[Mike M.]

Your best choice, in my opinion, is to take two sets of of Energizer Ultimate lithium batteries. These will easily give you a minimum of 2000 exposures (1,000 each set), assuming you use your flash 1/3 of the time. These batteries are very reliable and perform well even in extreme cold. I have a new K-x, and have logged 1858 exposures on one set of AA lithiums so far; that set is still going strong.

Mike

[bizi]

Yes, eneloops backed up by lithium batteries, that's what I have. Lithium has a long life and also very light (a bit expensive is the negative part).

[cadmus]

Sorry to resurrect old threads but it is on topic and thanks to for jslifoaw starting it.

This is the first time I've ever read of someone not being able to use a charger. Not that it hasn't happened, it is just the first time I've read a post about it. Why don't you get an adapter for your charger (and other electric items you may be carrying)? That question being asked, people claim to get over 1000 photos on a single charge of Eneloops. I know my rechargeable NiMh batteries are good for over 500 in my AA grip on my K7 (I shoot RAW+).

-I travel a lot and rarely have access to electricity. In the the last 5 months of traveling abroad I had <5 nights where I could have charged batteries. But i can always find AAs.
-I recreate domestically in wilderness settings or on a sailboat so no charging there.
-I work in a research setting that puts me in the back country(again no electricity) or in a lab such that I am taking photos so fast that I would burn through batteries faster than i can charge them (that was the case with my Olympus stylus)
-Many people share this love of AA because they are not able to use a charger, i know it is cited on this forum as a huge asset of shooting Pentax and since buying a k200d I have converted several canon/nikon users to Pentax for the sole reason that it runs on AA. As long as Pentax makes SLRs that run on AA they will have my business.

I have been trying to keep track of the number of photos i get out of alkaline, lithiums and eneloops. JeffJS's estimate of 500 is closer to what i am seeing with the eneloops (slow charge in a LaCross BC-9009) but some folks say 1000. I am also still learning so I fiddle with settings a lot.
1-Holding all settings constant, is the relationship between number of photos and miliamphours (mAh) truly linear? I feel as if I get more photos out of 1 mAh off the eneloops or lithiums then out of 1 mAh of the alkalins. I can think of ways that this is possible but it might just be my imagination as Lithiums and eneloops last longer and my memory might be unfairly fond for them?

2- I am sailing for a month this summer (Alaska, international waters, and BC) and will not have access to electricity. I will not be able to by AAs for much of it. I'll be packing 44 to 76 GB. Might as well shoot all of it. Weight doesn't matter.
Could i get an estimate of how many eneloops OR Lithiums OR alkalines are needed for that many photos. (i will pack a little extra. I am just hoping to draw on experience of others).

3- I own 2 sets(of 4) of enelopps and one set that came with the BC-9009 (2600mAh) and seems to work as well. How long after being charged will the eneloops hold their charge? Meaning after 3 weeks of no use what percent of the mHa is left in it? (note, these are pretty new, less than 5 charges on um)

I have limited cash. I would hate to buy disposables if i can buy more eneloops, but not if that leaves me out of batteries on this trip. thanks in advance for your advice.

[gp1806]

I have a properly functioning DL that has not had the Duraloops (same as Eneloops) charged in 7 months. Still shows full charge. I have taken about 50 shots with that camera in that time, about half with the pop up flash. There are solar powered chargers for AA batteries, should work while you sail.

[cadmus]

gp1806, OK thanks, 7 months is good.

There are solar powered chargers for AA batteries, should work while you sail.

By relying on solar power in Alaska the weather gods will punish me with nothing but rain (Holt 1877).
Yeah, the boat has a solar panel and if we have the misfortune of having to run the motor we might have some spare power. But I am a guest on this boat. The last thing I want to do is steal electrons from navigation and radio equipment. After I pay off my student loans and build my own boat, I will have a way to charge my toys, for now I can not rely on it. But I will look into this option for some of my field work this summer, any recommendations on brands?

