Energizer 15 minute charger cycle

[wptski]

Here's a few screen captures. The first two are the same but in order to show the current and voltage seperate, I had to post two. The third is a screen of the current input but there is something odd going on here! I have over 7A amplitude but it's at 38% duty cycle, so the effective output is only 38% of the total amps. I think that it's being caused by my connections to the charger. It's verified by the fact that the charge time is much longer compared to the same cells being charged in the unit.

The cycle time is around 2 seconds, slow like a MAHA C808M and not a La Crosse BC-900 which is at 51Hz. I'll try to work on a better connection but I'm unsure if I can come up with anything better.

This charger detects the difference between a AA and AAA by the lenght of the cell or how much the positive is depressed. I'll have to work on that also! I know that it does drop the current for AAA cells because I split the input wire from the wallwart and checked it there.

EDIT: Thanks to (bcwang), he suggested that I may not be depressing the positive enough to generate a AA charge cycle. I was about a 1/8" short of AA lenght which I thought was close enough, guess not . The third capture is AAA charge and the first two are really a AAA cell charging which shouldn't be any different for a AA, only the maximum current. The fourth capture is AA cell charging over 7A at 94% duty cycle which appears to have a bit of variable PWM(1.16S/.84S cycle lenght).

 

[bcwang]

Hi Bill,

My guess as to what you're seeing in the third graph is the AAA charge mode. If you just wired the socket without a battery, you probably didn't apply enough spring pressure to be in AA charge mode. 38% of the full charge sounds about right for 15 minute charging AAA cells. Probably AAA use PWM to control the overall current, and AA charging might just use constant current.

I don't know what those red lines in your first two graphs show, could you explain?

Thanks,
Ben

 

[wptski]

bcwang:

Hmmm, I never thought that I might be "not" be compressing the contact enough! Very good call.

If you mean the red vertical dotted lines are the cursors, you can just moved them to show the time frame from one point to another and the amplitude value. The readings would have been shown on the right but I cropped them off. I should have just turned the feature off as I did in the last capture.

 

[wptski]

bcwang:

You were indeed correct! I needed another 1/8" depression on the positive contact for the charger to detect a AA cell. They sure leave alot of room between the AA and AAA. I've edited the first post and added a fourth screen capture of a AA charge screen.

I was using two steel spacers with a piece of insulator between them, both about 7/8" long. I used a 1/4"x1" super magnet which made it easy to install while compressing the positive contact, the magnet held it all together.

I'm glad that you read my post and caught my mistake!:twothumbs

 

[bcwang]

Hi Bill,

I'm glad that I could help. Actually, I guess I should have said "pink" line instead of "red" in my previous question. So what is that pink line showing?

Also, since your scope has multiple channels, have you confirmed the charger can charge AAA and AA at the same time with independent pwm timings going to each slot?

Thanks,
Ben

 

[the_beast]

I think the pink line is the voltage and the black is the current - the only difference between the first and second plots is the scale on the side.

I'd really like to know if the different channels really are independant too - apparently someone has said that Energizer have said not to mix AA and AAA (in the Energizer vs Maha thread), but I thought the manual said you could?

If you could verify that each channel is independent (not arranged in banks of 2 or all 4 lumped together that would be great.

 

[the_beast]

Now that I checked the other thread, I realise that it was you who had the contact from Energizer. So I guess you already know about it...

Any other results from your testing would be great. Maybe charge an AAA in one slot and read the results from a different slot with your probes, then switch the AAA for an AA and read the other slot again and see if the reading changes?

 

[wptski]

bcwang:

The Beast is correct, black is current, pink is voltage. The scale is in minutes on those two and you can see that it took about 12 minutes to charge(green LED).

There was a post in another thead that somebody installed a AA and AAA together. The red charge LED started to blink(fault). When one or the other was removed, it charged normally! I know that you'll get a blinking red LED with a poor connection as I've run into this already. That means that it's truely not independent. It can't charge at two different currents at the same time. If you install cells that not in the same state of charge, the green LED lites when the last one is full.

 

[wptski]

Now that I checked the other thread, I realise that it was you who had the contact from Energizer. So I guess you already know about it...

Any other results from your testing would be great. Maybe charge an AAA in one slot and read the results from a different slot with your probes, then switch the AAA for an AA and read the other slot again and see if the reading changes?

TB:

Well, the third capture above is a AAA charging and the fourth is AA charging. Different pulse width/duty cycle. Is that what you mean?

 

[bcwang]

oh, I think I finally get it, the first two plots are actually the entire charge cycle. Until now, I thought that the screenshot was catching the falling edge of one of the pulses. I didn't realize both plots are exactly the same except for the scale on the side.

So since the charger is pwm, why does the scope shot show a constant ~7amp charge current during the whole 12 minutes. If it's averaging the current over time, shouldn't it be like 3 amp for the AAA measurement? Otherwise I'd expect to see dips all through that current graph.

 

[wptski]

bcwang:

That's the way PWM works, it's a percentage or duty cycle of the maximum current. It's just like the MAHA C808M, 2A maximum but a 50% duty cycle for soft mode or about 1A effective output. Actually the scope's screen shows the average value that your refering to but the above are the saved waveforms and not the actual screen. I can post a sreen later if you like? It'll show the average value but crappy dots for the waveform.

