Charging issues

cobra400hp · #1 (**permalink**) 10-22-2002, 08:41 AM

I am having an issue with my charging system. I have:
one electric fan 30 AMP
1 MSD 6AL box
1 Holley Projection 4DI box
1 Electirc fuel pump
no radio
no other accessories.
***under drive pulleys***

I had the battery wired straight to the battery through a switch on the dash so I could control that piece.

Here the problem.
If I heat up and run the fan for a period of lets say 20 minutes, I need to make sure that Ill have enough drive time to charge the system back up or Ill have to jump start the car.

Suggestions that I have been given:
1 - under drive pulleys are no to my advantage
2 - 100 amp alternator
3 - sell the car! NOT!

Anybody have any suggestions?

Mr.Fixit · #2 (**permalink**) 10-22-2002, 09:58 AM

Quote:

Originally posted by cobra400hp
I am having an issue with my charging system. I have:

I had the battery wired straight to the battery through a switch on the dash so I could control that piece.

Don't know what that means. What is the output amps of your current alternetor? Do you have an ammeter in the dash, or a voltmemter? A 90 amp alternator has worked fine for me with cars who's fans pull 25-30 amps, with an MSD and the headlights on. At idle at 850 rpm. If you put the oversized (underdrive) pulley on the alternator, put the factory one back on. The crank and water pump pulleys should be fine.

wrench · #3 (**permalink**) 10-22-2002, 09:58 AM

What is the alternator's rated output? (amps) What is it really putting out?

cobra400hp · #4 (**permalink**) 10-22-2002, 10:05 AM

Thansk guys. I have borrowed a amp meter but havent had the thrill of using it yet. THat should be tonight. When I bought the alternator i was told it was a 65 amp. Im going to do two tests. One with the new pulley then on without and see the difference.

Ill let you know my findings. should be tonight.

wilf leek · #5 (**permalink**) 10-22-2002, 10:11 AM

65 Amp alternator should cope easily with your load, it does for me.
I suspect it is not charging properly - could be a diode or two out, maybe worn slipring brushes etc.

Do you get 14.3Volts across the battery (most elec loads off, engine running above tickover)? that's the voltage you want to see, it means things are charging nicely.

HTH

Excaliber · #6 (**permalink**) 10-22-2002, 10:21 AM

Even 65 amp should be MORE than enough to power the fan AND keep the battery charged.
A couple of things, therefore, come to mind:

1. The battery itself is unable to "hold" a decent charge in the first place.
2. The alternator is not working properly.
3. The starter is drawing TO many amps and pulling down the battery EVEN though the battery is good!

Testing:
ENGINE CRANKING battery voltage should not fall below 9 volts when it is fully charged. If it does this can STILL point to bad starter or a weak battery! A carbon pile battery load test will determine battery condition. An AMP reading of the starter will determine starter health.

Bear in mind a 65 (or 100) amp alternator will rarely IF ever actually output that much current during "charging". 20 to 30 amp output IMMEDIATLY after engine start is more like it. And THAT for only a few minutes under normal circumstances.

You may well need a "specialist" to get to the bottom of it. One who has the "tools", NOT some "pump jockey" that just replaces everything. Carbon Pile BATTERY load tester. INDUCTIVE amp meter to read starter drain druing cranking is what I would use. Some alternator regulators can be "shorted" to "force" 100% output of the alternator, then take a reading, it shoud be 65 amps (this does NOT hurt the alternator if done correctly). The alternator regulator is also one of the "usual suspects", not allowing the alt. to output as much as it should.

It is VERY unlikely your fan can outdraw your alternator output EVEN if it is a fan "from hell".

Ernie

ASE certified electrical systems technician in another life, long long ago, lol.

Whaler · #7 (**permalink**) 10-22-2002, 10:46 AM

I agree
Get the battery load tested
may have a bad cell for all you know

Tim

cobra400hp · #8 (**permalink**) 10-22-2002, 10:52 AM

Thanks...

Not that the Gel Cells are immune to it but I would trust this battery over a conventional one.

if I take the battery to a battery shp like batteries plus, should I take it out or leave it in the car?

Whaler · #9 (**permalink**) 10-22-2002, 10:57 AM

either way
whatever is easiest for you or the tester....on the bench is obviously best for them.......but not you

It can be done in the car too

At least you can eliminate the battery from the equation after this

Tim

cobra400hp · #10 (**permalink**) 10-22-2002, 11:00 AM

can any of you run your fans constantly without fewar of battery drain?

Excaliber · #11 (**permalink**) 10-22-2002, 11:02 AM

Sure, LOTS of cars can do that. It's called "normal",,,,,lol.

Ernie

cobra400hp · #12 (**permalink**) 10-22-2002, 11:03 AM

oucchhhh..

thanks i needed a a dode of reality.

Whaler · #13 (**permalink**) 10-22-2002, 11:10 AM

Yes........the electric fan for most of us will be the biggest single load on the running system. Maybe a good set of headlights on high beam are next.

Anyhow your 65 amp charger should take care of all vehicle loads that are pulling off the battery. The initial engine start is one big draw on the battery.

I would check in this order.
Battery load test
Battery voltage running and sitting with engine off
Amperage on the charge wire to the battery or positve side of the solenoid. Use a clamp style/ induction amprobe ( don't have to break the cct. The battery shop may be able to do this for you too.

Tim

Cobra #42 · #14 (**permalink**) 10-23-2002, 09:45 AM

Paul, Check all your grounds, battery to frame in back (remove power coating) check your engine ground in the front, ( run from Starter to frame ground) take two asprin and it will be all better, db

cobra400hp · #15 (**permalink**) 10-24-2002, 09:07 PM

DB, when you say from the starter to the frame, are you saying actually have the ground strap attached to one of the mounting bolts for the starter? RIght now the ground strap is from the frame to the block. hmmm.. let me know...

check your email.

wrench · #16 (**permalink**) 10-25-2002, 07:58 AM

is it attached to block or head?

cobra400hp · #17 (**permalink**) 10-25-2002, 10:03 AM

I know its not in the head. Its in the block.