt bearings are getting rough in it still full 60amps output. I had to replace starter and battery cables. The starter was bad and the cables where cracked an loose.
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Fleet Owner
Joined: Mar 2003
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From: Blue Hill Township
Start with the basics. Check all of your connections at the battery, alternator, starter, solenoid, etc. Next, check your grounds. Make sure that they are large enough and that they are not corroded and the connections are clean. If this doesn't work, get the alternator tested at the auto parts store for free. That will tell you if any diodes are bad or what not.