For fifty years I have been involved in batteries in one form or another. And being a camera dealer and a battery supplier has taught me a few things.  Caution is one. Repairs from lack of caution are expensive.  Batteries are like tools sold at Sears for years.  Good - Better - Best.   

•  Leakage, lithium is bad stuff.
•  Swelling causing difficulty inserting or removing
•  Shorter useful life than OEM equivalent 
•  Incompatibility with camera and/or OEM charger 
•  Incompatibility due to firmware updates
•  Voiding your camera’s warranty

Here’s a Watson, thanks to www. John took (black label, light green cells) and Wasabi (white labels dark green cells) EN-EL15 broken open. The circuit boards are identical, but the actual cells are indeed different. 

From China, nothing is wasted, any and I mean any cells of dubious voltage, amperage and parentage, might get dumped into a plastic shell or cloned plastic shell and some number made up and dumped on the market.  Nothing personal, just tacky business they are known for.

In addition to the weight differences, the mAh rating of the batteries differs. In theory, a battery rated at higher milliamp-hours should give more shots per charge all else being equal. 

Most batteries have a chip in them. This communicates charge info to the camera. It also communicates if it is an OEM battery or not. 

Both Canon and Nikon have been known to issue firmware updates for their cameras that have disabled third party batteries (the charge meter no longer shows and perhaps other issues). 

•  You get what you pay for and all batteries are not created equal.

•  That the discounted batteries come from one vendor, sold to all distributors (via and with a great label printing service) and that the cells being from various batches can vary.  Basically a crap shoot. It’s whats available to the vendor, it gets stuffed in, thats just China.

•  There are weight differences, and in-consistency of the mash and smaller cells in some. The milliamp-hours (MAH) rating of the batteries differs based on truth, sometimes and who exploits false information. eBay in particular is notorious.

•  Some third party manufacturers use better quality cells than others. Some don’t and buy anything they can and no camera manufacturer makes their own cells or batteries. Instead they purchase them from a battery manufacturer, just like the third party companies do.  They sublet production of Flash units too.  

 •  How good a cell is used has a lot to do with the eventual retail price of the battery, what kind of a deal they got from the warehouse, and did they get what they ordered. After all 95% of this stuff comes from China. I manufacture battery equipment and deal with China and everyday is a new experience. In contracts we specify a 10% failure factor up front. We pay for 100 and get 110 because we know they will fail and want to have free returns if needed. try sending a package to China...Good luck.

•  Camera manufacturers warn that inserting non-OEM batteries into my camera could make the camera fail or give you a warning this is not the right battery.  Most batteries have a chip in them. This communicates charge info to the camera. It also communicates if it is an OEM battery or not.  It’s a crapshoot since many of these batteries are off branded by an eBay seller, they found a like to Euro distributors, got a good deal from an exporter, and so forth.

•  Both Canon and Nikon and possibly SONY have been known to issue firmware updates for their cameras that have disabled third party batteries (the charge meter no longer shows and perhaps other issues). This is no guarantee that a future update might not knock them out.

•  Wasabi batteries (Bluebook) worked batteries were OK.   Now I’m seeing some swelling after 16 months.  As well they are properly chipped so the camera display shows how much charge is left and how many shots were taken on the charge, just like with the OEM batteries.  I haven’t had issues charging the Wasabi and Watson batteries in the SONY chargers.

•  Weight is a clue, it has a lot to do with the eventual retail price of the battery.  One difference of note is that the weight differs by age and can differ by production run. This indicates what cells were purchased for that run.

SONY NP-FW50 battery weighs 1.4 oz.  @ 1020 MAH   (All three weighed the same) and the same voltage and amperage.
WASABI BTR-FW50-JWP battery weighs 1.6 oz. @1300 MAH, 
WASABI BTR-FW50-JWP battery weighs 1.5 oz. @1300 MAH,  Swollen 6/16 Charged but swollen
WASABI BTR-FW50-JWP battery weighs 1.3.5 oz. @1300 MAH, Swollen 6/16 - Ditto

RAVPOWER RP-PB056 battery also weighs 1.6 oz. 1100 MAH
DOT Batteries, all six have failed.  Thrown out and I believe they are now selling them again on AMAZON.