That's another point that you cleared up when you caught my AA/AAA lenght mistake! My screen value was showing like 7.3A early on but dropped to around 3A and I couldn't figure out why. I was thinking that 38% of 7.3A is around 3A but never put the two together because sometimes it goes wild at times for unknown reasons to me! Well, the 7.3A returned and I remember why now too. My spacers were 1/4" O.D. steel which cut with a hacksaw and faced off on a lathe. I noticed that the O.D. might be a bit too big for the positive contact, so I put one piece back in the lathe and chamfered one edge. I believe that it was making but cocked a bit but depressing the positive contact more giving me the higher reading. After the chamfering, just a bit less lenght and bingo, less pulse width/duty cycle of the AAA size.

 

[bcwang]

Hi Bill,

I guess the confusion is in your first post you said the first two screens were for AAA cell charging. However, the current shows around 7amp in those screens which would mean it is averaging for AA charging.

 

[wptski]

The first two are a AAA charging cycle although I had a AA cell connected but the charger thought that it was a AAA because I had my spacers too short and the amplitude is over 7A but the duty cycle is 38%, so the effective charging current is 38% of 7A or so. Charging a AA cell has the same 7A but the duty cycle is 96.5% or it almost get the full 7A or so.

 

[the_beast]

The test I was hoping for was to determine properly if the charger will treat different cells differently. Can you do this:

Set up your 'test cell' for AA size.
Put an AA cell into bank 1
Put the 'test cell' into bank 2.
Run a cycle and see what the duty on bank 2 is.
Replace the AA cell in bank 1 with an AAA cell, and run a second cycle.
Compare the readings.

If the AA 'test cell' is charged at the AA rate for both tests, then hopefully the banks are independant. To confirm this you could then repeat the above using an AAA sized test cell, and check that the AAA test cell is never charged at the AA rate. On second thoughts it would be better to have the AAA sized 'test cell' tests performed before the AA ones - you can then know for sure that an AAA cell will never be charged too fast and possibly damaged.

I hope this is clear, and I know it involves a lot more testing, but it should clear up properly if the charger is truely independant or not. If you don't understand what I mean (or why) then I'll try my best to be clearer.

 

[wptski]

the_beast:

I don't understand your test. In my first post, the third capture is a AAA charge cycle with a 38% duty cycle and the fourth is a AA charge cycle with a 96.5% duty cycle, so it does have two different charging rates based on PWM.

Now another user tried a AA and AAA at the same time. The red charging LED started blink(fault), if either cell was removed the blinking stopped and the charge continued. This proves that it doesn't have truely independent circuits like the La Crosse BC-900.

 

[bcwang]

If the first and second graph are of the 15 minute charger thinking it's charging a AAA battery, why is the current showing over 7 amps? Shouldn't the average be around 3 amps?

I think the_beast just wants you to verify that the charge current is or isn't the same for the two channels where one channel is identified as a AAA and the other is identified as a AA.

 

[wptski]

bcwang:

No, in the waveform it will always show the maximum of 7A. If posted a capture of the scope's screen with a numeric value, it would show around 3A though. If you look at the thread on the BC-900 where I posted a composite of the rates from 200ma-1800ma, all have a 1800ma amplitude but the pulse width or duty cycle is different for each ma settings which is what PWM is all about.

I see what the_beast wants now! I'll try that tomorrow.

I just install a AAA cell and AA side by side. I got "no" blinking red LED. The AA was a real old Radio Shack cell, so I grabbed a recently charge AA and inserted it. Now that caused the red LED to blink! I inserted a second AAA and in a short time the green LED came on, so I again inserted two AA cells that caused the red LED blink when the AAA was charging before but now, it didn't bother it!

I'm really starting to like this charger!

 

[the_beast]

Sorry for not making it clearer - yes, my intention is to find out what the charger does when it identifies 2 different cells. I've never managed to get my charger to flash red though, so I might try some combinations of charged and uncharged AA and AAAs to see if I can work out what might cause it to do this

 

[Ray_of_Light]

Hello

I'm trying to understand what is trickle charge allowance of the charger.
I charged two 2500 mAh batteries in the charger, then I removed only one.

After a week, the battery I removed was reading 1.35 volt, the same of the one left in the charger.
I'm not able to measure if there is any curent flowing trough the batteries when the LED is green, since it becomes "blinking red". The single-page PDF on the Energizer site says that there is trickle charge, but I would like to quantify it.

I have other chargers (Vanson) that top off at 1.42 Volts.
Thanks

Anthony

 

[wptski]

the_beast:

Here is a scope screen with a AAA cell test connections and AA cell inserted in the charger. It still is charging the AAA at around 3A but to be 100% positive, I'd need to make another connection with a AA setup. I'll look into doing that but I might need to make another spacer and even a cord. I'd need another current probe which I do have.

bcwang:

Here's a actual screen showing the 3A with 38.3% duty cycle along with the 7A waveform amplitude that we've been talking about.