AccuEvolution D Cells quality gone!

[Nubo]

I've received my order of 12 of these, along with a dozen Accu C-cells. While my charger doesn't show capacity numbers, what I can see does support the observation that these D's may be duds. When using a conditioning cycle, the C cells showed a fairly high charge (2 of 3 bars). They reached 3 bars quickly and were soon fully charged. The D cells showed a low level (1 of 3 bars) and took a long time just to get to 2 bars. Definitely not consistent with pre-charged LSD cells. 357, I appreciate your efforts in working with the company. I'm hoping they will make good on their product's promise.

 

[Lanque]

I also have 12 Accu D-cells and 12 Accu C-cells in the mail from Battery Junction. I will do some measurements and report back once I get them - hopefully within a week. Seems the postal service is a bit slow lately.

 

[357mag1]

I've received my order of 12 of these, along with a dozen Accu C-cells. While my charger doesn't show capacity numbers, what I can see does support the observation that these D's may be duds. When using a conditioning cycle, the C cells showed a fairly high charge (2 of 3 bars). They reached 3 bars quickly and were soon fully charged. The D cells showed a low level (1 of 3 bars) and took a long time just to get to 2 bars. Definitely not consistent with pre-charged LSD cells. 357, I appreciate your efforts in working with the company. I'm hoping they will make good on their product's promise.

You brought up another good point these newer cells take forever to charge compared to the older cells when using the AccuManager battery charger. Funny in the literature for that charger it mentions poor quality cells as a possible reason if they take too long to charge.

We will see if anything comes from working with the company. I'm still hoping we can at least get back to the quality of the original cells.

 

[Lanque]

Yesterday (Friday) I received my 12 AccuEvolution D's and 12 C's as well as a Titanium MD-3000 charger in the mail. I also received a Maha MH-C808 on monday.

This is my first delve into C and D NiMh cells and chargers, having used AA & AAA Enloops and Duraloops and 2 BC-9009's for some years.

Concerned about the quality of these cells, I did some experimenting. The D cells I received look like the left hand side cell in the image in post #26.

I read the voltages of 4 C's and 2 D's out the pack, under a 2 ohm load, and then after charging (hot off the charger) and resting.

I charged 4 C cells in the MD-3000 for about 2hours. The cells from the outer bays were cool on termination, but the inner two were warm. I noted that the charger was warm in the centre, and attributed the battery warmth to the charger heating up.

After doing some voltage testing, I then charged - or at least started charging - 2 D cells on the outer bays of the MD-3000. The centre of the charger was again warm after an hour. After about 3 hours of charging, 11:30pm last night, the D cells were still cool, but the plastic in the centre of the charger was too hot to comfortably touch, and on closer inspection, I noticed that the plastic had actually deformed from the heat. That freaked me out a bit, and I aborted immediately. I did not get to sleep for a while after the near meltdown.

This morning, I continued charging the 2 D cells in the C808. One cell (D-A2) terminated while cool after 45 minutes at 1.43V. On re-insertion it only showed 2 of 3 bars, and terminated again ~20 minutes later at 1.46V and only slightly warm. The other cell (DA-1) failed to terminate after 1h30, and was very warm (had been for 1/2 hour), so I pulled it. It read 1.44V. I am not sure how the C808 terminates, but the peak voltage due to the pulsed charge current was getting slightly lower with time, and the cell getting warmer. I do not know when/if it would have terminated, if I was being impatient, or if it was a cell/charger issue. More time and testing may shed some light.


