Test for how well batteries suit your charger

[PeAK]

Long: SKIP to BLUE TEXT 1/2 page below:

I've noticed that many on this forum will hunt for a charger, get one and feel temporary peace. This "hunt" then continues, this time for batteries, and is repeated and again the "peace" is temporary. Witness a sampling of the questions:

1. Should I break them in ?
2. What sort of numbers (capacity) should I be getting ?
3. Should I do a refresh (discharge and charge) ?
4. My batteries are hot, should I increaese (or decrease the charge rate) ?

I don't expect these posts and questions to go away but I do have a proposal (Xmas-Project ?) for those with a lot of batteries who do not know which ones "behave well" with their selected charger.

Interested in slaying the battery and charger "birds" with one stone, anyone ? TRY THIS:

1. Discharge: Before I go on, lets make a comparison of charging batteries to the task of filling a container with a quart (32 ounces of water). If I drain the whole container by pouring out 1 ounce/sec. The container will be empty after 32 seconds. Let us call this rate (1 ounce/sec) to be equal to a "Wamp"...you'll see why later. The volume is still 32 ounces or "32 Wamp-seconds".
2. Charge: Now if I were to pour at double the rate you poured it out (2 ounces/sec), you would be done in half the time (16 seconds).
3. SmartCharging: Sounds difficult, but humans do it all the time when they pour themselves a glass of milk without overflowing the cup. Blind people know when to stop by holding a finger inside the top edge and waiting for "the feel".

Bottom Line/The Test

Testing the smartness (stopping when full) of your charger depends on "it" and the "batteries". Discharging them completely takes too long and then charging them up takes more time. So do the following:

1. Take a battery that has just been fully charged (as indicated by the charger). Skip the trickle portion of the charge process. What we are testing for is the "detect/shut off" capability of charger with a particular battery.
   
2. Discharge them at half the charge rate for 10 minutes
3. Charge them a the normal rate (up to a max of 15 minutes). Note the time beyond 5 minutes at which the charger stops. A perfect battery/charger will stop at 5 minutes.
4. Use the following rating for each minute beyond 5 minutes:
   1 minute over: 20% overcharge
   2 minute over: 40% overcharge
   3 minute over: 60% overcharge
   4 minute over: 80% overcharge
   5 minute over: 100% overcharge

Note: The "overcharge" is relative to the small amount of charge that was taken out and not relative to total charge of the battery(i.e. capacity). So if I take a cup out of a gallon container but need to put back in two cups, then the overcharge will 1x (i.e. 100% more) the amount I took out.

For those using a "resistor" to discharge, the value will be:

R_dis ~= 2.9/('Charge Current')

So for a 1 amp charge rate, you should use a 2.9 ohm resistor to get about 0.5A disharge.

...tell me what you find,
PeAK

[Vikas Sontakke]

Another test to check a charger is to put the fully charged battery back in the charger and try to recharge it again. If the charger takes "too long" to realize that it is already charged, then it is a bad charger!

- Vikas

P.S. More than 5 minutes is "too long"

[TakeTheActive]

...tell me what you find...

PeAK,

Honestly, I feel that folks like you and me, trying to elicit MEMBER PARTICIPATION, are like 'snowFLAKES in hell'. (Yeah, that's right, not even snowBALLS! )

[TakeTheActive]

...Bottom Line:
Testing the smartness (stopping when full) of your charger depends on "it" and the "batteries". Discharging them completely takes too long and then charging them up takes more time. So do the following:

1. Take a fully charged battery
2. Discharge them at half the charge rate for 10 minutes
3. Charge them a the normal rate (up to a max of 15 minutes). Note the time beyond 5 minutes at which the charger stops. A perfect battery/charger will stop at 5 minutes.
4. Use the following rating for each minute beyond 5 minutes:
   1 minute over: 20% overcharge
   2 minute over: 40% overcharge
   3 minute over: 60% overcharge
   4 minute over: 80% overcharge
   5 minute over: 100% overcharge

Note: The "overcharge" is relative to the small amount of charge that was taken out and not relative to total charge of the battery(i.e. capacity). So if I take a cup out of a gallon container but need to put back in two cups, then the overcharge will 1x (i.e. 100%) the amount I took out...

I've been thinking about your 'CHALLENGE' over the past few days and 'somewhere' in the back of my mind, I keep thinking about reading of a (for lack of a better term) "NULL Zone" (i.e. xx minutes), where a 'SMART' (and maybe also 'inexpensive' / aka CHEAP! ) Charger will IGNORE *ANY* termination signals.

Thus, the PARAMETERS of your test MAY be too small...

IMHO, *MANY* Newbies here don't realize that the (*HIGHLY* regarded) La Crosse BC-900 (series) and Maha MH-C9000 'SMART' Chargers are *NOT* LABORATORY GRADE devices. And, neither are the cells (Eneloop, Duraloop, Durabrid, etc...).

Thus, if they see 2000mAh Capacity one time and 1968mAh Capacity the next, they immediately think DISASTER!

I personally see 'Unique Variances' *MANY* times during my 'Experiments'. But, unless they REPEAT CONSISTANTLY, I just ignore them.

[ronkar]

OK,

So I tried the experiment. It failed miserably, with a several minute overcharge.

