Sorry for such a delayed reply, but I was testing the battery out.
Two things:
1: The Battery kit came with the following:
-Wall charger (not the USB kind)
-Extended battery
-Back for the phone
and I spent a total of $15.
What I did was charge the battery nightly for 3 consecutive days/nights, each night draining the battery to 0% until the phone died, then taking off the back, putting the battery into the wall charger, and charging it to full, never touching it until then.
This worked well, and still does, the battery lasts anywhere from 12-22 hrs on a charge with moderate to high/mid-high usage.
Sadly though, I charged the battery on the phone, and took it off the charger this morning at 5:30am, and it's now 6:30am, and I get the typical 2-3% drop NO matter what I do, idle or otherwise, so I decided to run a 5 min video just to see what happened. Well to my disappointing finding, I am now at 90% battery, and that's JUST with a 5 min video, and NOTHING else.
2: I talked with multiple people, both techs and non-techs (not like the tech label means much) but still I talked around to see what their ideas and thoughts were on this issue. A couple of Sprint techs whom I trust and have proven themselves, said that they have discontinued selling the extended batteries at all, because of this exact same issue.
They stated that it's not just a single model or make, it's multiple phone models and makes, but they said the phones themselves didn't seem to either know how to charge the same as the wall charger or just didn't give the same "full type" of charge.
It seems that if you charge with the phone, it doesn't give it the (for lack of words) "deep" cycle charging that the wall charger does.
From what I have found in my testing, this seems to be the case. It would seem as if the wall charger I have is charging the battery to a fuller state, as compared to the phones charging system.
All in all, it's been an interesting test, but sadly I am disappointed, not that I spent the $15 and basically have a paper weight now, but that I can't use an extended battery

. I was SO looking forward to having the extra battery life. Oh I could use the battery and wall charger, that's true, but can you imagine the abuse the back phone cover would take, taking it off and on, even at every 2 days charge, over a extended period of time the back would be wasted and of no use, and then I'de really be in a bind, because the backs aren't exactly plentiful.
So for now I'll bite the bullet on this purchase and learn from it, and move on.
All I can say is, if you are thinking about buying an extended battery, please be leery of how it charges in your phone.
I am in NO way saying "all" extended batteries and/or phones have the same results, but I can say from what I was told and have tested, it seems to be the case, more-so than not.
If you still want pics I can upload them, but I don't really see a point, since the results are not so good.
Update:
I have been on this charge for longer than expected, so I have to retract what I initiall posted (even though I left the post).
I am currently coming up on 14 hrs now on a single charge, that is with moderatly high usage I would consider....perhaps above avg, and not high (shrug), and I still have 20% battery life left.
Initially I had thought because of the way it was draining and acting, I would have the same results as my 1600mah battery, but it seems as though the way it acts and drains is different. By different I mean no 2-3% drop at the first, and no sharp drop then level off.
It seems as if it drops that initial 2-3%, then levels for a couple hours, then drops off again, more-so than the first, then levels off again for quite awhile, then goes down in normal increments.
When I used the wall charger, I didn't get that 2-3% drop at first, and the drop offs were at different stages than they are now IE: with wall charger it would stay at like 80% for quite a bit, then drop off to about 60%, then stay then down to like 50, then 35, then 25, then 20, and stagger off at around15-20%, then stay a bit and then down to the 10% and gives me that warning.
Now it seems to do basically drop 2-3% about 98-97%, then drop to 65% or 60% and stay for a bit, then down to 50%, then 45%, then stagger every couple % down to 20% and stays at about 20% for an hr or 2, then I'm not sure after that, because I'm still at 20% this will amke like 2 1/2 hrs it's been at 20%.
So it's kinda hard to gauge really, but it seems as if it does indeed work...I guess. From asking around it seems as if 14-15 hrs is good, even for an extended battery.
Things I have done thus far are (and not in any certain order):
-Watched approximately Four to Five 3-4 min videos, namely becasue I was researching phones from boost, such as Samsung Transform Ultra, Lg Marquee, and also vs. like Warp vs. marquee, and transform ultra vs. warp.....checking to see about battery life and smoothness with the phone.
-posted 2 times on forums here, about 2-3 mins each one along with loading times
-about 40-50 texts
-10-15 phone calls, avg of 20-30 min each call.
-used GPS once for about 10 min
So I would consider that to be above avg use, if not moderately high maybe, maybe I'm exaggerating, but not intentionally. Each person has a different idea as to what high usage is and avg usage is.
I appologize if I mislead anyone with the post, it wasn't meant that way, just I jumped the gun, so I apologize for not waiting it out.