Weird battery problem

[sagaboy]

On Sunday morning I started the car and drove to the supermarket 1km away and after 1 hr shopping and returning to the car I switched on the digital Volt meter and it indicates 12.9v not bad still in floating charged mode. When I turned the starter key nothing happened, no sound etc. Tried turning the key twice, same result by now the Volt meter display 12.5v

Humme ..... Must be the added-on starter relay faulty, I then crawled under the car n short the relay ok it worked but no click sound from the starter solenoid Humme..... Now I noticed that when I turn the starter key the voltage drop to zero, must be an internal shorted solenoid.

I walked home to collect some tools to dismantle the starter motor for further check and on second thought I took along a spare battery.... Well, you know what? After hooking up the spare battery it started without problem, ah so, it was a dead battery problem or so I thought.

I the drove the bug to my friendly neighbourhood petrol station mechanic and he tested the battery with a bosch bat 110 hand held tester and found that my 66AH battery had a cca or cold crank amperes of 400amps and after 15 minutes it dropped to 350 cca and further down to 300 cca after 30 minutes OK confirmed dud battery after more than 7 years of usage.

I got a new 55AH battery and tested it for cca of 550amps fitted it and happy that it was not the starter motor solenoid problem. Now comes the weird part, the next morning the Volt meter showed 12.5v Humme... A bit low on the side, i started and it drove the car for breakfast (1km away) with Volt meter showing health charging voltage of 13.8v an hour after breakfast, checked the voltage; good 12.9v started the car with good 13.8v charging, just after driving 1km and on a 4 lane highway as brake to slowed down the engined stopped and turning the starter key nothing happen just exactly like what happened on Sunday but the digital Volt meter showed 12.6v

With cars zooming past me, I was really concerned in a serious n dangerous situation..... Luckily, I was on the left lane (where I live we drive on the British system) and the road was slopping down wards, rolled just 300 meters into a petrol station on a slip road and stopped right in front of my friendly neighbourhood mechanic and he was sitting on his door step (that's some real luck)

He came over and I showed him the Volt meter displaying 12.6v he took out his bosch bat 110 tester n found that the battery got only 250amp cca. He tested the car alternator and it was charging, he put in another new 55AH battery and checked with 650cca, he told me that he will re charge the faulty battery and then leave it overnight to see if it is retaining a charge.

Until then, stay tuned, I will post any up date info on w the problem. In the mean while any suggestions on potential faults to look out or to be checked please let me know. I have lread. checked for leakaged--there are none and my mechanic friend cracked his head, checked and couldn't find or thing of what cause the problem other than a dud new battery.

[Ol'fogasaurus]

If it continues and the old new battery charges and tests OK then test your system out with a AMP gauge: starting the engine, with the engine running then turn it off and continue to check for a while looking for a rogue draw. I've seen funny things like something not showing up when running but waiting to draw after. Also check all grounds real well, especially the braided one if you still have it, and all other working connections including the ends of the wires. Also, if you have a regulator have it checked especially if it still has contact points as they can stick. These things can drive you nuts!

[sagaboy]

Problem solved.
It is caused by corroded earth cable from the car chassis to the battery negative cut-off switch. The other side of the cut-off switch cable to the battery is OK. I think the corruption is caused by solder flux when I soldered the wire to the lug.

Althought due to poor earth connection the volt meter reading of 13.8V was correct as there is still sufficient connection/pressure for the volt meter but insufficient connection for proper charging of the battery or sufficient current discharge to the starter/solenoid.

Although testing the alternator B+ terminal with the car running did show that it was generating voltage/amps but made the mistake of not checking whether battery was receiving sufficient current.

My more than 7 years old battery is still going strong after charging and leaving it alone for four days and then upon testing, it is still capable of producing 450CCA compared to 650CCA with a new battery.

[Dale M.]

Mmm.... Cable connector seems to be soldered.... Wonder if custom made and person who made it used acid core solder.... Would explain internal corrosion, with no visible sign of corrosion externally.....

HINT: NEVER ever use acid core solders on electrical, ALWAYS use rosin core solder...

Dale