[Marc Sabatella]

1-Holding all settings constant, is the relationship between number of photos and miliamphours (mAh) truly linear?

Not at all. That number measures the total amount of "juice" in the battery, but it doesn't come out at a constant rate. The voltage is always highest right after being charged, then it gradually drops off with use until it finally hits 0. More mAh means it will last longer before hitting 0, but the camera gives up on the cells once their voltage drops below around 1.2V each. And higher mAh cells may well drop below 1.2V sooner than lower mAh cells. Eneloops not only have low self-discharge, but they also maintain their voltage above 1.2V under load longer than most other rechargeables.

3- I own 2 sets(of 4) of enelopps and one set that came with the BC-9009 (2600mAh) and seems to work as well. How long after being charged will the eneloops hold their charge? Meaning after 3 weeks of no use what percent of the mHa is left in it?

I've never failed to get around 500 shots from Eneloops or similar "hybrid" cells on my K200D, even when starting with cells that had been sitting around for a close to a month.

If this were the only trip like this you were foreseeing taking, I'd probably be stocking up on lithiums primarily - it would be simpler and more cost-effective in the short run. But if you do this often, then having a huge stash of Eneloops would be great.

[UnknownVT]

Not at all. That number measures the total amount of "juice" in the battery, but it doesn't come out at a constant rate. The voltage is always highest right after being charged, then it gradually drops off with use until it finally hits 0. More mAh means it will last longer before hitting 0, but the camera gives up on the cells once their voltage drops below around 1.2V each. And higher mAh cells may well drop below 1.2V sooner than lower mAh cells. Eneloops not only have low self-discharge, but they also maintain their voltage above 1.2V under load longer than most other rechargeables.
I've never failed to get around 500 shots from Eneloops or similar "hybrid" cells on my K200D, even when starting with cells that had been sitting around for a close to a month.
If this were the only trip like this you were foreseeing taking, I'd probably be stocking up on lithiums primarily - it would be simpler and more cost-effective in the short run. But if you do this often, then having a huge stash of Eneloops would be great.

First a VERY WELCOME BACK Marc.

The main differences between AA battery types in Pentax dSLRs is their operating voltage maintenance under-load (this is the battery voltage when actually being loaded or used in the dSLR - as opposed to open circuit voltages).

Batteries start off with a good level of voltage - then gradually sag as they are depleted - some types maintain their voltage levels better than others - this is unfortunately not merely dependent on their capacity (mAh) - otherwise it'd be easy to choose a battery - by their capacity alone.

This operating voltage under-load is very important for Pentax dSLRs - as they use voltage level as thieir meter indicator and threshold for shutdown.
Pentax dSLRs using AA batteries are notorious for being battery fussy.

If a battery drops operating voltage under-load early - this can result in a (premature) shutdown in Pentax dSLRs - yet could retain substantial capacity for use in other devices.

Alkalines are typical for this in Pentax dSLRs - that is why they are NOT recommended other than for testing purposes.

Lithium (primary) batteries not only have good (high capacity) they also maintain their operating voltage under load well - but the downside is they are relatively expensive and disposal - so are not as "green".

Rechargeable (regular) NiMH are OK - but depending on their condition and/or capacity can drop their operating voltages early - as they start with a nominally lower voltage of 1.2V (close to the Pentax dSLR threshold of ~1.15V/cell) - Higher capacity regular NiMH use thin materials to cram in all that capacity - so are more fragile and are relatively easily damaged - so can lose their capacity and show high self-discharge - there have been reports as short as a few days.

The other class of NiMH rechargeable is the LSD (Low Self-Discharge) the most well known example is the eneloop - they generally maintain their operating voltages under-load well - with the eneloop - being the best under test.

As the operating voltage under-load is so important for use in Pentax dSLRs -
is the reason why eneloops are overwhelming recommended here.

[cadmus]

Sor stewardship reason it sounds like investing in more eneloops is better than buying lithium disposables.

