Battery charging question

[tcsenter]

I have 18V battery pack that I'm trying to resurrect, comprised of three x 6V SLA cells wired in series. It was discharged for quite a long time (in storage about three years). Individually, the most discharged cell was 4.6V, the next was 5.2V, and third was 6V, using multi-meter (with no load other than the measuring circuit and digital display). I'm stuck with 12V charging source since I don't have 6V (or 18V) charger, so I'm charging with two cells connected in series.

But wondering whether series charging will produced cell balancing that were initially discharged to different levels? i.e. will each cell end-up with approx. same voltage and charge level? I don't want to overcharge the one cell that was giving 6V in an attempt to bring up the cell that was only giving 4.6V. TIA!!

 

[tcsenter]

Discovered that connecting in parallel will equalize the charge between them (eventually, it takes several hours or longer).

 

[LTC8K6]

It's good to have an example.

I searched a lot and only got conflicting info, but parallel makes the most sense for voltage eq.

 

[tcsenter]

Well it appears I killed the battery. I don't think I 'killed' it, it was just too deteriorated to take full charge that I was trying to get into it. These cells were at least 12 years old, possibly older. Two of the cells got really hot and the weaker of them started to bulge a bit around the negative terminal. So it's off to recycler.

Already purchased three new cells to rebuild; same specs. $24.00 delivered!