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06-18-2017, 10:13 AM - 8 Likes   #1
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Capacity measurements of some 3rd party batteries

Happy Father's Day everyone,
After getting my K-3 about 2.5 years ago, I picked up a pair of Wasabi batteries, which worked well to compliment the OEM battery. But recently, the Wasabis have been giving poorer performance. I used all three in pretty regular rotation, so they all have similar use. So it seemed to be time to look for some new batteries.

After much searching, I could not find any actual Ah measurements of capacity for the batteries, just discussions on how they seem to perform (or not) in camera. From a different project, I had a constant current Ah measurement circuit that can integrate the current down to a set cutoff voltage. This seemed like a great opportunity to collect some data.

So first I tested my 2.5 year old batteries. I used a cutoff voltage of 6.8V under load. In my K-3, this is where I get the one bar remaining (pretty much dead) while in live view mode. I got the following results:
Pentax OEM: 1.17 Ah
Wasabi (1): 0.35 Ah
Wasabi (2): <0.01 Ah

OK, it looks like the Wasabi's have not withstood the test of time.

Now it's time to evaluate some new batteries. So I decided to buy a collection of third party batteries from very cheap to abut 1/2 the OEM cost. I got two more Wasabi batteries (claimed to have 2.3 Ah) for $25 (that included a charger, since it was still cheaper per battery), two DSTE batteries (claimed to have 2.8 Ah) for $14, and a single Watson battery (claimed to have 1.8 Ah) for $22. I an them through a couple charge and discharge cycles and got the following results:
Wasabi (3): 1.07 Ah
Wasabi(4): 1.13 Ah
DSTE(1): 1.01 Ah
DSTE(2): 0.97 Ah
Watson: 1.49 Ah

Unfortunately, I do not have a new OEM to test (I didn't want to drop $50 on a new one). So the comparison is incomplete. But clearly, the Watson is the hands down winner for initial capacity. And it had a more honest Ah rating.

For those interested in the weights:
Pentax 77g
DSTE 71g
Wasabi 73g
Watson 77g

As a bonus investigation, I dissected one of the old Wasabis to see what is inside. What I found were two 18490 li-ion batteries. I thought, maybe I can rebuild with new cells. Not a common cell, and the vast majority of raw cells are only rated at 1.1 Ah (there was one that claimed 15, but I am skeptical). I'm starting to wonder if the Ah spec claimed by some manufacturers is based on summing the two cells, when it should be rated as one cell, when wired in series.

I will keep testing these over time to see how see how well the brands hold up. This is a small sample and I would love to test a new Pentax and another Watson, but I can only justify so much money to the project. But I hope this helps others in looking at third party batteries.

06-18-2017, 10:54 AM   #2
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Great information. Thanks for doing these tests.
06-18-2017, 11:23 AM   #3
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Nice info! I use the off-brand ones simply because I can buy four for the price of one OEM and I don't expect the OEMs to last four times longer. I have to junk the 3rd parties after a year or so of use (b/c they just start to have poor voltage performance and the camera acts kinda weird), and this confirms what you say about capacity falling in time.
06-18-2017, 11:30 AM   #4
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They call you 'doc' for a reason don't they?

This is good info to have for sure. I am tempted to buy a couple more OEM batteries but I still have several unused Wasabi batteries just sitting around.

06-18-2017, 12:37 PM   #5
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QuoteOriginally posted by MadMathMind Quote
I don't expect the OEMs to last four times longer
You'd be surprised at how long the OEM batteries can go. The battery of my K10D is at least 6 years old and still going strong. Others will tell of similar experiences.
06-18-2017, 12:53 PM   #6
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QuoteOriginally posted by Not a Number Quote
You'd be surprised at how long the OEM batteries can go. The battery of my K10D is at least 6 years old and still going strong. Others will tell of similar experiences.
To be fair, though, I absolutely beat the heck out of my equipment. Or rather use it a lot (I care for it as much as I can). Just this year, I've done 22 location shoots...and I took the month of January off, for the most part.
06-18-2017, 10:08 PM   #7
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Thanks for the tests. I always wondered how accurate the stated numbers were. Especially for cell phone replacement batteries on eBay, they are mostly lies.
06-22-2017, 06:52 AM   #8
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This is very useful information.

