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2010 AA Low Self Discharge Battery Review - "The big one"
2010 AA Low Self Discharge battery review
By Chris Dowling (December 2010)
Welcome to my 2010 review of low self discharge (LSD) AA batteries. I was not planning to do a follow up to my first review but somehow it seemed like a good idea a couple of months ago. The number of different brands tested has more than doubled and you will find a new champion unveiled at the end. I hope you will find it both informative and useful.
Changes since my last review in 2009
The LSD battery market has exploded. We the consumer have suddenly got an amazing choice of brands and capacities. I am amazed at how many brands are now for sale, but I do wonder how many are just rebranded products that all lead back to the big battery manufacturers somehow. Inevitably, as LSD technology matures battery capacity has risen. The largest capacity that I have spotted is a mighty 2500mAh. I only discovered these after I had already invested my money in the 8 new brands that I have added to the test line up this year. Perhaps next year I could add them to see if the claimed capacity is just that, or not. A total of 14 brands tested this time around which is far more than I planned for. I simply got carried away; will I find an excuse to expand the review again in 2011?
My interest in LSD batteries now means that I have more batteries than I need to power my gadgets. Some may say that I getting a little obsessed with the subject but my fascination added to the interest from readers gives me a good excuse!
Introduction
Parts of this review are taken from my 2009 article, the background to which was my rather mixed feelings about rechargeable batteries to that point. I wrote that I have had somewhat of a love/hate relationship with rechargeable batteries as I have found it very frustrating going to use a set which turned out to be flat. Even worse, if a set had fully discharged, even after investing in some expensive battery chargers they would then fail to charge, and be effectively useless. I then discovered that battery technology had moved on and low self discharge batteries had become available, which seemed to be the answer to my problems.
Up to that point, I had no real way of objectively testing rechargeable batteries, but after a failure of one of my Ansmann chargers I did a lot of research to look for a replacement. I bought the very impressive Maha (Powerex) MH-C9000 charger which allows control of charging and discharge rates; most importantly it is able to give the capacity of each battery. It was this purchase that gave me the inspiration and the ability to test batteries that led to me writing a review of LSD AA batteries.
What are Low Self Discharge batteries?
Low Self Discharge batteries (LSD) are a development from standard nickel metal hydride (NiMH) batteries. They are ideal for digital photographers and offer some real advantages. The most significant ones in my view are:
1) They will keep their charge when stored for a long time. Typically, the battery capacity will remain around 90% after six months and 80% after 12 months. Remember, standard NiMH will continuously discharge after charging when not in use. Sanyo now claim their new version of Eneloop will still retain 75% of their charge after 3 years; impressive.
2) LSD batteries have a flatter discharge curve under load which gives longer effective use when compared to a standard NiMH battery (assuming like for like capacity).
3) LSD batteries are supplied from new charged, so you can use them straight away; no delays while charging them.
4) Compared to standard NiMH batteries, the life of a LSD battery is significantly longer. LSD batteries can be recharged (cycled) many more times. You can reasonably expect the life of a LSD battery to be approx 1000 cycles before failure. This compares to approx 600 cycles for a NiMH battery. Sanyo has recently claimed that later versions of their Eneloop battery can have a life of 1500 cycles.
5) LSD will remain cooler than standard NiMH when discharged quickly.
6) LSD are capable of delivering higher current more quickly.
7) LSD battery performance at low temperatures is excellent, better than even regular alkaline batteries. They will be the ideal choice for that polar photo shoot that you have always dreamed of.
However, it is not all good news. LSD batteries do have disadvantages when compared to normal NiMH batteries:
1) The maximum capacity of an AA sized LSD is lower than standard NiMH batteries.
2) Standard NiMH batteries are generally cheaper, but the price of LSD batteries continues to drop as their use becomes more widespread.
3) Standard NiMH batteries are lighter due to the construction of LSD batteries.
Remember, the terminal voltage of rechargeable batteries is lower than standard non rechargeable batteries. Rechargeable batteries will only have a nominal terminal voltage of approx 1.2 volts compared to 1.5 volts for a non rechargeable. This needs to be considered when using rechargeable batteries in devices that are primarily designed for non rechargeable batteries. A good practical example of this is my GPS receiver in which I use LSD batteries: the battery indicator shows less than full power available when I insert a fully charged set of LSD batteries. Manufacturers will sometimes offer a selection in the setup menu of the device that allows the user to select what type of battery is being used to solve this issue.
LSD batteries still remain a relatively new development in the battery market. They started to become available in 2006.
