charging a sulfated battery

[sky jumper]

When jumping the car, have the car that is running raise the rpms to 2500...wait about 2 minutes..then try to start the dead car, ive never seen where this did not work, even with crappy cables

oh yes I tried that. revved it way up, held it there for a bit, etc. the problem may have been corrsion on the jumper vehicle's battery terminals preventing good connection, combined with the crappy clamps on the $8 menards cables. I tried grounding to a chunk of metal on the engine block but couldn't reach it. was too lazy to clean up the terminals.

 

[sky jumper]

so I think the warranty issue is a moot point as the sulfated battery appears to have made a full recovery. now measuring 550cca and 5.6mohm, and easily holding voltage with 200A load applied. into the old minivan it goes.

I must say using a DC power supply with voltage and current control totally works. I have a bunch of different chargers and none could deal with this battery. 8 hours on the DC supply at 16v, followed by overnight on the 3 stage charger completely cured it.

 

[ripcord]

What you did is called an "equalizing" charge and it sounds like it helped. If anyone else wants to try this, it's important to keep a close eye on the battery and make sure the temperature stays under 125f as it can start to runaway and out gas pretty violently, releasing lots of hydrogen gas.

 

[sky jumper]

the DC supply worked so well I put it on an old junked group 27 marine battery from 2009 thats been in my garage for years and measured 9.2V. obviously the chargers just choked on it. 15 mins on the DC supply and it could then take a charge from my 25A charger. its been on that for 6 hours hovering at about 5.7A. temp is 87F. YES significant offgassing --- keep the room ventilated.

 

[wrcsixeight]

How much amperage is your power supply rated for?

The smart charger is likely dropping to float voltage prematurely,

If you can be there to remove the Adjustable voltage power supply when amps taper to very low levels, then it will be far superior to the so called 'smart' charger in the baility to truly fully charge a battery.

If you can't be there to monitor it, set its voltage to 13.8v, and when you can be there, return it to 14.4 to 14.8v, remove when amps no longer taper, or they start rising.

After amps stop tapering, remove charger, let battery cool, then initiate the Equalization upto as high as 16.2v @ 77f.

A battery drawn to 9.2v from self discharge over many months, is heavily sulfated, don't expect much from it in the capacity or cranking amps department.

 

[sky jumper]

its a 30v 10A supply. your suggested charging scheme makes sense. at 14.8v the current is staying steady at about 5.5A