Intending to do the experiment, I took an LSD cell from my stash, and discharged it at 0.3A for 10 minutes. Then I started a charge at 0.6A, and after 10 minutes the battery was still charging. I think it went about 15 minutes to termination by -dV. I never looked at the amount of charge in. So because I was NOT sure that this cell had ever been fully charged, I let it go for the day. Prior charges had been terminated not by -dV, but by 750 mAh input to prevent possible overheating. I had charged a similar pair in series, and they got hot by the time they had absorbed 850 mAh. After that, I set the charger to terminate at the cell max, just so as not to abuse. This particular cell was terminated with only 750 mAh input in its prior cycle.

Eight or so hours later, I ran the test again. In 10 minutes of discharge at 0.3A my charger said I used about 50 mAh. Without resting the cell, I started a charge cycle at 0.6 Amps. The cell took a whopping 167 mAh input. The battery was warm to the touch, but not hot. It terminated by -dV without intervention. I looked away, so it could have been after 11 minutes or so.

Unfortunately, I used an UltraLast Green, precharged (LSD) 750 mAh AAA cell which in its short life has never output the same values twice. It could be that in spite of a one time slow "break in", the cell is just not ready to perform. It has been through 3 "test" discharge/charge cycles before this test.

I can try the test again when this batch of cells is a little more mature, or when I break down and open the Costco pack of Eneloops, and get them broken in. But being cheap, I want to experiment and beat on the worst cells first, and preserve the good stuff for later.

So in summary, my inconsistent cell remains inconsistent, and I know my charger can detect -dV in this cell if I give it a chance. Not a total loss after all.

The charger used was the Accucell-6 (on manual to allow input/output parameter setting).

[Henk_Lu]

I use Eneloop type cells, the Panasonic Infinium with the 2-bay charger provided with the cells.

Due to devices-failures after only 10 to 20% of the tme the cells should work, I began "double-charge" the cells, which means that once the *smart* charger finished, I put the cells back in with reversed bays. The charger somtimes takes another 5 hours to finish!!!

The charger has already been replaced by the same model, same result. I guess it has only one circuit and I don't understand they sell cells with a sucking charger, people who have no idea at all about rechargeables think that the cells are crap...

I recently bought the Titanium 8800 AA/AAA smart charger and hope I can at last enjoy using the LSD when I have it!

[PeAK]

TTA...good point about the "Null Zone". I'll get back to this when I respond to Vikas's point.

.
.
. ...I keep thinking about reading of a (for lack of a better term) "NULL Zone" where a 'SMART' Charger will IGNORE *ANY* termination signals.

Thus, the PARAMETERS of your test MAY be too small...

IMHO, many Newbies here don't realize that the highly regarded 'SMART' Chargers (LaCrosse BC-900 and Maha MH-C9000) are *NOT* LABORATORY GRADE devices...
.
.
.

I personally see 'Unique Variances' *MANY* times during my 'Experiments'. But, unless they REPEAT CONSISTANTLY, I just ignore them.

Vikas (below) assumes the value of this "Null" is zero...see below. The introduction of a discharge forces the charger to deal with some "minimum level" of useful charge activity. Think of it as a warmup or offset before the real test begins. It also serves as a useful number for reference purposes and when expressed as a percentage (i.e. overcharge) takes the charge rate out of the question.

Another test to check a charger is to put the fully charged battery back in the charger and try to recharge it again. If the charger takes "too long" (5 minutes) to realize that it is already charged, then it is a bad charger!
.
.
.

The problem with Vikas's test, as TTA pointed out, is that the chargers need time to detect small differences or as mentioned "They are not LAB grade" and need a certain minimum amount of time to analyze the battery before making a decision. His test probably cannot do a "ton of damage" as 5 minutes is pretty small and even with a 1,000 milliamp charge, it would amount to 83 mA-Hr of extra charge. Not much in the scheme of things if the battery was a 2,000 mA-Hr battery. So Vikas's proposal has it's merits to gauge the charger/battery for peace of mind in the case when we charge in a non "smart" fashion and take our scientific hat off.


I tried to open up this test to more people by not having specified a particular charge rate but realize that many chargers do not have a discharge function. So for them I'll suggest they use a 1/2 watt resistor of 3 ohms and discharge for 10 minutes. This will draw about 400mA and will amount to a charge of 66 mA-Hr.

This all assumes that the null time is around 5 to 10 minutes for the charger.

PeAK

[PeAK]

OK,

So I tried the experiment
.
.
...I took an LSD cell from my stash, and discharged it at 0.3A for 10 minutes. Then I started a charge at 0.6A, and after 10 minutes the battery was still charging. I think it went about 15 minutes to termination by -dV...
.
.
.
Eight or so hours later, I ran the test again. In 10 minutes of discharge at 0.3A my charger said I used about 50 mAh. Without resting the cell, I started a charge cycle at 0.6 Amps. The cell took a whopping 167 mAh input. The battery was warm to the touch, but not hot. It terminated by -dV without intervention.

Thanks for running the test. Based upon the results of your second test, I'd assume that the battery was charged initially so you have provided two numbers (i.e. 15 minutes and 11 minutes).

You results seem consistent with my results and are related to the lower charge efficiency (i.e. how of the charge put in gets stored in the battery and is not lost as heat) when the battery is almost full.

I find that for NiMH I need to put in at least 2x (usually 4x for older batteries) the small discharge amount that I take out. The best results are for NiCads which almost have a perfect result of no overcharge and take in the same charge as I discharge.

