Battery Issues

[Xavier]

When I first built my car to a driving state I noticed the battery could not hold a charge and for a while I could not figure out why. I replaced the battery free of charge (Optima); the battery could still not hold a charge; me thinking it was just a battery I let get bad, becuase it was in storage for such a long time not getting charged. Not surprisingly, the battery still did not hold a charge and a friend assured me I had the alternator wiring incomplete and nothing was getting back to charge the battery. He told me the voltage would jump up 2 to 3 volts when the engine was running, this is the easiest way of determing the alternator is charging the battery. Long story short, we took off the alternator, noted it was wired improperly, put it back together and it seemed to be fine.

The problem is now, when the car sits for more than 2 weeks, the battery will not start the car - needs jumped. Before, you can clearly tell the battery was not getting charged as the lights would be dim, and every function was very weak from start up. This time around, everything is strong, everything lights up bright when driving; however if the car sits for more than 2 weeks, it needs jumped. Everything is dead.

So after not driving the Cobra for a month, due to an upgrade I was performing, the battery is dead. I jump it and it runs fine.

Before I jumped it however, I ran a volt meter to the battery terminals when the car is off; it only read 10v, when the engine is running 13.4v. I compared it to the daily drivers and they sit at 12.5v and climb up to 14 or 15v when running.

I do not want to run out to the store and buy another battery. But I can not trouble shoot this on my own and I have no idea why its initial voltage would start at only 10v DC?

I have a Optima Redtop Battery, I have a solid ground to the frame with very heavy gauge wire, another ground from the block to the frame with a batery cable. I have a keyed battery disconnect that is alway turned off when the car is sitting - always. When I do have power, it starts up on a dime - no problem. 60a Alternator.

How can a battery lose power if not in use? How can I see something is using the battery when it is sitting there? Or, if the battery has a bad ground, and the motor does not, would that physically drain the battery?

[patrickt]

Pull the negative cable off of the battery and attach an ammeter between the negative cable and the negative battery post. With everything turned off, if the ammeter is reading over 25 milliamps, something is sucking the juice out of your battery. Start pulling your fuses, one at a time, starting with the lowest amp fuses first. The fuse that stops the current drain is the circuit that is causing the problem. You then check each device on that circuit. On non-Cobra cars, common parasitic offenders are the little light bulb switches in the glove box, trunk, etc. The ammeter will tell you what's doing it though. My car battery sits from Thanksgiving to the Spring without any maintenance, charging, etc. and the car still cranks hard and then fires right up.

[Ronbo]

If you have a cut-off switch put a amp meter across it when off and check for leakage...

If you don't have one, get one. they're a must for vehicles that sit for days.

Since it's reading that low I can't imagine it's a load issue, sounds like a shorted cell in the battery. Since each cell is 2v you're reading is right on for a cell short.

This needs to be addressed since the alt is trying to essentialy charge a 10v battery to 12v so the rest of the cells will boil-off.

[shark]

I saved this from somewhere: God luck -- Sharkey

> "One Simple Battery Test:
>
>
> 1) Connect the voltmeter directly across the "Battery Terminals".
(NOT to the Cable Clamps)
>
> 2) While watching the meter, Start the Car.
>
> 3) The Battery Voltage should Never fall below about 10 Volts.
> If it does:
> a) The battery is either "Low in Charge".
>
> b) Or The Battery is "Low in Water".
> (The water level in the battery should be about 1/4 of an inch,
Above the Plates.)
> "DO NOT" Fill it up FULL.
>
> c) Or The battery has a "High Internal Resistance".
> (Possibly Sulfided Plates and probably Time for New Battery?)
>
>
>
> **NOW Repeat This Test BUT:
>
> 1) Connect the voltmeter directly across the "Battery Clamps on the
Battery Cables".
>
> 2) This Reading should be Within 0.1 Volt Maximum, the Same as 3
Above.
> ***If NOT, Clean Battery Terminals and Clamps.
>
> 2a)If Necessary, Repeat Test to Verify it is now OK.
>
>
> **NOW Repeat This Test Again, BUT:
>
> 1) Connect the Voltmeter Directly Across the Positive Terminal of
the Starter and it Case Ground.
>
> 2) If the voltmeter reading is More than 1/2 Volts Lower than the
Previous Test,
> ** You Probably have a Cable or Connection Problem!
> Check the Connections between the Cable and the Cable Connectors.
ON BOTH ENDS.
>
>
> One Very Simple Alternator Test:
>
>
> 1) Start Car and run at a normal idle.
>
> 2) Connect a Voltmeter Directly Across the battery Terminals.
>
> 3) Turn on Headlights to High Beam.
>
> 4) check the battery Voltage.
> *** The Battery voltage Should read between about 13.8 to 14.2
volts. (Possibly up to 14.5 Volts.)
>
> 5) Increase motor speed to about 1500 RPM. The Alternator should
now produce a battery voltage between 14.2 and 14.6
> Volts.
> *** If it is Lower than 14.2 volts, the Alternator probably has one
or more Bad Diodes.
>
> 6) Now, Maintain the 1500 RPM and Turn off the Headlights. Run this
test for One Full Minute.
> "The Battery Voltage should NEVER Exceed about 14.8 Volts".
> ***If it Does, the Alternators Voltage Regulator is probably
Faulty, OVER CHARGING the Battery.