It might be worthwhile to deplete a battery in a camera body and measure to voltage to see what the voltage cutoff that Pentax bodies use. Since the K-50 and other bodies can use AA batteries at least for those bodies it must be less than 5.8 v.

06-22-2017, 11:27 AM   #9
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QuoteOriginally posted by docswanson Quote
Happy Father's Day everyone,
After getting my K-3 about 2.5 years ago, I picked up a pair of Wasabi batteries, which worked well to compliment the OEM battery. But recently, the Wasabis have been giving poorer performance. I used all three in pretty regular rotation, so they all have similar use. So it seemed to be time to look for some new batteries.

After much searching, I could not find any actual Ah measurements of capacity for the batteries, just discussions on how they seem to perform (or not) in camera. From a different project, I had a constant current Ah measurement circuit that can integrate the current down to a set cutoff voltage. This seemed like a great opportunity to collect some data.

So first I tested my 2.5 year old batteries. I used a cutoff voltage of 6.8V under load. In my K-3, this is where I get the one bar remaining (pretty much dead) while in live view mode. I got the following results:
Pentax OEM: 1.17 Ah
Wasabi (1): 0.35 Ah
Wasabi (2): <0.01 Ah

OK, it looks like the Wasabi's have not withstood the test of time.

Now it's time to evaluate some new batteries. So I decided to buy a collection of third party batteries from very cheap to abut 1/2 the OEM cost. I got two more Wasabi batteries (claimed to have 2.3 Ah) for $25 (that included a charger, since it was still cheaper per battery), two DSTE batteries (claimed to have 2.8 Ah) for $14, and a single Watson battery (claimed to have 1.8 Ah) for $22. I an them through a couple charge and discharge cycles and got the following results:
Wasabi (3): 1.07 Ah
Wasabi(4): 1.13 Ah
DSTE(1): 1.01 Ah
DSTE(2): 0.97 Ah
Watson: 1.49 Ah

Unfortunately, I do not have a new OEM to test (I didn't want to drop $50 on a new one). So the comparison is incomplete. But clearly, the Watson is the hands down winner for initial capacity. And it had a more honest Ah rating.

For those interested in the weights:
Pentax 77g
DSTE 71g
Wasabi 73g
Watson 77g

As a bonus investigation, I dissected one of the old Wasabis to see what is inside. What I found were two 18490 li-ion batteries. I thought, maybe I can rebuild with new cells. Not a common cell, and the vast majority of raw cells are only rated at 1.1 Ah (there was one that claimed 15, but I am skeptical). I'm starting to wonder if the Ah spec claimed by some manufacturers is based on summing the two cells, when it should be rated as one cell, when wired in series.

I will keep testing these over time to see how see how well the brands hold up. This is a small sample and I would love to test a new Pentax and another Watson, but I can only justify so much money to the project. But I hope this helps others in looking at third party batteries.
GREAT JOB docswanson! I agree I have found that 3rd party's batteries are a good value IF and only IF they contain battery protection! In my younger days I had Canon 1DMII and would not pay $150 for a Canon battery and then the made in China 3rd party batteries came ing and most were junk, until a battery that was as good in life as the Canon and for years I would use both and towards a year or 2 the Canon was still going strong but the 3rd party was holding less and less of a charge and so 1 day I opened it up and found to my surprise battery protection nice! But have read that some of the cheap 3rd party batteries were junk and had little or no protection which can cause major failure and DAMAGE your camera, so only use batteries that you can trust. I have since been using Wasabi as it's on Amazon and for $25 2 batts and charger can't beat that and Wasabi claims that the cells are made in Japan well I call BS! But when I switched to Sony I again got the 2 for $25 and they would not last as long as the Sony did so as in experiment I took 2 Sony bodies and 1 had the Sony and the other had the Wasabi and after leaving the cameras on the Sony lasted about 15% to 20% longer, so what I did was to recharge both batteries with the Sony charger and the Wasabi lasted about 10% longer as I don't think the Wasabi charger was charging it to 100% like the Sony did. So as long as you understand that the good quality 3rd party batteries do have protection then use them and note that the Wasabi has a 2 year warranty from Blue Nook and all you do is contact them from your Amazon account and they will just send you out free replacements, well that's what they did for me as long you are within the 2 years for purchase date. So will try the Watson and see how well they work out! Thank you docswanson for the info! Zman
06-22-2017, 05:51 PM   #10
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QuoteOriginally posted by Not a Number Quote
This is very useful information.