.
.
.

I can try the test again when this batch of cells is a little more mature, or when I break down and open the Costco pack of Eneloops, and get them broken in.

This test will not harm the Eneloops...even if they are new. Please report back.

So in summary, my inconsistent cell remains inconsistent, and I know my charger can detect -dV in this cell if I give it a chance. Not a total loss after all.

Again, I thought the results were pretty good for old cells. I find that eneloop batteries tend to be very consistent across a package with termination using a charger with independent channels that can be timed down to the second.

The charger used was the Accucell-6 (on manual to allow input/output parameter setting).

I'm not worthy....Accucell-6!!!!

PeAK

[Vikas Sontakke]

I use my test routinely myself using the old Rayovac 1hr charger. After the charger has stopped the charging, I will just power cycle it and it will stop re-charging within few minutes.

I have similar issues with my hobby charger which is exactly like Turnigy; being a copy of Bantam6 :-) I too only used my old cells and not tried Eneloop and Duraloop in them. I am NOT too fond of the charger algorithm. It does some funny business for few minutes. I purchased this hobby charger hoping to re-vitalize my crappy cells and that did not work! As a matter fact, each subsequent charge/discharge cycle was getting worse than before!

If anybody can come up with the necessary tweaking to measure cell capacity correctly, I will give another shot at it.

I have 9 year old 14.2 Ryobi Drill/Light set. The charger that came with it no longer works. I opened it up and found that the hefty input transformer winding has a break. Out of the two 14.2 batteries, one has gone bad. The other is still good and I was able to charge it using alligator clips and the hobby charger. The other one I charged it but it never reached the 14.2V. Some of the internal cells must have gone completely to zero. Interestingly, the charger stopped on its own.

- Vikas

[TakeTheActive]

As time permits, I'll return to this post and add more 'Experiments'. Since I own both a Maha MH-C9000 and La Crosse BC-900, I've modified the test slightly.

TEST PARAMETERS CHANGED (11/22/09):

• DISCHARGE amount changed from 100mA to 10% of published Capacity
• 'PRIMING' "Watermark" CHARGE on Charger X added before actual Overcharge / UNDERcharge measurement

Test #A1: (Complete)
Duracell CEF-23 Mobile Charger w/NEW Durabrid 2000mAh LSD #1 (1948mAh/1.50ICV last C9000 Break-In)

• CHARGED in C9000 @ 1000mA until 'Done'
• DISCHARGED in C9000 @ 1000mA for 212mAh
• CHARGED in CEF-23 until Green LED On: 43 minutes (550mA x 43/60hr = 394mAh) 86% Overcharge ['Watermark' Primer Charge]
• DISCHARGED in C9000 @ 1000mA for 201mAh
• CHARGED in CEF-23 until Green LED On: 33 minutes (550mA x 33/60hr = 303mAh) 50% Overcharge

Test #A2: (Complete)
La Crosse BC-900 Charger w/NEW Durabrid 2000mAh LSD #1 (1948mAh/1.50ICV last C9000 Break-In)

• TOPPED OFF in CEF-23 (Test #1)
• DISCHARGED in C9000 @ 1000mA for 200mAh
• CHARGED in BC-900 @ 1000mA until 'Full': 313mAh / 18 minutes / 57% Overcharge ['Watermark' Primer Charge]
• DISCHARGED in C9000 @ 1000mA for 201mAh
• CHARGED in BC-900 @ 1000mA until 'Full': 289mAh / 17 minutes / 44% Overcharge
• DISCHARGED in C9000 @ 1000mA for 201mAh
• CHARGED in BC-900 @ _700mA until 'Full': 301mAh / 25 minutes / 50% Overcharge
• DISCHARGED in C9000 @ 1000mA for 200mAh
• CHARGED in BC-900 @ _500mA until 'Full': 306mAh / 37 minutes / 53% Overcharge
• DISCHARGED in C9000 @ 1000mA for 206mAh
• CHARGED in BC-900 @ _200mA until 'Full': 275mAh / 86 minutes / 33% Overcharge
• DISCHARGED in C9000 @ 1000mA for 204mAh
• CHARGED in BC-900 @ 1500mA until 'Full': 326mAh / 13 minutes / 60% Overcharge
• DISCHARGED in C9000 @ 1000mA for 200mAh
• CHARGED in BC-900 @ 1800mA until 'Full': 320mAh / 10 minutes / 60% Overcharge

Test #A3: (Complete)
Maha MH-C9000 Charger w/NEW Durabrid 2000mAh LSD #1 (1948mAh/1.50IVC last C9000 Break-In)

