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Old 02-09-2014, 10:16 PM   #1
2lbox
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Power source

I want to grab power for my new accessories, fans headlight upgrade and a few others upgrades I have in mind. My question to You guys is Where is the best place to tap into to grab power for a junction box. My car is a 79 so the Horn relay is not and option. I am upgrading to a cs144 and going with a thicker wire to the starter 8 gauge with 12 gauge fusible link. Is there a better method to do this. My main concern is where to get the power for a junction box though. Thanks for any help....
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Old 02-09-2014, 11:11 PM   #2
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2 options-
1. Get power right from the alternator output stud. Run an 8 or 10 gauge wire to a HD circuit breaker, then to an insulated post. Use the post for whatever you want. The circuit breaker can be whatever you want it to be- figure the load and get one that will carry the load.
2. Run right to the starter. Be aware- '79 uses a starter extension harness. The connector is just to the right side of the distributor and comes out of the harness on the firewall. Check that for signs of overheating. The terminals in that 6 way connector have been known to corrode and get hot.

#2 is probably a better option since it bypasses that 6 way connector in the extension harness. Either way- a circuit breaker close to the source is a good idea.
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Old 02-10-2014, 11:10 AM   #3
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I pulled a distribution block from like a 90 caprice and ran a cable from the batt to the block and then to the starter, I get all my power from there.
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Old 02-10-2014, 05:18 PM   #4
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My thoughts...

This topic has been brought up sooooo many times. And the conclusion has always been- "it worked for me"...but is it the best way?

I was actually in the 12volt industry for a number of years- started out installing stereos to put myself through college...and ended up working for a couple of the bigger Car Audio manufacturers. So I do have some thoughts on what I was taught by the industry.

The engineers of this car- my example pics- weren't influenced by the been counters as some of less expensive cars. So- I'm thinking this was done right. Please let me know if you disagree...and why.

Here's how they - or rather a team of engineers from Germany- wired this car w/ not only powered and heated front seats - but the rear seats as well.

Three large gauge wires can be found running down the side of the car- the battery is in the trunk. The largest gauge wire from the battery to the starter- the next smaller - runs to the alternator 140amp. (Sidenote-The Japaneses version has TWIN alternators- since it sits in traffic a lot- the second smaller alternator -is driven via a separate pulley /belt so it turns full speed at idle when the AC is turned on-sorta confirmation they -engineers- thought of everything) The smallest wire runs to the fusebox under the hood.

Another interesting electrical feature is the positive junction under the hood- where as the owners manual states to ONLY jump the car from that point- not at the battery were it may damage the electronics.

Here's some pics- this is a BMW 750 IL V12- new (1997) MSRP was $98K.











Twin alternators-


So...where am I going?

I do NOT recommend using the lug on the alternator as anywhere near the best source to pull power. Remember these cars were built way before 500watt car stereo amps. electric cooling fans and heated seats were even thought about. It is not good for the alternator to deal w/ surges-such as caused by electric fans turning on. Headlight filaments don't last as long. And electronics hate surges.

Notice the large junction block (White plastic) next to the battery-that's what I recommend-get your power right off the battery.

The battery does more than just start your car. I helps w/ surges-stabilizes the voltage in the electrical system and filters the AC ripple not cleaned up by the alternator. Electronics like clean power- ever heard of "alternator whine?"

Here's some of the junction blocks I like-

This came off a BMW 7 series-twin relays-5 fuse- can use the relay to power the junction block only when the ignition is on. Less than $10 at you local junkyard




This is my favorite- stackable- can custom wire the relay- and set up w/ 3 fuses- which you can also custom fuse- relay output or the source power.

And I found a nice sealed plastic box- out of a 7 series BMW that will work great for relaying the cooling fans/electric headlight motors and headlights.

And if looking at headlight upgrades- get some good connectors-these are ceramic and supposedly won't melt.


Richard




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Old 02-10-2014, 07:18 PM   #5
2lbox
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Quote:
Originally Posted by Richard454 View Post
This topic has been brought up sooooo many times. And the conclusion has always been- "it worked for me"...but is it the best way?

I was actually in the 12volt industry for a number of years- started out installing stereos to put myself through college...and ended up working for a couple of the bigger Car Audio manufacturers. So I do have some thoughts on what I was taught by the industry.

The engineers of this car- my example pics- weren't influenced by the been counters as some of less expensive cars. So- I'm thinking this was done right. Please let me know if you disagree...and why.

Here's how they - or rather a team of engineers from Germany- wired this car w/ not only powered and heated front seats - but the rear seats as well.