It might be worthwhile to deplete a battery in a camera body and measure to voltage to see what the voltage cutoff that Pentax bodies use. Since the K-50 and other bodies can use AA batteries at least for those bodies it must be less than 5.8 v.
I tried to get close to that by checking out some depleted batteries. When I took the load voltage of the battery down to 6.8V and put it in the camera, I was on the last bar, which I figure is the practical point where one will change batteries. For these Li-ion batteries, going below 6.6V (3.3 per cell) is the lowest you can safely go before the battery can be damaged. The K3 uses 6 AA in the battery grip as an alternate, and since NiMh peter out at about 1.1V, there is 6.6V volts to the camera when the AA's die. But, if I remember, I will put my next depleted battery under a test load to check the voltage.

Last edited by docswanson; 06-23-2017 at 06:14 AM.
07-02-2017, 11:10 AM   #11
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QuoteOriginally posted by docswanson Quote
Happy Father's Day everyone,
After getting my K-3 about 2.5 years ago, I picked up a pair of Wasabi batteries, which worked well to compliment the OEM battery. But recently, the Wasabis have been giving poorer performance. I used all three in pretty regular rotation, so they all have similar use. So it seemed to be time to look for some new batteries.

After much searching, I could not find any actual Ah measurements of capacity for the batteries, just discussions on how they seem to perform (or not) in camera. From a different project, I had a constant current Ah measurement circuit that can integrate the current down to a set cutoff voltage. This seemed like a great opportunity to collect some data.

So first I tested my 2.5 year old batteries. I used a cutoff voltage of 6.8V under load. In my K-3, this is where I get the one bar remaining (pretty much dead) while in live view mode. I got the following results:
Pentax OEM: 1.17 Ah
Wasabi (1): 0.35 Ah
Wasabi (2): <0.01 Ah

OK, it looks like the Wasabi's have not withstood the test of time.

Now it's time to evaluate some new batteries. So I decided to buy a collection of third party batteries from very cheap to abut 1/2 the OEM cost. I got two more Wasabi batteries (claimed to have 2.3 Ah) for $25 (that included a charger, since it was still cheaper per battery), two DSTE batteries (claimed to have 2.8 Ah) for $14, and a single Watson battery (claimed to have 1.8 Ah) for $22. I an them through a couple charge and discharge cycles and got the following results:
Wasabi (3): 1.07 Ah
Wasabi(4): 1.13 Ah
DSTE(1): 1.01 Ah
DSTE(2): 0.97 Ah
Watson: 1.49 Ah

Unfortunately, I do not have a new OEM to test (I didn't want to drop $50 on a new one). So the comparison is incomplete. But clearly, the Watson is the hands down winner for initial capacity. And it had a more honest Ah rating.

For those interested in the weights:
Pentax 77g
DSTE 71g
Wasabi 73g
Watson 77g

As a bonus investigation, I dissected one of the old Wasabis to see what is inside. What I found were two 18490 li-ion batteries. I thought, maybe I can rebuild with new cells. Not a common cell, and the vast majority of raw cells are only rated at 1.1 Ah (there was one that claimed 15, but I am skeptical). I'm starting to wonder if the Ah spec claimed by some manufacturers is based on summing the two cells, when it should be rated as one cell, when wired in series.