• TOPPED OFF in BC-900 (Test #2)
• DISCHARGED in C9000 @ 1000mA for 222mAh
• CHARGED in C9000 @ 1000mA until 'Done': 268mAh / 18 minutes / 21% Overcharge ['Watermark' Primer Charge]
• DISCHARGED in C9000 @ 1000mA for 200mAh
• CHARGED in C9000 @ 1000mA until 'Done': 202mAh / 14 minutes / 01% Overcharge
• DISCHARGED in C9000 @ 1000mA for 200mAh
• CHARGED in C9000 @ 700mA until 'Done': 220mAh / 21 minutes / 10% Overcharge
• DISCHARGED in C9000 @ 1000mA for 220mAh
• CHARGED in C9000 @ 500mA until 'Done': 252mAh / 33 minutes / 15% Overcharge
• DISCHARGED in C9000 @ 1000mA for 201mAh
• CHARGED in C9000 @ 200mA until 'Done': 375mAh / 125 minutes / 87% Overcharge
• DISCHARGED in C9000 @ 1000mA for 200mAh
• CHARGED in C9000 @ _200mA until 'Full': 315mAh / 105 minutes / 58% Overcharge [RETESTED after another 1000mA 'Primer' - Hmmm ]
• DISCHARGED in C9000 @ 1000mA for 214mAh
• CHARGED in C9000 @ 1500mA until 'Done': 171mAh / 7 minutes / 20% UNDERcharge
• DISCHARGED in C9000 @ 1000mA for 200mAh
• CHARGED in C9000 @ 1800mA until 'Done': 181mAh / 6 minutes / 10% UNDERcharge

Test #A4: (Complete)
Rayovac PS-23B Charger w/NEW Durabrid 2000mAh LSD #1 (1948mAh/1.50ICV last C9000 Break-In)

• TOPPED OFF in C9000 (Test #3)
  
• DISCHARGED in C9000 @ 1000mA for 206mAh
• CHARGED in PS-23B until Green LED On: 16 minutes (1300mA x 16/60hr = 347mAh) 68% Overcharge ['Watermark' Primer Charge] NOTE: Noticeably Warm!
• DISCHARGED in C9000 @ 1000mA for 200mAh
• CHARGED in PS-23B until Green LED On: 18 minutes (1300mA x 18/60hr = 390mAh) 95% Overcharge [101°F]

Test #A5: (ABORTED!!! 60 minutes / 150% Overcharge / 98°F)
Rayovac PS3 Charger w/NEW Durabrid 2000mAh LSD #1 (1948mAh/1.50ICV last C9000 Break-In)

• TOPPED OFF in PS-23B (Test #4)
  
• DISCHARGED in C9000 @ 1000mA for 200xmAh
• CHARGED in PS3 until Red LED Off: xx minutes (500mA x xx/60hr = yyymAh) zz% Overcharge ['Watermark' Primer Charge]
• DISCHARGED in C9000 @ 1000mA for xxxmAh
• CHARGED in PS3 until Red LED Off: xx minutes (500mA x xx/60hr = yyymAh) zz% Overcharge

Test #A6: (ABORTED!!! 150 minutes / 150% Overcharge / 104°F)
Rayovac PS1 Charger w/NEW Durabrid 2000mAh LSD #1 (1948mAh/1.50ICV last C9000 Break-In)

• TOPPED OFF in PS3 (Test #5)
  
• DISCHARGED in C9000 @ 1000mA for 200mAh
• CHARGED in PS1 until Red LED Off: xx minutes (200mA x xx/60hr = yyymAh) zz% Overcharge ['Watermark' Primer Charge]
• DISCHARGED in C9000 @ 1000mA for wwwmAh
• CHARGED in PS1 until Red LED Off: xx minutes (200mA x xx/60hr = yyymAh) zz% Overcharge

[HR]----------------------------------------------------------------------

Test #B1: (Complete)
Duracell CEF-23 Mobile Charger w/*CRAP* Duracell 1600mAh non-LSD #A4 (1192mAh/2.00ICV last C9000 Break-In)

• CHARGED in C9000 @ 600mA until 'Done'
• DISCHARGED in C9000 @ 1000mA for 200mAh
• CHARGED in CEF-23 until Green LED On: 43 minutes (550mA x 43/60hr = 394mAh) 97% Overcharge ['Watermark' Primer Charge]
• DISCHARGED in C9000 @ 1000mA for 202mAh
• CHARGED in CEF-23 until Green LED On: 36 minutes (550mA x 36/60hr = 330mAh) 63% Overcharge

Test #B2: (Complete)
La Crosse BC-900 Charger w/*CRAP* Duracell 1600mAh non-LSD #A4 (1192mAh/2.00ICV last C9000 Break-In)

• TOPPED OFF in CEF-23 (Test #1)
  
• DISCHARGED in C9000 @ 1000mA for 202mAh
• CHARGED in BC-900 @ 1000mA until 'Full': 296mAh / 17 minutes / 47% Overcharge ['Watermark' Primer Charge]
• DISCHARGED in C9000 @ 1000mA for 200mAh
• CHARGED in BC-900 @ 1000mA until 'Full': 292mAh / 17 minutes / 46% Overcharge
• DISCHARGED in C9000 @ 1000mA for 215mAh
• CHARGED in BC-900 @ _700mA until 'Full': 312mAh / 26 minutes / 45% Overcharge
• DISCHARGED in C9000 @ 1000mA for 202mAh
• CHARGED in BC-900 @ _500mA until 'Full': 296mAh / 35 minutes / 47% Overcharge
• DISCHARGED in C9000 @ 1000mA for 202mAh
• CHARGED in BC-900 @ _200mA until 'Full': 820mAh / 255 minutes / 306% Overcharge
• DISCHARGED in C9000 @ 1000mA for 200mAh
• CHARGED in BC-900 @ 1500mA until 'Full': 287mAh / 11 minutes / 44% Overcharge
• DISCHARGED in C9000 @ 1000mA for 200mAh
• CHARGED in BC-900 @ 1800mA until 'Full': 312mAh / 10 minutes / 56% Overcharge [107°F]

