battery (purchased separately) lasts a good while (can't give a time
936105
I've been quite impressed with this... battery (purchased separately) lasts a good while (can't give a time, but here and there all day). Replacement chain isn't too easy to find though.
2928439
It's too soon to really say as I've only had the battery for a few days but so far the performance is very good. i go through a full ten to twelve hours and still have around 40 percent of a charge.
I did leave the battery off of the charger until I got a "low battery" warning (15 percent charge) once and that happened at hour 18, pretty good.
This is still what I call the 'break in' period, charged over night once a day for 4 days.
I'll write again in a couple of months to say more.

Other than that I can say that I ordered the battery at 2 AM on Wednesday and received it a 8 PM the same day - and the delivery guy actually rang my doorbell and waited instead of just leaving the package at the door with no doorbell ring. Nice.
1855637
Update Sept 2016.  While I initially posted a 5 star review (see below), the battery only lasted 6 months before it failed and would only last about 10 mins before dying.  Perhaps these are old stock - not sure.  For the price, I guess I can't complain too much but these typically last several years or more - so there is obviously some issue with them.  I am ordering some of the newer versions of this battery.  I have had good luck with these even though they aren't the OEM battery.  https://www.amazon.com/gp/product/B008TLW56E/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A20H555M9MROEP

Just like the battery inside the phone.  This is used in an older Uniden cordless phone (900 megahertz model from the late 1990s) that incredibly is still working.  The antenna broke off in the  last year - but it still works.  It's amazing how durable these older products were - much more solid than the current cordless phones.  This is my wife's favorite phone so when it starting dying after just 30 minutes of use, I knew it was time to get a new battery.  This one works perfectly.  Now if Uniden would bring back phones like this we would be all set.
4293372
It's been 2 years since I purchased this product. The user experience has been ok. It works as advertised. I don't care about sound quality that much, so this headphone works for me. However, as time goes by, the battery life slowly declines, until today it only lasts 15 minutes, which is clearly unusable anymore. Had to throw it away and get a new one. I would expect the product to longer life time.
2690700
Battery life has a short shelf life, otherwise it is a good piece
1002441
The only time I use the battery is when I am out for long periods of time and need to recharge my phone. Maybe a couple times a month, with normal usage. I keep it in my bag while it's charging my phone, so it doesn't get jumbled around a lot or anything like that. I have had it for less than a year and the built in cord NO LONGER WORKS, which is pretty annoying and makes me unhappy with the product. Yes, the battery still works, but the whole point in buying this one was that I wouldn't have to carry an extra cord around with me. I am definitely going  to contact the seller to see that they can do about this.

Take your chances, hopefully the cord doesn't stop working on you too.
494615
The battery doesn't fit my mac perfectly, one corner sticks out a bit. In terms of performance, the first couple of months I got about 75-90 minutes of use, which is what I was expecting. However, after 2-3 months, that dropped to 30 minutes of average use. I contacted the seller and they agreed to replace the battery if I first return the faulty one. I would have been without a battery if I sent it in so I decided to just keep it. 2 years later, I mainly use my laptop while plugged in and get about 20-30 minutes if I have to use the battery.
278636
Purchased for my XPS 13 L322X that couldn't get more than 1hr anymore on its original battery, and that was in battery saver-mode besides.

Took about 30min to install, but this isn't my first time taking apart laptops.  It worked for a few minutes, then the laptop started saying there was no battery.  I took the laptop apart, and realized I didn't plug the battery in all the way.  Certainly no fault of the product.

I charged the laptop last night, and have been using the laptop for about 2.5 hours, and still have about 2.5 hours left on the battery, which was about what I remember when it was new.  For the price, I wish I had bought this battery a year ago.

Will update in ~6 months to say how it's working then.

Update ~6mo later:  getting anywhere from 3.5-4.5 hours still. I have noticed a couple keys on my keyboard aren't working reliably, so I'm going to clean it out, then am probably going to re-install the keyboard and see if that helps. May just be a hazard of doing such an install yourself.

Update ~12mo later: the battery is still lasting 3.5-4.5h depending on use, however the keyboard is still having issues and the touchpad has since starting sticking up strangely.  I just opened the laptop up to try and get the keyboard working fully again, and realized the battery is swollen in multiple places- thus causing the touchpad to stick out.  I'm wondering if this is the cause of the keyboard issues as well.

After a quick google, I found: "Dont charge or use it at all, because lithium-ion (Li-ion) batteries that are bulging have already bypassed built-in safeguards and are swollen with gases. Continued charging or use could lead to a runaway reaction that results in a fire or an explosion."

