AccuEvolution D Cells quality gone!

[45/70]

I've cycled all the replacement AccuEvolution cells about six times and now have them setting on the shelf. Hot off the charger voltage read from 1.408 to 1.431v on the 28th of March.

It seems to me that part of your problem may be the charger, rather than the cells. Even cells in poor condition should charge to voltages higher than you're getting. The voltage may then drop off drastically when removed from the charger, if the cells are in poor condition, but should typically come right of the charger at a higher voltage than what you're getting.

I'm not saying that the charger is the whole problem, but it seems to be undercharging cells. Do you have another charger to charge these cells in? It could be, I guess, that the charger, due to poor cells, is just terminating too soon. Anyway, it'd be interesting to see if the cells behave the same when charged in an alternate charger.

Dave

 

[jayflash]

Dave expressed what I also had wondered. The charger's performance could matter. However, even if it's not reaching the proper cut-off voltage, knowing the charging current and duration of charge will give approximate results.

For example: if the cells are charged at one amp for ten hours you might expect they took in, roughly, 8Ah. After sitting for a few weeks, an open circuit voltage of ~1.35 might be an expected average, I think. Put those cells under a known load to determine capacity. That should give you some valuable info. Of course, the LSD qualities would take much more time to determine, unless there were none!

I'm using a Maha 808 which will charge at 2 amps. Would charging at 500mA create any problems provided the charger recognizes proper cut-off?

 

[45/70]

Dave expressed what I also had wondered. The charger's performance could matter. However, even if it's not reaching the proper cut-off voltage, knowing the charging current and duration of charge will give approximate results.

Good points, Jay.

Thinking further about the possible charger issue, I've noticed that when charging eneloop AA cells with my C9000, that when the cell voltage initially reaches about 1.40 volts, the cells have only received about 25% of the total charge. Actually most of the charge takes place between 1.40 and 1.43, or so Volts. I'll have to observe that more closely next time. It does seem though that most of the charge takes place around 1.40 volts.

I realize that different chargers using slightly different algorithms, as well as differences between cells, may affect this voltage reading, but that still seems like a low "hot off the charger" voltage. And, as I said, in my experience, even cells that are known to be in poor condition, end with a voltage of 1.47 volt, in the Maha. In other chargers, such as the BC-900 (which don't have a Vmax of 1.47 Volt), the voltage is often over 1.50 Volts, at termination.

Dave

 

[357mag1]

AccuEvolution wants me to try a different charger as well. I'm up for trying anything but here are my thoughts. Why do Eneloops and my original AccuEvolution cells come off the same charger (Titanium MD-3000, bought from Battery Junction when I still did business with those folks) at 1.5 volts or very close if the problem lies with the charger?

It seems if the charger were the problem all batteries would be coming off with a low charge. I would love this to be a charger problem but fear that is not the case. The original AccuEvolution D cells had a fairly short positive button and the new cells that are giving problems have a much longer positive button. This applies to both the ones I purchased and the replacements sent direct from the company. The performance is nothing like the older cells.

I will still hold out hope for the charge because like many of you here these were my go to D cells with LSD properties. I'm trying some of the new Tenergy D and C LSD cells along with the new Imedion D cells. So far none of them work as well as my original AccuEvolution cells.

 

[alpg88]

Tenergy came out with Centura lsd cells, my previous experience with tenergy nimh ws very good, i'll buy some and post results, thou i can't imagime how to test their lsd claim without waiting a year.

 

[357mag1]

Here is a photo showing the difference.

The newer battery is on the left and as you can see has a much more pronounced positive terminal.

The older batteries sometimes did not make contact in a few of my Maglites but I can easily fix that. I would take more of the older short terminal batteries any day.

 

[357mag1]

Tenergy came out with Centura lsd cells, my previous experience with tenergy nimh ws very good, i'll buy some and post results, thou i can't imagime how to test their lsd claim without waiting a year.

It actually doesn't take a year. The new Tenergy C and D Centura cells that I have are only slightly better than the AccuEvolution cells I'm having trouble with.

I will say the AccuEvolution C cells that I purchased at the same time as the new D cells seem to still be of outstanding quality. They charge to 1.5V or very close in the same charger.

I guess I should have stated it doesn't take a year because they drop their voltage so quickly. The Tenergy Centura D cells I charged on the 15th with the AccuEvolutions were down to 1.34 volts on the 25th. In comparison to my Nuon standard Nimh C cells charged at the same time which were at 1.34 as well. The original AccuEvolutions were at 1.364.

 

[45/70]

......but here are my thoughts. Why do Eneloops and my original AccuEvolution cells come off the same charger (Titanium MD-3000, bought from Battery Junction when I still did business with those folks) at 1.5 volts or very close if the problem lies with the charger?