Test #B3: (In Progress...)
Maha MH-C9000 Charger w/*CRAP* Duracell 1600mAh non-LSD #A4 (1192mAh/2.00ICV last C9000 Break-In)

• TOPPED OFF in BC-900 (Test #2)
  
• DISCHARGED in C9000 @ 1000mA for 207mAh
• CHARGED in C9000 @ 1000mA until 'Done': 194mAh / 13 minutes / 6% UNDERcharge ['Watermark' Primer Charge]
• DISCHARGED in C9000 @ 1000mA for 200mAh
• CHARGED in C9000 @ 1000mA until 'Done': 200mAh / 13 minutes / 0% Overcharge
• DISCHARGED in C9000 @ 1000mA for 201mAh
• CHARGED in C9000 @ 1000mA until 'Done': 218mAh / 15 minutes / 8% Overcharge ['Watermark' Primer Charge / New Day]
• DISCHARGED in C9000 @ 1000mA for 201mAh
• CHARGED in C9000 @ 1000mA until 'Done': 203mAh / 13 minutes / 1% Overcharge
• DISCHARGED in C9000 @ 1000mA for 200mAh
• CHARGED in C9000 @ 700mA until 'Done': 232mAh / 22 minutes / 16% Overcharge
• DISCHARGED in C9000 @ 1000mA for 200mAh
• CHARGED in C9000 @ 500mA until 'Done': 235mAh / 31 minutes / 18% Overcharge
  
• DISCHARGED in C9000 @ 1000mA for 201mAh
• CHARGED in C9000 @ 200mA until 'Done': xxxmAh / yy minutes / zz% Overcharge
  
• DISCHARGED in C9000 @ 1000mA for wwwmAh
• CHARGED in C9000 @ 1500mA until 'Done': xxxmAh / yy minutes / zz% UNDERcharge
• DISCHARGED in C9000 @ 1000mA for wwwmAh
• CHARGED in C9000 @ 1800mA until 'Done': xxxmAh / yy minutes / zz% UNDERcharge

Test #B4:
Rayovac PS-23B Charger w/*CRAP* Duracell 1600mAh non-LSD #A4 (1192mAh/2.00ICV last C9000 Break-In)

• TOPPED OFF in C9000 (Test #3)
  
• DISCHARGED in C9000 @ 1000mA for wwwmAh
• CHARGED in PS-23B until Green LED On: xx minutes (1300mA x xx/60hr = yyymAh) zz% Overcharge ['Watermark' Primer Charge] NOTE: Noticeably Warm!
• DISCHARGED in C9000 @ 1000mA for wwwmAh
• CHARGED in PS-23B until Green LED On: xx minutes (1300mA x xx/60hr = yyymAh) zz% Overcharge [°F]

Test #B5:
Rayovac PS3 Charger w/*CRAP* Duracell 1600mAh non-LSD #A4 (1192mAh/2.00ICV last C9000 Break-In)

• TOPPED OFF in PS-23B (Test #4)
  
• DISCHARGED in C9000 @ 1000mA for wwwxmAh
• CHARGED in PS3 until Red LED Off: xx minutes (500mA x xx/60hr = yyymAh) zz% Overcharge ['Watermark' Primer Charge]
• DISCHARGED in C9000 @ 1000mA for wwwmAh
• CHARGED in PS3 until Red LED Off: xx minutes (500mA x xx/60hr = yyymAh) zz% Overcharge

Test #B6:
Rayovac PS1 Charger w/*CRAP* Duracell 1600mAh non-LSD #A4 (1192mAh/2.00ICV last C9000 Break-In)

• TOPPED OFF in PS3 (Test #5)
  
• DISCHARGED in C9000 @ 1000mA for wwwmAh
• CHARGED in PS1 until Red LED Off: xx minutes (200mA x xx/60hr = yyymAh) zz% Overcharge ['Watermark' Primer Charge]
• DISCHARGED in C9000 @ 1000mA for wwwmAh
• CHARGED in PS1 until Red LED Off: xx minutes (200mA x xx/60hr = yyymAh) zz% Overcharge

[HR]----------------------------------------------------------------------

Test #A:
Duracell CEF-23 Mobile Charger w/OLD Rayovac 2000mAh non-LSD #2 (1512mAh last C9000 Break-In)

• CHARGED overnight in CEF-23 (LED Green)
• DISCHARGED in C9000 @ 1000mA for 100mAh
• CHARGED in CEF-23 until Green LED: 23 minutes (550mA x 23/60hr = 211mAh) 111% Overcharge

Test #B: (Cancelled)
La Crosse BC-900 Charger w/OLD Rayovac 2000mAh non-LSD #3 (1401mAh last C9000 Break-In)

• TOPPED OFF in CEF-20 (Test #A)
• DISCHARGED in C9000 @ 1000mA for 100mAh
• CHARGED in BC-900 @ 1000mA until 'Done': xxx mAh

Test #C:
Maha MH-C9000 Charger w/OLD Rayovac 2000mAh non-LSD #2 (1512mAh last C9000 Break-In)

• TOPPED OFF in CEF-23 (Test #B)
• DISCHARGED in C9000 @ 1000mA for 100mAh
• CHARGED in C9000 @ 1000mA until 'Done': 129mAh / 9 minutes / 29% Overcharge
• DISCHARGED in C9000 @ 1000mA until 0.90VDC: 1553mAh
• CHARGED in C9000 @ 1000mA until 'Done': 1811mAh / 120 minutes / 17% Overcharge

