AccuEvolution Low Self Discharge NiMH D Cells

by AccuEvolution

Product Details

• Shipping Weight: 1 pounds (View shipping rates and policies)
• ASIN: B00124BN4U
• Item model number: AP-E-10000-2
• Average Customer Review: 4.0 out of 5 stars  See all reviews (13 customer reviews)
• Amazon Best Sellers Rank:
  • #15 in Electronics > Accessories & Supplies > Batteries, Chargers & Accessories > Household Batteries > D
• Date first available at Amazon.com: January 1, 2008

Product Description

The AccuEvolution ready-to-use rechargeable battery offers the advantages of both alkaline and NiMH cells without their disadvantages. Similar to NiMH rechargeable batteries AccuEvolution can be recharged up to 1000 times. But unlike NiMH batteries they keepmost of their capacity over time.

AccuEvolution batteries outperform even top-notch NiMH batteries with higher initial capacity. While conventional rechargeable batteries loose 20% of their capacity every month, AccuEvolution looses only 2% of its capacity every month. After only 1 month the AccuEvolution 2200mAh AA cell offers more useable capacity than a more expensive, conventional NiMH 2700mAh AA battery. Meaning, for instance, that your flashlights will still shine bright even after months of storage.

Customer Reviews

Most Helpful Customer Reviews

23 of 25 people found the following review helpful:

5.0 out of 5 stars Great Batteries (THESE BATTERIES ARE WITH IN SIZE SPEC), May 6, 2009

By 

ultrabike "ultrabike" (Irvine, CA) - See all my reviews

This review is from: AccuEvolution Low Self Discharge NiMH D Cells (Electronics)

I almost did not buy these batteries 1 year ago based on a review criticizing their size (too long or so). In the end I bought a set of 8 AND I CAN TELL YOU THAT THEIR SIZE IS NOT A PROBLEM based on my experience.

I use a battery charger that does not use springs to recharge these batteries(POWEREX MH-C808M BATTERY CHARGER AA AAA C D NiMH NiCD), and I have NO PROBLEMS placing the battery in the charger. The advertised capacity is correct and they are indeed very low self discharge.

Sure Eneloop AA are great SANYO eneloop 4 Pack AA NiMH Pre-Charged Rechargeable Batteries(I own quite a few of them and couldn't be happier), but they drain fast if your application requires D batteries and it's a pain to recharge them on a weekly basis.

Previously I used AA Eneloop with their D size adapters, but I started to get annoyed about having to replace/recharge batteries almost every week.

**** Update May 14, 2009 ****

THESE BATTERIES ARE WITH IN SPEC.

I measured my AccuPower D batteries and they are about 59.6 mm. The ANSI spec call for 60.5 mm +/- 1.0 mm (not 61.5 mm). Therefore, the battery should measure between 59.5 mm to 61.5 mm. This makes the battery with in spec!

In fact, these are their specs:
[...]

**** Update Sept 12, 2009 ****

In response to a comment I remeasured these batteries stacked using a Stanley 30' Powerlock measuring tape. I did this because I do not have a caliper and my previous measurement may be off compared to a caliper measurement.

The premise is that if the batteries are too long, then stacking them will make the length problem obvious even to a measuring tape. Here are the results:

1) I staked four cells and measured again as best as I could with my measuring tape and got almost exactly 9.5 inches or 241.3 mm which translates to 60.325 mm per battery.
2) Next I staked eight cells and did the same thing. I got about 19 3/16 inches or 487.3625 mm which translates to about 60.92 mm per battery.
3) Next I staked twelve cells and got about 28 10/16 inches or 727.075 mm which translates to about 60.59 mm per battery.

The measurements were not caliper quality but I got a measurement range between 60.325 to 60.92 inches. This new set of measurements puts Bill King and I about 0.875 to 0.28 apart. Note Bill King, my previous and new measurements are all with in ANSI spec though.

