Is there a piece of equipment that can accurately measure the mAH capacity of a Canon camera battery

[henryrgold]

In the radio control airplane field, there are devices that get connected to a battery and will accurately measure the mAH capacity by discharging through a known resistance and periodically measuring the voltage.  A calculation is done of the total mAH, then you will know if the battery is still good.  Is there such a device for Canon camera batteries (like the BP-511A)?

[cicopo]

I have the type of charger you're talking about & I guess I could (if I wanted to) rig it up to do that but I've never seen anyone talk about one for camera batteries. I use mine to charge my LiPo's (which power my R/C models). I have only used it once to see just how much I had discharged a battery after a flight. I know lots of people do use them that way but the way I fly I don't run my batteries down enough to worry about how close I am to the cut off point. 

The only time I've ever load tested my camera batteries was years ago with the batteries used in the older 1 series ( Pro) bodies which are old technoligy.

[Waddizzle]

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@henryrgold wrote:

In the radio control airplane field, there are devices that get connected to a battery and will accurately measure the mAH capacity by discharging through a known resistance and periodically measuring the voltage.  A calculation is done of the total mAH, then you will know if the battery is still good.  Is there such a device for Canon camera batteries (like the BP-511A)?

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The devices that forcibly discharge a battery like that tend to destroy the battery in the process.  Batteries are designed to provide just so much current over a given unit of time.  Subjecting the battery to provide that amount of current in 1% of the time, or less, is most often destructive to the battery that is "under test."  Heat is the enemy.

[cicopo]

Without finding the manual for my charger I know that it does several common types of battery but I don't know if it will do the BP 511 BUT it's designed to do it WITHOUT straining the battery being tested. It doesn't punish the battery being tested (drained) & in return isn't cheap either. R/C er's who fly EFD (Electric Ducted Fan) Jets rely heavily on their batteries & are hard on them due to the heavy load but these chargers can keep them in good order for a few seasons of use.

[RobertTheFat]

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@cicopo wrote:

Without finding the manual for my charger I know that it does several common types of battery but I don't know if it will do the BP 511 BUT it's designed to do it WITHOUT straining the battery being tested. It doesn't punish the battery being tested (drained) & in return isn't cheap either. R/C er's who fly EFD (Electric Ducted Fan) Jets rely heavily on their batteries & are hard on them due to the heavy load but these chargers can keep them in good order for a few seasons of use.

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It's probably just my ignorance, but this thread puzzles me a bit. I know that some chargers have an option to drain a battery and then subject it to one or more intense charging cycles; but the object is to try to jar a failing battery back to normal functionality, not to test its ability to hold a charge. The idea of risking damage to a battery that isn't showing serious signs of failure seems counterintuitive. Is it really ever considered a sensible course of action?

[cicopo]

I'll try to explain in relatively easy to understand terms but this is off the top of my head.

The type of charger we (Radio control people) use doesn't try to load test the battery like an auto mechanic does. They are computerized & we input the following info so the charger knows exactly what it's hooked up to. Battery chemistry, (LiPo in my case which runs 3.7 V per cell), and how many cells it has (3S means 3 cells in series) which is an 11.1 Volt battery. Our batteries have both a positive & negative terminal & a safe (sometimes very questionable) discharge rate which can be relatively low to quite high & that affects price. If you fly an electric powered plane or helicopter that runs at full throttle most of it's flight you need high discharge rate batteries. All of this info is on the label so you set the charger accordingly. The batteries also have another terminal known as the balance terminal & it connects to each individual cell & the charger constantly monitors the voltage of each cell & not the total voltage. If one cell is charging faster than the others the charger loads that cell to bring it down to what the other cells are at & then starts charging all of them again & this cycle repeats over & over again until the battery is fully charged OR the charger alarm goes off because it can't balance all the cells. We set the charger to know the desired battery charge in milliamps & a charging rate from low to fast, and fast can shorten battery life if used all the time. The ideal charge rate is .8 to 1 X the milliamp rating BUT high discharge rated batteries can be charged using the first figure in the rating, (IE 50 Amp rate can be charged at 5 times the Milliamp rating). Our batteries have the voltage, Ma rating & safe discharge rating on the labels. Some come in hard shell cases (usually used in boats or vehicles where weight isn't so important) or soft packs which are more or less like vinyl & easily damaged in a crash but weigh less.

Conversly the same charger can measure how much power is left in the battery AFTER use (as in how much more flight time did you have). It doesn't apply a heavy load but one within the rated constant discharge rate you've set & drains the battery down to the cut off point our components can still work properly at. We can learn just how long you can fly a given model before hitting the limit on the battery where you may loose control. We then set our flight timers so we prepare to land well before that limit is hit. The charger can also fully charge a battery & then do a discharge cycle to test how well the battery chemisrty is doing it's job, and again tell us the battery looses it's charge too fast to be reliable. We need reliable batteries when flying. A bad cell can cause a very expensive crash.   

[Waddizzle]

"It's probably just my ignorance, but this thread puzzles me a bit. I know that some chargers have an option to drain a battery and then subject it to one or more intense charging cycles; but the object is to try to jar a failing battery back to normal functionality, not to test its ability to hold a charge. The idea of risking damage to a battery that isn't showing serious signs of failure seems counterintuitive. Is it really ever considered a sensible course of action?" 

Nope, that's your common sense kicking in. 

I have seen the military implement regular testing regimes on the backup batteries for their building systems.  These systems would include their critical HVAC systems, Access Control, Fire Alarm, and CCTV systems, etc.  They want to be sure that the battery backups can last for their rated service times, which is typically between 24 and 72 hours depending upon the system. 

I'm talking about pretty sizeable battery arrays, each rated by the dozens of amp-hours, not millliamp-hours.  You can also find these types of systems in broadcast studios, and other communication systems.  I have seen entire floors in some of NYC's skyscrapers dedicated to just battery arrays.

Those types of tests date back decades, back to the days when lead-acid batteries were common.  Those monsters could take being violent discharged, and they needed regular testing and exercising to ensure their performace.  But, with the introduction of Ni-Cad batteries, which cannot tolerate high discharge rates, the charging systems have been improved to the point where the chargers themselves can actually self-test the batteries every couple of minutes, and report back to a remote central station the state of the batteries.

[ScottyP]

Call B&H or Adorama and ask if they can test batteries for a small charge (pun intended).

But seriously, if such a tester in fact exists, it would not likely make sense to actually buy your own when the camera batteries are only $35-$40 or so. 

[Waddizzle]

"But seriously, if such a tester in fact exists, it would not likely make sense to actually buy your own when the camera batteries are only $35-$40 or so." 

I think that is the best answer that you will get.  it ain't worth the expense.

[cicopo]

I totally agree with that too. When in doubt buy a battery.

On another note my first real job was working for Bell's division that installed the equipment in telephone offices. We either upgraded old equipment or filled new buildings with the equipment, wired & tested it & turned it over to Bell when it was ready for them to put it on line. Telephone offices (back then, not sure about now) had huge battery back up systems & the batteries in some buildings were the size of smaller SUV's of today.