Test #D:
Rayovac PS-23B Charger w/OLD Rayovac 2000mAh non-LSD #2 (1512mAh last C9000 Break-In)

• TOPPED OFF in C9000 (Test #C)
• DISCHARGED in C9000 @ 1000mA for 100mAh
• CHARGED in PS-23B until Green LED: 13 minutes (1300mA x 13/60hr = 282mAh) 182% Overcharge

Test #E: (Cancelled)
Rayovac PS3 Charger w/OLD Rayovac 2000mAh non-LSD #3 (1401mAh last C9000 Break-In)

• TOPPED OFF in BC-900 (Test #D)
• DISCHARGED in C9000 @ 1000mA for 100mAh
• CHARGED in PS3 until Red LED off: xx minutes (500mA x xx/60hr = xxxmAh)

Test #F: (Cancelled)
Rayovac PS1 Charger w/OLD Rayovac 2000mAh non-LSD #3 (1401mAh last C9000 Break-In)

• TOPPED OFF in PS-23B (Test #E)
• DISCHARGED in C9000 @ 1000mA for 100mAh
• CHARGED in PS1 until Red LED off: xx minutes (200mA x xx/60hr = xxxmAh)

Test #G: (ABORTED! 365 minutes and still counting!)
Duracell CEF-20 Mini Charger w/OLD Rayovac 2000mAh non-LSD #3 (1401mAh last C9000 Break-In)

• CHARGED overnight in CEF-23 (LED Green)
• DISCHARGED in C9000 @ 1000mA for 100mAh
• CHARGED in CEF-20 until Green LED: xx minutes (280mA x xx/60hr = xxxmAh)

I plan to repeat the above 7 tests with a NEW Durabrid (MIC) and then finally with a NEW Sanyo Eneloop...

[PeAK]

As time permits, I'll return to this post and add more 'experiments'. Since I own both a Maha MH-C9000 and La Crosse BC-900, I've modified the test slightly.

Test #1:
Duracell CEF-23 Mobile Charger w/Rayovac 2000mAh non-LSD #2 ...
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Test #7: (Queued)
Rayovac PS1 Charger w/Rayovac 2000mAh non-LSD #3 (1401mAh last C9000 Break-In)

• TOPPED OFF in PS-23B (Test #5)
• DISCHARGED in C9000 @ 1000mA for 100mAh
• CHARGED in PS1 until Red LED off: xx minutes (200mA x xx/60hr = xxxmAh)

I plan to repeat the above 7 tests with a NEW Durabrid (MIC) and then finally with a NEW Sanyo Eneloop...

Great stuff. I can't wait to see your conclusions. I like your use of mA-hr (instead of time) as it offers a clearer picture of the "overcharge ratio". It is especially convenient for those who have the number available readily on their Maha/Lacrosse units. Those who only have a two ohm resistor can report the time and I'll volunteer to calculate the equivalent mA-hr amounts.

When I said to take a "fully charged battery", what I meant was a battery that was indicated as full by LED status indicating so. Leaving it on in trickle mode is not necessary. The idea is that if I charged to a "watermark" and then let a trickle of charge continue, I will lose the watermark (i.e. Charge state when LED status changes to full). When I discharge, it needs to get rid of this additional charge, first, and then the remaining portion of the discharged amount...this will confuse the results and lead to lower than actual "charge ratios". Tell me what you think.

cheers,
PeAK

[Light Sabre]

In my opinion you are all wasting your time. Variability in mAH in NMH cells is + or - 10%. It takes approx 120-130% mAh give or take to recharge a NMH. So for a depleted 2000 mAH battery it's could take up to 2600 mAh to recharge it. The 100 mAh that you're disharging your battery is gonna take up to 130 mAh to finish off the charge. The charger is also gonna have to measure the -dV time. So IMHO they all or most are gonna fail your test.

[TakeTheActive]

...When I said to take a "fully charged battery", what I meant was a battery that was indicated as full by LED status indicating so. Leaving it on in trickle mode is not necessary. The idea is that if I charged to a "watermark" and then let a trickle of charge continue, I will lose the watermark (i.e. Charge state when LED status changes to full).

...this will confuse the results and lead to lower than actual "charge ratios". Tell me what you think.

I agree. I mixed Apples with Oranges.

Also, since one of my goals for today was to fill in my Charger and Cell Inventory in Do You Maintain *CRAP* NiCD/NiMH Cells?, I wasn't giving YOUR 'Experiment' my FULL attention.

I believe that the PARAMETERs need a slight re-wording. Since the user may own and actively use more than one charger, it's CRITICAL that the 'watermark' be reached BOTH TIMES in this 'Experiment' on the SAME charger.

NOTE: To save time, select what you believe to be a FULLY CHARGED cell. WHERE it was charged does not matter at this point.