So, I'll now be removing this battery and disposing of it out of fear of it starting a fire.  1 star, as this should have lasted more than 12 months.
3418832
UPDATE from November-2016 purchase:  After working fine for 2+ months, the battery life has just died.  I charge it completely -- the same way I've charged it and the previous 2 batteries in the past.  But it just won't hold a charge anymore.  I purchased the same battery from this vendor in July-2010 and it lasted until November-2013 -- the same battery life as the originally installed battery -- so I gave it 5 stars.  But not this time around.  Reading other reviews, I see inconsistency in performance and few recent reviews.  I'm going to look for another vendor..
234504
Good and cheap...but...after a few months the battery dies in a couple of hrs!
1355059
Batteries don't last long, but I'm always charging the extra one so I can replace it right away if I'm low
255248
Would give this 5 stars if the battery didn't die out so quickly.
4746066
I have no complaints about the battery.  Upon installation it showed 3 usage cycles (which I assume comes from testing at the factory) and after 10-15 cycles its holding up just fine.  The tools that are included with the battery are made from such soft metal that they are useless after turning a few of the screws.
3984
Still have mine battery lasted a year or so i don't use it and it can be a little off after a long time like it may go 4 mins ahead or back
4633503
Not sure I saw anyone mention how short the battery life is? I'm happy with the function otherwise. But an hour or so of battery is just not good to get from a new unit.
4248964
Just got the battery, it was nicely packaged and came on time. The box had a very useful and informative guide on how to charge the battery and such. It offers detailed instructions about the discharge and recharge process--but I thought this was unnecessary with Li-ON batteries? Odd. Anyhow, I drained the battery almost completely and will charge the battery for 12 hours per the instructions. I will make an update on this review when the battery is at full charge and compare it to my old OEM battery. I will also update in 3 months or so, to see whether the battery will be reliable and keep its original charge, whatever that might be.

As for the battery fitting, it fits perfectly into my Dell Studio 1555 and the computer recognized it with no problems. I didn't notice that the "Wh" for the OEM battery is 56 while for this battery, it says 49 Wh (which it does say in the description). Guess this might affect battery life? From what I estimate, it should hold a maximum charge around 2 hours. My old battery lasted around 4.5 years until the "replace battery" icon popped up. I think the old battery lasted at max for 3 hours but the last 2 years or so, it barely holds around 2.5 hours. This is on power saver mode and fairly low screen brightness. I got this laptop back in 2009, however, in the last two years, I haven't used the laptop extensively. Mostly used during travel to watch TV shows and basic web surfing and Youtube. It also has a dedicated graphics card--affects battery life most likely.

Update One- 8/23/2013- The battery has been charged to a full 100% charge with no problems. The longest the battery will last in power save mode is just short of 2.5 hours. I will (almost) completely discharge the battery and charge it to full again for the 12 hour period--to see if there are any gains in battery life. If there isn't any discernible difference, I will stop doing the whole discharge/recharge process and see how that goes from there.

Update Two- 8/24/2013- The Battery seemed to increase in battery life somewhat. When I first turned the laptop on, it said the battery would last roughly 2.5 hours. At about 84% remaining battery life, it is saying a little under 3 hours. Of course, I am just allowing the battery to drain and am not actively using it. From this, I will guess that the battery will last around 2.5 hrs with moderate usage and 2 hours with heavy usage. This is with the "high-performance" power option.

On power save mode, I am convinced it'll last at least 2.5hrs, maximum 3. For my purposes, this is sufficient. I don't even remember how long the OEM battery lasted. Most of the time, I plugged it in. But, from what I have observed, both the OEM battery and this one are the same, difference is, the OEM battery is easily over 100$ (I think its around 120$ on the dell.com website). I will do a three month review (or earlier) depending on the reliability of the battery!

Update Three- The battery is still going strong! I still don't use it very often on my Dell Studio 1555 (esp since the laptop's heatsink is completely non-functional) but from using it solely on battery on the airplane or times where I need to move it around the battery life seems just as good as the original battery the laptop came with. I haven't noticed any loss of charge or degradation of any kind.
3647734
Mixed feelings about this battery, so I'm going to merge the two times I've had it into one review. The first one I had died within the year which is why I'm leaning towards a 3 star. On the other hand, it's a mini battery and has been great in my EVO the second time around, and is currently holding strong. The price point is also nice and having it on prime is definitely a big plus. I don't know what battery would be better than this, as it is highly recommended across various forums, and so depending how long this battery lasts, I will probably continue purchasing these.