It depends on what you mean. I find with heavy use they last just less than other batteries before they need to be recharged. And again with HEAVY USE I find them to last about 24 months before they need to be replaced (sometimes longer).

it depends which company you buy but if you buy from a normal company it usually works about 6 hours on stuff that regular duracell works 8 hours.

There are two ways to address 'How Long will they last'. How long will a battery power a device before it needs to be recharged, and how long will a battery be able to be charged / discharged before it stops doing that? This answer addresses the 1st question. In a simple view, the total time is simply the total battery capacity (Ah) divided by the average current draw(A) with will result in Hours. But in more detail, there are five factors which effect 'how long batteries will last'. 1) Total energy capacity of the battery, typically stated in Amp-Hours (Ah) 2) Average current draw of the device being powered 3) Design point for battery to be discharged to. 4) Age of the battery and its prior care 5) Self discharge characteristics of the battery. WARNING! The following is a WHOLE LOT of TMI, and includes math... If you want to jump to the end to get a slightly simpler approach, scroll down to "<<< QUICK WAY TO GET ESTIMATE >>>" ==================================== The Detailed answer ==================================== Batteries storage capacity is typically stated in AHs. This is the total amount of energy stored in the battery that can be drawn out until it if fully discharged. In a simple view, one would take the amount of power the device is using, divide the total AHs of the battery by that, and you would get the 'life' of the battery. For example. If you have a 12v lamp bulb that draws 2Amps, and you connect it to a car battery that has say 120Ah capacity, then you would be able to light the lamp for 120Ah/2A = 60 Hours before the battery is totally discharged. This simple approach works for others, for example if you have a radio which draws say 0.2A, and power it with AA cells which have say 0.44Ah capacity, then you get 0.44/0.2, or approx 2 hours of play time. These are the two most important figures to know when calculating battery life. AHs of the battery, and current draw of the load. But, like most things in life it is not that simple. Batteries typically do not like to be 100% discharged. Different batteries have different rated discharge points, but they all have a designed discharge point. Example, the Car Battery above: These are typically Lead-Acid batteries and they like to be discharged no more then 50%. And that is only if the 'battery' is a special 'Deep Cycle' battery. A typical car/starter batter might like to go down to only say 20%. But we will assume you have a Deep Cycle battery. One can go beyond this design point, but doing so might damage the battery and very likely will shorten its total number of charge/discharge cycles it can do before failing. So, using the above example, we are now looking at: 120Ah, with 50% 'usable' capacity gives us 60Ah usable capacity. So, now we do 60Ah / 2A lamp --> 30 Hours us run time. Now, the NiCad AA batterys we are using to power our radio can go down to say 80%, so our 0.44Ah is now 0.44 * .8 = 0.352Ah usable. At the 0.2A draw, we are down to 1.75 hours. A little less, but not a much of a 'drop' as the car battery. But, it is not that simple :-) Batteries are typically chemical devices, and store energy in a chemical form. And the total capacity of energy that can be removed from a battery is effected by how fast you try to remove it. In short, if you try to get it out very quickly, well, you will often not be able to get as much out. Using our car battery example. Lets say instead of the 2A bulb, we connect up a couple of head lights. Now, assuming each head light draws say 10A (these are 'powerful headlights), we have a total current draw of 20A. Now our situation looks like: 120Ah, 50% usable --> 60Ah available, divided by 20A = 3 hours. But at a 3 hour draw, the battery may again be de-rated by say 40% (in the math, we would actually multiply by 60%) So, we now need to figure in: 120Ah * 60% de-rated capacity * 50% usable capacity = 36Ah. Diving that by 20A gives us a little short of 2 hours (1.8 hours by the math) Ok, so now we have: Total battery capacity, Total current draw, Usable discharge design point, and a factor to include if we are trying to pull the power out in a short time. What else is there? The last two: 4) Age / number of prior charge / discharge cycles a battery has done, and 5) How long ago was it that the battery was charges? As a battery ages, both in terms of time and the number of charge/discharge cycles it goes through, its capacity is reduced. Foe example with out car battery. lets say it is 2 years old, and been around the block a few of times. Might even of had the Head Lamps left on by mistake a couple of times and been totally 100% discharged. Well, this 120Ah battery might only have 60Ah ability left in it! You can do the math, just like above, but now we are starting with half the capacity as before.... Taking care of your battery. Keeping it clean and charged and not overly discharging it beyond the design point will help extend a battery's life. Not doing that will quickly shorten it. For example, a typical life expectancy for a 'Deep Cycle' car battery is around 100 charge / discharge cycles. But if you routinely take it down to say 90% discharged, well, you might only get 10-15 total cycles out of it... And finally, All batteries will 'self discharge' just sitting there doing nothing. Some self discharge faster then others. Example: Lead-Acid will typically loose 2% / mo, which a Nicad might loose 10-15%/mo. So, if a battery had been charged, and then left on the shelf it might have a bit less energy left in it before you even start using it. So, what does all this mean. Is there a simpler way to look at this. Well, kind of: ================================================== <<< QUICK WAY TO GET ESTIMATE >>> ================================================== What you can do it start the AH of the battery (should be listed somewhere on the battery its self), do some discount factor to adjust for the issues above. For NiCads and LiIon batteries (like you will find in computers and small consumer items) I would multiply the stated Ah capacity by 80%, and for larger Lead-acid (ala Car batteries) multiply the stated capacity by 40% to get a quick estimate of the total usable energy in those batteries. Then simply divide that number by the rated current draw of the divide you are powering. Examples. How long can I leave the 2A dome light on in my car? Take battery Ah capacity, using only 40% of that and divide by 2A 120Ah * 40% of that gives 48Ah divide by 2A, gives 24 hours. But then you will have nothing left to start the car! Another example: My Radio uses 0.2A, and I power it using 440Mha batteries. 0.44Ah at 70% capacity = 308mAH, divide by 0.2A gives 1.54 hours. Around 1 and a half hours. This is for new batteries. If they are older, well, expect about 1/2 of the above. And do remember, that all batteries will wear out over time. Hope this helped, and so sorry for the LONG answer!

