[WheresWaldo]

Sorry if this is a repeat to what has already been mentioned, I did not read every word of thread.

Just some additional info to support Vincent. One of the main reasons that eneloops or its rebadges last so much longer than high capacity NiMh even the newest 2700mAh is that under load these low self discharge (LSD) cells hold their voltage longer than any other cell. If you were to plot a graph of cell voltage over time under a constant load you would see they are relatively flat until dead where there is a sudden drop off.

This characteristic allows a camera, like all Pentax DSLRs, which are very voltage sensitive to actually last longer under these LSD types than other similar batteries even though those may have more rated power. The batteries and camera can use all the available cell energy rather than letting some of it remain because the voltage drops too low.

Because of this behavior I have replaced all my aging NiMh with eneloop or rebadge or other LSD cells. The other good thing about LSD cells is that they can retain their charge for longer periods of time compared to high capacity NiMh. As a matter of fact, the higher the capacity the faster they self discharge. How many times have you grabbed a handful of rechargeables and found them to be dead, all the while scratching your head telling yourself "I know I charged these a month ago!" With LSD NiMh even up to a year later they can retain as much as 80% of their charge.

If you are still using Alkalines or Lithiums or CR-V3 you owe it to yourself to get some LSD NiMh, save the Lithium primarys for your survival kit along with your duct tape, weather radio, blanket, etc.

[UnknownVT]

One of the main reasons that eneloops or its rebadges last so much longer than high capacity NiMh even the newest 2700mAh is that under load these low self discharge (LSD) cells hold their voltage longer than any other cell. If you were to plot a graph of cell voltage over time under a constant load you would see they are relatively flat until dead where there is a sudden drop off.

This characteristic allows a camera, like all Pentax DSLRs, which are very voltage sensitive to actually last longer under these LSD types than other similar batteries even though those may have more rated power. The batteries and camera can use all the available cell energy rather than letting some of it remain because the voltage drops too low.

Because of this behavior I have replaced all my aging NiMh with eneloop or rebadge or other LSD cells. The other good thing about LSD cells is that they can retain their charge for longer periods of time compared to high capacity NiMh. As a matter of fact, the higher the capacity the faster they self discharge.

Many thanks for the confirmation WheresWaldo.

Although it may seem nitpicking, but even among LSD batteries the eneloop maintains its operating voltage under load better than other LSD batteries -
I have a long (and somewhat messy) thread over at CPF batteries section comparing the otherwise really excellent Kodak Pre-Charged (LSD) with eneloops actually in the Pentax K100D -

eneloop vs. Kodak Pre-Charged Voltage Maintenance - summary in post #57

Here's an animated GIF showing the discharge curves at various current rates for 3 LSD batteries (note these were produced by SilverFox in his threads - NiMh Battery Shoot Out and Eneloop Self Discharge study - CandlePowerForums )


I've also drawn a horizontal red line at approx 1.19V the cutoff threshold voltage for the Pentax K100D
(Ref: Post #49 (link) in thread - K100D - "Low-Battery" Problem gives details of the meter voltage levels)

One can see that there are more curves above the red line for the eneloop than the other two LSD batteries -
although this may seem minor, I think this is very significant for the battery fussy/voltage sensitive K100D and *ist D family of Pentax dSLR.

So although I do own Kodak Pre-Charged LSD (which are otherwise excellent) - I suspect these are re-badged GP ReCyko? - I use eneloops and confirmed re-badged eneloops in my K100D over any other batteries.

To get over 1,100 shots out of a set of DuraLoops (Duracell Pre-Charged - confirmed re-badged enloops for the made in Japan white top versions) is incredible to me.

[WheresWaldo]

I also lurk at Candlepower forums and have seen these tests that Silverfox has done. Didn't you also have a rather long thread at DPReview about battery usage?

I have started doing what Silverfox and you have done with NP-400/D-LI50 clones over in the Accessories sub-forum. I already tested some really cheap Chinese batteries and have two more pair coming that I will test the same way. LiIon are a different beast than NiMh but battery testing is battery testing, and even low power batteries can perform adequately if you know what to expect from them.

Thanks for all the info.

[UnknownVT]

Didn't you also have a rather long thread at DPReview about battery usage?

Don't think that was me -

But here's some very useful LSD battery testing by archae86 over at dpReview -
AA and AAA NiMH low self-discharge tests--Round 2

There was an interesting article in "What Digital Camera?" an UK magazine - Sept/2008 Issue 139 - where they conducted their "WDC Olympics - Batteries and Memory Cards" (pages 52-3 for the battery part).

They compared and tested various AA battery chemistries -

I scanned the relevant sections (note: these images belong to "What Digital Camera?") -

Comparison table -


Precedure and battery types -


about rechargeable batteries -


It is interesting what they say about the aged/used NiMH.

They also mentioned in passing voltage sensitivity (the Pentax istD dSLR - was the predecessor to the notorious K100D which is very battery fussy/voltage sensitive - see summary Post #57 in eneloop vs. Kodak Pre-Charged Voltage Maintenance) but did not say that was a contributing factor for the older NiMHs - which definitely would have had lower operating voltage under load than the eneloops.

[Saaby]

Hey I've just glanced through these 5 pages...just slightly more in-depth than skim.

It's fun to see the CPF links (I'm a longtime CPF-er) -- who knew that the hobby with the simplest device -- flashlight -- would spur the most in-depth information on batteries.

Anyway, one thing that I didn't see mentioned here, in regards to fast charging vs trickle charging cells, is that most fast-chargers switch into a trickle once the fast charge is done.