1. DISCHARGE approximately 100mAh from the cell
   - EASY with a MH-C9000 or BC-700 / BC-900 / BC-9009
   - Otherwise, requires a RESISTOR, DMM and STOPWATCH (Instructions TBD)
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2. CHARGE the cell until JUST the point of termination on Charger X
   - 0.5C is recommended on an Adjustable Charge Rate Charger
   - Record the Charge Rate on a Fixed Rate Charger
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3. DISCHARGE approximately 100mAh from the cell
   - EASY with a MH-C9000 or BC-700 / BC-900 / BC-9009
   - Otherwise, requires a RESISTOR, DMM and STOPWATCH
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4. RE-CHARGE the cell until JUST the point of termination on Charger X
   - 0.5C is recommended on an Adjustable Charge Rate Charger
   - Record the Charge Rate on a Fixed Rate Charger
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5. NOTE the Elapsed Time in minutes.
   - EASY with a MH-C9000 or BC-700 / BC-900 / BC-9009
   - Otherwise, check your STOPWATCH.
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6. CALCULATE the Overcharge.
   • MH-C9000 or BC-700 / BC-900 / BC-9009:
     - (CHARGE IN / 100mAh) - 1 x 100
   • Fixed Rate Charger:
     - (Charge Rate x (Elapsed Time / 60) / 100mAh) - 1 x 100

Note: The "overcharge" is relative to the small amount of charge that was taken out and not relative to total charge of the battery(i.e. capacity). So if I take a cup out of a gallon container but need to put back in two cups, then the overcharge will 1x (i.e. 100% more) the amount I took out.

Overkill?

Since I also missed the "100mAh Cutoff" on Cell #2 for Test #5 (and DISCHARGED @ 1000mA down to 0.9VDC), I'm now 'adding on' to the results by CHARGING @ 1000mA on the C9000 and recording the mAh and minutes when 'Done'.

Then, the next time that I'll be sitting here at the computer for an hour or more, I'll follow my NEW instructions and record the results.

P.S. 100mAh (from a 2000mAh 'Vibrant' or ~1500mAh *CRAP* cell) might be TOO SMALL, based on the Overcharge Percents that I'm recording. Since my CEF-20 is *STILL* going (at 290 minutes!), I may try 200mAh (or 10% of CAPACITY) next time.

[SilverFox]

Hello PeAK,

I will caution those who use hobby chargers that this test could result in overcharge conditions.

For example, my Schulze charger cautions against charging cells that are already charged. The reason is that the charger doesn't check anything until the charge has progressed for at least 5 minutes. This means that it will charge at the rate selected for 5 minutes before it begins monitoring for changes in cell voltage. Since it takes some sampling to determine a value, it could take several minutes longer before the charger would have enough information to terminate.

There are many reports of battery packs venting during topping off. The cause of this is the shut down in monitoring during the early part of the charge.

It may be better to extend your discharge from 10 minutes to 20 minutes.

Tom

[J_C]

I have 9 year old 14.2 Ryobi Drill/Light set. The charger that came with it no longer works. I opened it up and found that the hefty input transformer winding has a break. Out of the two 14.2 batteries, one has gone bad. The other is still good and I was able to charge it using alligator clips and the hobby charger. The other one I charged it but it never reached the 14.2V. Some of the internal cells must have gone completely to zero. Interestingly, the charger stopped on its own.

- Vikas

I can't be certain of the fault there but one very common one I've seen may be the problem. When the battery pack has some cells with internal shorts, the transformer ends up running hotter and trips it's thermal fuse. They're supposed to be resettable fuses (automatically closing the circuit again after it cools) but over time they lose the ability to re-close.

Point being you can probably replace that fuse under the outer transformer wrap and have it functional again, or as a temporary test just jumper across the fuse to see if it then works.

[J_C]

I tried to open up this test to more people by not having specified a particular charge rate but realize that many chargers do not have a discharge function. So for them I'll suggest they use a 1/2 watt resistor of 6 ohms and discharge for 10 minutes. This will draw about 400mA and will amount to a charge of 66 mA-Hr.

PeAK

So @ 400mA you're discharging a 2.4V pack, 2.4*.4= 1W, that 1/2W resistor is going to get pretty hot and bothered, I'd suggest 2W resistor if nothing larger is lying around to use.

[PeAK]

Hello PeAK,

I will caution those who use hobby chargers that this test could result in overcharge conditions.

For example, my Schulze charger ...
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It may be better to extend your discharge from 10 minutes to 20 minutes.

Tom

Tom,

As most know, your deserved reputation precedes you: I'm sure that you know hobby equipment well enough to make your suggestion useful for the Schulze. User TTA pointed out this same point, in a more general vein, as the null zone.

The Schulze (and other hobby chargers) are more the exception due to their larger memories that afford sampling over longer time intervals. The 10 minute discharge already had a safety margin and will likely cover most of the sub $30 chargers. For those patient enough, try SilverFox's 20 minute discharge but also the 10 minute discharge for comparison. The numbers will shed some light on this issue.

[PeAK]

So @ 400mA you're discharging a 2.4V pack, 2.4+.4= 1W, that 1/2W resistor is going to get pretty hot and bothered, I'd suggest 2W resistor if nothing larger is lying around to use.

I thought 2.4+.4 is equal to 2.8 Earlier I assumed an independent channel charger. This means a complimentary 1.2V discharge across the resistor. This works out to 0.48W or just less that a 1/2 watt.

[J_C]

I thought 2.4+.4 is equal to 2.8 Earlier I assumed an independent channel charger. This means a complimentary 1.2V discharge across the resistor. This works out to 0.48W or just less that a 1/2 watt.

