I think i desulfated a battery

[ltcom]

Battery flat on car this morning.
Stuck a battery charger on it which had 3 settings...... min amps, mid amps, high amps.
On high amps the battery should have taken 15 A and dropped slowly if it was healthy. It didnt. The amp needle hit the red.....meaning internal resistance i think. Yes i am no expert. I turned amp setting down for a few hours ..... 6 amps in..... then turned dial to setting 3 (high amps) and it settled at drawing 10 A then dropped GRADUALLY as it should ..... so i hope i saved my battery. If amps increased it would have been bad news again.
Car not used alot.... should have trickle charged it....my fault..... will see later if battery is ok or broken.
So dont leave cars unused for a month at a time....is what ive learned.

 

[Ningaloo]

Or disconnect the battery.
My car was left for over 18 months when I got locked out of Australia during Covid. Started first time on.my return.

 

[ltcom]

Or disconnect the battery.
My car was left for over 18 months when I got locked out of Australia during Covid. Started first time on.my return.

Thats a good one too.

 

[William_H]

I presume "hit the red" meant too much current into battery, typical of a very low voltage flat battery. You did right to start at low current.
Have you recharged the battery and it is OK? Have you desulphated the battery to resurrect it or have you just sqeezed a bit more life out of a very tired battery? I would suspect the latter. However time will tell. Just anticipate it may let you down again soon. I reckon a battery over 5 years old in a car is not to be trusted. ol'will

 

[KompetentKrew]

Or disconnect the battery.
My car was left for over 18 months when I got locked out of Australia during Covid. Started first time on.my return.

Did the radio ever stop flashing CODE though?

 

[geem]

I presume "hit the red" meant too much current into battery, typical of a very low voltage flat battery. You did right to start at low current.
Have you recharged the battery and it is OK? Have you desulphated the battery to resurrect it or have you just sqeezed a bit more life out of a very tired battery? I would suspect the latter. However time will tell. Just anticipate it may let you down again soon. I reckon a battery over 5 years old in a car is not to be trusted. ol'will

We leave our cars for typically 9 month until used whilst we are sailing. This time we left them for 12 months. We disconnect and install battery chargers to come on for 5 hours once a week. Been doing this since 2014. Batteries still good

 

[Refueler]

Modern cars are a pain ... my Volvo - if I leave it for a couple of weeks - I'm risking not starting due to all the electronics eating away at batterys charge.
If I disconnect battery luckily unlike many others - I don't get Radio Code problem.
My solution is to connect a $10 auto trickle charge unit designed for caravans etc in storage ...

Smart Car Battery Chargers Maintainer Auto 12V Trickle For Truck Van Motorcycle | eBay

I have a bunch of them ... two installed in my boat to maintain the two batterys .... in my barn to maintain my garden tractors ... and one in my workshop for general car / van etc.

I have 'De-sulfators' .... dedicated units as well as 'Rejuvenation' setting on my fancy charger. Does it work ? On a battery that has discharged as OP's - quite oftern yes as the battery has not sulfated to any real extent .. its just flat. But any battery that has actually sulfated - rarely do they recover .....

De-Sulfators work by basically pulsing shorted current ... this 'shocks' the plates. OP's method of varying charge rates actually does not de-sulfate ... but will bring back a flat battery that has not stood long ...
Whether that battery is any good after ... can only be known when tested ...

 

[Refueler]

Just a comment ..... OP's flat battery ....

This is a situation that shows up often that 'smart chargers' have trouble with. Many smart chargers will shut off it they detect a flat battery. Hard to get them to charge ... so repeated pressing of start or even disconnect - reconnect .. press start is needed to get an initial charge in for smart charger to then accept and stay charging.
Another factor - is when you have auto detect charging ... lets say you have charger - which is then connected to a smart relay that detects when battery needs charge and when full. Relay allows charging ... battery gets full ... relay cuts off. Smart charger then shuts down. Relay later detects battery needs charge - but smart charger has shut down and does not supply charge.

Its why I have a simple 4A non-smart dumb charger as well. 1. It will charge a flat battery without defaulting off .. 2. will charge when relay connects again.

Difficulty now of course ... most chargers you see on shop shelves are Smart .... I had to visit a whole run of shops before I found a simple charger.

 

[vyv_cox]

Or disconnect the battery.
My car was left for over 18 months when I got locked out of Australia during Covid. Started first time on.my return.

That's encouraging info. My totally disconnected batteries have stood for three years in Greece. I fully expect them to be dead when we return in September but your experience gives me some hope.

 

[ltcom]

I presume "hit the red" meant too much current into battery, typical of a very low voltage flat battery. You did right to start at low current.
Have you recharged the battery and it is OK? Have you desulphated the battery to resurrect it or have you just sqeezed a bit more life out of a very tired battery? I would suspect the latter. However time will tell. Just anticipate it may let you down again soon. I reckon a battery over 5 years old in a car is not to be trusted. ol'will

Yes i think i have only made it last a little longer. I had to use an old fashioned charger to do as i described because as another poster noted the modern clever charger was not happy..... i could feel it getting hot.
Resting at 13.5 volts after 12 hours. Have not checked since but have it on 30W of solar via a controller ....... will check how it is later. I carry a tiny jump starter now.

 

[vyv_cox]

That's encouraging info. My totally disconnected batteries have stood for three years in Greece. I fully expect them to be dead when we return in September but your experience gives me some hope.

Update: my disconnected batteries survived three years remarkably well. I reconnected them and was pleased to see about 12.0 volts. Mains charged for a few days and solar/engine charged since, they run my fridge overnight, down to 12.3 volts in the morning, which is what I would expect at this time of year.

 

[dslittle]

That's encouraging info. My totally disconnected batteries have stood for three years in Greece. I fully expect them to be dead when we return in September but your experience gives me some hope.

I replaced my batteries two years ago for ‘better’ ones when we were going further afield… The Lead Acid batteries that I replaced had always been looked after. They still seemed good when I replaced them. I gave two to a friend for his boat. They are still going strong two years later but are getting used.

The remaining two have sat idle since being removed. Last month, I checked the voltages. One was sitting at 12.54v and the other at 12.52v without any charging or maintenance.

I would hope that your totally disconnected batteries will also survive as well as mine have.

P.S. Should have read to end of thread before replying!!!