There are two ways to address 'How Long will they last'. How long will a battery power a device before it needs to be recharged, and how long will a battery be able to be charged / discharged before it stops doing that? This answer addresses the 2nd question. A rechargeable battery life is measured in its ability to be recharged to some level near its original rated capacity when it was new. Over time, this ability is reduced until a battery gets to the point where is only able to hold a small portion of its original capacity. For example. A battery might be rated at say 120Ah total energy capacity when new, and designed to preform 100 charge / discharge cycles until it can only 'hold' 80Ahs, at which time it is considered 'used up'. A cell phone battery might last say 200 charge / discharge cycles (about a couple of years) until its capacity is so small you can not get it to 'hold a charge' one day. All batteries have different design points, and it is a factor of the battery make up (lead acid, NiCad, LiIon, etc), as well as the quality of design. This is a case where you will typically get what you pay for :-) In the case of small batteries like those using in Cell Phones, or Radios, well. Those might give you 200to 300 cycles before their ability to hold a charge is so low it just bugs ya and you go out and get a new one. Larger 'industrial' batteries might be good for 4,000 cycles, but then they might also weigh 1,000lbs! Some things that will shorten batteries total life cycle include: 1) Quality of design and battery in 1st place. This is perhaps the biggest factor. 2) Quality of charger, this is the 2nd biggest factor. 3) Not routinely overly discharging the battery. Some batteries like to be discharged (ala NiCads), while others REALLY do not, like the Lead Acid battery in your car 4) Other small factors, like excessive heat, rate of discharge, etc... In the end, with typical use, you should expect maybe 2 years out of a Cell phone battery. Maybe 1-2 years out of a Lap Top battery. 4-6 years out of a car battery (much depends on the quality of the battery in the 1st place). Hope this helps.

NOT that long i do not recomend them

They seem to wear out pretty quickly.

