Dual battery question

[lectric80]

Based on what you are seeing, I would say that it is apparent your alternator isn't keeping up with the demands. That's why you see reducing voltage at idle. A bit bigger could easily handle it, without getting into high amp units that tend to be big bucks and not neccessarily as reliable. A few guys here have done the CS144 swap, and I will be doing it when I get to the 383 this year.

I also have a friend that might be able to get you a good deal on a alternator.

 

[Fordum]

Theoretically, you should see 14.5 volts at fast idle with everything on. But, since you seldom have everything on, a slight drop would be fine. If you are going below 13.5 with on at fast idle, then you almost certainly need a bigger alt.
Make sure that the belt is tight and not glazed before you spring for a new alternator though.
Also, you should certainly see 14.5 with a charged battery at fast idle with a high normal load.
What you really need is a DC clamp-on Amp probe. It just clamps around a wire and reads the current running through it.
NOTE: Most clamp-on amprobes are Ac only. The DC ones are out there, I have got one myself.
It has to be rated high enough to handle the total amount your alternator is rated for.
Mine is 1000 amps, and it lets me check alternator outputs, and do tool less compression checks. Where I can check for a dead cylinder without taking any plugs out.

J.

 

[Blue90]

Alright....so now I'm really wondering... Do I have to figure out exactly how much amps my fans are puling? Or can/should i try out this cs144 lecrtic is talking about?
What are the specs of this cs144?
What is its normal application?
Will it bolt right into my stock location or do i need to swap bracketry?
Can I just go buy one of these down at auto zone/checker? or is it a rarity?
Sorry fellas if I'm askin too many questions, I just like to have all my ducks in a row.


((UPDATE)) Look what i found....Is this it?
http://www.autozone.com/autozone/ca...otType=oem&itemId=86-0&displayName=Alternator

 

[BILTIT]

Just as a reference, my single MKV fan draws 45 amps continuos on full load. Im sure your fans will draw 25A-40A.

 

[lectric80]

That would appear to be the right one. Those put out 140 amps rated, although remember the rating is 80% load. Should be easily adaptable to what you have. Requires a new two prong plug, and if your dash doesn't already have an alternator light, you will need a simple resistor.

 

[Blue90]

That would appear to be the right one. Those put out 140 amps rated, although remember the rating is 80% load. Should be easily adaptable to what you have. Requires a new two prong plug, and if your dash doesn't already have an alternator light, you will need a simple resistor.

Okay cool...um...well I have no idea it I have the resistor cause the guy that owned the 77K5 before me did the motor swap.....maybe i do need you to pay me a visit....

 

[lectric80]

When I get into work tonight I will find the thread here about it. Pretty easy, and should work perfectly for you since the CS144 puts out 140 amps.

 

[Blue90]

When I get into work tonight I will find the thread here about it. Pretty easy, and should work perfectly for you since the CS144 puts out 140 amps.

Sweet! Thanks man!

 

[lectric80]

Here is the thread I was thinking of. It is a stock alternator off a Pontiac Transport, so it is readily available, and it puts out 140 amps.

http://coloradok5.com/forums/showthread.php?t=185231

Should be fairly easy to adapt, especially with all the information in that thread.

I plan to do it, but it won't be until I finish the engine build and get the serp setup installed. My heads don't have the holes I need for the serp setup, but the new heads should.

 

[RootBreaker]

few things to note...

i too have what is needed to do the 140a pontiac trans sport alt upgrade..

you either need the $25 2 wire to 3 wire alternator cable or the $6 3 wire wire that you just tie into your setup. The $25 has a resister in it...

I tried both with an alternator 2 years ago but was getting 17v out of the truck.. i since removed it and put my stock 63a alt in!!!! YEAH 63a STOCKER!!!!!

but I am going to be revisiting this once i get my truck wired back up (currently redoing entire harness)...


also something else that can free up some juice to your setup...

my truck at idle.. with headlights on and high beams on.... sits at 11v to the headlights.......

chevies have a big power draw through the headlights.. so search for headlight relay upgrade and you will find how to use relays to drive your headlights.. sending 14v straight to your headlights.. not only do you free up the power loss but you also gain brighter headlights!!!!!!!!!!!!

here is the post
http://coloradok5.com/forums/showthread.php?t=164429

here is a link provided...
http://www.73-87.com/7387garage/exte...ight_relay.htm

 

[Blue90]

Very helpful thanks!