So if you pull your cells out of a fast charger after the 2 or 3 hours, the might not be 100% charged, but if you leave them in for 8 or 10 like you would with a trickle-charger, they should be charged.

This is due to the fact that the "fuller" the battery gets, the harder it is to charge.

This is most pronounced, as far as I know, in the LiIon chemistry. My ProBook, for example, will go from dead to ~80% charge in about an hour, and then take 2 or more to trickle that last 20% in. That's a good thing though! It extends the life of your batteries.

[UnknownVT]

Anyway, one thing that I didn't see mentioned here, in regards to fast charging vs trickle charging cells, is that most fast-chargers switch into a trickle once the fast charge is done.

So if you pull your cells out of a fast charger after the 2 or 3 hours, the might not be 100% charged, but if you leave them in for 8 or 10 like you would with a trickle-charger, they should be charged.

I'm no battery expert - but I'm not too sure about that - by definition if the termination is by -dV (delta voltage) the battery is actually just past the point of fully charged (ie: over-charged) - that's why there is that small down turn in voltage curve the -dV.

However, some very smart chargers like the Maha C9000 have many safety termination strategies to prevent over-charge and one which seems to be active is the peak voltage termination at 1.47V - this means often the charger terminates before the -dV is detected - hence not "fully charged" - but I believe it's pretty close (please see this for an explanation) -
and as you say it's better to be slightly under-charged than over-charged - as over-charge and over-heat are the two killers of NiMH rechargeable batteries

[Nick1946]

Have had good results with Kodak recharbeables

[Big Dave]

cznut,
I find that the best solution was a Travor battery grip for about $56USD shipped off of Feabay. I charge it about once a month and never have to worry about battery life. The camera feels naked now without it.

Dave

What has worked out best for you guys?
Need something that lasts long yet economical

[dave sz]

I'd probably agree about the grip. I don't have one myself, not yet, but as soon as I put some money aside I'm going to order one. Problem is none of the ones I've seen look good and if they do, they're only vertical shutter grips and don't actually house batteries. I might have to wait til after I change bodies...
As for batteries, I ordered a few sets of the duracel hybrids. Also quantaray has some new batteries out, rechargables but not 1.2v like all others. These are the 1.5v like normal AAs...

[UnknownVT]

As for batteries, I ordered a few sets of the duracel hybrids. Also quantaray has some new batteries out, rechargables but not 1.2v like all others. These are the 1.5v like normal AAs...

Oooo - many thanks for the heads up - those Quantaray batteries are Nickel-Zinc (NiZn - Wikipedia)

Here's the enGadget link , and the manufacturer - PowerGenix about the batteries

according to the NiZn AA pdf spec sheet - the nominal voltage is 1.65V.

This is good news, as the discharge curve -

shows that the battery remains above 1.19V (Pentax dSLR cutoff threshold) for the tested currents up to 1C = 1.5A - until it's truly depleted - so it may be capable of delivering all of its rated capacity before the Pentax dSLR shuts down

The not quite as good news is the capacity - typical 1500mAh with a minimum of 1350mAh (compared to 2000mAh typical and 1900mAh min for eneloops)


in a kind of mitigation - because it maintains higher voltage it appears that the batteries may be able to deliver its full capacity before Pentax dSLRs shuts down.

Some have said that the self-discharge rate is supposed to be about the same as typical (non LSD) NiMH.......

The other problem is that because of the higher nominal voltage chargers have to be different - one cannot use existing NiMH chargers.

FWIW - although "hybrid" battery seems to be used as a generic term -
it is actually the RayOVac name for LSD - Low Self-Discharge NiMH batteries.

Other names that have been used are "Pre-Charged" (Kodak, Duracell) and "Ready to Use" (Delkin, Panasonic)

[WheresWaldo]

This could be a problem with NiZn adoption. Needing a new charger and the fact that they discarge as fast as normal NiMh and the low power capacity. I think I will stick to LSD cells for a while.

[dave sz]

well, we didn't have LSD batteries til last year? I'm also pretty sure that the first rechargables didn't start out with more han 1500mah like the zinc batteries. This time in a couple years we'll have 2500mah LSD NiZn batteries. Progress takes time. ..

[pentaprism]

I've tried a range of batteries through my K100d, i found the best to be Duracel NiMH 2650mAh, generally available for AUD$20 pk 4. I bought some panasonic 2700mAh, but was very disappointed as they didint even register in the camera when fully charged. Enegiser lithium were also always on standby in the camera bag when travelling as I always got good 'value' out of those batteries regardless of shooting conditions.

[dave sz]

I saw a test where the duracel 2650 were the clear winner among 20 or so other batteries. I was going to order them however I found a deal on a couple sets of the duracel "hybrids" that I'd rather have. I don't use my camera that much so knowing that the batteries are still almost full and don't need a charge...

[Marc Sabatella]

I saw a test where the duracel 2650 were the clear winner among 20 or so other batteries.

Yeah, but was that with Pentax DSLR's in particular? I doubt it. High capacity NiMH cells are great for devices that can actually use most of that capacity, but as has been explained here, Pentax DSLR's cannot - they give up when the battery's voltage drops below some threshold, even though they've got lots of charge left. So you need cells that hold their voltage up under load for a relatively long time, even if the total capacity isn't the greatest. That why the low self-discharge cells are so great - even though their total capacity is very mediocre, they hold their voltage well. So Eneloops beat any higher capacity NiMH cells I've tried in my camera, although they don't do nearly as well in devices that are capable of using up more of the charge in the battery. Thus, the Duracell 2650 might beat the Eneloops in a clock radio but lose big time in a K200D.