I have an old battery show 2v and I charged it up with a 1.5amp trickle charger took about 2days. I then use a old fashion battery tester on it it was marginal. So I cycle the battery discharge it to about 11-10.5 v with a headlight and charge it back up again. for about five times. It tested still marginal. Voltage stabilized at 12.4ish volts.

So I decided it to cycle it a few more times. But this time I test it this way using the battery tester I tested it 1st time for 7 sec and wait a few sec test it a 2nd time and wait a few minutes and test it 2 more times a few minutes later then discharge.

But the battery is worst then before. It is testing lower on the battery tester no longer marginal (it is testing bad) and voltage stabilized at 12.1ish volts. I cycled it a few time since not better.

So can you damage a battery by repeating testing with a battery tester???

Does anyone have an idea what is going on here???

Any ideas on how to repair the battery at this point???

thanks

__________________
Silver Honda Accord, 2006
Silver G500, 2003
Silver SLK-320, 2002
Black ML-320, 2000
Bule Porsche 993 Targa , 1997
Silver Merkur XR4Ti, 1987

A 12V battery at 2v is no good. It was bad before being charged or tested. Hope this helps.

Good luck!!!

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Can you damage it? Yes if you discharge it much below 10V and let it sit discharged. At 2V that one was long gone before being charged.

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Bringing the battery voltage down to 2 volts damages it.

Testing it is putting a load on it and is just as you did like living the head lights on which shortens the life of the battery.

This is a different subject but there was a magazine that was about alternative energy.
They built a little shed and setup solar panels to charge batteries that powered the Lights in the shed.
They expected the batteries to last for 5 years instead they lasted for 1/2 off that.
When they did research on it what they found out was that if the battery was discharged (which happened when the lights were on) under 11 volts it shortened the expected life of the batteries.
They did another test with a larger amount of Batteries and they lasted nearly the 5 years because the kept the discharge voltage above 11 volts.

And those were deep discharge batteries. Automobile batteries are not deep discharge betters and do even worse when their amperage and voltage is drained off.

Here is my story. I got into my Volvo Diesel and drove 10 miles to visit a relative. When done there I started normally and went to a restraint. When I was done at the restraint I turned the key and nothing at all happened.
I had a voltmeter in the car and I was showing 12.5 volts. and that sounds good. So I guessed there was some issue like the ignition switch or so on. So I scrounged some wire to jump the Starter.
When I did that nothing happened and except that I got a really weak spark.
I tried the wire a cross the better terminals and still got a weak spark and the wire did not get hot. I determined that even though I had good voltage the inside of the batter was shot and I was not getting amperage.

There was a Autozone across the street and I bought a Battery and with that the Car started right up and I was on my way.

The sort story is that if the plates inside of the batter are used up or cracked or so on your battery is shot.

__________________
84 300D, 82 Volvo 244Gl Diesel