GENorkus Loc: Washington Twp, Michigan

Both of my dslr's have four batteries each. I've had battery grips on them so two at a time is normal. All the batteries have been marked as to when I purchased them. Two factory batts came with the purchase of Pentax K20D camera with grip in March 2009, (8 years old). A non-factory batt on January 2010, (basically 7 years old) and another non-factory batt on March 2011, (6 years old). They all get regular use since I switch then around all the time.

Last year I noticed the non factory batts were getting a touch snug in the camera portion of my K20D but they came out fine so I let things go. This "snugness" slowly increased over six months and became, (for lack of a better word), "snugger".

Tonight I used them at a high school basketball game and found the camera battery was almost impossible to remove. I had to pry it out with a dentil pick since nothing else was small enough to reach in. Looking at both non-factory batts, I noticed a very small bulge. The two factory batts are 1 to 2 years older but do not show any signs of bulging... yet.

Looking at my other camera Pentax K5, all four of the batts, (purchased June 2013, almost four years old), are non-factory and are all just starting to feel snug in the camera body.

Recapping batt conditions:
LI50 = 8 YO = Both Pentax batts are good.
LI50 = 6 and 7 YO = Both non-factory batts do not fit well at all.

LI90 = 4 YO = All four non-factory batts are just starting to swell a bit.

Question:
Yes I know it's time to replace a bunch of batteries but I'd like to know what caused them to slightly swell up and why the non-factory only. (Are they that cheaply built?)

St3v3M Loc: 35,000 feet

What would cause a phone battery to bulge in the middle? https://www.quora.com/What-would-cause-a-phone-battery-to-bulge-in-the-middle
"Bulging batteries mean only one thing- buildup of gas inside. The gases are produced due to electrochemical oxidation of the electrolyte. Such oxidation occurs usually due to overcharging of the battery due to a faulty battery, or faulty charging electronics in the phone or battery charger."

dirtpusher Loc: tulsa oklahoma

batteries are over heated, over charged, or simply failing due to old age.

Lithium ion batteries have circuitry inside to prevent overcharging and short ...
It is failing.

They are filling with gas. And is deadly lethal breathing it.

lamiaceae Loc: San Luis Obispo County, CA

Interesting post. I have the same two Pentax cameras, A K-20D and a K-5. I only bought an accessory grip for the K-20D, a Pentax factory branded one. I have two batteries for each camera; 2 D-LI50 and 2 D-LI90. All four are Factory Pentax batteries (yes, expensive). I have had no issues with any of them to date. Swelling sounds bad to me. Makes me think of those exploding SmartPhone Lithium batteries. I'd monitor them closely. I really don't want a camera exploding or burning up. I'd say, yes time to replace ASAP!

rjaywallace Loc: Wisconsin

Serious suggestion (not intended as 'smart-a$$'): write to Elon Musk and ask the acknowledged battery expert...

GENorkus Loc: Washington Twp, Michigan

The offending batteries must have cooled off since my writing this post, they slide well in my camera and are not bulging. It is now about four hours since last using them.

Something else. The batteries were bulging from after using them in my cameras. I never recharge batteries in my cameras. I doubt that both my cameras failed at the same time. This is like being used or "drained" too fast not really from the charging cycle.

Cheap batteries is all I can guess since the factory ones never did anything like that.

*(Just looked up the present cost of factory batts. $50 bucks each! (Yuck!))

Leicaflex Loc: Cymru

The moral of this story is, you get what you pay for.

rjaywallace Loc: Wisconsin

May we ask if the non-factory batteries were all same brand or a random mix?

wdross Loc: Castle Rock, Colorado

Yes, it is a chemical gas build-up. The overcharging causes the chemical break down of the internal compounds. Gas is one of the products. Once off the charger some of the gas will recombine and the remainder will shrink as it cools down. Eventually the gas recombines less and less and the battery will be at a point of no return. Before you truely reach that point, replace the battery.

tmehrkam Loc: Houston,Tx

Are you using an after market charger?

DaveO Loc: Northeast CT

The way I interpreted this issue is that the problem lies only with the cheapy batteries used. Price was good though.

lamiaceae Loc: San Luis Obispo County, CA

Perhaps I should have been more clear. I have the same two Pentax cameras, A K-20D and a K-5. My all factory batteries don't swell or even get appreciably warm when recharging. The charger unit itself does. I don't have a way of recharging in the camera. Not sure if the optional camera A/C adapter charges the batteries in camera and operates the camera say in the studio or not since I don't have the units. Also none of my batteries ever offer any resistance to going in or out. Did any one else with the same equipment reply? If you are not going to listen to me and replace the knock-off batteries ASAP, please at least respect your cameras and send them to me before they detonate. I could use back-ups.

leftj Loc: Texas

Quick answer. They're old and need to be replaced. What the heck is a non-factory battery? Is it a battery that someone made in their garage? That's a first for me.

lamiaceae Loc: San Luis Obispo County, CA

After market, third party, something non-Pentax Branded in this case.

mas24 Loc: Southern CA

Constant charging and use by a battery can cause swelling. This can also happen with cell phone batteries. When I turned in my old cell phone for a new one, I noticed a bulge in the middle of the battery. It was a 4 year old battery. Never replaced.