Can I connect a 12v transformer to a 12v rechargeable battery to recharge the battery?

No. If it is a PB battery you need a CC/CV charger with an output voltage of 14~14.4v
If it is a NiMh or NiCad battery you need a constant current charger with the right current depending the capacity of the battery.

If you have a lab power supply with an adjustable current and voltage it is possible to charge all kind of batteries but you do need some controll on temperature, current and voltage,

And simple B6 style charger will charge them all with an automatic shut off.

Just a home-hobbyist here...

12v |???| 12V3.5AH/T1 Lead-acid-battery

I scanned some B6 chargers... Wasn't clear on the input... 12v or 110v?

If possible, a link to one you would suggest?

Thanks!

I took a quick look at some B6's. Couldn't determine 110v in or 12v in?

Could you provide a link to a product you would suggest using?

Thanks!