Battery Problems after Rebuild

[MercuryMarc]

Just installed my 1970 250/C4 in the Comet.
Had the battery sitting on the garage floor for 4 months.
Charged up the battery and it worked fine for a week.
Now the battery will not hold a charge overnight, so I recharged it with my trickle charger again.
Took the battery to Kragen and they tested it - said it was fine yesterday. Drove the car yesterday afternoon, and it was fine, even restarted after sitting a few hours.
Now this am the voltage gauge reads only 10 volts , and it won't crank (lights do go on).

I wonder if it is my battery (less than 2 years old).
I wonder if I did not hook up my alternator properly (one wire - 4 years old) and if it is not charging the battery.

Suggestions? How to check the alternator? Or should I just replace the battery?

Thanks-

Marc in SF
63 Comet Ragtop
1970 250I6/C4
http://mercurycomet.net

 

[Anonymous]

Here's a very simple and quick test you can do to see if there is a short (drain) in your electrical system that is sucking the life out of the battery.

Disconnect the negative battery cable from the post. Clip the lead of a 12v test light to the disconnected cable, and touch the probe of the test light to the negative post on the battery. If the test light lights up, you have a short somewhere. Disconnect the alternator wiring harness to see if the light goes out. If it does, then you have a problem in the alternator. If the light stays on, pull each fuse until the light goes out, and when it does, you'll know which circuit it is in.

If the test light doesn't go on when you hook up the probe as described, then there is no short and we need to look elsewhere.

Keep us posted.

 

[pedal2themetal45]

HI
The only prob with this kind of test is if you have a new stero or a clock its going to show a drain as a clock and the radio with a clock is going to draw power even when turned off.. as well as maybe a stero power amp or an alarm system.
Tim

 

[Anonymous]

That's a good point. Newer stereos have inline fuses in the power lead, so you could pull the fuse for the test. As for the clock, I'm not sure how you'd work around that.

That's the process that is outlined in the Haynes automotive electrical manual, though...funny they don't mention what you just did.

 

[MercuryMarc]

Thanks Everyone-
The guy at the auto store said that leaving a battery on the floor will somehow kill the battery...
But the battery was "just fine" when they recharged it and tested it on their test machine.
I checked the ground - seems fine (and I cleaned all the contacts). I was having funny issues with my "gen" light after conversion to the alternator, so I disconnected it and now have a under dash voltage gauge. Read 14 volts while driving fast, 12 when idling.
I have not checked the alt yet.

But I think it still might be that battery- wouldn't the battery last more than 24 hours after a full charge, even with a bad alternator? No current draw when I tested with the ignition keys out.

Thanks and I'll keep you posteded

Marc

 

[Anonymous]

Thanks Everyone-
The guy at the auto store said that leaving a battery on the floor will somehow kill the battery...
But the battery was "just fine" when they recharged it and tested it on their test machine.
I checked the ground - seems fine (and I cleaned all the contacts). I was having funny issues with my "gen" light after conversion to the alternator, so I disconnected it and now have a under dash voltage gauge. Read 14 volts while driving fast, 12 when idling.
I have not checked the alt yet.

But I think it still might be that battery- wouldn't the battery last more than 24 hours after a full charge, even with a bad alternator? No current draw when I tested with the ignition keys out.

Thanks and I'll keep you posteded

Marc

Not realy sure why laying a battery on concrete kills it as you said the guy told you above but, beleive me he's right it does! More than likely when they tested your battery it was holding a charge just not for long. I had a battery in my truck that was bad that there machine said was fine. Then the day after i replaced my battery i found out the alternater is no good too.

BTw about the battery lasting at least 24 hours even if the alternater isn't working. I wouldn't count on that.

 

[Anonymous]

Not realy sure why laying a battery on concrete kills it as you said the guy told you above but, beleive me he's right it does!.

I have never found that to be true. I had a brand new battery sitting on my garage floor for three years, and I swaped it into my truck without ever putting a charger on it. It cranked right up.

I am pretty sure you have a draw somewhere. 78 Monarch's idea is the way to go. Eliminate circuits until you find the right one.

 

[48fordnut]

The battery on the floor myth. this was disproved on tv, on mythbusters. never had that problem.I think your alt is not putting out the correct voltage.most cars will crank several times and many miles of running on just the battery.

 

[MercuryMarc]

Thanks for all the input!

I did not see a current draw, but I'll leave the charged battery in the car overnight disconnected. If it still works, then my battery is OK, right? If it dies, then it's a battery problem.

How do I check the alternator?

 

[BIGREDRASA]

Just pull it and take it to your nearby parts store, where they can put it on a machine designed for the test.

As far as battery, was it tested with a load tester?

 

[Anonymous]

A Charged battery should read about 12.5 volts on a multimeter.

Once the car starts and the alternator is working, you should be well over 13 volts.
On mine, with two big electric fuel pumps and a huge electric fan, I see about 13.6 at idle and 13.9-14.0 running about 1500 RPM and up

 

[BIGREDRASA]

Was the alternator new or rebuilt? Had a similar problem, and both battery and alternator tested OK. Turns out the rebuilt alternator had an integral regulator, which was not replaced. The regulator would fail when hot, so it tested OK when cold. Had to pull the alternator and test it when hot (ouch)!