Yeah, that is a good point, 357.

While I don't remember ever experiencing this myself with LSD cells, it may be that the cells need to be cycled a few more times in order to act "normally". Looking at the comparison picture you posted though, you've got me worried. It would appear that something has changed. If the source of the cells has changed, it may very well be that the "new" ones are simply inferior. I hope not, but......

I don't use "D" size cells much, but when I do, I depend on them. I wish now that I had bought some of these earlier. As I said in a previous post, it's time for some new D cells, and now, I don't know what to get. I've never been real impressed with the reports I've seen about Imedions and their other Chinese brethren, but the AccuE's seemed to perform well. At least until now.

Dave

 

[jayflash]

Your new AccuE cells may well be bad and I can't be positive that mine are good, yet. A little more time and testing may be necessary. I've a few more thoughts and questions.

My two MD-3000 chargers don't inspire confidence, but that doesn't mean yours is bad. The first one developed one problem after another until it failed and I returned it. The second one is inconsistent, however it's plugged into a good filter and I don't have these problems with my other smart chargers. Sometimes the MD-3000 works fine while other times it terminates early.

After sitting a month or more, a reading of ~1.34v may not be bad. If the cell provides near rated capacity without excessive voltage depression, maybe a lower "storage" voltage isn't important.

Some of my bad and oldest cells will charge to over 1.5v and old NiCds go to 1.63v. Could 1.43v be OK as long as the cells attain their rated capacity and hold ~1.25v under a load? Again, accurately determining the capacity your new Accu's retain, initially, and after a couple months will tell you everything.

As 45/70 indicated; I don't often use my D cells and they sit for months between use, I do rely on them for long run time or emergency needs. If these new AccuE D & C cells have poor LSD qualities, I'll be most disappointed because it'll take months to know that for sure and then I may have warranty issues.

 

[45/70]

Some of my bad and oldest cells will charge to over 1.5v and old NiCds go to 1.63v.

Interesting about your problems with the MD-3000 chargers. Makes me wonder.

About NiCd cells, maybe you already know this Jay, but NiCd cells will always charge to a higher voltage than NiMH cells. It's their chemical nature.

Dave

 

[357mag1]

Dave,

You summed up my feelings exactly on the AccuEvolution and the available D cell options.

Jayflash,

I have an extensive collection of Nimh cells and it has been my experience that when cells won't reach at least 1.47v during the charge cycle they are inferior cells. This has held true if the cells are LSD or not.

You are right about testing their capacity unfortunately the only capacity checker I have is my Maha C9000 and it won't do D cells.

Initially I cycled these cells and then started using them without doing any voltage checks due to the excellent performance I received from the original cells. I noticed right off that my 6 cell Maglite was not as bright running a 3854H bulb and didn't last near as long compared to using the original cells.

I also have a Lambda V1000 that is set up to use 3D cells. It will draw more current the higher the voltage is maintained. It drops to less than 3.5amps using these cells if they have sat for a day. The originals or a battery holder using Eneloops will give over 5amps. That is telling me they sag badly under load as well.

 

[jayflash]

I'll have to keep an eye on the peak charging voltage for my collection of cells as that would be a simple way to flag those which may be going down hill or suddenly failed.

Might you try placing four AccuE's in your Titanium charger and press the discharge button, start a stopwatch or mark down the time. Keep an eye on the discharge and use your meter to check voltages occasionally and try to catch the discharge before it begins recharging. Multiply your times by .200mA to determine capacity. I have verified my MD-3000 discharges at the advertised rate.

After that try to time the recharge and multiply that times ~1.6A - 1.8A, which is the claimed rate. You may be able to insert your probes and check the charge current, which is what I did. That's how I noticed the charger terminated too early on occasion. It should have taken several more hours a couple times and did charge for more time when I restarted those cells.

Have you got a battery operated fluorescent light, fan, or other item which you can check the load and use it to determine cell capacity. I have several different D & C cell lanterns which consume from 1A - .300mA and use those to check the capacity of cells. You'd have to monitor light output or voltage and time and check periodically so cells don't over discharge, but I haven't had problems.

How often do you try a deep discharge down to ~.9v - 1v at a low load of, say 200mA - 500mA?

 

[357mag1]

Jay,

I have flashlights I could stick them in to discharge. My lantern takes 8 cells and I only have 6 of cells in question. I've never tried deep discharging them but have used the discharge button on the MD-3000 to cycle the batteries. I usually just let it run for a four or five hours and then restart the charge process.

