Ive searched around and cant really seem to find a good answer on this, and I don't know anything about electricity.

I bought a new battery which came empty with the acid in a separate container. Is there any problems with performing the initial charge with the battery tender Jr?

First check for an answer was the manufactures website. While it states it can be done with a battery tender plus, it does not reference the Jr model.

http://batterytender.com/faqs.php/#20

They estimate it will take 48 hours to fully charge a new battery with their 1.25 amp model. The Jr is a 0.75 amp model.

Is the Jr able to charge the new battery if i leave it on for three or four days?

No problems at all, in fact that would be my first choice of chargers. Add electrolyte to the battery and you will probably find the BTJ is not even required?  

because it's brand new, once you put the acid in, the battery will already be at about 70% charged simply because of the acid reacting with the plates. put it on the battery tender jr. for like, 9 hours. and blamo you're good. this is what i did and it worked great.

As others have said, the Jr. model will be fine. I just put a new battery in my bike friday, the battery shop added the acid to the battery. Since I had brought my Battery Tender Jr. with me to work, I put the battery on charge and in a 3-4 hours the light on the charge changed to green and my battery was ready to be installed.

could you also just use a 2amp trickle charger?

Quote from: Desert Rat on June 08, 2009, 11:17:17 AM
could you also just use a 2amp trickle charger?

yeah, thats fine, just make sure you take it off once its charged, or you'll overcharge/damage the battery

Quote from: daliumong on June 08, 2009, 11:33:39 AM

Quote from: Desert Rat on June 08, 2009, 11:17:17 AM
could you also just use a 2amp trickle charger?

yeah, thats fine, just make sure you take it off once its charged, or you'll overcharge/damage the battery

I asked as i dont want to buy another charger. Thanks guys. Ill leave it on the tender jr for a while.

Worry not, respite.  Charging slow never hurts, and like the others said, a new lead acid battery is mostly charged so only a few hours on the charger or an hour-long ride is fine to top it off.  Why the instructions say 48 hours to charge at 1.25 amps makes no sense at all.  My battery is only 11 amp-hrs, meaning if I draw 1 amp from it for 11 hrs it'll be almost dead, so even charging from almost dead at 1.25 amps shouldn't take more than half a day.  There is some charging loss so it takes a little longer to charge than to discharge at the same rate, but it's more like 10% rather than 25% so a tender at 1.25 amps should be able to fully charge a dead battery overnight, as long as the battery is in good condition.  Since yours is new, you're good to go!