LSD Technical Information
If you are interested in the technology of low self discharge batteries read on, otherwise just skip this section as I will not discuss any test results in it.
I have spent a while surfing the mighty web to try and find out a bit more about the technology that goes to make low self discharge batteries work. I thought this section would be useful just to give an insight into LSD. I could have included a lot of techno jargon but I have tried to keep it more as an overview. If you are keen, then there is an awful lot of in depth information to be discovered on the web.
Construction & Composition
In a nutshell LSD batteries are effectively pretty much the same as the established nickel metal hydride (NiMH) batteries that are so common. The difference is that the chemical construction of LSD batteries uses much purer chemicals and improved constructional techniques that give the result of a very slow discharge rate when the batteries are stored. The greater the amount of impurities in the battery, the greater rate of self discharge. New alloys have been produced especially for LSD batteries that further reduce the rate of self discharge. The composition of an LSD battery results in less chemical activity during storage. It is the amount of chemical activity that determines the amount of self discharge during storage. To be clear, both types discharge when not in use but LSD, as their name suggests do it at a much slower rate.
StorageCapacity & Current
The internal resistance of an LSD battery is lower, which contributes to the ability to remain cooler and deliver high current flow quickly. In theory, a battery that has a capacity of 2000 mAh should be capable of delivering a current of 2000mA (2 amps) for a period of 1 hour or 1000mA (1amp) for 2 hours. However, heavy current flow will reduce the effective capacity of the battery to prevent this being achieved. Lower current flow will result in a larger effective capacity before the battery will need to be recharged.
LSD batteries still cannot match the large capacity of NiMH batteries but the the advantage of being useful after long periods of storage really makes a powerful argument for using them. At the time of writing the largest NiMH battery that I could find for sale had claimed capacity of a whopping 3100mAh. That compares to 2500mAh for an LSD battery, a difference of 700mAh or approximately 22%. I am still amazed that for a battery the size of an AA it is possible to hold such large capacities. Certainly if you demand a battery with very high capacity, NiMH batteries have an advantage. But do remember that standard NiMH batteries will get hot when delivering high currents and do not have the ability to give high current quickly. For goodness sake don’t put your high capacity batteries in your pocket with a bunch of keys or coins otherwise you might just start a fire!
Charging
Charging rates are a significant factor that will ultimately decide the life of your batteries. Charging at a high rate will produce some apparent “benefits” as the capacity of the battery will likely be higher. Before you all rush and charge your batteries at a high rate there is a penalty to be paid in the long run as it will shorten the life of the battery. We all like the recharge time to be a short as possible but it is a delicate balance. I could write at length about charging times, rates, temperatures etc but I don’t think it would be of great benefit to this review. The web again is a good resource if you do happen to be interested.
Brands of LSD AA batteries
Last time, I tried to compile a comprehensive list of brands that you can buy at the time of writing. However, I have lost count of all the brands that are currently on the market. It is more appropriate to list more information about the brands tested and give a list of others to give an indication of the range of options that are now available. Please feel free if you spot other brands to let me know. As I said last year, “Even better, buy a set and lend them to me for testing so that we can see just how good they are!!” I will be more than happy to return them after testing.
Brands Tested
A total of 14 different types are tested which should give a good guide to the state of the market. As manufacturers develop their LSD batteries new versions will emerge. I purchased a set of “Vapextech Instant 2300mAh” for this review to see how they compared to the previous 2100mAh version. I also have added latest version of “Varta Ready 2 Go” to the review which offers a 2300mAh capacity against the previous 2100mAh version.
It might appear to be a strange thing to do but I have bought an industrial version of the Uniross Hybrio to see if there is any difference between this and the previously tested type.
(Note – AA capacity data is manufacturer’s claimed figures.)
Other available brands
Accu Evolution
Camlink ready 2 go
Digibuddy LSD
Digimax ready 2 use
Ene super
Enerpro
Enix nx-ready
Fujicell Prolife
JCB Ready Charged Rechargeable
Just Power LSD
Kodak pre-charged
Lloydtron Accu Ready
Maha Imedion (Lagest claimed capacity of 2500mAh)
Microbatt ready to use
Nex Cell EnergyON
Samsung Pleomax
Sony CycleEnergy pre-charged
Tenergy Centura
Turnigy AA LSD
Rayovac pre-charged
Ultra Max Rechargeabe Ready to Use
No doubt there are many more!!
Battery testing
I have not changed the method of testing from my original review. Every brand of battery was tested as a set of four. Each set were subjected to two different tests using the “Refresh & Test” mode offered by the Maha MH-C9000 charger. In this mode the charge and discharge rates are set by the user then the battery is fully charged and rested for one hour before fully discharging the battery. Then the battery is rested again before fully charging the battery again. At the end of the test the charger displays the capacity of each battery.