 

[MercuryMarc]

Q: As far as battery, was it tested with a load tester?
A: Not sure- the guy in the parts store had it hooked up to some sort of meter on a dolley and after 45 seconds it rendered the verdict.... "good."

Q: Was the alternator new or rebuilt?
A: New (3 years ago) Powerbuilt 30 amp 1 wire alternator.

Q: Was it a really nice looking chrome alternator?
A: Why yes, it was (they ran out of the plain ones...).

Thanks again- will have the alternator checked out.

Marc

 

[jwb68c]

How about the voltage regulator, I had a similar problem on my Impala a few months back. Did the checking with one of those inductive amp guages and found the problem. Good luck, I hate electrical problems. J

 

[Lazy JW]

The battery on the floor myth. this was disproved on tv, on mythbusters.....

Yet another old wive's tale that refuses to die :roll: (But A'hm a'tellin' ya, mah Uncle Wilmer's cousin Billy-Joe-Jim-Bob had a friend who knew this guy that left his battry on the cement floor and went to use it and it wuz shore'nuff DEAD!).
Joe

 

[MercuryMarc]

Took the alternator to Autozone and the Kragen- same response.
They can't hook the thing up to test it without a part/code number.
Since I have an aftermarket one wire alernator with no code stamp they will not test it since the computer needs a code to run the progam...

So I put the thing back into my car and I'm charging the battery overnight.

Now I've got to figure a way to test the alternator and the attached voltage regulator by myself.... I do have a voltmeter/ammeter in my garage.

And just to be safe, I'm keeping the battery off the floor....

Marc

 

[BIGREDRASA]

When you get home, check the voltage (engine on), is at least 13.5 volts. Next that battery voltage is at least 12.5 volts (engine off). Try disconnecting the negative terminal when you leave it overnight, and see if the battery is still aliver in the AM. If it still has 12.5 volts and starts the car OK, that would increase the probability of a short. If it's dead or below 12.5 volts, then the battery likely has a dead cell.

 

[Anonymous]

I strongly suggest that you pick up a copy of the "Haynes Techbook Automotive Electrical Manual". You can get it at Amazon.com, among other places, for under $20. It explains basic electrical theory, automotive electricity, and has troubleshooting and repair sections for all the major electrical systems on your vehicle. I'm still new to electrical work, but this book is like my flashlight in the dark.

Some very basic steps you can take to test your alternator:

With the car off, check battery voltage and make sure it is around 12.5 volts.

Star the engine, increase speed to about 2000 RPM and check voltage again...should be approximately 14-15 volts.

Turn on the headlights, the voltage should drop and then come back up if the charging system is working properly.

If the volts are more than 15, then I'd replace the alternator, unless someone here knows of a way to check the internal regulator on one.

I don't know if you've mentioned it or not, but make sure to check your battery cables on both ends to make sure they are clean and the conections are tight. If the cables are old, just replace them, even if they look ok. I just spent many, many hours troubleshooting a starting issue on my '74 Jaguar XJ6...problem turned out to be the battery cables, even though they appeared to be in good condition. Added a set of Taylor Diamondback cables, and the problem was solved. Also, make sure that you have enough ground straps/wires in place. You want connectons between the battery and engine block, engine block and chassis, battery and chassis etc. Clean with grit cloth or a wire brush your battery posts, and then coat them with Vaseline.

Basically, what I am saying here is to make sure you check the fundamentals before you start throwing money at the car...batteries and alternators aren't cheap, at least not to me.

Keep us posted.

Dave

 

[MercuryMarc]

Thanks- I just bought the manual on eBay for $3!
Good thought about the cables...
After I first got the car I had "issues" with starting- turns out the starter to ground cable had corroded, but was only visible after the cable was removed and inspected on my bench. Replaced them all for good measure a few years ago.
Marc

 

[Nathan289]

Kragen should be able to test the alternator, battery, and starter with everything in the car.
They should have a hand held Midtronics Battery tester it comes in a nice yellow plastic case. they hook it up to the battery at the cables punch in some numbers useing the arrow keys. it first test the battery, then asks you to start the car, tells you the cranking volts and if its normal. then checks the alternator. With loads off and loads on at idle and while reving.
ASk me how I know??? Hmmm Because i work at schuck's
Washington's version of Kragen's

that 30 amp alternator sounds really low amps. usually they are 45 to 50 amps or the higher 60 amps. unless you start playing around and find higher versions.

Btw. stereo amps should not be drawing power with the radio off. if it is then its not hooked up right. most newer stereos have a amp power wire that turns off the amp when the radio is off.
Newer radios do have a constant power wire that will draw power, like a clock.

Checking draw with a test light was a good suggestion so is using a volt meter/ ammeter.

I've seen cars with dead alternators with fully charged batteries last 30 minutes driving. alot of it has to due with how much draw your ignition and accessories are pulling.

Nathan