eneloop review

General Description:

Sanyo Eneloop is a special type of low self-discharge nickel-metal hydride (LSD NiMH) rechargeable battery first introduced by Sanyo in November 2005. Eneloop batteries are one of the most environmentally friendly and long lasting batteries available to consumers. Sanyo Eneloop is backed by revolutionary technology that separates itself from the conventional NiMH Batteries. Sanyo Eneloop cells have considerable advantages over the conventional NiMH Battery. It overcomes a major disadvantage (high self discharge) of conventional NiMH Battery. A conventional NiMH Battery can be charged only up to 500 times and looses about 10-15% of its charge on the first day itself. In contrast the Sanyo Eneloop retain up to 85% of its charge even after one year. Not only that but they can be recharged up to 1000 times. DepotEco.com offers an excellent deal on this environmentally friendly Sanyo Eneloop Power Pack. Sanyo Eneloop ready to use Power Pack is a super saver, very economical pack with loads of accessories. It mainly consists of all the types general purpose batteries you will ever need. The pack contains 8, yes that’s right EIGHT standard AA sized cells and 4 standard AAA sized Sanyo Eneloop cells. Accessories include one 4 bay overnight charger, two C size cell adapters and two D size cell adapters.

Let’s have a detailed look at some of the features, advantages and disadvantages of Conventional NiMH and LSD NiMH Batteries.
Conventional NiMH Battery:

 

• Conventional NiMH Batteries were first introduced in 1980’s but the commercialization occurred in mid 1990’s
• High Energy & Power to Weight ratios. Energy/weight about 70 Watt Hr/kg; Power/weight about 900 Watts/kg
• High Energy to Size ratio about 250 Watt Hr/L
• Nominal voltage of conventional NiMH Battery is approximately about 1.2 Volts per cell (1.45 Volts “hot off” charger)
• Conventional NiMH Battery has low internal resistance
• Conventional NiMH Battery have ability to deliver consistently high currents
• Typical life span of conventional NiMH Batteries is about 500 charge discharge cycles
• But the major disadvantage of conventional NiMH Battery is high self discharge rate; typically of the order of 1% per day. The first day discharge is considerably higher typically of the order of 10% to 15%

The main cause of high self discharge rate for conventional NiMH Battery is mainly because of the positive electrode reduction reaction due to dissolved negative electrode material, decomposition of the positive electrode and “shuttle effect” of nitrogenous compounds. Researchers at Sanyo found out that the self discharge mechanisms can be significantly suppressed by using a super lattice Hydrogen absorbing alloy that is free from Co & Mn as a negative electrode and by improving the material used for separator. More improvements were achieved by change in electrolyte from KOH to NaOH rich electrolyte. All this gave birth to a totally new type of rechargeable NiMH batteries. Commonly called as low self discharge nickel-metal hydride i.e. LSD NiMH. Due to the low self discharge, cells are often marketed as pre-charged or ready to use rechargeable batteries.

Sanyo Eneloop LSD NiMH features all the advantages of conventional NiMH Battery over and above here are typical features of Eneloop LSD NiMH battery.
Sanyo Eneloop LSD NiMH Battery:

 

• Pre charged and ready to use. Note: Sanyo pre charges cells up to 75% of capacity
• Twice the typical NiMH life span. Eneloop LSD NiMH battery can last for about 1000 charge discharge cycles
• When fully charged batteries are stored typically at room temperature (20 deg-C) Eneloop NiMH batteries retain about 85% of the full capacity even after one year in storage

Inside Sanyo Eneloop Power Pack ‘suit case’, a well organized, beautiful white colored blister type content holder secures all the contents nicely. The container is divided in to three sections. Placed centrally is a 4 bay charger. Four Sanyo Eneloop AA batteries are placed on either side of charger along with one C size & one D size battery adapter. Four AAA sized cells sit just below the charger. Overall the available space utilized in almost optimum configuration. Printed copy of charger manual is also included. It’s hiding behind the charger.