I chose to test each set of AA batteries twice as I wanted to see if there would be any difference in battery capacity if the batteries were charged and discharged at both low and high rates. Another benefit of testing each set twice was that I hoped that it would validate and highlight any suspicious test results. These tests took a long time to complete as testing just one set at the low rate, for example, took in excess of 10 hours.
One area of battery performance that I have not tested is the self discharge performance of each brand over time. This is a shame really, but I would actually like to use the batteries that I have bought rather than having them all stored for 6 or 12 months. I am just going to have the trust the manufacturer’s figures: this is an obvious weakness of my review.
Test 1 Low rate charge/discharge
Test 2 High rate charge/discharge
Test Notes
Capacity = mAh
Range = Difference between the highest and lowest battery capacity in mA
% = Range as a percentage of the lowest capacity battery tested
Claimed = Manufacturers claimed battery capacity mAh
% Lowest = Lowest capacity battery of tested set as a percentage of the claimed capacity
% Highest = Highest capacity battery of tested set as a percentage of the claimed capacity
% Set = Average capacity of set of 4 batteries as a percentage of the claimed capacity
Test data
Let me first explain the test data
Capacity – Columns 1,2,3,4 are just the capacity of each battery in mAh. For example, if a battery has a capacity of 2000mAh it would in theory be able to supply a load of 500mA for 4 hours or 1000mA for 2 hours.
Range - Ideally, range should be 0 but there will always be a difference between batteries; the lower the number the better.
% - is the range figure as a percentage of the lowest capacity battery tested; again, the lower the percentage the better.
Capacity of manufacturer’s specifications – Just to see if the capacity of the batteries under test actually matched the manufacturer’s claimed figure. The best result would be 100%. Would it not be a nice change if a battery exceeded the manufacturers figure to give a > 100% value?
Best individual battery – The individual battery of the set under test with the highest capacity. To be honest, this in my view is just a nice to know figure and is not really relevant, as a set of 4 batteries will be limited by the worst battery in the set.
Worst individual battery – The individual battery of the set under test with the lowest capacity. This is the result that I was most interested in as the weakest battery of a set will be the one that limits the useful life of a set of batteries.
Conclusions / Final thoughts
By Chris Dowling (December 2010)
Welcome to my 2010 review of low self discharge (LSD) AA batteries. I was not planning to do a follow up to my first review but somehow it seemed like a good idea a couple of months ago. The number of different brands tested has more than doubled and you will find a new champion unveiled at the end. I hope you will find it both informative and useful.
Changes since my last review in 2009
The LSD battery market has exploded. We the consumer have suddenly got an amazing choice of brands and capacities. I am amazed at how many brands are now for sale, but I do wonder how many are just rebranded products that all lead back to the big battery manufacturers somehow. Inevitably, as LSD technology matures battery capacity has risen. The largest capacity that I have spotted is a mighty 2500mAh. I only discovered these after I had already invested my money in the 8 new brands that I have added to the test line up this year. Perhaps next year I could add them to see if the claimed capacity is just that, or not. A total of 14 brands tested this time around which is far more than I planned for. I simply got carried away; will I find an excuse to expand the review again in 2011?
My interest in LSD batteries now means that I have more batteries than I need to power my gadgets. Some may say that I getting a little obsessed with the subject but my fascination added to the interest from readers gives me a good excuse!
Introduction
Parts of this review are taken from my 2009 article, the background to which was my rather mixed feelings about rechargeable batteries to that point. I wrote that I have had somewhat of a love/hate relationship with rechargeable batteries as I have found it very frustrating going to use a set which turned out to be flat. Even worse, if a set had fully discharged, even after investing in some expensive battery chargers they would then fail to charge, and be effectively useless. I then discovered that battery technology had moved on and low self discharge batteries had become available, which seemed to be the answer to my problems.
Up to that point, I had no real way of objectively testing rechargeable batteries, but after a failure of one of my Ansmann chargers I did a lot of research to look for a replacement. I bought the very impressive Maha (Powerex) MH-C9000 charger which allows control of charging and discharge rates; most importantly it is able to give the capacity of each battery. It was this purchase that gave me the inspiration and the ability to test batteries that led to me writing a review of LSD AA batteries.
What are Low Self Discharge batteries?