C-cells
Voltage Load V V After 1h30 14h00 17h25 18h20
from Pack 2 ohm charge rest rest rest rest
C-A1 1.295 1.285 1.464 1.436 1.408 1.404 1.401
C-A2 1.296 1.285 1.466 1.436 1.408 1.405 1.402
C-A3 1.288 1.280 1.464 1.431 1.405 1.402 1.399
C-A4 1.294 1.283 1.462 1.436 1.410 1.404 1.403

D-Cells
Voltage Load V V After 1h10 1h30 2h15 3h00 4h15 5h15
from Pack 2 ohm charge rest rest rest rest rest rest
D-A1 1.285 1.271 1.445(hot) 1.406 1.402 1.398 1.396 1.391 1.389
D-A2 1.286 1.275 1.460 1.408 1.405 1.401 1.398 1.394 1.391


For pre-charged cells, their voltage out the pack was quite low (C and D), and the fact that the C's charged for 2 hours, and the D's for approx 3 + 1 hours, bears with the fact that they were indeed more than half empty.

Not very scientific or conclusive, what with 2 different chargers and the limited cells I tested, but the D cells do seem to sag slightly quicker after charging. Than the C's. I do not have any other C/D NiHM cells to compare these againt, so I do not know if these figures are good or bad.

The fact that the one D cell did not seem to want to terminate and was heading towards hot also does not look good.

I will keep track of these cells, and charge some more C's and D's up later on the C808. Unfortunately I do not have any equipment to measure remaining capacity, short of measuring runtime under load.

The MD-3000 is getting an early retirement after its fiasco last night. Hopefully it can go back for replacement, but i fear that with the cost of shipping it will not be worth it.

 

[Lanque]

I charged some more D cells up this morning. They were pretty low out of the packaging. After 4h30min they started getting warm. The C808 terminated 2 cells just after 5 hours. They were more than a bit warm. After 5h20, and no termination, I pulled the remaining 2 cells before they got too hot. All cells were warmer than I would normally be comfortable with. Once again, I do not know it its the charger, or the cells, both being new.

D Cells:
D-A3:
1.267V Out of packaging
1.249V under 2 Ohm load
5h20 till pulled - cell was very warm - heading towards hot
1.443V hot of charger

D-A4:
1.285V Out of packaging
1.273V under 2 Ohm load
5h05 till termination - cell was very warm
1.445V hot of charger

D-B1:
1.288V Out of packaging
1.275V under 2 Ohm load
5h07 till termination - cell was very warm
1.456V hot of charger

D-B2:
1.286V Out of packaging
1.273V under 2 Ohm load
5h20 till pulled - cell was very warm - heading towards hot
1.450V hot of charger

I would have pulled all the cells sooner because of heating, but was curious to see if the charger would terminate. Since all cells charged for 4h30 before any sign of warming, and charge current of 2A on the C808, I would say the
cells were fairly empty to start with.

25 minutes have passed since the last 2 cells were pulled, and they are now sitting at between 1.405V and 1.420V

C cells from Friday are at about 1.391V (3mV between best and worst) average and D cells from Sat are at 1.371V average (2mV between).

Time to go charge some more C cells in the c808 for comparison.

 

[fnsooner]

Crap, I've been following this thread with a smug smile on my face thinking how lucky I was that I purchased all 30 of mine last year. Out of curiosity, pulled four cells out of a 4d maglight I have here in my office(Sunday night finishing my taxes). Two of the four were the newer cells per the pictures on the first page.

Luckily I marked all my Accu Ds the date of purchase. Now its back to the house to dig through all my D powered devices and do some testing of my own.

The newer looking cells were purchased 07/10 from Bear Wobble.

 

[VidPro]

wow, what could be worse than having a bunch of lesser batteries you paid good money for, having them Be DIFFERENT and ending up using them as a team.

from what you guys are saying the reason they are getting hotter on the maha 808 style of charger, is because of the lower voltage, it is not terminating based on voltage, so termination will be based on the v-drop instead. Because the charge rate is not really high, it is probably not terminating AS quickly via the V-Drop termination, and because it isnt terminating at 90-95% charged , there is going to be the usual heat that you would get from other chargers.
And NO, i am not saying that everything will be fine, you certannly have a bad situation. i am saying that it could still eventually terminate using the other method.

