[marmitse]

I have altogether six DLi90 batteries for my K-3. Two original Pentax and four generic of different make and brand. The reason for the multitude of batteries was to be on the safe side on a two week safari, with limited charging capabilities. Anyway, most of the batteries (original and generic) have lost their stamina. When I go out for a photo-shoot I often consume two batteries and each die after 50-300 exposures (not using LiveView or on camera flash). Also the power level indicator often goes from full charge green to yellow after a shot and during the writing to the SD-card very early on. Letting the battery rest for a while makes it "recover" a bit. In cold weather this is even more accentuated. Most of this is natural behavior of Li ion batteries, and has been reported in other Pentax Forum threads (one extensive is "K5 generic battery", but ends in 2011: https://www.pentaxforums.com/forums/115-pentax-k-5/126068-k5-generic-battery.html). I believe battery technology is still on a steep development curve and improvements should have trickled down also to the DLi90 battery!?

I have some specific questions to the community:

1) Could the charger deteriorate the batteries? I am using both the original charger and this one with dual charging capabilities: DUAL Battery Charger D-Li90 Pentax Optio K5, K-5, K7, K-7 | eBay
2) Do you see any main difference in generic vs original battery life?
3) How many charge cycles should a battery take before end-of-life?
4) How to measure the battery quality, so that I can dispose the worst ones? (Beyond just shooting and counting, which is a bit random process)
5) Is there a way to "shock" a Li ion battery to regain some of its original stamina?
6) Any 3rd party DLI90 replacement brand you could recommend based on long term use? (Ebay reference/Europe prefered)

[PePe]

I have been using both Pentax original and Hähnel batteries with my K 7, K 5 and K 3 bodies. The cold-temperature behaviour you described is typical for Li-batteries, and I don´t think there is much you can do about it. SDM AF seems to momentarily draw a rather hight peak current, which draws the voltage down and brings the power indicator down for a while.
Generic batteries are a mixed bag, some of them are outright rubbish while some provide good value for the money. My understanding is that Hähnel is among the better brands in this category. None of them have let me down so far. However, their lifetime is still shorter than that of OEM batteries. Considering the price, i think it is still a viable option. The capacity of the battery reduces gradually. Once it has come down to about half of its original capacity, I ususally replace it, as the remainder often drops rather quickly.

[pete-tarmigan]

The cold-temperature behaviour you described is typical for Li-batteries, and I don´t think there is much you can do about it.

In my experience that cold-temperature behaviour is as bad or worse in carbon, alkaline, NiCd, and NiMH batteries, not to mention automobile batteries, whatever they're made of (lead-acid?). The conventional wisdom is that the chemical reactions in the batteries occur more slowly at lower temperatures.

I was shooting during circa 6 hours a day for six days this febuary when below -20 degrees C and did'nt have to charge any of my two batteries. The camera hanging arround my neck turned on all the time but in sleep mode between shots. A total of approx. 400 shots taken. I was surprised that they lasted so long used to using the NiMH and NiCd but obviously the Li-Ion seems to be less affected by the cold.

EDIT: I checked the amount of images taken, 820 frames, no flash but 25 of them night shots @ 30-180 seconds

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Last edited by Unregistered User; 11-24-2014 at 09:24 AM. Reason: Changed amount

[jhmos]

I have had 2 other cheap batteries so far and have yet to notice much difference in their capacity compared to the original Pentax battery. One of them is about 9 months old and the other two are about 4 months old. I have been using the Pentax battery for 11 months, however I haven't used the camera in cold conditions at all so maybe (even with about a 29000 shutter count) non of my batteries have been stressed that much.

[marmitse]

One of the Pentax original and one of the Generic are 4 years old and from when I shot with Pentax K5, I guess these will be retired, but in replacing them it would be great to know if there are any brands that stand out with decent performance and quality.