Low Self Discharge batteries (LSD) are a development from standard nickel metal hydride (NiMH) batteries. They are ideal for digital photographers and offer some real advantages. The most significant ones in my view are:
1) They will keep their charge when stored for a long time. Typically, the battery capacity will remain around 90% after six months and 80% after 12 months. Remember, standard NiMH will continuously discharge after charging when not in use. Sanyo now claim their new version of Eneloop will still retain 75% of their charge after 3 years; impressive.
2) LSD batteries have a flatter discharge curve under load which gives longer effective use when compared to a standard NiMH battery (assuming like for like capacity).
3) LSD batteries are supplied from new charged, so you can use them straight away; no delays while charging them.
4) Compared to standard NiMH batteries, the life of a LSD battery is significantly longer. LSD batteries can be recharged (cycled) many more times. You can reasonably expect the life of a LSD battery to be approx 1000 cycles before failure. This compares to approx 600 cycles for a NiMH battery. Sanyo has recently claimed that later versions of their Eneloop battery can have a life of 1500 cycles.
5) LSD will remain cooler than standard NiMH when discharged quickly.
6) LSD are capable of delivering higher current more quickly.
7) LSD battery performance at low temperatures is excellent, better than even regular alkaline batteries. They will be the ideal choice for that polar photo shoot that you have always dreamed of.
However, it is not all good news. LSD batteries do have disadvantages when compared to normal NiMH batteries:
1) The maximum capacity of an AA sized LSD is lower than standard NiMH batteries.
2) Standard NiMH batteries are generally cheaper, but the price of LSD batteries continues to drop as their use becomes more widespread.
3) Standard NiMH batteries are lighter due to the construction of LSD batteries.
Remember, the terminal voltage of rechargeable batteries is lower than standard non rechargeable batteries. Rechargeable batteries will only have a nominal terminal voltage of approx 1.2 volts compared to 1.5 volts for a non rechargeable. This needs to be considered when using rechargeable batteries in devices that are primarily designed for non rechargeable batteries. A good practical example of this is my GPS receiver in which I use LSD batteries: the battery indicator shows less than full power available when I insert a fully charged set of LSD batteries. Manufacturers will sometimes offer a selection in the setup menu of the device that allows the user to select what type of battery is being used to solve this issue.
LSD batteries still remain a relatively new development in the battery market. They started to become available in 2006.
LSD Technical Information
If you are interested in the technology of low self discharge batteries read on, otherwise just skip this section as I will not discuss any test results in it.
I have spent a while surfing the mighty web to try and find out a bit more about the technology that goes to make low self discharge batteries work. I thought this section would be useful just to give an insight into LSD. I could have included a lot of techno jargon but I have tried to keep it more as an overview. If you are keen, then there is an awful lot of in depth information to be discovered on the web.
Construction & Composition
In a nutshell LSD batteries are effectively pretty much the same as the established nickel metal hydride (NiMH) batteries that are so common. The difference is that the chemical construction of LSD batteries uses much purer chemicals and improved constructional techniques that give the result of a very slow discharge rate when the batteries are stored. The greater the amount of impurities in the battery, the greater rate of self discharge. New alloys have been produced especially for LSD batteries that further reduce the rate of self discharge. The composition of an LSD battery results in less chemical activity during storage. It is the amount of chemical activity that determines the amount of self discharge during storage. To be clear, both types discharge when not in use but LSD, as their name suggests do it at a much slower rate.
StorageCapacity & Current
The internal resistance of an LSD battery is lower, which contributes to the ability to remain cooler and deliver high current flow quickly. In theory, a battery that has a capacity of 2000 mAh should be capable of delivering a current of 2000mA (2 amps) for a period of 1 hour or 1000mA (1amp) for 2 hours. However, heavy current flow will reduce the effective capacity of the battery to prevent this being achieved. Lower current flow will result in a larger effective capacity before the battery will need to be recharged.
LSD batteries still cannot match the large capacity of NiMH batteries but the the advantage of being useful after long periods of storage really makes a powerful argument for using them. At the time of writing the largest NiMH battery that I could find for sale had claimed capacity of a whopping 3100mAh. That compares to 2500mAh for an LSD battery, a difference of 700mAh or approximately 22%. I am still amazed that for a battery the size of an AA it is possible to hold such large capacities. Certainly if you demand a battery with very high capacity, NiMH batteries have an advantage. But do remember that standard NiMH batteries will get hot when delivering high currents and do not have the ability to give high current quickly. For goodness sake don’t put your high capacity batteries in your pocket with a bunch of keys or coins otherwise you might just start a fire!