And as far as the voltage goes, a very great resistance battery might not get so high of voltage on the charger, and that could be a better resistance battery, BUT this does not sound like the situation at all. it just sounds like it says in the title , they changed something, and not for the better.

for the other cooker http://www.candlepowerforums.com/vb...nium-MD-3000-battery-cooker....I-mean-charger
well.

 

[jayflash]

I took my second MD-3000 apart because one channel quit working. My first MD had several problems before failing entirely.

I had to resolder the negative lead to the spring loaded contact. I noticed the power device which is centrally located on a small, flat, heatsink, had separated from it and had no thermal compound. I forced some between the two and shimmed them to, hopefully, keep them together when the charger is screwed back together.

This charger will randomly terminate on different channels at different times even when all cells are equally discharged. I have to restart to finish charging, sometimes. This is the second unreliable MD-3000 and not worth the $40, IMHO.

 

[fnsooner]

Here is a follow up from a couple of posts back.

When I purchased my last ten Accu Ds, it was in 07/10, around nine months ago and these were the newer style. I decided to charge all of my D cells including the twenty I purchased around 01/10(these were the older style). So all thirty cells were completely charged 07/10/2010.

So I go home last night and pull six cells from my 6D maglite that is mounted next to my bedroom door. I have tons of flashlights and this maglite has been relegated as a glorified battery carrier and club. Except for checking that it is working, I have not used it since charging the batteries nine months ago.I check the voltage on these
batteries and I get a range from 1.30 to 1.31VDC. Remember these cells are the new style.

So now I pull six batteries from a battery pack that plugs into a Coleman tent fan and the fan had not been used since charging the batteries. Surprisingly enough they have a voltage range of 1.30-1.31VDC. These are the old style cells purchased in 01/10.

So I take four of the new and four of the old style and put them in my Maha MH-C808 and start a conditioning cycle. The Maha manual says it could take thirty hours to finish this cycle. Hopefully I will be around when it is finished so I can check the voltage on all cells. One thing I noticed is when the initial stage of the conditioning, all batteries were charged and they all finished this charge stage within ten minutes of each other in about an hour or so.

These are just the facts as I find them. I'll leave diagnosing to you guys. I plan on running all thirty through a conditioning cycle, then check the voltages in a month. Any other testing suggestions.

 

[jayflash]

The ~1.3v seems normal for NiMH LSD cells stored since 7/10 and the fact they all charged up within 10 min. may be a good sign. What I'd have done first, and plan to do soon with mine, is to discharge my stored Accu's and record their capacity. Next, I'll charge them at the 2A rate in my Maha 808 and record the time and voltage for future reference.

The 10 D & C Accu's I've got will have only been stored about 2.5 months, so whatever LSD properties they have won't be as apparent as a longer storage time. I'll post when the results are complete. May I suggest first discharging cells with a reasonable load first and check voltages periodically? Good cells will plot a very gradual drop in voltage which is handy to record on graph paper for us low-tech type.

 

[Fresh Light]

The transformer on my md-3000 failed, the charger still worked on the 12v plug. BJ sent me a new transformer, however it did not work out of the box, nor did it test to have any voltage. They sent me another transformer and i've been using it since. I've only charged TiD's and TiC's and Tenergy C's. I'll have to check the voltages, but i don't remember seeing anything as higher than around 1.35. Yeah the cells get pretty warm after charging, but it seems to work fine and the cells have always charged ok.

 

[Rezolution]

This thread is really depressing to me

I've been trying for a week now to find the discharge curves of 3 different LSD NiMh D batteries that were my choices (Imedion, Tenergy Centura, and AccuEvolution). Imedion are the most expensive and I cannot find a spec sheet for them that has a discharge curve with useful information on it. Tenergy Centura were the cheapest. I originally wanted LSD type since these are going into my 4-cell D-cell maglite with a current regulated P7 in it. It has a continuous drain of 2.8A at about 3.7V.

