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03-27-2011, 02:55 AM   #1
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Totally rubbish INOV8 batteries

I bought the K5 with the one original Pentax battery.

I also bought two of these from Amazon.

It was immediately obvious that the INOV8 batteries were basically crap. Their life was far shorter than the Pentax one; far shorter than could be accounted for by their 1400mAh capacity against the 1860 for the Pentax battery.

So I did some tests. All 3 were fully charged overnight with the Pentax charger. The test load was 11 ohms.

The Pentax battery ran for nearly 3 hours, confirming its capacity quite closely.

The INOV8 batteries ran down after 30-40 minutes, so they are actually about 400mAh.

Interestingly, the INOV8 batteries seem to have an internal cutoff, which disconnects them around 6.9V. The Pentax one just keeps running down; I stopped the test at 5.98V.

I am returning these to Amazon for a refund, obviously, but I wonder how widespread this is. I have often found "cheap" batteries to be "obviously" worse than the original ones. This was across a range of cameras, camcorders, etc, going back to my first Hi-8 camcorder in 1991 for which all the no-name NICD batteries were basically crap. But this is the first time I did an actual test.

03-27-2011, 04:44 AM   #2
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will the k5 continue to run when the voltage hits 5.98v?

you should stop your time measurements at that point where the battery reaches a voltage that the k5 no longer works.
03-27-2011, 04:54 AM   #3
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It seems there are batteries that are essentially counterfeit in the sense that the stated capacity is nowhere near of that reported, have seen these before as dirt cheap cell phone replacement batteries, otoh in the latter category there are perfectly good replacements too which are substantially cheaper than the OEM item. I suppose a reputable seller is the key when trying some unfamiliar brand. On the grand scheme of things returning such should work against the originators of substandard products.
03-27-2011, 05:03 AM   #4
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The fully charged voltages for the INOV8 batteries were both 8.0V, while the Pentax one was 8.35V

The former immediately dropped to about 7.5V, while the Pentax dropped to 8.0V. That is a big difference which suggests a much smaller battery (with a larger internal resistance) inside the package.

I don't know what the camera actually needs but the Pentax dropped quite rapidly at the very end from say 6.5V to 6V within 30 minutes so I regarded it as the end of its life.

I think the INOV8 batteries are either poor fakes, or there is something strange about the Pentax charger. However, since the INOV8 batteries have a slightly lower voltage, one would think that any given charger would charge them for longer!

Of course, Amazon advertise the INOV8s specifically for the K5 so in any case there is something very badly wrong.

Finding a contact email address for Amazon customer service is impossible (obviously intentional, looking at their website) and I eventually send a message using some unrelated form on their website. To their credit they responded quickly (on a Sunday!) with the mailing label.

However I also eventually found (using google!) an address for them here:
Amazon.co.uk Legal Department, Patriot Court, 1-9 The Grove, Slough, Berks, England SL1 1QP which I have sent the test results to.

Which still leaves me with which battery to buy? Can anybody recommend a battery as good as the Pentax one?

03-27-2011, 06:13 AM   #5
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I have an INOV8 battery as my spare and whilst it has a lower capacity I find it far exceeds 40mins of use. I have used it whilst on on a photoday taking over 500 images on one charge.

Can I ask how you tested the batteries for 3 hours of use? Were you shooting photos or was the camera just left switched on?
03-27-2011, 06:16 AM   #6
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Someone did a fairly in depth test ( K-5/K-7 battery packs - D-LI90: Pentax SLR Talk Forum: Digital Photography Review ) a couple of months ago on Pentax OEM vs. several other cheap compatibles for the K-7, ebay ones, and well known battery manufacture name equivalents. The Pentax was easily the best and the only one to reach its rated capacity, but the best of the remainder were the cheapies from 7dayshop with about 1400mAh real world performance. The best of the non-Pentax ones was Hahnel but I believe they are higher priced than 7dayshop's.

To some extent I can confirm that 7dayshop sell decent batteries because a friend has used theirs in his 5D for about 3yrs with no problems and good per charge life.
03-27-2011, 07:03 AM   #7
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QuoteQuote:
Can I ask how you tested the batteries for 3 hours of use?
As I wrote, with an 11 ohm test load, and measuring the voltage.

There is no way to compare batteries on a camera because every small thing like the recovery time between shots will affect the total life.

The only way to measure the real mAh capacity is to load it up and see how long it takes to run down.

The INOV8 is about 1/3 of the claimed capacity. The Pentax did about 100% using the same method.

That DPREVIEW article is interesting. All the batteries except Pentax and Hahnel are basically fakes because the shortfalls are too great to be production variations. INOV8 do not come out too bad; maybe the ones I have are duff.

I will get some Hahnel ones. Can anybody confirm the Pentax D-LI90 charger works well with them? I suppose one cannot be sure without doing a proper measurement.
03-27-2011, 07:20 AM   #8
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QuoteOriginally posted by peterh337 Quote
As I wrote, with an 11 ohm test load, and measuring the voltage.
sorry misread that part...

As I said my INOV8 was used in my K7 and now my K5 and I find it will easily last a full day of photography if not more. I know it won't last as long as the Pentax battery but I haven't had an issue with mine yet.

Unfortunately cheap compatible batteries are just that - cheap. If you get good life out of them well you got a good one...

03-27-2011, 07:32 AM   #9
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I find it will easily last a full day of photography if not more
A day?

I would expect it to last a 2-week holiday, taking about 1000 shots. That is about the K5 spec, IIRC.

As regards spare batteries, it is the usual tossup between carrying extra batteries and carrying just one spare plus a charger. I tend to prefer carrying extra batteries, because I have the same issue with other items (camcorder, etc).

This is why I kept the K200D - 4 x AA cannot be beaten because you will never get caught short. And if you buy primary lithiums, they last about a year....
03-27-2011, 07:50 AM   #10
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Yes a day... of taking between 500 to 800 shots.... by then usually I'm home or have somewhere to charge my batteries up. I have never run out of charge whilst out (touch wood ).
03-27-2011, 07:53 AM   #11
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Seeing as they stole the name of my favorite shoe brand (wearing a pair now) I'm not surprised they're terrible!
03-27-2011, 09:41 AM   #12
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Try the ZEIKOS ZE-LI90. 2800 mAh, 20.1 Wh

I've had no problems at all in my K-5. I am pretty sure this outlasts even the Pentax battery.
Amazon.com: Zeikos ZE-LI90 Lithium Ion Battery Replaces the Pentax LI90 Battery: Electronics
03-27-2011, 10:32 AM   #13
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That's a US Amazon site. Nobody sells it in the UK AFAICT.
03-27-2011, 10:39 AM   #14
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QuoteOriginally posted by peterh337 Quote
That's a US Amazon site. Nobody sells it in the UK AFAICT.
so the best generic batteries we can buy in uk is in fact hahnel 1560mAh? I have fistfull of unknown/el chipo batteries so far and apart of reasonable shorter life i cant complain.... i mean i didnt experience any explosions, flames etc so far...
03-27-2011, 08:01 PM   #15
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I have two generic ones from ebay from china they work fine for $12 dollars each better than $140 here in Australia for pentax. I have been using them and chinese grips for years and no problems
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