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post #1 of (permalink) Old 10-15-2000, 08:11 PM
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headlite upgrade

I didi the headlite upgrade from JC Whitney and was wondering if I needed to upgrade the alternator or not - seems fine now but with winter coming up I don't know . . . . the high beams are rated at 110 watts I believe. How do you test the draw to find out if you're pulling too much current? JW

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post #2 of (permalink) Old 10-15-2000, 10:33 PM
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Re: headlite upgrade

Yes it would be a good idea to upgrade to at lest a 100amp
to test just trun on the head lights put them on high next turn the heater on high your head lights will dim a bit, there is a froumle to find out how many amps they will draw I can't think of it right now

Bindernut
post #3 of (permalink) Old 10-16-2000, 08:19 AM
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Re: headlite upgrade

What are the benifits of this upgrade? How much, and is JC Witney a company/ catalogue?

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post #4 of (permalink) Old 10-16-2000, 11:31 AM
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Re: headlite upgrade

The formula you're thinking of is Ohm's Law. It allows you to calculate values when as many as 2 variables are present.
The key to the table is as follows:
E = ELECTROMOTIVE FORCE = VOLTS
I = CURRENT = AMPERES
R = RESISTANCE = OHMS
P = POWER = WATTS



So, known values in this case are: 12V, and 110W load (one bulb?) So solve for I.
According to the table, (P/E) = I
If you only calculate (110W/12V), you get just over 9A.
Consider all other loads on the vehicle at once, stereo, heater fan, other lights, etc. You'll come up with more than you think.
Either way, you might as well get the biggest amperage alternator you can stuff in there.
Hope this helps,
Mike

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post #5 of (permalink) Old 10-16-2000, 12:50 PM
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Re: headlite upgrade

I am running Bosh h4 head lights and a 100 amp alnt. out of a chevy one wire hook up I am always putting out 14.5 volts. under a full load it will drop too 14 volts, upgrade.

Bindernut
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post #6 of (permalink) Old 10-16-2000, 04:24 PM
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Re: headlite upgrade

Rcblackdog I have question concerning your answer if you put the biggest alt. in there that you can get what about the rest of the electrical system? will the other components be able to take the extra power? especially considering the age of some of the other parts and the rather old wireing. Is there an upper limit to how big you can go amp wise?

post #7 of (permalink) Old 10-16-2000, 06:22 PM
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Re: headlite upgrade

Steelerfan, an alternator will only produce what is required of it. Amperage is the amount of load an appliance has on a circuit. That appliance is what draws the amperage to it, for it to function.
If you have a cig. lighter plug, for example, it has 12V (voltage, remember) and with nothing plugged into it, there's no load (12V, 0A). If you put your 12V space heater on it, you're going to DRAW amperage through the wires to the heater. The alternator will produce it, but not if there's no reason. Your heater is what will make the wiring fail. It's when you put aftermarket things on the factory wiring (that wasn't designed for it) that draw a lot of current, that you run the risk of damage.
In other words, the stock components won't draw any more amperage than they used to, so that wiring will be fine. If you add on, put in new wiring for that item that has an appropriate rating.
Components don't take power, they use power.
So far, if I need to replace an alternator, I've gone to the parts store, gotten the "biggest" alternator offered for that model to replace my usually puny one, and been on my way. It can't hurt to have the extra potential there. I have a 140A alternator in the truck, and you should see the needle go UP when I use the winch. I'd like to have all the amperage available when it asks for it.
Mike

post #8 of (permalink) Old 10-16-2000, 10:07 PM
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Re: headlite upgrade

jcwhitney.com has the 4h highput headlites for offroad use. I never could see that well with the stock headlites so these help alot but you must also add relays to upgrade the stock wiring. If you go back a few pages on here you'll see my previous post that tells what web page to go to for installation instructions on the relays. JW

post #9 of (permalink) Old 10-17-2000, 01:04 PM
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Re: headlite upgrade

RCblackdog thank you for the reply you cleared up something thatI didn't understand.

post #10 of (permalink) Old 10-17-2000, 02:16 PM
 
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Wiring Upgrade

If you upgrade your alternator - particularly beyond the stock 63amp (and it's questionable then) you really need to change how the wiring system works.

You'll need to buy a Voltmeter and install it under the dash or somewhere. You're going to make your ammeter useless.

The stock setup has all of the alt output going through the "bulkhead" connector and to the ammeter, then back out to the rest of the truck. With stock alternators, I've seen this connector melt/burn!

What you'll need to do is run a heavy gauge wire from the alt output directly to the battery post. This will divert all of the "charging" of the alternator back to the battery, and bypass the weak-link in the firewall.

Of course, your ammeter will show a discharge most of the time with this setup, but that's OK. Just keep an eye on the voltmeter instead.

Ideally, I'd switch to a Ford starter solenoid on the firewall (I had a hot-start problem anyhow). You can then run some battery cables from the alternator output right to the Ford solenoid (which in turn goes back to the battery directly). This is the easiest way.

You can then built an auxiliar fuse panel on the firewall. Maybe even two.

Wire one up directly to the Ford solenoid to get it's juice. On the other, you might hook up a 30amp (or a couple if you really need that much juice) relay between the aux fuse panel and the Ford solenoid/battery terminal. Energize this relay with a "keyed on" lead from the ignition system.

That way you can run "always hot" wires from the "always hot" fuse panel (maybe you want your KCs to be "on" even if the truck isn't running) - bypassing the weak factory wiring harness in the cab.

Use the "keyed on" aux fuse panel to wire up the rest of your stuff that should only be on when the key is ON or ACC - like a stereo amplifier, CB radio perhaps, maybe your foglights or KCs, etc.

-Tom Mandera, Helena MT
http://www.tmcom.com/~tsm1/scout
(I wrote a "wiring FAQ" some time ago that has some useful info for wiring aux stuff)

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