I have some D-cells that I ordered from Ebay China that are rated at 10,000maH and only perform at 4,000maH and those are going to go in the garbage when I can get some good replacements.

I was going to get 4 of these AccuEvolution batteries but after reading this thread, there is NO WAY I'm buying them.

Should I go with the super expensive Imedion from Maha or should I just get plain old Tenergy (non-LSD). I just need a good set of batteries that will give me a long run time. I don't see the flashlight ever sitting for more than a month. Since all of the LSD batteries in D size are getting terrible reviews, does anyone have a recommendation for me?

 

[fnsooner]

My cells finished the conditioning cycle, but I wasn't able to check voltage fresh off termination. You all will have to exuse my rookie attempts to trouble shoot these cells.

This weekend I am going to initiate a more systematic aproach to this.

But in the mean time.
My 6D mag has a 600 lumen terralux drop-in in it and last night I had one set of six charging while the other set of six were being depleted in the maglite. I didn't take notes but was checking amp draw on the mag when I put fresh batteries in it. I was getting 2 amps initially on both sets of batteries but it rapidly dropped off to around 1.85 amps.

I also checked voltages (kind of hap-hazardly) when the done signal displayed. I was getting 1.4-1.5VDC. None of the cells were getting hot although the right end of the Maha charger was getting warm and transfering the heat to the far right battery, I think.

Some of these numbers don't really mean much to me, but what pops out is that the new and old style cell numbers seem similar.

 

[HarryN]

Hi, you need to use some care when comparing different cell sizes to each other. For an equivalent level of technology, cell mfgs have to make a decision - optimize discharge rate, or capacity.

The r/c crowd has tended to push the Sub Cs more toward discharge rates, and the smaller diameter helps with heat removeal.

Ds tend to be pushed more towards capacity, partly because that is what people tend to think of when they buy a D vs a sub C, and heat removal is a lot harder.

Some of you mentioned that you didn't have a good way to test for discharge rates, but that is actually easy to solve, since you must have a good voltmeter there to be getting this very nice data.

Consider testing each cell individually by discharging it through a resistor network. Assuming that the goal is to discharge them in the 5-10 amp range, then 1.xx volts wil need either 0.2 ohms or 0.1 ohms.

I would like to suggest building this up from 1.0 ohm resistors such as this one:

http://www.newark.com/rcd-resistors...0-fbw/resistor-wirewound-1ohm-5w-1/dp/42K5286

The are about $ 1 each at newark in case the link doesn'tt work.

It is basically a reasonably high precision 1 ohm wire wound resistor with a 5 watt (each ) rating, in an axial format. 5 of these in parallel are 0.2 ohms, and 10 of them are 0.1 ohms. These are easy for anyone to make into a bundle or mount on a simple perf board, soldered or not.

Just set this up with your cell discharging through it, and measure the voltage drop through the resistors. Using V=IR, you can calculate current, and draw up a simple table of results.

Even if all of the results are different, at least you can sort your cells to match them as sets if you like.

I have read through this thread several times, and still can't tell if this is a cell problem or a charger problem.

 

[alpg88]

wow, i did look up imedion, $37 for two!!!! did anyone try them, are they so much better than everything else, is it really worth $37 a pair?

 

[jayflash]

"I was going to get 4 of these AccuEvolution batteries but after reading this thread, there is NO WAY I'm buying them. "

" Since all of the LSD batteries in D size are getting terrible reviews, does anyone have a recommendation for me?[/QUOTE]"

1) We don't know for sure that the Accu's are generally bad. So far my experience is different, but I must retest my batch of C & D LSD cells. It could be that a bad or mistreated batch was purchased by Mag.

2) ARE all LSD D cells poorly reviewed? So far mine are holding up, but they're only a few months old and I'm going to retest them.