[Xavier]

Thanks for the responses; I am kind of weak with the volt meter, if I measure DC Milli-amps on the volt meter will that suffice as the ammeter?

Am I right in thinking that when a battery drains, its volt output is unaffected; only its available load (cranking amps) is. Correct? If this is true, then even a voltage leak would not cause a battery to go from 12v to 10v.

[patrickt]

Originally Posted by Xavier

I am kind of weak with the volt meter, if I measure DC Milli-amps on the volt meter will that suffice as the ammeter?

The ammeter needs to be in series (meaning you need to pull the cable off of the battery and hook the ammeter between the battery and cable you pulled off of it. Your VOM might be able to do that; check the instructions and give it a try. You can test your gauge by turning on your headlights to see if the amp reading increases and decreases when you turn your lights on and off. An inductive DC ammeter is a little pricey, but nice to have. You just clamp it around the wire and *poof* it's done. Here's one:



Another very cheap method of testing your battery is to disconnect both cables, charge it up fully with a battery charger, and then let it sit for a week without the cables hooked up. If the battery is then dead, then the battery is no good. Now that's a cheap and easy test. But to fully check your overall charging system, an ammeter is really the way to go.

[Ronbo]

I don't know if they're still available but I have a couple of the Blue point current indicators.

They're pretty neat, they look like a dash amp gauge and you lay them across the wire and it shows current flow. (inductive)

I think they were also available from cal-van tools.

Here's the PN's for the Blue Points:

Alternator meter (100-0-100) MT110

Starter meter (600-0-600) MT109

Found 'em: http://buy1.snapon.com/catalog/item....re&dir=catalog

[JeepSnake]

Xavier,

Everything these guys have told you is right on. I'm going to just mention that I experienced an identical problem with the Optima Redtop in my non-Cobra cruiser (i.e. Chevelle). It turned out that it had an internal short, just as Ronbo described above.

Good luck,
Zach

[Xavier]

Thanks for everyone's suggestions. I am going to order the inductive meters suggested by Ronbo. I have a feeling it is a dead short as well. I just thought about all of the variables the other evening and I believe there is a positive side of something feeding off of the negative side of the battery and vise versa. I had problems with the Painless wiring harness for the gauge cluster and found out something from them was labeled wrong before; I think I am going to find out what is what and toss the harness in the garbage and rewire from scratch to be sure what is what. I have some minor gauge issues, weak turn signal lamps, a tach that is about 1000 RPM too high on everything, although everything from the MSD 6AL is installed correctly. Even as I type this I am wondering if this all the same problem...The inductive meters should tell me what is happening.

Thanks for the suggestions.

[Jerry Clayton]

We have found on many rear battery or fiberglass cars poor grounds---we normally will run an extra groung wire directly from the battery to the block
Also underdrive pulley systems won't let the system charge enough and electric fans that run after engine shutdown
In fiberglass cars and boats, everything needs its own ground back into the electric system .

[Xavier]

Jerry,

Thanks for the comments. This is how I have mine ground now, tell me what you think. I have a ground wire from the alternator to the frame (I found out the hard way the March clear powder coating makes a worthless ground) 12ga to the frame. I have a pre-made battery wire - say about pinky finger diameter - run from the engine block to the frame (same point as alternator to the frame). I have the battery ground in the rear 1/0 run to the rear of the frame. On the negative battery terminal I have a 10ga wire that runs from the battery in the rear to underneath the dash to a terminal strip. This terminal strip is mounted on a cowl bar (has a main connection for the 10ga wire) and is the ground source for all of my gauges, lights and components etc.

[Jerry Clayton]

Yep powdercoating ( even clear) is a great insulator---

There are three primary functions on the cobra electrical system ----starting, ignition and cooling---all of these need a strong ground lead run directly to the battery negative.On the charging side---the alternator needs a good ground AND strong positive feed back to the battery AND to the electrical distribution.

On cars that we have serviced with electrical shortcomings---we have also ran a large positive from the alternator directly to the relays for the fans and doubled the lead to the battery.

MSD ignitions need to be connected directly to the battery, positive AND negative
Many of the cars we have had in our shop are carrying many AMPS in the covering of braided AN lines and we feel it is mostly because of inadequate grounding issues