Battery Mystery

[distant.star]

.
Any ideas why this happened?

Shooting yesterday in bright sun, lot of contrast between people in shade under portable shelters and sunny backgrounds. So I was using a 270EX II for fill flash (hi-speed synch). I didn't shoot a lot, fewer than 100 pictures over three hours.

Before starting, I tested batteries. I have some AA lithium batteries I bought years ago (2021 expiration date) so I'm using them until they run out. The two in the flash had been used previously (perhaps 25 shots), and when I tested them yesterday morning on a load meter, they were both 100%. Eneloop backups I brought along also tested 100%.

Two hours into the morning, the flash stopped working. I took the batteries out, very hot. I put Eneloops in and continued on with no problem. When I got home, here's what I found:

Lithium one: 80% on load tester and 1.51 on voltmeter
Lithium two: 20% (red) on load tester and 0.97 on voltmeter

Eneloops: Both still at 100% although they probably weren't in for more than 20 shots.

I don't think I've ever seen one battery in a pair fail. Battery issue? Flash issue?

I'll keep monitoring it. I especially want to see what happens to the Eneloops over time -- this is first I've used them. If one of them goes to 20% in service and the other doesn't, that will tell me something.

 

[Loswr]

I don't have a good explanation, but Li-based batteries aren't optimal for a flash. They're great for sustained, high-drain applications, but a flash intermittently draws a very high current. The NiMH chemistry has a lower internal resistance which is better suited to high current draws.

 

[heptagon]

Neuro, that could check out. The flash draws such a high current that the voltage of one battery breaks down completely and it's in short circuit or reversed. Then the chemistry of that battery breaks down really fast and it goes bad. Luckily it didn't explode or catch fire.

 

[Mt Spokane Photography]

If you've had them for a few years, is it possible that one was used previously while the other wasn't?

Its also possible that one was defective. Unlike Li-On batteries, Lithium AA's are are rated for flash use, and high current should not make a difference.

Lithium batteries have a much flatter discharge curve, the voltage remains fairly constant until they are almost dead.

http://data.energizer.com/PDFs/l92.pdf

 

[distant.star]

If you've had them for a few years, is it possible that one was used previously while the other wasn't?

Its also possible that one was defective. Unlike Li-On batteries, Lithium AA's are are rated for flash use, and high current should not make a difference.

Lithium batteries have a much flatter discharge curve, the voltage remains fairly constant until they are almost dead.

http://data.energizer.com/PDFs/l92.pdf

Both batteries came out of the original package a month or six weeks ago. They went into the flash unit and have been there ever since.

There are only two possibilities I can think of. Either that battery is defective or the flash unit is defective. The former seems far more the likely of the two. That's why I'm going to closely monitor the Eneloops that are in there now.

Thanks.

 

[Mt Spokane Photography]

If you've had them for a few years, is it possible that one was used previously while the other wasn't?

Its also possible that one was defective. Unlike Li-On batteries, Lithium AA's are are rated for flash use, and high current should not make a difference.

Lithium batteries have a much flatter discharge curve, the voltage remains fairly constant until they are almost dead.

http://data.energizer.com/PDFs/l92.pdf

Both batteries came out of the original package a month or six weeks ago. They went into the flash unit and have been there ever since.

There are only two possibilities I can think of. Either that battery is defective or the flash unit is defective. The former seems far more the likely of the two. That's why I'm going to closely monitor the Eneloops that are in there now.

Thanks.

The batteries are in series, so its hard to know see how a flash could damage one and not the other. The batteries have been tested continuously at 2 amps, I think that's far more than a flash would draw.
If you have a meter, it would be something easy to measure. I had 3 of the Energizer Advanced Lithium's on my desk, along with a old Triplett meter I just bought. Open circuit voltage was 2 volts on two of them and 1.6 volts on the other. All had been used a equal amount, so there appears to be substantial variation. I think the 4th battery was tossed and dead. Sometimes things lay around here too long.

 

[Rocky]

Are both batteries hot or just the 20% one is hot???

 

[Sith Zombie]

Maybe check your battery cover end on the flash? I lost a cover to one of my flash units once so I made a cover from a few pieces of card and some strips of tin foil. Anyway, I didn't know which way the current was supposed to flow so I took a guess. The flash worked but when I checked the batteries they were really hot [burn your fingers hot], so I changed the foil strips and go it right, the flash worked and the batteries remained cool. Perhaps something is making a connection somewhere and interfering with the correct flow of the current? Check inside the battery chamber and the cover.

 

[Forceflow]

The batteries are in series, so its hard to know see how a flash could damage one and not the other. The batteries have been tested continuously at 2 amps, I think that's far more than a flash would draw.
If you have a meter, it would be something easy to measure. I had 3 of the Energizer Advanced Lithium's on my desk, along with a old Triplett meter I just bought. Open circuit voltage was 2 volts on two of them and 1.6 volts on the other. All had been used a equal amount, so there appears to be substantial variation. I think the 4th battery was tossed and dead. Sometimes things lay around here too long.

Interestingly enough I saw this too before I started using Eneloop. Often when I tried rechargeables the batteries were empty really fast. Yet when I put them in my charger only one would show being depleted while the other ones usually looked on the okay side. (I only did this a couple of times however since there really was no point of using the rechargeables with so little capacity)
Never had that issue with my Eneloops however, they all seem to discharge at the same rate.

 

[emag]

It was just luck of the draw, you got a defective battery, don't over analyze it. I've gradually replaced all of my batteries with Eneloops, bought in bulk via Amazon. Very pleased with them.

 

[brad goda]

lithiums are great. light and have high capacity... but when close to 60% they do not just fade when power is low they just die. Ive used lithiums flash and feel ive got almost 4X the use compared to alkalines...
you did check the batteries before the shoot and thats good rule of thumb... but sometimes there are just duds...
100 shots for daylight HS fill is quite alot of shots for a flash that only holds 2 AAs.
just carry back ups