3) HarryN has emphasized the same thing I've been after. We should determine the capacity and voltage of these cells after some time for more accurate understanding of their quality. Harry's set up is good, but you may use something like a lantern or battery fan, etc. and check the discharge current and voltage several times to see if it changes. It's likely a higher drain will exist at first and reduce somewhat as the voltage drops, but you should be able to get a general idea of a cell's capacity.

 

[357mag1]

UPDATE!!!

I purchased a cheap Accucell 8150 hobby charger so I could better understand what is going on with these cells. I feel the information was important enough to this thread to warrant posting immediately.

I had the new and original cells setting after being charged 10 days ago. I started discharging at a 2amp rate and the new cells are actually testing out approximately 400mah to 600mah GREATER capacity than the originals.

Now everyone is probably wondering why I came on here complaining about the quality of the new cells. I still think they stink!!! We gained a little capacity but sacrificed the ability to maintain voltage under load. My lights were enough dimmer using the new cells compared to the originals that it led me to believe these batteries were almost dead and needed recharging. Voltage readings appeared to agree.

How bad is the voltage drop under a load compared to the originals? Bad enough that in my Lambda SST-50 Maglite with freshly charged cells there is over 2amps difference measured at the tailcap. Huge difference in output. Even a relatively low draw light like the Mag Charger Ican (using an extension to allow five D cells) is appreciably brighter with the original cells.

Bottom line if you use the AccuEvolution cells in lights like a TK50, Malkoff Maglite dropin, or the Mag LEDs you will probably be satisfied with these batteries. If you need them for direct drive LED lights or Icans you will probably be disappointed. The new Tenergy LSD cells act just like these new AccuEvolutions coming off the charger but maintain their voltage under load as well or better than the original AccuEvolution cells.

Just one more example of how bad these new cells are under a load. I set the Accucell to discharge at 5amps with a cutoff voltage of .8V and the new cells that were charged 10 days ago almost immediately cause the discharge to terminate because they have dropped below the cutoff voltage. The original cells charged at the same time don't do this.

 

[jayflash]

Thanks for the update. I agree that a little more capacity isn't worth noticeable voltage depression. When I finally test my batch I'll post the results. My hope is still that you've got an abnormal bunch of new cells and the manufacturer replaces them.

 

[Mr Happy]

There's a slight puzzle here with regard to capacity and discharge rate. Consider that an Eneloop (AA) has a moderate capacity of 1900 mAh and a comparatively good discharge rate (up to 5 A is comfortably achievable). Then consider that a D cell has approximately 7x the volume of an AA cell. So using similar technology, we might therefore expect a D cell to have a capacity of 7 x 1900 = 13 000 mAh and a discharge rate up to 7 x 5 = 35 A. It is notable that real D size NiMH cells rarely get close to that. Either there is insufficient market for anyone to make them, or there is some kind of patent encumbrance that prevents them being made.

 

[357mag1]

Mr Happy makes a good point. By the way I did try a standard Eneloop AA at the 5amp discharge rate and it lasted longer than the big AccuEvolution D cell before the charger terminated the cycle. That is compared to the new cells, the originals lasted much longer than the Eneloop.

I also just discharged one of the new Tenergy Centura LSD D cells. It holds voltage better than the original AccuEvolution cells (at least this single cell did) and had a capacity of 8901mah. Not bad for a battery listed as having 8000mah.

The highest capacity I've recorded on the original cells after a day off the charger is 8907mah. All of the original cells seem to run between 8800 - 8900mah. The new cells average 9350 - 9600mah.

The one Imedion tested so far had a capacity of 7759mah but it was charged 10 days prior. It doesn't hold voltage under a load much better than the new AccuEvolution.

I only have two cells each of the Tenergy Centura and Imedion so my testing is limited.

The Centura is actually starting to look pretty good which is surprising as voltage readings were only slightly better than the new AccuEvolution cells. I will test some more but they appear superior to the Original AccuEvolution when it comes to maintaining voltage under a load.

Maybe all is not lost yet. It doesn't hurt that these Tenergy cells are cheaper than the AccuEvolution cells.