Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: What is the battery life span? How often will I need to buy a replacement?
Document: I haven't had the need to do that.The vacuum is quieter than I had expected. The battery life may seem short, but if you use it often and clean regularly, then the charge is enough time. There is also a low battery indicator light/warning. You choose when you need the more powerful suction mode, which will drain the battery faster.
This vacuum is fantastic for what it is, so think about what your needs are before you buy it. We have a rather small apartment with two small carpeted rooms. We're talking probably just over 200 sqft of carpeting + a couch. As such, this vacuum is perfect for us! It is lightweight, doesn't take up a lot of space, and the 15 min battery life is more than enough for what we need. It detaches REALLY easily when I want to use it to vacuum the couch.
The replacement battery varies from around $60-$80. I thought that rather than buy a battery, I'd just get a new one. So, when I hit Amazon looking for the latest, I came across the DC35. This model Is nearly perfect. Not only does it have a new digital motor, but it has the ability to be that great handheld I loved AND a floor vac.
I think this feature makes sense so you don't waste battery time. I have a small home (under 1200 sq. ft.) so I have never run the battery out, yet. I also rarely use the MAX setting. I don't really need to for my purposes. Remember, this vacuum is not meant to replace a full size machine. It is made for quick pick-ups. I use mine every day & often more than once a day.
And I did not feel any of 1-3 with sweepervac.Problem with sweepervac is that its life ends with battery life. But you can buy 10 of those with the cost of dyson.Cleaning easy? The dumping the dust is probably so.
This was after about 10-12 minutes of intermittent use variously with and without the powerhead. Contacting Dyson revealed the probable cause as a discharged battery. The battery life is rated at between six and 15 minutes, depending on power setting and powerhead use. So for 10 minutes of use the machine requires an hour or more recharging.If I had it to do over again I would not buy a Dyson.
No need to drag out the shop vac for normal cleaning.- The battery can be removed easily (with a button). The power cord plugs directly into the battery pack, meaning you can charge the batteries even when they are not inside the vacuum itself. This means you can buy an additional battery and have double the cleaning time by switching them out. It is so easy to use (and so much nicer than using a corded vac!)
Review? Does a Dyson really need a review? Ok. Here goes. Its a Dyson. Period. I works like a Dyson. Period. Nuff said. Ok I'll say that the battery life is good and that the suction is excellent. Yeah its a Dyson.
I'm pleasantly surprised at the suction of this cordless unit. it picks up as much as my Miele canister.With all of the comments I read about the short battery life, I was concerned, but the battery lasts long enough to do a room. If more rooms need to be vacuumed, pull out the corded unit.I like the ability to collect dirt in a visible container.
I love the idea of this stick vac but the battery life is much too short and the fact you have to hold the button in to use it is cumbersome. Yes, I understand it saves the charge time, but it's not worth the hassle. I read a few reviews that said life is too short to vacuum more than 15 minutes at a time. Maybe, but that's not reality. I have a dog and the house gets dirty. I need more than 15 minutes to do a thorough job.
Answer: I have this  Dyson for 4 years and the battery is fine, It is used regularly and has been perfect with excellent cleaning power. Remember to clean the head regularly and also to clean the filter as per the instructions.