I was wondering if a old laptop battery charger could be used to charge an SLA BATTERY? If not what would I need to use?

What is the battery charger rated for, output? And tell the same about the SLA please.

I use one for trickle charging. Look at the SLA battery 12 volt? What is output voltage and amperage of laptop battery charger. Its obviously DC output.

I use one for trickle charging. Look at the SLA battery 12 volt? What is output voltage and amperage of laptop battery charger. Its obviously DC output.

output=18.5v
amps=3.5a
HP spare charger

18.5 volts may be a bit too high for a 12 volt battery.. 3.5 amps is fine. Goodwill stores have loads of battery replacements that only cost $1 at the store. I got a 12 volt that measured 14 volts at 1 amp. I use it on a trolling motor or you could use a resistor to stop the voltage.

I agree, 18.5 is too much for a 12 volt battery. 15 volts with 1000 milliamps is more in the ball park.

18.5 volts may be a bit too high for a 12 volt battery.. 3.5 amps is fine. Goodwill stores have loads of battery replacements that only cost $1 at the store. I got a 12 volt that measured 14 volts at 1 amp. I use it on a trolling motor or you could use a resistor to stop the voltage.
Okl what about a ac-dc adapter output-12v/1a and is the negative wire the one with the broken lines.

okl what about a ac-dc adapter output-12v/1a and is the neg wire the one with the broken lines.
Usually is but easily checked with a VOM set to DC. Connect across the wires. If wired right, will read voltage, otherwise will show a negative sign or nothing.