Three large gauge wires can be found running down the side of the car- the battery is in the trunk. The largest gauge wire from the battery to the starter- the next smaller - runs to the alternator 140amp. (Sidenote-The Japaneses version has TWIN alternators- since it sits in traffic a lot- the second smaller alternator -is driven via a separate pulley /belt so it turns full speed at idle when the AC is turned on-sorta confirmation they -engineers- thought of everything) The smallest wire runs to the fusebox under the hood.

Another interesting electrical feature is the positive junction under the hood- where as the owners manual states to ONLY jump the car from that point- not at the battery were it may damage the electronics.

Here's some pics- this is a BMW 750 IL V12- new (1997) MSRP was $98K.











Twin alternators-


So...where am I going?

I do NOT recommend using the lug on the alternator as anywhere near the best source to pull power. Remember these cars were built way before 500watt car stereo amps. electric cooling fans and heated seats were even thought about. It is not good for the alternator to deal w/ surges-such as caused by electric fans turning on. Headlight filaments don't last as long. And electronics hate surges.

Notice the large junction block (White plastic) next to the battery-that's what I recommend-get your power right off the battery.

The battery does more than just start your car. I helps w/ surges-stabilizes the voltage in the electrical system and filters the AC ripple not cleaned up by the alternator. Electronics like clean power- ever heard of "alternator whine?"

Here's some of the junction blocks I like-

This came off a BMW 7 series-twin relays-5 fuse- can use the relay to power the junction block only when the ignition is on. Less than $10 at you local junkyard




This is my favorite- stackable- can custom wire the relay- and set up w/ 3 fuses- which you can also custom fuse- relay output or the source power.

And I found a nice sealed plastic box- out of a 7 series BMW that will work great for relaying the cooling fans/electric headlight motors and headlights.

And if looking at headlight upgrades- get some good connectors-these are ceramic and supposedly won't melt.


Richard




Thanks for the response. Since You recommend the battery as the power source for my accessories, Do You think since the battery has that heavy gauge wire going to the starter anyway, this would be a good point to run power to a junction box from. That way I would not have to go all the way to the battery.....
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Old 02-10-2014, 07:23 PM   #6
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Quote:
Originally Posted by TimAT View Post
2 options-
1. Get power right from the alternator output stud. Run an 8 or 10 gauge wire to a HD circuit breaker, then to an insulated post. Use the post for whatever you want. The circuit breaker can be whatever you want it to be- figure the load and get one that will carry the load.
2. Run right to the starter. Be aware- '79 uses a starter extension harness. The connector is just to the right side of the distributor and comes out of the harness on the firewall. Check that for signs of overheating. The terminals in that 6 way connector have been known to corrode and get hot.

#2 is probably a better option since it bypasses that 6 way connector in the extension harness. Either way- a circuit breaker close to the source is a good idea.
Tim. thanks for the response, Do you happen to know if that point in the harness is where the load sensing happens. I am liking that starter to power my junction block but I want to make sure that I am not bypassing the point where the alternator senses how much power to put out. Thanks
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Old 02-11-2014, 08:13 PM   #7
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Quote:
Originally Posted by 2lbox View Post
Thanks for the response. Since You recommend the battery as the power source for my accessories, Do You think since the battery has that heavy gauge wire going to the starter anyway, this would be a good point to run power to a junction box from. That way I would not have to go all the way to the battery.....

I personally think going to the battery is the best- a little more effort- not that much more in materials.

Next best location-would be the starter lug. Running from the starter you also have to contend with routing wires around the hot exhaust...AND at each junction point you do have a chance of some voltage loss. Less junctions/ connections are best.

When adding the larger gauge wire from the alt to starter- there's no need to remove the factory wires.

Contrary to popular belief saying- "electricity follows the path of least resistance"- it follows ALL paths. And running the stock wire AND the larger gauge - effective adds to the ability of more current flow.
Think of draining a pool- a large hose AND a small hose will drain more than just the larger one...

HOWEVER don't add anything (high current devices-fans-amps) of to the stock side of the wires.

Richard
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Old 02-12-2014, 07:14 AM   #8
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Quote:
Originally Posted by 2lbox View Post
Do You think since the battery has that heavy gauge wire going to the starter anyway, this would be a good point to run power to a junction box from. ....
This is what I did for my car. I have a nice fused distribution block for aftermarket accessories: spals, electric lights, MSD, etc.

If I ran a new heavy gauge for power back to the battery, I would probably install a second battery "as long as I am at it"
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