I have a vector charger that will handle 2, 6 or 10 amps.  If charging one deep cycle battery what setting should I use?  I have been using 10 amps but am afraid I am not getting the most out of my charge due to it charging so fast.   Will the setting change if I decide to charge 2 batteries hooked parallel at the same time?

10 amps is your best setting for a battery that's in the 100 amp hour range (85 - 130). Some will say to use the 2 amp setting but that's actually too low. Just about all battery manufactors recommend a charge rate of 10% of the Ah capacity. The reason is you want producing a reasonable amount of gas bubbles as it charging. This is required to keep the electrolite properly mixed in the battery. Extremely low charge rates can cause a battery to stratify.

You can go actually go much higher than 10% up to 80% charge to get it charged back in a hurry but I needs to be cut back to 10% to finish it off.

A good smart charger/Intili charger does this for you and is the best way to charge your battery. Most will have a mainenance/float mode they drop into when fully charged and can be left on the battery 24/7.

If your charger is the Vector High Frequency Intilli charger, you have a good charger and should be left on the battery 24/7 while not using the battery, that's what's it's designed for. That's also why it charges so fast. It can charge a battery in three hours that your old automatic chargers will take eight hours, and it's better for the battery than those cheap automatics.

While keeping it on batteries for a maintenance charge, you can have several batteries in parallel and it will keep all them up.

This is my charger.  Should I leave it connected 24/7?  I did not get a manual for it as I bought it for $20 as a open box at lowes a few years ago.  I did not think that it had a float charge at the end so I have just been unplugging it

I know some guys that use that one (not sure is exact model) but they leave it on because it is suppose to be automatic and should be ok. If not sure I would just walk by it everyday and maybe make sure the fluids are not boiling and it should be fine. I would google it and see what ou find. Good luck

NOMALLY, Smart and Intilli chargers have have a three stage charge cycle

stage one, Fast charge

Stage two, Absorption charge

Stage three, Float charge or maintenance charge

Easiest way to tell if it is going into a float mode is to leave it on and connected after it has finished charging. 24 hours later check the battery with a digital voltmeter. The ideal float voltage for most deep cycle batteries is approx 13.2 VDC. If the battery is still showing close to this, then the charger is in a float mode. If the battery has dropped back to 12.6 - 12.8 VDC, then it's not going into a float mode and there would be no reason to leave it connected.