This is how I maintain my batteries - I use a standard test meter, you can get them free at Harbor Freight at times with purchase and coupon,  or spend 15-30 dollars and get a good GF, or a base KLEIN, many available on Amazon. 

So you need the following and you can use it on all camera batteries and a million other things.  READ the manual that comes with the meter. 

Since I check many per day , I bought several Sears meters (they had better ones for ten dollars each on sale) and have one per size with test modules for Canon, Nikon and Sony. 

I also have a load tester but they can run hundreds to a thousand dollars.

  1. Meter - Your Choice
  2. Find extra cables with the ends as shown.   Cables for each module we’ll build, also find them on the web. They are called banana plugs, wired and cheap.
  3. A battery charging module from one that went bad or a spare you don’t trust. They are on the web and cheap. Usually they came with the battery eg, Wasabi.
  4. Send me the mess with return postage.  It’s a freebie.  I’ll test it, disassemble it, solder the leads,  and then mail it back to you.
  5. The purpose is safety and accuracy for this tool. It’s too easy to cross the wires and short the battery plus getting a good connection for accuracy is important.
  6. It will work on Nikon and Canon stuff too, I have SONY and usually have Canon and Nikon batteries to test from friends and associates so I made a test module for all.

I use a simple Digital Caliper and measure them. A good SONY, relatively new measures 1840mm in thickness.  The swollen WASABI measured 1971 mm.  That will almost jam in the camera. I used to use the old Mark One Eyeball but the inexpensive digital works a lot better and doesn’t fool you.

The Tenergy Lithium battery charger is excellent for topping of all Lithium cells within it range limits.  I built several ends pieces as all are not the same for all sizes of SONY’S. It also took a few cells that needed a little refreshing back.

The Watson, Flashpoint, Ravpower, Dot and Wasabi batteries look like they are the same battery but with different labels. The Sony has a embedded halo-logo. The others have slight differing mold cuts.  

Very slight weight difference suggested otherwise. One way to find out.  You weigh them.  Do not cut them open. That will tell you more than guessing, heavier batteries might have more mash and power reserve.  And the labels mean nothing about MAH.  Untruths prevail... lot more than you think.  I use a very good gram postal scale, very accurate.

Technically,  some popular sizes like for Nikon and Canon might be clones of clones.  Again since rules are loose in China, when one understands QC does not stand for Quality Control, it might stand for Queer Crap.  

Like the old INTEL chips, the chips were made and the subjected to testing to determine the megahertz values.  Some capped at 60, some at 80 and some at 120, then they were stamped appropriately.   Batteries are the same selling theology and the poorer examples might  go out with a different label and to a different distribution network.  Nothing gets wasted in CHINA and nothing is excluded by dumping.  The trick is this, it cost next to nothing to ship to the USA, they come bulked on pallets but you send one piece t6o China and you got a twenty dollar bill.  Screwed, blued and tattooed as we used to say.

Again, generally the heavier battery in theory might contain more mash, the compost of chemical electrons.  In addition to the weight differences, the MAH rating of the batteries differs. In theory, a battery rated at higher milliamp-hours should give more shots per charge all else being equal. 

A relative newcomer came on the scene sold by Amazon and I pitched the last one out last week,  totally dead all four.  It was named "SPOT". Good name, like my friends dog Spot,  they all took a crap.

Because the OEM batteries last longer, they are more economical if you shoot a lot. If you shoot sparingly you might find the Wasabi and others to be adequate. 

I build these systems for SONY but they work on all 7.2/8/4 systems and if you buy the parts and drop ship to me, I ‘ll build one for you as long as you pay the shipping. Usually $7.15.

The factory SONY charger plate after I modify it both charges the SONY and tests the SONY using the Tenergy


There is no standard in the industry, so manufacturers can use the terms in different ways.  The selling point is the amount of time it takes to charge a battery is dependent on the capacity of the battery being charged and the MAH the charger can produce.  In other words, politicians, strobe makers, and charger manufacturers all make up their own statistics since no one really cares about checking on them... then there is me...