Charging
Charging rates are a significant factor that will ultimately decide the life of your batteries. Charging at a high rate will produce some apparent “benefits” as the capacity of the battery will likely be higher. Before you all rush and charge your batteries at a high rate there is a penalty to be paid in the long run as it will shorten the life of the battery. We all like the recharge time to be a short as possible but it is a delicate balance. I could write at length about charging times, rates, temperatures etc but I don’t think it would be of great benefit to this review. The web again is a good resource if you do happen to be interested.
Brands of LSD AA batteries
Last time, I tried to compile a comprehensive list of brands that you can buy at the time of writing. However, I have lost count of all the brands that are currently on the market. It is more appropriate to list more information about the brands tested and give a list of others to give an indication of the range of options that are now available. Please feel free if you spot other brands to let me know. As I said last year, “Even better, buy a set and lend them to me for testing so that we can see just how good they are!!” I will be more than happy to return them after testing.
Brands Tested
A total of 14 different types are tested which should give a good guide to the state of the market. As manufacturers develop their LSD batteries new versions will emerge. I purchased a set of “Vapextech Instant 2300mAh” for this review to see how they compared to the previous 2100mAh version. I also have added latest version of “Varta Ready 2 Go” to the review which offers a 2300mAh capacity against the previous 2100mAh version.
It might appear to be a strange thing to do but I have bought an industrial version of the Uniross Hybrio to see if there is any difference between this and the previously tested type.
(Note – AA capacity data is manufacturer’s claimed figures.)
Other available brands
Accu Evolution
Camlink ready 2 go
Digibuddy LSD
Digimax ready 2 use
Ene super
Enerpro
Enix nx-ready
Fujicell Prolife
JCB Ready Charged Rechargeable
Just Power LSD
Kodak pre-charged
Lloydtron Accu Ready
Maha Imedion (Lagest claimed capacity of 2500mAh)
Microbatt ready to use
Nex Cell EnergyON
Samsung Pleomax
Sony CycleEnergy pre-charged
Tenergy Centura
Turnigy AA LSD
Rayovac pre-charged
Ultra Max Rechargeabe Ready to Use
No doubt there are many more!!
Battery testing
I have not changed the method of testing from my original review. Every brand of battery was tested as a set of four. Each set were subjected to two different tests using the “Refresh & Test” mode offered by the Maha MH-C9000 charger. In this mode the charge and discharge rates are set by the user then the battery is fully charged and rested for one hour before fully discharging the battery. Then the battery is rested again before fully charging the battery again. At the end of the test the charger displays the capacity of each battery.
I chose to test each set of AA batteries twice as I wanted to see if there would be any difference in battery capacity if the batteries were charged and discharged at both low and high rates. Another benefit of testing each set twice was that I hoped that it would validate and highlight any suspicious test results. These tests took a long time to complete as testing just one set at the low rate, for example, took in excess of 10 hours.
One area of battery performance that I have not tested is the self discharge performance of each brand over time. This is a shame really, but I would actually like to use the batteries that I have bought rather than having them all stored for 6 or 12 months. I am just going to have the trust the manufacturer’s figures: this is an obvious weakness of my review.
Test 1 Low rate charge/discharge
Test 2 High rate charge/discharge
Test Notes
Capacity = mAh
Range = Difference between the highest and lowest battery capacity in mA
% = Range as a percentage of the lowest capacity battery tested
Claimed = Manufacturers claimed battery capacity mAh
% Lowest = Lowest capacity battery of tested set as a percentage of the claimed capacity
% Highest = Highest capacity battery of tested set as a percentage of the claimed capacity
% Set = Average capacity of set of 4 batteries as a percentage of the claimed capacity
Test data
Let me first explain the test data
Capacity – Columns 1,2,3,4 are just the capacity of each battery in mAh. For example, if a battery has a capacity of 2000mAh it would in theory be able to supply a load of 500mA for 4 hours or 1000mA for 2 hours.
Range - Ideally, range should be 0 but there will always be a difference between batteries; the lower the number the better.
% - is the range figure as a percentage of the lowest capacity battery tested; again, the lower the percentage the better.
Capacity of manufacturer’s specifications – Just to see if the capacity of the batteries under test actually matched the manufacturer’s claimed figure. The best result would be 100%. Would it not be a nice change if a battery exceeded the manufacturers figure to give a > 100% value?
Best individual battery – The individual battery of the set under test with the highest capacity. To be honest, this in my view is just a nice to know figure and is not really relevant, as a set of 4 batteries will be limited by the worst battery in the set.
Worst individual battery – The individual battery of the set under test with the lowest capacity. This is the result that I was most interested in as the weakest battery of a set will be the one that limits the useful life of a set of batteries.
Conclusions / Final thoughts
Benedict
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