I realize this is subjective and differs user to user but...
Since I don't have a feel for it, how many fully (slow) charged eneloops will be needed for 48 or 76 GB of photos?

If you can do the same request with disposables I would also love to hear it.

I realize this estimate will have large error bars. I use a k200d if it matters

(I am kinda trigger happy and end up reviewing and deleting a lot. I also am messing with settings a lot and doing time lapse, So I will likely double whatever is recommended. My estimate of 500 per eneloop might have been low because of this. I used to shoot only jpg adding the raw button 5% of the time... but I am starting to shoot a lot more raw and that likely sucks a lot of juice)

[Marc Sabatella]

Since you mention K200D specifically, I can help there.

I'd count on 500 images per charge. How that translates into GB depends on whether you shoot JPEG, PEF, or DNG. To a lesser extent on the nature of the scene (simpler scenes often compress better than more complex ones). If you shoot JPEG, the quality and resolution settings also come into play. So you'll have to figure out for yourself what your average images size for the file format, options, and types of scenes you'd like to be shooting.

For me, shooting PEF, and an unusually large number of images that tend to compress better than average, my images normally come out around 10MB each. That's 100 images per GB. So 48GB would be 4800 images. Call it 5000 and that sounds like 10 sets of cells to me. 75GB sounds like 15 sets. You could potentially cut those numbers in half by going with lithium, but I don't have any personal experience to back that up. I might try taking 5 sets each, start off using with the Eneloops, then use the lithiums until either a) they run out, b) you have a chance to recharge the Eneloops, or c) your trip ends. When in doubt, just take more.

[UnknownVT]

So 48GB would be 4800 images. Call it 5000 and that sounds like 10 sets of cells to me. 75GB sounds like 15 sets.
I might try taking 5 sets each, start off using with the Eneloops, then use the lithiums until either a) they run out, b) you have a chance to recharge the Eneloops, or c) your trip ends. When in doubt, just take more.

These calculations sound about right using a conservative figure of 500shots/charge of eneloops - I regularly get well over 1,000 shots/charge (K100D, K-x) - my "best" being over 1,500 (K-x) - but my shooting habits may well be different.

Flash, Live View and Movies are the eaters of batteries -
if none of those are used then 500 shots/charge is a conservative figure.

I have to take it that shooting 48-75gb is unlikely to be in one single session or in a single day?

Then the number of sets of batteries is only valid if there is no chance of recharging the eneloops.

Should really count the number of shots likely in a single day - 500? 1,000?

Let's take 1,000 - this is pretty high even for being trigger happy -
then 2 fully charged sets of eneloops is likely to suffice.
Have a spare set handy and also carry a set of fresh lithium disposables for backup - ought to do it -
then even if one actually manages to deplete two sets of eneloops - probably over 1,000 shots per day(!) -
then plan on charging the two sets, so they are ready for the next day......

It's a myth that slow charging is "better" for batteries -
it's missing end of charge termination - leading to over-charge and over-heat that damages batteries.

The most recommended charge rate is actually 1/2C
- for eneloops this is 1000mA -
that's about 2 hours' charge -
just make sure to use a good reputable/reliable charger

[Marc Sabatella]

These calculations sound about right using a conservative figure of 500shots/charge of eneloops - I regularly get well over 1,000 shots/charge (K100D, K-x) - my "best" being over 1,500 (K-x) - but my shooting habits may well be different.

Could be, but I'm also betting you don't really get 1000 shots out of Eneloops as often on the K100D as the K-x - I'm pretty sure the latter is more power efficient. Anyhow, I've got the same model (K200D) as the person to whom I was responding, and I think other K200D owners have reported similar results - 500-1000 shots, but closer to the 500 end than the 1000 end of that range. The K200D has no live view or movies, and I essentially never use flash.

Then the number of sets of batteries is only valid if there is no chance of recharging the eneloops.