Simple math - Simply divide the capacity of the battery by the charge rate of the charger, then increase the amount of time by about 20% to allow for a certain amount of inefficiency.  As an example, a battery with a capacity of 1600 mAh will require about 4 hours to be fully charged by a charger with a charge rate of 500 mA.

The most common cause of premature battery failure is overcharging.  The type of chargers most likely to cause overcharging are the 5 or 8 hour so-called  “rapid chargers” that they really don’t have a charge control mechanism.  These are chargers that are not smart and simply deliver a charge for a period of time rather than reading the battery.

If the  charge cycle is interrupted part way through the charge and re-established the cycle starts over and you cook the battery.  The easiest way to avoid these scenarios is to use a smart charger, a charger with microprocessor control. 

A trickle charge is a charge rate that is high enough to keep a battery fully charged, but low enough to avoid overcharging. Maintenance charge is another way to describe trickle charge.

Although most  manufacturers do not recommend that you leave a battery in the charger for long periods of time, many people leave their batteries in the charger on trickle charge for days or weeks to keep their batteries "ready to use". If you know the rate of trickle charge that your charger puts out and it is around one tenth of the battery capacity or less, then you should be alright if you are just going to do this occasionally. Generally speaking, though you do not want to leave a battery charger plugged in unattended for long periods of time.

Many battery manufacturers do not recommend long term ( months at a time) trickle charging.  If trickle charging is used then the charge rate should be very low or only intermittent.  The best smart chargers will only send an occasional pulse charge to the battery once it is charged.  

Using a properly designed smart charger, most NiMH batteries can be recharged in about an hour without any damage or significant reduction in their life. However, NiMH batteries must only be rapid charged with a charger specifically designed for charging NiMH batteries.  

Many of the inexpensive NiMH battery chargers are simply NiCd chargers that have been modified slightly.  Typically a 5 hour NiCd charger has a switch that allows the charge time to be increased from five hours to eight hours. Thus a 5 hour NiCd charger becomes an 8 hour NiMh charger.  Pass on this approach

NiMH smart chargers have actually been designed to detect when a NiMH battery is fully charged and then shut off or go into a trickle charge mode.  Because of the more complex circuitry, this type of charger costs more to make, but should lead to greater battery lifeSome of these chargers only cost slightly more that the "dumb" chargers.  We strongly recommend investing in a smart charger for your NiMH or NiCd batteries.

This really depends on what you are going to use them for exactly. NiCD batteries are commonly used for power tools and in that capacity they are in many ways superior to NiMH batteries. 
For high drain digital devices where weight is of primary importance, NiMH batteries are the best choice. NiMH batteries are also considered an environmentally friendly battery chemistry. NiCD's are toxic and recycling them is mandatory.

Any charger that uses a computer chip to control various aspects of the charging process can be considered a smart charger. Technically even a charger that can detect and adjust the charge rate based on the battery inserted into the charge station can be considered a smart charger, but anything that is either manual (steady charge rate as long as it is plugged in) or uses a timer to manage the charging process, we do not consider a true smart charger. There are even various levels of smart chargers. 

Different features that work together, sometimes in mysterious ways because there are just so many variables with batteries and chargers. In order for us to consider a battery charger a smart charger it needs to have a common charging feature known as negative delta V. Negative delta V  is basically a technical method for a charger to know when a battery has reached its charge capacity and then shut the charging off, or sometimes change to trickle charge mode. 

Other features that contribute to a battery chargers “ smart" status are: battery rescue (implemented in various ways to attempt to "jump start" an overly discharged battery - i.e. less than 1.0 or 0.9 volts - so that it will take a charge), temperature sensors, discharge and conditioning features, battery test features and even timers to limit the total length of the charge so even if you leave it plugged in, it turns itself off after a preset time. 

Remember, all manufacturers consider their chargers "smart" with any or all of these features and they are not all the same!? Hey, neither are we for that matter... but we get to evaluate them all.