Sanyo NiMH Battery Charger: The charger included in Sanyo Eneloop Power Pack is 4 bay overnight charger. The charging current per channel is about 300 mA for AA sized Eneloop Battery where as it is 150 mA for AAA sized battery. The charger is designed to charge cells in pairs. It takes about 10 hours to fully charge the Eneloop NiMH AA Battery. The charge time may vary depending upon battery condition and temperature. The LED indicators placed at the bottom most portion of charger inform user the state of the cells. Flashing LED’s imply cells are currently charging. When the cells are fully charged, LED’s are in steady state switched ON position. No LED glow means either the battery is inserted incorrectly or power is switched off or there is no battery inserted. Here are a few pictures of charger.

 

On back side of Sanyo 4 bay charger, you will notice a foldable wall plug; no wires to worry for. Below the foldable wall plug, there is embossing of important information about the charger. The Sanyo NiMH charger is specified as “Class 2” charger with Model #NC-MQN06. Charger accepts input range of 100 to 240 Volts AC at 50/60 Hz. It typically consumes 8 Watts of power. The output charging current for Sanyo Eneloop 4 bay charger is 300 mA for AA cell and 150 mA for AAA cell. There is a precautionary note informing user to read instructions carefully before using the equipment. The charger is designed to charge NiMH type cells only. The charger is manufactured in China by Sanyo Electric Co., Ltd.

 

How to Charge using the included 4 bay Sanyo NiMH Charger
Note: These instructions are taken straight from the charger manual.

1) This charger is designed to charge 2 or 4 pcs of AA or AAA NiMH rechargeable batteries. AA and AAA batteries can be charged at the same time.
2) If you want to charge 4 pcs of AA or AAA, put batteries into the charger compartments, taking care to observe polarity (+/-) as indicated inside the charger.
3) If only charging 2 batteries at a time, place the batteries in the left or right side compartments of the charger.
4) Swing plug out and plug into AC100-240V outlet.
5) Confirm that the indication lights begin to flash. Do not plug in upside down. If plugged in upside down, it will finish charging before it is fully charged.
6) When charging is complete, the indicator lights will turn on constantly. Refer to charging chart for typical charge time.
7) After charging is done, unplug the charger from the outlet and swing plug back into place.

Complete charger manual can be downloaded from Panasonic 

Sanyo NiMH Battery Size Comparison: From Left to Right arranged are AAA sized Sanyo Eneloop Battery, AA sized Sanyo Eneloop Battery, C Cell Adapter & D Cell Adapter.

 

 

Test Results :

Sanyo Eneloop AA Batteries Testing Basis: Minimum specified capacity for Sanyo Eneloop AA sided batteries is 1900 mAH where as typical capacity is 2000 mAH. For this, out of 8 AA Sanyo Eneloop Batteries supplied, 4 batteries were randomly selected for the 1 Amp (1/2 C) current draw test and remaining 4 were selected for higher 2 Amp (1C) current draw. Normally, the manufacturers rate the cells at 1/5 C or 0.2 C where capacity of cells appears to be more. But the 0.2 C test is relatively impractical considering the applications in which these cells will be used. Normally, for the typical applications of Sanyo Eneloop Batteries, the current draw is of the order of 1Amp or more.

1 Amp Test : As Sanyo ships cells pre-charged to 75%, for the 1 Amp test, it is required to charge the cells completely before testing. So, all 4 batteries were charged overnight prior to performing the test. It should be noted that this was the first charging of cells. i.e. Forming charge/discharge cycles were not performed. These tests were carried out using West Mountain Radio CBA II. Here are the test results.

Noted that since the cells were not given forming charge/discharge cycles, there exists variation in the capacities. Yet, all 4 cells performed quite well; in fact none of the cells were below 1800 mAH. Even after just a single charge, the cells performed within the specifications. This is an achievement in itself. Especially considering the 1 Amp (1/2 C) discharge.

2 Amp Test : The remainder of 4 Eneloop cells were subjected to three charge discharge forming cycles. The 2 Amp (1 C) current draw test was then performed and here are the results.

 

Combined Test Results : Here are the combined test results. You can see how closely capacities match for 1 Amp (1/2 C) and 2 Amp (1 C) test indicating excellent performance of Sanyo Eneloop Batteries.

 

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