riderxlx Loc: DFW area Texas

Putting them in the camera and reading the charge works best for me. I also 'top off' the spare and camera batteries periodically and before going out to shoot.

boberic Loc: Quiet Corner, Connecticut. Ex long Islander

longevity also depends upon the load (usage) placed upon a given battery. If the load is constant over a given time the longevity projection may be accurate. But the load is impossibile for a battery tester to project. So a battery longevity meter is virtually useless

burkphoto Loc: High Point, NC

Even if you could get camera batteries with charge indicators, they can deceive! I had a couple of rechargeable Apple PowerBook batteries back in the early 2000s. BOTH of them had charge indicators on them. BOTH of them got to the point where all the LEDs would light up, but the battery would not boot the computer. If the computer was running, unplugging the charger would shut it down. Around the same time, I had a Canon EOS 20D with several batteries. A couple of them got to the point where they would power the camera for about ten minutes, displaying the full charge indicator the whole time. Then, without warning, the camera would just shut down. When that happened (4-5 years of service after buying them), I simply recycled them and bought new ones.

Simply carry spares. It's a good idea to number and date your batteries with labels. It's also a good idea to have a car charger for them. I have an inverter in my car and use my OEM charger with that, to top them off on the way to a job. However, many third party chargers can charge two batteries at a time, and connect to both AC power and 12 VDC car outlets, using adapter cords.

Murphy's Law of Spares states that if you don't have a spare, the one you have will fail when you need it the most.

charles tabb Loc: Richmond VA.

Try asking B&H about this.
I bought a duel battery charger for my Sony RX-10 IV and it came with a screen and would charge two batteries at the same time.
All I do before going out to take pictures is to pop one in the charger and it gives me the % charge on the batteries.
Not all camera batteries are the same, hence different chargers.

riderxlx Loc: DFW area Texas

You are right Burk, just have a spare(s). Rgrenader nailed it right on the head, just charge the battery(s).
In my opinion, the best way to tell the health of your batteries is by using them and see how long they hold up. Period ! That is the final test isn't it ?
Keep them healthy, being, keeping them charged. Unlike auto batteries I do not know of a way to do a load test on camera batteries to test the health of them.
I only have two batteries for my Nikon D200, they will last allllll day long and more. Now I keep mine charged and change around so one is never just in the bag as a spare and the other one staying in the camera. I am amazed how long they will last in the Texas heat and even cold while shooting hundreds of shots all day long and the battery level hardly drops. Once home or at night after shooting I top off the battery. I believe this is just good maintenance. And as Burk said, when they get old and start loose their capacity life, recycle it and get another one. Keep it simple.
My two cents worth today,
bruce

burkphoto Loc: High Point, NC

Thanks.

I'll add that most rechargeable batteries in small portable devices have a life of around five years, give or take a couple. The large, NiMh high voltage Batteries in Prius automobiles last ten years or 150,000 miles with less than a five percent failure rate. Treat them right, and they last twice as many miles.

One of the worst things you can do with any rechargeable battery is to NOT use it.

larryepage Loc: North Texas area

My interpretations around the questions that have appeared here recently are that they were not anywhere near as complex as the answers that were provided. I think the original questions really revolved around sorting a pile of batteries into those which have been freshly charged and those which have been used and are in need of recharging. In the days of carbon zinc and even alkaline batteries, this was easy... These were linear discharge batteries (or cells) whose output voltage declined gradually throughout the discharge cycle. Even the no-load open circuit voltage was detectably lower for a discharged cell than for a fresh one.

Modern (and even not-so-modern) rechargeable cells and batteries are much more constant voltage devices...even NiCads. Their output voltage, even under load, remains fairly constant throughout the discharge cycle. A lithium ion cell that is completely discharged is essentially unidentifiable using a voltmeter. This is one of the reasons that these cells are almost all equipped with a chip to help communicate their charge status both to the charger and to the device they are powering.

So the best plan is to develop a simple management system to keep charged and discharged batteries separated. As an example, I have two families of camera bodies. Each family uses a single type of battery. I have used a Sharpie to make sure that each one of the batteries in each of the types are marked with a number. My process (which is not nearly as perfect as I'd like it to be) is that all batteries are always used in consecutive order. I simply note which batteries are in the camera when I start a day's shooting with fully charged batteries, and I when one of those batteries is depleted, it is replaced with the next available battery in the series. At the end of the day, all batteries from the one that started the day through (and including) the one(s) in the camera(s) are charged. There are certainly enhancements that could be made, like recording each time the cycle starts over (each time battery #1 is charged) to help keep track of periods when usage might be lower, but the current system has always insured that I have fresh batteries to work with so far.

In the case of generic AA rechargeables, the system is a little different. My flash and accessory bag has two pockets on the front. One contains fresh AA cells and the other (which always starts the day empty) collects the depleted cells to be recharged at the end of the day. I have two stocks of these cells of different brands. These are always used only in groups of the same brand and charged only on their own respective charger, which helps them stay together.

Battery age and condition is managed separately...using the life indicator on the camera or simply noting too-rapid discharge in the case of the AAs.

riderxlx Loc: DFW area Texas

Amen Burk,
un-used batteries loose their useful life that is why I responded before with just saying 'keep them charged' or at least use them and rotate them around so they all get used enough to keep them in shape. Please do not get me wrong on this Ok, I am not trying to be a smart-ass, but. Today's batteries are very good and reliable. If you have a device, any kind of device. That is not used enough to where the batteries will start to go bad, then you really probably do not need that device. There could be exceptions. Yea I found another penny so I spent it on this post.
Now penny less bruce.

PGHphoto Loc: Pittsburgh, PA

If you are interested in a quick assessment, use a small handheld mutli meter (sometimes Harbor Freight gives them away with a purchase) and take a voltage reading to give you a rough idea of charge based on difference between voltage % of a fully charged and 'fully discharged' battery. Fully discharged is when the camera body says its dead - most batteries will not be 0 volts when the camera refuses to operate because of low battery.

Getting the difference between the camera's 'fully charged' voltage and the camera's assessment of 'fully discharged' voltage gives you a base to compare your current battery life state. (but probably easier to just put it in the camera !)

-- k --

riderxlx Loc: DFW area Texas

These are handy devices and I have a few of them. I never thought of using on my camera batteries. My point'n shooter uses AA regulars and when they are draining down the camera is pretty accurate letting me know. The multi meters I use to test the batteries and other stuff too. Very handy. You can get a good one for like 10 bucks or so at the hardware stores. A very good tool to have.
Still penny-less bruce.

charles tabb Loc: Richmond VA.

You might try Batteries +.
I got a nice battery tester for AA's from them.
It also shows the charge on C's D's etc.

riderxlx Loc: DFW area Texas

Yup, Batteries + is a great place. If they don't have it or can not get it, then it aint made or long out of use. They have saved my butt several times on batteries I could not get anywhere like for a built in battery for a shaver, motorcycle batteries and even odd ball camera batteries for old film camera. Can't go wrong with them.
b

Daryl New Loc: Wellington,New Zealand

We use a multi Meter....if need be.

PhotosBySteve

RUDE and unnecessary!!!

nadelewitz Loc: Ithaca NY

There ISN"T impedance in a DC circuit. Only resistance. Impedance is induced by a sine wave, as in AC current, and audio signals from an audio/stereo amplifier. That's why speakers have impedance ratings.