Restoring an SLA battery one experiment

Around 2017m05d22 I pulled a 12V  SLA battery from a trailer.  The SLA was being used to power the emergency braking system for the trailer.  I did not know how old the battery was or when it was last charged.  Here is a photo of the battery.

My DMM  measured 6.3V across the SLA.  My experience says this means the battery is near death and cannot be restored.  I chose to mess with it anyway.  I put the battery on a 14.3V / 2A charger and measured a voltage of 13.9V.  This usually means the battery is not accepting charge and is presenting a high impedance to the charger.  I left the charger connected overnite.  The next day the voltage was still 13.9V.   I disconnected the charger and the voltage was 12.2V ...... this was a surprise.  I do not yet have an explanation for it.

I shorted the SLA with a spoon for 2 seconds and got a big spark and some glowing metal.  Afterward the voltage was still 12.2V.   With the charger connected the voltage was now 13V.

I will continue to monitor this battery.

Gus in Denver



tags:   99guspuppet  777SLA  777restoreSLA