11 of 11 people found the following review helpful:

4.0 out of 5 stars EXCELLENT PERFORMANCE, CAN IS A BIT TALL, October 21, 2010

By 

Jesse Knight (woburn ma usa) - See all my reviews
(REAL NAME)   

Amazon Verified Purchase

This review is from: AccuEvolution Low Self Discharge NiMH D Cells (Electronics)

UPDATED MAY 9, 2011

ELECTRICAL:

TESTING A HOME BREW TESTER: D cells are hard to measure as the only home use charger that gives actual data in numbers, that are accurate, is the Powerex Wizard. Unfortunately this charger is for AAA and AA cells. After much thought I decided to make an external D cell adapter, giving much consideration to making it's impedance as low as possible. First, tests were made with other NIMH D cells. These tests produced reasonable and consistant results. Most importantly, the negative delta voltage sensing shut off program in the charger shut off the charge at the right time. The discharge test also worked for all my old cells. It flunked a NUON D cell which was running down faster than it's two mates in the Rayovac lantern. Two weeks later a second NUON D cell failed to fully charge on the Wizard and gave erratic readings on the Wizard's display. A battery autopsy (DON'T OPEN BATTERIES IF YOU DON'T HAVE EXPERIENCE) revealed that inside the D size can was two AA cells in parallel! It is better to find bad cells before a power outage and only a charger with full metering will do this accurately. All my NUON cells went to recycling.

TESTING 12 ACCUEVOLUTION D CELLS: The Accuevolution D cells required only about 500- 1500 milliamp/hours to fully charge after opening the package. These cells are from three orders to two suppliers at different times. Each cell( in a 2 pack) took the same amount of charge, indicating that the self discharge of each cell is almost the same. Discharge testing of four cells at the 10 hour rate, shows the 10,000 milliamp/hour rating to be plausible, assuming that the advertised capacity is for a 20 hour discharge rate. At a 10 hour rate I got 8800 MAH. These are the first rechargeble D cells that came with 85%+ charge, that I have found.

All cells were set aside for a day and charged again at 500 mA. Even at the the final 1/20 C rate of 500 mA the charger shut down at the right time, causing no overcharge. A cell that gives a good negative delta at this low a charge rate is probably very well made. The 500 mA charge test was repeated once on all cells. Repeated charging at less than 900 mA is not recommended, in addition, depending on auto shut off is not recommended below a 2000 mA charge rate as a general rule for this size cell.

MEASURING SELF DISCHARGE: This is not easy as self discharge is high at first and decreases with elapsed time. In addition, the first 200 MAH of charge in a D cell is spent raising the cell voltage to a level that results in charging. Ideally one would put aside several cells for a year and run a discharge test. My method is faster as it relies on measuring charging current and time for cells that have been set aside for different amounts of time. Six cells were fully charged and set aside for 69 days. They required a recharge that ranged from 923 to 1012 MAH for an average of 956 MAH. From this I subtracted the recharge amount for cells that have been set aside for 3 days. For 12 cells this ranges from 365 MAH to 428 MAH for an average of 391 MAH. The result is the self discharge for days 4 thru 69 and is 2.6% per month. A more fair test for the long term is to subtract the average self discharge over a 17 day period to get the self discharge for days 18 thru 69. This calculates out to 1.7 % self discharge per month. Testing for self discharge from day 60 to day 90 after charging would give an even lower monthly self discharge. All charging was at 1300 mA and cells were stored at about 70 degees F.

CONCLUSION: These are very consistant superb cells if you have a good charger and they fit your battery holders.


CHARGING PROBLEM:

In my opinion the bad review of this cell is not the fault of the cell, but rather the charger being used. Most timer based chargers only put out 400 to 440 mA which is too little for this cell. At this rate the cell might not charge, it might just generate heat. NIMH chemistry does not like low current charging, for this cell anything under 900 mA is uncharted territory in my opinion. The best charge rate will be in the range of 900 - 2000 mA. I WOULD NOT RECOMMEND MAKING AN ADAPTER FOR THE WIZARD. Check out reviews of the large powerex charger, but do not fill all the slots with cells as it might run too hot if you do this. always leave the slot near the power supply in D cell chargers empty. Any cell in this position will be cooked. Ideally one should use only every other slot so that air can circulate between the cells and cool them.

BATTERY SIZE, OR WILL IT FIT?