[hcc]

I have 3 Pentax DLi90 batteries and 1 generic (Inca), for my K-7, K-01 and K-3 bodies. Last year, I used two Pentax and the generic in winter in Switzerland, with temperatures between -15 C and -3 C. From that experience, I learned first hand that the batteries depleted more rapidly in the cold weather: afterwards, I fully-charged each battery as soon as I could. I also tried to reduce battery consumption: no flash, no replay, no LCD, no Liveview, sleep mode, .... This does work and help to maximise the number of shots per battery.

During that experience,I found that the generic depleted more rapidly than the two Pentax ones, although one Pentax was older than the generic (and the other Pentax was younger).

My 5 cents...

Forgot to say that the batteries are original. One came with my K-5 and is 3-4 years old and the other came with the K-3 which is one year old.

[CarlG]

I have had 2 other cheap batteries so far and have yet to notice much difference in their capacity compared to the original Pentax battery. ...

I have 6 or 7 in total, originals and generic.The newest ones came with the K3 and grip which I preordered but the older ones are from years back. No issues with any of them. Certainly they appear weaker in the cold, but that doesn't last.

Only rule I have is to store them fully loaded and not leave them around in a run down state (but I'm not removing them from the cameras before the indicator is indicating low effect).

[marmitse]

OK, thanks for input. I now got three new generic DLi90 batteries, Chinese, branded "Original OTB". The short user guide says that half of the battery power will be gone after ~500 charge cycles. I will stay with the original Pentax charger to see how long they last.

[kadajawi]

I have one original and one generic battery for my K-5. The original is about 2 years, the generic about 1 year old. Capacity for the generic one wasn't as good from the start (I managed to shoot around 50 GB of stills and video on one day with one charge on the original battery... maybe 1000+ stills and some 30-50 minutes of video... the generic one maxed out at I'd say 70% of that?). It has died by now. In video mode it won't survive a few minutes.

Small tip for when you are out... get a charger that takes USB power too. Then you can buy an external battery, which can charge your phone... and camera. I have one by Xiaomi with 10400 mAh, that will charge my camera a couple of times, as well as my phone. Bigger ones are available too, and it may cost you less than keeping a couple of camera batteries... let alone the trouble of keeping them charged. These big power banks can be charged over night, without having to swap all the time.

[Mikesul]

I have one original and one generic battery for my K-5. The original is about 2 years, the generic about 1 year old. Capacity for the generic one wasn't as good from the start (I managed to shoot around 50 GB of stills and video on one day with one charge on the original battery... maybe 1000+ stills and some 30-50 minutes of video... the generic one maxed out at I'd say 70% of that?). It has died by now. In video mode it won't survive a few minutes.

Small tip for when you are out... get a charger that takes USB power too. Then you can buy an external battery, which can charge your phone... and camera. I have one by Xiaomi with 10400 mAh, that will charge my camera a couple of times, as well as my phone. Bigger ones are available too, and it may cost you less than keeping a couple of camera batteries... let alone the trouble of keeping them charged. These big power banks can be charged over night, without having to swap all the time.

Do your recall the brand or vendor of the generic? There seems to be quite a bit of difference in quality between brands.

[kadajawi]

Do your recall the brand or vendor of the generic? There seems to be quite a bit of difference in quality between brands.

It says battery pack for D-Li90. And some technical data. Maybe I just left it in my bag for too long without charging, who knows.

[Zafar Iqbal]

OK, thanks for input. I now got three new generic DLi90 batteries, Chinese, branded "Original OTB". The short user guide says that half of the battery power will be gone after ~500 charge cycles. I will stay with the original Pentax charger to see how long they last.

Any update on how these particular batteries are?

[marmitse]

I am sorry to say that I can not recommend the batteries branded "Original OTB". I bought three of them ~seven months ago and I have only used the original Pentax charger with them. All three deplete very fast in cold temperatures and one of the batteries only lasts for some 100-200 shots even in room temperature. I use Liveview sparsley. All three have less stamnia than 1,5 years old Pentax original battery that came with my K-3.
Not sure it is worth the worry to be out of power with white label batteries indtead of buying original.