I think that was indeed the expectation for this particular trip. Sounded like there might be a chance of having power occasionally at random intervals at best.

The most recommended charge rate is actually 1/2C
- for eneloops this is 1000mA -

I had never heard this before. Makes me feel less guilty about often turning my Lacrosse up that high.

[cadmus]

I have to take it that shooting 48-75gb is unlikely to be in one single session or in a single day?

Over the coarse of 4 weeks.

Then the number of sets of batteries is only valid if there is no chance of recharging the eneloops.

Correct, I can not recharge on this or most of my trips.

Sounded like there might be a chance of having power occasionally at random intervals at best.

correct, no chance of recharging or so slim it is not worth bringing the charger. This is a small 30' boat with 4 on board packed full for a circumnavigation, i am a guest.

Should really count the number of shots likely in a single day - 500? 1,000?

I can not estimate that. That all depends on weather, and whether i end up taking night watch. The week in Glacier Bay National Park will be a lot of photos but the weeks in open water less so (waves all look the same).

Flash, Live View and Movies are the eaters of batteries - if none of those are used then 500 shots/charge is a conservative figure.

I don't think the k200d has live view or movies, if it does i want to know. I think my reviewing of photos is the culprit, that and my 'immature, crossed fingers, rapid fire' technique needs to be replaced by a composed 'more professional, wait for the right shot' technique.

...Could be, but I'm also betting you don't really get 1000 shots out of Eneloops...

....These calculations sound about right using a conservative figure of 500shots/charge of eneloops - I regularly get well over 1,000 shots/charge....

I am still figuring out this cammera, I spend a lot of time in the menu screen and the review screen. I am guessing as I trust the shot more this will get up to 1000. I may also be deleting more then I thought, that garbage can button is handy. I should have kept better track of shutter count and battery change dates and plan to do so in the future and post my results here.

UnknownVT, Marc and gp1806, Thanks for the estimates, I realize the user and format causes huge variance so averaging the estimates helps me plan. The more observation/options/guesstimates the better the sample size.

[UnknownVT]

I had never heard this before. Makes me feel less guilty about often turning my Lacrosse up that high.

BatteryUniversity.com on charging NiMH

The charge algorithm for NiMH is similar to NiCd with the exception that NiMH is more complex. The NDV method to measure full charge shows only a faint voltage drop, especially when charging at less than 0.5C. A hot battery or one with mismatched cells works against the already minute voltage drop.

It is difficult, if not impossible, to slow-charge a NiMH battery. At a C‑rate of 0.1 to 0.3C, the voltage and temperature profiles fail to exhibit defined characteristics to measure the full-charge state accurately and the charger must depend on a timer. Harmful overcharge will occur if a fixed timer controls the charge. This is especially apparent when charging partially or fully charged batteries.

I realize you would not know SilverFox from Adam -
but he is the resident battery expert and moderator over at CPF (CandlePowerForums) this is his short post explaining the charge rates for eneloops

[Marc Sabatella]

Cool, thanks! My takeaway from those links are that I might as well use the 1000 or 1500 settings by default, and 200 is probably fine too, but I should probably skip the 500 or 700 settings.

[UnknownVT]

Cool, thanks! My takeaway from those links are that I might as well use the 1000 or 1500 settings by default, and 200 is probably fine too, but I should probably skip the 500 or 700 settings.

Yep that's about the size of it -
either between 0.5-1C (1-2A) for quicker (2-1 hour) charging
or REAL slow at 0.1C (=200mA) for 14 hours but must set timer for 14 hours to make sure it doesn't go over time.

Anything in between may seem kinder than the faster charge - but may actually be harmful - unless the charger is very sophisticated and uses multiple end of charge strategies - the Maha/PowerEx C9000 and LaCrosse BC-900 and now BC-9009 are such chargers.

That's reason why people tend to suggest 1/2C (=1A=1000mA)
as the optimum charge rate for eneloops (~2hours)