Reading other reviews suggests that in some cases the distance between the top of the cell(positive contact) and the bottom is too long. I found no problem with this. What I did find was that the can length (distance from the negative contact to the top of the can) is 2.326 inches. This is longer than any other D cell, primary or rechargeble, that I have on hand. Some battery compartments that have deeply indented positive contacts may not accept this long can. I suggest only buying two if your equipment has a tight fit, and see if there is going to be a problem with the positive contact, or whether the can hangs up on something. The factory may be having trouble maintaining tolerances making all the reviews correct, depending on the production batch. Hence my four star rating.

FINAL THOUGHTS:

This could well be the best NiMH D cell available. With the dominance of palm sized devices, larger electronic items are in retreat.
Demand for D cells is low, hence few are made. Few chargers exist that can properly charge these cells. Although not ideal, the Powerex D cell charger is probably the best choice, provided you watch out for overheating. What follows are some precautions when using this and other chargers.

The Wizard charger allows air to reach the cells from under the cells by convection. The cells are spaced apart so this air can rise up between the cells. This charger is limited to AA and AAA sizes. Positive contacts are recessed, hence a cell that is put in backwards will not connect, unless the bottom of the cell is very "bulged out". Bad cells will not heat up the other cells, so they are easily indentified. I check for overheating periodically, especially if I am charging old cells that would overheat if the power is interupted and then returns. Interupting the power causes the charge current on the wizard to default to 1000 mA, too much for low capacity cells. Fortunately the display gives the charge current for each cell on a rotating basis.

All D cell chargers available as of Nov 2010, have the cells almost touching each other, even worse no air can convect as the bottom of the battery holder has no air holes. Some even have covers which contain the heat from any overheating cells.
Although providing extra space between cells would not increase cost much, many would object to the size of a properly vented charger. I am not certain that the Powerex D cell charger is reverse connection proof. The Powerex D cell charger has a reputation for not shutting down if a cell overheats, in my opinion it requires constant supervision. Hence I have not bought one yet.

Fully loading an unventilated charger, set on fast charge, with inefficient low capacity D cells, that are rewrapped Sub C cells, is the ultimate disaster or perfect storm. Accuevolution cells appear to be very efficient and run cooler that any other cells I have tested. They probably will work fine in the Powerex D cell charger. Maha PowerEx MH-C808M Ultimate Professional Charger - Battery charger 8xAA/AAA/C/D


8 Bank Powerex Ulitmate Professional Battery Charger w LCD Display

13 of 15 people found the following review helpful:

2.0 out of 5 stars Unknown battery or charger problem, October 18, 2009

By 

Edward S. Episcopo (Fredericksburg, VA United States) - See all my reviews
(REAL NAME)   

This review is from: AccuEvolution Low Self Discharge NiMH D Cells (Electronics)

I purchased a large number of AccuEvolution rechargeable D, AA and AAA batteries from RealGoods last year. Eight of the batteries I received were dead on arrival and they wouldn't charge in the AccuManager 20 charger, which I purchased at the same time. I sent those batteries back to RealGoods and received replacements. Over the next few months more batteries failed to charge on the same changer. I had over a 50% failure rate in the most expensive D batteries and they continue to fail. I had a fairly high rate of failures on the AA batteries, although no where near the failure rate of the D batteries. After three months RealGoods would no longer replace the batteries and they referred me to the manufacturer. The manufacturer agreed that my usage pattern should not have been the cause of the failures. I returned several of the D batteries to them and they stated that one of the batteries could not be charged and they had to wakeup the other two. In the mean time four additional batteries have failed to recharge (3 D batteries and 1 AA battery). I have also been using a lot of the Sanyo eneloop AA rechargeable batteries and I have had no failures so far on the same charger.

Followup:

Since I first reported this problem, I ordered 8 D batteries from Tenergy and I now appear to be having the same problem with the Tenergy batteries. Two of the first four I tried to charge would not charge, but after leaving them in the AccuManager20 charger for a couple of hours, one of the batteries started to charge. The AccuEveloution manufacturer sent 6 new D batteries on 10/22/2009 to replace the batteries that appear to be failing. After months of testing and rotating various batteries the problem appears to be more pronounced and the problem may be the charger. On 10/26/2009 a representative of the manufacturer offered to send a replacement charger to see if the charger is causing the problem. I will upgrade this review, if that turns out to be the case.