I will keep testing these over time to see how see how well the brands hold up. This is a small sample and I would love to test a new Pentax and another Watson, but I can only justify so much money to the project. But I hope this helps others in looking at third party batteries.
doc, I may have missed it but did you mention somewhere which charger you're using?
07-17-2017, 07:58 PM - 1 Like   #12
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QuoteOriginally posted by TomTom Quote
doc, I may have missed it but did you mention somewhere which charger you're using?
I used the OEM charger for the tests. One thing I want to do next is compare the OEM charger to the Wasabi and another 3rd party charger I have.
07-18-2017, 03:57 AM   #13
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With respect to the test, what was the current and duration of your original setup. It would be interesting to compare this to the stated rating of the battery because the discharge current can influence the apparent capacity.

Did you repeat the test at 1/2 the initial test current and 2x the initial test current.

Some batteries may perform better at different loads.

Also fif you do a couple of charge / discharge cycles, to condition the batteries and also ensure that they all reached the same exact state of charge before you did the measurements?


Lastly although I would not expect with the same technology employed everywhere, you should test to the level that is results in your camera saying battery depleted, just to make sure you have used the entire capacity of the battery. Batteries DO NOT have a purely linear voltage vs time discharge curve, so stopping the discharge earlier than when the camera reports battery depleted is not necessarily a valid test.

When I shoot I run my batteries down to the point the camera stops.

The are also standards that govern the rating of batteries, have you looked at any of these to see how your ad hoc test compares to the standards?

Just curious
07-18-2017, 06:39 PM   #14
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QuoteOriginally posted by Lowell Goudge Quote
With respect to the test, what was the current and duration of your original setup. It would be interesting to compare this to the stated rating of the battery because the discharge current can influence the apparent capacity.

I discharged at a constant 500 mA (about .3C to .5C). I stopped at 6.8 V because this was the voltage where my camera had a single yellow bar and would shut down if I switched to live view. I figured that was close to a practical limit.

Did you repeat the test at 1/2 the initial test current and 2x the initial test current.

No, I didn't try any other discharge currents. I will try it on a couple batteries to see the difference.

Some batteries may perform better at different loads.

Also fif you do a couple of charge / discharge cycles, to condition the batteries and also ensure that they all reached the same exact state of charge before you did the measurements?

Yes, I did cycle them a couple times. And I used the same charger for consistency.

Lastly although I would not expect with the same technology employed everywhere, you should test to the level that is results in your camera saying battery depleted, just to make sure you have used the entire capacity of the battery. Batteries DO NOT have a purely linear voltage vs time discharge curve, so stopping the discharge earlier than when the camera reports battery depleted is not necessarily a valid test.

The tests I did with my K3 showed it is effectively discharged at 6.8 V, depending on the mode. Live view takes more power, and will cut out a bit earlier than when taking pix with the screen turned off.

When I shoot I run my batteries down to the point the camera stops.

The are also standards that govern the rating of batteries, have you looked at any of these to see how your ad hoc test compares to the standards?


I looked a bit. For Li-Ion, some take it to 3.3 V per cell at anywhere from .2C to 1C. But I do realize that this would not be rigorous in the ANSI sense. But it did allow me to compare the batteries under similar testing conditions.

Just curious
Good questions, it keeps me thinking.
08-01-2017, 01:32 PM   #15
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I'm a little curious about the K-1/K-01lithium ion batteries myself, and wondered what the pin-outs on the K-1 battery are connected to inside the battery. Since you dissected one, do you have that information. I assume the third pin is a measurement or protection pin (temperature sense)???

I'm currently using a Pentax OEM and a Watson and haven't found too much difference in performance but I've only gone through a few charge cycles on each. It's pretty difficult to judge from actual use because of variations in camera operation during each use cycle (camera on/camera off, live view sometimes, bulb use occasionally, etc., etc.).

Your tests provided some great information and the standards you used (though not lab standards) closely represent the conditions when using the batteries in a camera so the data you got is excellent for battery comparison purposes. Thanks for sharing it.
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