Upgrade Alternator or add 2nd battery?

BearClaw · Jul 27, 2015

I seem to be following that old adage that "You never have enough lights", and I am wondering at what point do you need to upgrade your electrical system to handle the additional load on the system?

I have 120 watts (12 pack of M&R fogs) in bumper, 40" light bar (240 watts) behind grill, (2) 4.5" light canons on hood (50 watts), 30" light bar (180 watts) rear facing and (2) 7" LED work lights(72 watts), side facing.

Grand total of 662 watts.

And am considering adding (2) 8.7" HID's , another 100 watts. would bring to 762 watts. Roughly 64 amps of draw.

Thoughts?

The Car Stereo Company · Jul 27, 2015

do you plan on running them all at once? eventually your battery will crap out. i dont think your alternator will have an issue with it. my stereo system has 180 amp draw. and all my lights equals about 90 more) my battery died about 3 months later. i have a yellow top in there now and has been going good ever since. (roughly about a year and 3 months)

the oem alternator is going to be the most reliable. when i did spl competitions, i went through 3 high output alternators in a 4 year period. since aftermarket alternators are wound so tight, they will never have the longevity of an oem. but for a 70amp draw, that is like adding a good amplifier and subwoofer to your system. not enough to warrant a new alternator. once you reach about 125% of an alternators maximum, you will start to damage the coils, which will reduce the life of the alternator.

i still have the oem alternator in mine and with lights (offroad and disco) dual air compressors, and a very large stereo system, it does take a toll on the system, however i dont run everything at once and that is the important part. it can handle each part seperately, just not all together.

BearClaw · Jul 27, 2015

The Car Stereo Company said:
do you plan on running them all at once? eventually your battery will crap out. i dont think your alternator will have an issue with it. my stereo system has 180 amp draw. and all my lights equals about 90 more) my battery died about 3 months later. i have a yellow top in there now and has been going good ever since. (roughly about a year and 3 months)

the oem alternator is going to be the most reliable. when i did spl competitions, i went through 3 high output alternators in a 4 year period. since aftermarket alternators are wound so tight, they will never have the longevity of an oem. but for a 70amp draw, that is like adding a good amplifier and subwoofer to your system. not enough to warrant a new alternator. once you reach about 125% of an alternators maximum, you will start to damage the coils, which will reduce the life of the alternator.

i still have the oem alternator in mine and with lights (offroad and disco) dual air compressors, and a very large stereo system, it does take a toll on the system, however i dont run everything at once and that is the important part. it can handle each part seperately, just not all together.

When we do night runs up in Maine, I would be running most, if not all, at once.

Would adding a second battery to the system help reduce the draw on main battery? And not have it crap out when I am in the middle of nowhere.

Deleted member 12951 · Jul 27, 2015

I only run my lights when the engine is running and never just off the battery when off. I thought that makes a difference?

The Car Stereo Company · Jul 27, 2015

well the way it works is that your alternator is going to power everything. once the load becomes too much, then it will draw off the battery. adding a second battery just means the alternator ha something else to charge on top of what you already have. if the draw beome too much, our oem batteries arent capable of the type of performance, and it will diminish the life. but at a 70 amp current draw on occasion is not going to be a big issue. i would replace the battery with a higher performance one and be done with it.

Deleted member 12951 · Jul 27, 2015

How many amps is the oem alternator rated for?

The Car Stereo Company · Jul 27, 2015

unfortunately my ammeter broke a long time ago. i have no way of measuring actual current. but if someone wants to try, they can measure at idle, and at 2000rpms.

im sure we can dig up specs if someone has that info, or knows where to look. @pirate air @wiz1500 @Hockster

hagak · Jul 27, 2015

Measuring the alternator while unloaded will not give you any idea what it amp rating it can handle. Best to research the specs for it, and if you want a wild as guess check the gauge wire running from it and you know it won't go over that wires rating.

Upgrade Alternator or add 2nd battery?

BearClaw

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The Car Stereo Company

aka grumpy car stereo guy and frf rolodex

BearClaw

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Deleted member 12951

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The Car Stereo Company

aka grumpy car stereo guy and frf rolodex

Deleted member 12951

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The Car Stereo Company

aka grumpy car stereo guy and frf rolodex

hagak

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