Oops, prior post edited to change "+" to "*". make that 2.4 * 0.4 = 0.96 (rounded up to 1). So, if you are discharging a pack of two cells in series (nominal 2.4V) with the 6 ohm resistor, you have one watt dissipation across it. Even if it were 0.48W you don't want to run a power resistor near max values, derate to about 1/2 for long life, easier thermal management, handling, etc.

If you are discharging individual cells with a 6 Ohm resistor you have 200mA, rather than the 400mA you'd written previously. Perhaps I have misunderstood exactly what you are doing.

[Vikas Sontakke]

I can't be certain of the fault there but one very common one I've seen may be the problem. When the battery pack has some cells with internal shorts, the transformer ends up running hotter and trips it's thermal fuse. They're supposed to be resettable fuses (automatically closing the circuit again after it cools) but over time they lose the ability to re-close.

Point being you can probably replace that fuse under the outer transformer wrap and have it functional again, or as a temporary test just jumper across the fuse to see if it then works.

I saw a fuse *after* the transformer and at least to my eyes, it did seem intact. I am ashamed to admit here that I did not thoroughly checked it though :-(

Do you believe the fuse would be in the primary (110V) or in the secondary (20V?) winding? I know that I have a break in the primary.

Thanks,
- Vikas

[J_C]

I saw a fuse *after* the transformer and at least to my eyes, it did seem intact. I am ashamed to admit here that I did not thoroughly checked it though :-(

Do you believe the fuse would be in the primary (110V) or in the secondary (20V?) winding? I know that I have a break in the primary.

Thanks,
- Vikas

While you should check that fuse for continuity, it is not the one I refer to. The likely fuse is just outside of the windings and a temperature cutoff type. Yes it is likely/typically on the primary windings just under the wrap you'll probably have to take off to see it. It doesn't look like a traditional glass or ceramic bodied fuse, is typically a small square shape or cylinder with a tapered end.

While the safest thing to do is of course to replace with another fuse, for the time being you can just solder a jumper across it's leads to monitor whether the charger works again. I do not recall what temperature ratings those use but if you were to source a replacement you might pick something roughly 120C rated as a guess, or the original might have ink markings you can try to look up for specs.

[Light Sabre]

Was just thinking that maybe a better way to test your charger and battery compatability would be to run a discharge/charge cycle on the batteries and see how hot the batteries get. Use a thermometer that has a wired remote sensor (Target has 1 model) (they're getting harder and harder to find) and place it on/between/under the batteries and see how hot the batteries get at a given charge rate. Place the batteries near the charger over night. Insert them into the charger. Install the probe. Wait 30 minutes so that the probe temperature and battery temperature equalize. Reset the thermometers min/max feature. Run the test and read the max temperature. The min temperature would be the ambient temperature at the beginning of the test. The charger that gets the batteries the hottest means it's probably not a good match.

Try different charge rates to see how hot the batteries get for each one.

[PeAK]

... maybe a better way to test your charger and battery compatability would be to run a discharge/charge cycle on the batteries and see how hot the batteries get.
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... The charger that gets the batteries the hottest means it's probably not a good match.
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While I agree that "heat" is something that could provide a measure of how well the charger and batteries match. Most people lack a well calibrated thermometer and your tests would last much longer than the 10 minute test that was proposed.

The idea here is to gauge if the charger could potentially have Lacrosse-like (BC-900) meltdown issues.

PeAK

[Ron Schroeder]

I think the most important thing for consistancy of the tests is that the batteries be at a consistant temperature (preferably room temperature) before put back in the charger. I put mine in the flow of a fan in a 70 degree room for a while before putting them back in the charger.

[ieslei]

A friend gave me one 2.7Ohm resistor with 5% tolerance....Does it work to discharge a battery??

[J_C]

A friend gave me one 2.7Ohm resistor with 5% tolerance....Does it work to discharge a battery??

Yes you could discharge batteries with it, BUT what wattage is it? It is going to get pretty hot and for DIY applications where it isn't heatsunk well by large or thick copper traces, I usually derate the wattage by 50%.

In other words in a 2.7Ohm resistor you'd want at least 1W rated resistor to discharge 1 x ~ 1.2V NiMh, or 10W rating for 1 x Li-Ion. Obviously you'd not want to use it for non-protected Li-Ion cells since it would drain below minimum acceptable voltage, unless you babysit it the whole time with a multimeter so you know when to terminate the discharge.

[ieslei]

Well, about the wattage I dont know...All I know is that the colors are RED, PURPLE,YELLOW,GOLD AND BLACK meaning 2 7 4 5% 0

I used it to discharge my energizer 2500 NiMH and i was pretty hot, simple untouchable, and after a couple of hours the battery was depleted.... I`ll only use it to discharge NiMH

How do I know the wattage??


Thanks a lot!

[J_C]

If it is standard carbon, (resistor) and no specs, size determines wattage.

I have not measured, but guesses about size... 1W is about 4mm diameter. 2W, about 7mm diameter, probably less. 5W or 10W is a power resistor in sandstone block (usually ceramic brick) format.

[ieslei]

The shape is cylindric, the background color ir brown and it`s exactly 6mm in diammeter......
This picture shows the overall body of my resistor(the colors are no the same)
Thanks a million!!

[J_C]

^ I can only guess that it's 2W. Resistors are dirt cheap, worst that would happen so long as you keep it away from anything it would melt is that you lose a 5 cent part from overheating.