 

[jayflash]

It may not matter, but it's been recommended for NiMH & NiCd cells to slowly discharge them down to a volt or slightly below. Recharge at a .5C - 1C rate or as close as you can get to that after the deep discharge This may help to restore capacity. It may be possible your bad cells may respond to several deep cycles, which is what I've done to all of mine and they perform well, so far.

Deep discharges won't do much for crap cells and, who knows, your's may have a manufacturing defect, improper chemistry, etc. I'm still hoping your cells may be OK and if not, are not typical of what AccuE's normally represent.

Thanks for communicating. I hope we can get to the bottom of this and determine the true condition of your new cells and charger.

 

[357mag1]

Here is the latest on these cells and it isn't looking good. Posted below is my last email to Armando at AccuEvolution.

Armando,

I've cycled and tested the new cells. Here is how they stack up against the old cells.

Fully charged and left on the shelf for 5 days.

Original cells voltage all at 1.375v.
New cells (with larger positive post) between 1.335 and 1.345v.

Current reading in a high current SST-50 light that will pull more current the higher the voltage (using 3 cells).

Original cells - 5.03amps
New cells - 3.54amps

Current readings in a high current SST-90 light (using 4 cells).

Original cells - 14.12amps
New cells - 10.15amps

To put this in perspective a set of Tenergy regular NIMH cells charged over a month ago had a voltage reading of 1.315volts per cell.

In the SST-90 light they managed 12.65amps.

Clearly your current LSD D cells can be outperformed by regular NIMH cells.

Obviously there has been a change in the manufacturing of these cells possibly coinciding will going to the higher positive terminal.

At this point in time I cannot recommend these cells as their performance is less than regular NIMH cells.

Scott.

 

[357mag1]

Yeah, that is a good point, 357.

While I don't remember ever experiencing this myself with LSD cells, it may be that the cells need to be cycled a few more times in order to act "normally". Looking at the comparison picture you posted though, you've got me worried. It would appear that something has changed. If the source of the cells has changed, it may very well be that the "new" ones are simply inferior. I hope not, but......

I don't use "D" size cells much, but when I do, I depend on them. I wish now that I had bought some of these earlier. As I said in a previous post, it's time for some new D cells, and now, I don't know what to get. I've never been real impressed with the reports I've seen about Imedions and their other Chinese brethren, but the AccuE's seemed to perform well. At least until now.

Dave

Dave,

I tried to babysit some cells while charging to see what they come off the charger at but never managed to catch one just as it terminated. It appears the voltage reaches at least 1.467 on some cells. I never caught them at that voltage when the charger signaled they were done but did pull some during charging and measured between 1.447 and 1.467volts. I have walked out of the room when the charger was still in the charge cycle and come back in about 5 minutes to find the battery done. Never measured them above 1.43 or so at that time, generally less.

This would indicate the voltage drops quickly after full charge and that generally is another sign of a substandard cell.

 

[JA(me)S]

Current readings in a high current SST-90 light (using 4 cells).

Original cells - 14.12amps
New cells - 10.15amps

A related, but slightly off topic query...

Does anyone know what the long term effect of high current discharge might have on LSD NiMH as it relates to life and capacity? 357mag, I'm not suggesting anything - I've just wondered about this for a while...

- Jas.

 

[357mag1]

These new cells haven't seen much in the way of high current discharge. Just the testing that I have done. The original cells and the little Tenergy C cells were used in the Lambda SST-90 light and have seen a fair amount of high current discharge and they seem to be doing well. At least much better than the hardly used new D cells from AccuEvolution.

To answer your question though high current discharge will definitely shorten battery life and have a negative affect on internal resistance of the battery. Just goes with the territory. Almost any battery chemistry will last longer and perform better if treated gently on the discharge and charge cycle.

 

[JA(me)S]

Thanks 357mag1. The irony of your answer lies in the reason for my query: Kevin and I are in email discussion of this very topic! (now need to ascertain eneloop viability - plausible, just haven't found evidence)

Looks like if AccuEvolution can get this sorted out, I'll join in your use of LSD in Lamda's creations (whoa man, trippin').

Sorry for the slight derailment - back to your regularly scheduled programming.

- Jas.

 

[357mag1]

I just tried the new AccuEvolution D cells in my Lambda light straight off the charger. They can barely supply 12amps of current freshly charged. Compare this to the month ago charged Tenergy C cells (normal nimh not LSD) that were able to supply 12.65amps.

Armando from AccuEvolution did reply to my email and stated they are looking into this issue. Hopefully something positive (like quality D cells) will come out of all of this.

Any of you who think the new Imedion or Tenergy LSD cells might work I can say they haven't proved much better than these cells. I have two of each and would rate them just slightly better than the present AccuEvolution D cells. Not even close to the original cells.