1500mah battery

I think stock is 1440 or somewhere around there, I doubt you see any difference using the 1500. Im sure its safe to use.

What do you mean "external charger"?  Is it something you put your battery in to charge it?  If so, can you post a name or a link to who sells it?

I ask this because the Sprint Instinct included a battery charging case to charge an extra battery and I want one for the Moment.  I've looked for an external battery charger but haven't found one yet.

I purchased one of these on Ebay.  It came with 2 batteries and a wall charger.  Don't waste your $8 on this.  The batteries can't be charged via USB/car charger/or factory wall charger.  They can only be charged in the wall charger they come with.  If you attempt to charge them with any of the items I listed above a screen will pop up saying something to the effect of, "these bootleg batteries cannot be charged...because they're bootleg"

Oh yeah, even more importantly they have like no life whatsoever.  With moderate use mine was dead after like 3 hours.

I found an ebay seller of these 1500mAh batteries w/ the best reviews, and started writing people who've bought them.  I wrote roughly 10 people on ebay and only 1 person said it didn't seem any better than the stock battery, and 1 mentioned the occasional funny message about battery compatibility w/ no rhyme or reason.  He said removing and replacing the battery would make the message disappear.

I've also seen wall chargers that can both be plugged into a normal outlet or power via USB, so it seems like it'd be the best of both worlds that you can change an extra battery two different ways and always have one on standby.  I just wish the charger would provide enough power that I could swap batteries w/o the phone actually dying...I wish it'd provide enough power to keep the phone going between quick swaps.