Revival of Old Sealed Lead-Acid Batteries.

I now have some more solar panels, but not enough batteries to match them.

Enter an amateur radio friend of mine. He has a large solar array at his house, and he has a bunch of old dis-used 12V/48Ah batteries. Only trouble is that they have all but died.

He told me that it is possible to bring them back to life, probably not with full capacity, but also warned that it could take quite some time, sometimes a month or so, to bring them into a useful state.

The trick is to provide a voltage of 14.2 to 14.4V to the batteries, and if there is any current, even a few mA, it should be possible to revive the batteries. 

I got 4 batteries to try out.

Talking about this on the radio I may have found a second source of (used) batteries, we shall see how that goes.

For that purpose I got myself some modules from China:

- a 24V/14A switch mode power supply

- a few adjustable DC/DC buck converters with voltage as well as current limitation, both adjustable.

Now the DC/DC converters can be set to 5 - 23V, the current limit to 0 - 5A. That is the specification, but I intend to limit the current to considerably less for the revival process.

Having the modules connected, the process has now started.

After a week or so, the first (best initial voltage) battery does draw more than 1A current with 14.2V, but because a cell might be bad I have set the current limitation to 300mA. The voltage is now slowly - very slowly - increasing, and has reached 9.7V. Yes, there is still a long way to go, so we shall see how it goes, and how long it takes.

The second battery was connected a few days ago, and is now drawing about 100mA at 14.2V. It is slowly increasing, in the beginning the current draw was just about 5mA.

It may be a good idea to mount the two regulator modules in a box, at the moment they are just loosely attached to a shelf - or maybe make it wall mounted, with the 24V supply at the back of the shelf.

The two other batteries had an extremely low initial voltage, so I doubt that they can be revived. They may truly be dead, and if so they will go to scrap metal.

Apart from the radio activities there are some interesting times ahead.

The battery revival does not claim too much time, just some monitoring a few times a day, so other activities can slowly re-start. The electronics workbench/test-bench is still quite messy after starting the reference oscillator activities as well as the battery revival equipment. 

I see a lot of tidying and organizing  in my future ;)