Another AA battery question

[jeffpolaski]

<p>If on a Sunday I put 4 fully charged Radio Shack 1800 MnH batteries into my Pentax DS, and on Friday I scoop it up, turn it on and see a half charge, is this normal? If normal, then nothing wrong with the batteries or camera and I'll act accordingly, but a half charge was a bit surprising. (this, BTW, was what prompted my automobile charging experiment post a short while ago).</p>

[Matt Laur]

<p>Not unusual. Try Sanyo Eneloops. They seem to hang onto the charge much, much better than most of the cheapies.</p>

[rob_wall]

<p>It may have to do with voltage. I believe NiMH batteries run at 1.2 volts vice 1.5 for ordinary alkalines. Your camera is probably expecting 6 v but is betting 5.2. I got a cheapo voltage meter from Radio Shack and it has settings for NiMH as well as ordinary batteries.</p>

[jim_momary]

<p>Jeff -<br>

... 6 days later half charge ... +/- = abnormality?<br>

As discussed by Matt & Rob-<br>

1. Non-modern NiMH (i.e. not Sanyo Eneloops, MAHA Imedions, etc.) lose charge, but still should be a bit above 50% I'm guessing in 5-6 days. (SWAG - sophisticated wild ass guess)<br>

2. Any short in the camera might do this, unlikely tho.<br>

3. The Pentax istDS is expecting two cr-v3 batteries which will be 6.0 V dead nuts 'til they go legs up.<br>

My best guess -<br>

Likely a combo of 'fading 'cuz they're 6 days since charged' normal older style NiMH cells and since they start out at 4.8 V max (4 X 1.2 V) the camera is doing what it was told and reporting a depleted battery state.<br>

Ever since I got Eneloops and Imedions & a real quality charger, my life is a lot simpler.<br>

Jim M.</p>

[Ed_Ingold]

<p>Most chargers handle batteries in pairs. After a few use cycles, some of the batteries will discharge more than others. When paired, the first battery to reach full charge will put the charger into trickle mode. The battery with the lower charge may never reach full status. When you put them in a device (e.g. a flash or camera), the battery with the lowest charge level determines the status and charge life.</p>

<p>The extent of this problem became clear when I started using a Maha 8-battery charger, which charges each individual battery at its own rate, and displays the status continuously. Prior to this I was getting poor life and extended recycle times in my SB-800 flash. Restoring all the batteries to full charge (and identifying the klunkers) solved this problem.</p>

<p>That said, NiMH batteries have an high self-discharge rate - about 15% a week. Recharging them the night before a job is a necessary ritual. I just got a set of eight low discharge batteries, which also have a lower power rating. We'll see how they work out.</p>

[bill_tuthill]

Ray-o-vac Hybrid is another good NiMH battery that that doesn't lose charge quickly. After a year, the Sanyo Eneloop has > 80% capacity remaining, according to various independent tests posted on the Internet. In my view there is no point buying a "regular" NiMH battery.

[les_lammers]

<p>My solution was to use Lithium AA's. They last a long time and no charger. :-)</p>

[vrankin]

<p>I agree with Les. Some will say Lithium AAs are too expensive. However, they also have considerable advantages. They are a full 1.5 volts; they last much longer than rechargeables on a shoot; they hold power much better in storage; they're better in the cold. I had a pair of Lithium AA in my Canon A590, using it moderately for six months. Never got a low battery signal. After that I changed to a fresh pair in the camera, put the old pair in my toothbrush and got many brushings!</p>

[les_lammers]

<p>They are a full 1.5 volts..and they stay at 1.5 volts throughout their life. :-)</p>

[les_lammers]

<p>Jeff,<br>

There was a series of posts on the Pentax forum about AA's. A poster who is an EE concluded that lithium AA's were almost as economical as rechargables w/o the hassle. Also, there is no voltage drop with lithiums as they discharge.</p>

[bill_tuthill]

Depends where you buy them. They are $3.66 each at Thomas Distributing including shipping, but $6.50 each at my local drugstore. That could get awful expensive awfully fast. Les, where is this thread? I can't find anything about AA batteries in the Pentax forum.

[leo_tam1]

<p>Actually, Lithium batteries in AA size are 1.7V<br>

My other hobby is LED flashlights and voltage really doesn't matter as there is an onboard voltage regulator. Some of the Newer NiMH batteries self discharge VERY quickly. A pair of Eneloops are only 2000mAh, but they'll last me a full day of shooting (150-175 shots) on my canon A520 without flash and the low batt warning doesn't even come on. Sometimes, the warning will come on and you're still good to go for a long while.<br>

Alkaline AAs are 1.5V, but under load, they may drop to 0.9V. Thats why when you run Alkys on a camera, it'll say Change your Batts, but when you restart, it'll be okay.<br>

NiMh and Lithiums keep their voltage under heavy loads</p>

[les_lammers]

<p>Bill,<br />I get them at Costco or Sam's.<br />Here is the blog: <a href="http://thebs413.blogspot.com/2007/07/li-ion-is-not-lithium-eg-li-mn-li-fe.html">http://thebs413.blogspot.com/2007/07/li-ion-is-not-lithium-eg-li-mn-li-fe.html</a><br />and the post: <a href="../pentax-camera-forum/00PjPX">http://www.photo.net/pentax-camera-forum/00PjPX</a> There are other posts bu Bryan too.</p>

<p><br />Searching has improved on Photonet but could still be better. :-)</p>

[nsfbr]

<p>Rob, you are thinking of NiCd. NiMH are closer to alkalines when charged. My guess is that they were either not fully charged to start with, or are reaching end of life and are self discharging a bit faster than normal. </p>