The life of a rechargeable battery operating under normal conditions is generally between 500 to 800 charge-discharge cycles. This translates into about three years of battery life for the average user. As the rechargeable battery begins to die, the user will notice a decline in the running time of the battery. When a battery that originally operated the flashlight for a whole shift is only supplying the user with an hour's worth of use, it's time for a new one. http://www.laptop-battery-inc.co.uk http://www.power-batteries.net http://www.battery-chargers.org

Do you mean how long will the charge last or how many rechargings will they last for? The former depends on the current drain of the item using the batteries and how well charged the batteries are. With NiCads which have a 'memory' they should be fully discharged, and I do mean fully discharged, before recharging. Mickel Metal Hydride, Lithium Ion or Lithium batteries do not have 'memories' so the discharge state is not important so even 'half' charged ones can be rechagered to full capacity. The vital issue with all batteries, and this cannot be stressed strongly enough, is to only recharge at the makers ratings, or less. Fast charging will result in a drastically shortened life, don't do it whatever the makers say, buy a few more batteries and keep them topped up by 'trickle charging'. A good rule of thumb is that the charge rate should be 1 tenth of the battery capacity, for example if the battery has a rating of 1 Amp/hour the charge rate should be no more than 100mA for a 12 to 16 hour cycle, if the charge rate is cut down the time can be lengthened. If these rates of charge are adhered to 500 recharge cycles are the minimum that can be expected with a good quality battery. I personally have NiCads which are 20 years old and have had over 1,000 recharges although I am slowly converting to Nickel Metal Hydrides. Over 30 years ago I built a multirange charger with a number of plug-in battery boxes to serve for PP3 and PP9 batteries and AAA, AA, C and D cells for torches and the like. It isn't as pretty as shop bought ones but 'handsome is as hansome does', and I have modified all of the mains/battery equipment at my home I have trickle charging, 20mA for D cells and 10mA for C cells.

The life of rechargable batteries vary from the type of material to how it is used and maintained. Here is an example: Table of rechargeable battery technologies Type VoltageEnergy de Power EfficiencE/$ Disch. Cycles Life (V) (MJ/kg) (Wh/kg) (Wh/L) (W/kg) (%) (Wh/$) (%/mo) (#) (years) Lead-acid 2.1 0.11-0.1430-40 60-75 180 70%-92% 5 – 8 3%-4% 500-800 3 (automotive Alkaline 1.5 0.31 85 250 50 99.90% 7.7 < 0.3% 100-1000 <5 Ni-iron 1.2 0.18 50 N/A 100 65.00% 5 – 7.3 20%-40% N/A 50 Ni-cadmium 1.2 0.14-0.2240-60 50-150 150 70%-90% N/A 20.00% 1500 N/A NiMH 1.2 0.11-0.2930-80 140-300 250-1000 66.00% 1.37 20.00% 1000 N/A Ni-zinc 1.7 0.22 60 170 900 N/A 2 – 3.3 N/A 100-500 N/A Li ion 3.6 0.58 160 270 1800 99.90% 2.8 – 5.5%-10% 1200 2 – 3 Li polymer 3.7 0.47-0.72130-200 300 3000 99.80% 2.8-5.0 N/A N/A 2 – 3 LiFePO4 3.25 N/A 80-120 170 1400 N/A 0.7-1.6 N/A 2000 N/A Li sulfur 2 0.94-1.44400 N/A N/A N/A N/A N/A N/A N/A Nano Titanat2.3 N/A 90 N/A 4000 87-95%r 0.5-1.0 N/A 9000 20 V redox 1.4-1.6N/A 25-35 N/A N/A 96.00% N/A N/A 14000 10(stationary

I have 4 rechargable batteries (for camera and remote) that I have been using for almost 3 years now.

It depends on what you are using the batteries for. For example, I use my nimh batteries on my xbox 360 controllers and i receive about 18 plus hours of play time off of one charge, but if i used them in something like a flying model airplane the batteries would be dead in a matter of minutes. In my expierence if you purchase a good brand, like sanyo rechargeable nimh(Nickel metal hydride) batteries they can be recharged like over 1000 times and last well over a year. Furthermore, it only costs like 30 bucks for 8 AA and 2 AAA batteries so it is well worth your money. Plus they on one charge Nimh batteries last more than triple times the one time use batteries in a device. So you would definitely save money in the long run. Oh ya and it came with a charger

Too vague a question. What sort of load is on it? (What are you using it for?) What is the mAH rating of the battery? What chemistry is the battery; NiMH, NiCad....? Too many variables.

The packaging will usually say how many good recharges you can expect. Read before throwing away the packaging.