More 600EX-RT/Battery questions...fun!

[nuncle]

Greetings all!

I've seen several discussions about batteries and the flash, but I'm just trying to get the "definitive" answer 🙂

I've got two 600EX-RT's. The first one died on me at Christmas last year. While shooting, I discovered that the batteries became hot...really hot. The next time I tried to turn on the flash...nothing. Brand new batteries did nothing.

I had some extra money at the time and my flash was almost 2 years old so I bought a new 600 in January. While shooting with it about a month ago, the same thing happened. The batteries got so hot that, after I took them out and put them into my pants pocket I had to take them out because they were burning my leg!

That flash was still under warranty, so I sent it in and it's fixed now.

I have always used non-rechargable batteries...and I've used the Duracel Ultimate, for the most part...or the Eveready version. Don't remember the name, but I've always bought the "strongest, longest-lasting" type of whichever brand, on the theory that "The stronger the bettery, the longer it'll last".

Are rechargeable batteries better for the 600EX-RT? Are they worse? What's the Straight Dope? 🙂

[TCampbell]

I use rechargeable Eneloop batteries.

Eneloops are low-self-discharge.  A regularly rechargeable battery will drain merely sitting unused at a fairly quick rate... quickly enough that a few weeks after charging it will have lost quite a bit of power.  A low-self-discharge battery has a shelf like almost like a non-reusable battery... a year after charging they still have about 90% of their charge.

That means if you charge up some batteries to be prepared for the next time you need them...  you don't have to worry that they'll be very low or drained the next time you need them.

But I am a bit worried about these batteries becoming "hot".   When batteries are either charging or draining, they'll get a little "warm" but generally not "hot".  Usually "hot" means you're draining the batteries very quickly.  Were you running the flash hard?   If you _do_ need to run the lights hard (rapid fire and high power levels) you can split the load across multple flashes (there are mounts that will let you cluster 3 or even 6 flashes on one stand.)

[Skirball]

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@nuncle wrote:

Are rechargeable batteries better for the 600EX-RT? Are they worse? What's the Straight Dope? 🙂

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Yes, recharageables are better.  They are quicker to recycle, hold more flashes, generate less heat, and cost less (in the long run) than alkaline.  Not to mention you're not tossing batteries in a land fill.  It amazes me how many photographers regularly use alkaline.

Now, that said: there have been a few reports of issues with using rechargeables in the 600exRT.  THere's a few threads on here you might want to read.  In the manual it even says to use alkaline.  The issue is sporadic, otherwise there would be a lot more complaints about it, and Canon would have been forced to fix the issue instead of just put a warning in that the flash needs alkaline.  It's asanine, there is absolutely no reason, from an engineering standpoint, of why the flash would need alkaline.  I'm not sure what happened, but Canon f-d up.  It's the first issue I've ever heard about flashes having a problem with rechargeables.

As to which brand, there's only one: Eneloops. The white ones, not the XX (I can discuss why if you want).  Panasonic bought out Sanyo, so make sure the package says Panasonic so you're getting the latest.  They did a minor upgrade (4th generation), stating it has more recharges than before (2100 vs 1500).  Not sure if it makes a difference, but if you're going to buy, might as well get the latest.  Also, get a good charger, like a Maha.

[TCampbell]

On the charging note... I bought the Maha, but it was dead on arrival and returned. I opted for a different charger (I don't recall which one, but I'm not nearby to be able to check it.)

In any case, there are a number of 3rd party chargers that allow you to set the charging rate. Slow charging is always better (less heat generated) if you have the time to let it slow charge.

[nuncle]

I'm definitely going to look into the rechargeable option, I think 🙂 How long does a slow charge vs a fast charge take, approximately? Maybe I'll head down to Best Buy today and see what they have. I'm not assured of anything online getting here in time for a Tuesday morning flight, unless I pay more in shipping than the item costs... 😛

[Skirball]

I've been happy with my Maha.  The only thing I would do differently is get an 8 battery charger instead of a 4.

The other major brand is Lacrosse.  I debated between the two for a bit, and came to the conclusion that it's like Canon and Nikon.  I'm sure they both work fine, allow various charging rates, reconditioning, etc.

[Skirball]

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@nuncle wrote:
 How long does a slow charge vs a fast charge take, approximately?

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It depends on the rate you choose.  There's a lot of discussion on various charging rates on the internet, nobody really agrees. Many recommend a slow charge 0.1C - 0.2C; in other words, 10 - 20% of the max capacity, which is about 2000 mA, so 200 - 400 mA.  Others claim that that chargers can't reliably determine charge at that slow a trickle and use 0.5C.

Usually I just charge them overnight, so I use 200 mA, which takes about 8-9 hours.  If I'm in a hurry I use 1000 mA, which takes about 2.  I've done a 1 hour charge in a pinch.

The good battery chargers have a recondition phase, which charges them up, slowly discharges, and slowy chargers again.  It takes a good long while, but I've heard stories of it bringing dead batteries to life.  I do it after doing a 1 hour charge.  I have no data to support if it does anything, but I figure it can't hurt.  That said, even my 3 year old Eneloops are still going strong.

[Skirball]

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@nuncle wrote:
 Maybe I'll head down to Best Buy today and see what they have. I'm not assured of anything online getting here in time for a Tuesday morning flight, unless I pay more in shipping than the item costs... 😛

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You can check out Best Buy, but you're going to pay a premium for them.  I just picked up a 16 pack of the new ones for $40 something on Amazon.  If I were you I'd just buy them cheap online and use Alkaline for the trip if they don't get there in time.

[TCampbell]

Like Skirball -- I typically set my charger (which I think might be the Lacrosse) to the 200mA rate and let it charge overnight. These chargers let you set the charging rate -- you can pick a faster rate.

When I bought my Enelooops, it came in a pack with many AA and a few AAA size... but also included a charger. When I checked the charging rate on the included charger, it was fairly low (200 or 300mA as I recall.) I'll try to remember to check it when I get home and post back with the answer.

[RobertTheFat]

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@TCampbell wrote:

I use rechargeable Eneloop batteries.

Eneloops are low-self-discharge.  A regularly rechargeable battery will drain merely sitting unused at a fairly quick rate... quickly enough that a few weeks after charging it will have lost quite a bit of power.  A low-self-discharge battery has a shelf like almost like a non-reusable battery... a year after charging they still have about 90% of their charge.

That means if you charge up some batteries to be prepared for the next time you need them...  you don't have to worry that they'll be very low or drained the next time you need them.

I too use Eneloops - the black professional series. My experience so far suggests that their low-self-discharge characteristics are somewhat exaggerated: they appear to lose power on the shelf at about the same rate as the "Enercells" sold by Radio Shack. But the Eneloops have been very reliable.

But I am a bit worried about these batteries becoming "hot".   When batteries are either charging or draining, they'll get a little "warm" but generally not "hot".  Usually "hot" means you're draining the batteries very quickly.  Were you running the flash hard?   If you _do_ need to run the lights hard (rapid fire and high power levels) you can split the load across multple flashes (there are mounts that will let you cluster 3 or even 6 flashes on one stand.)

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All modern Canon speedlites are supposed to automatically shut down for a few minutes if the flashtube starts to overheat. (I've had it happen to me.)

But batteries overheating are a different matter. A battery overheats when the current flowing through it is too high. What may be happening is that as the batteries deplete, they may be unable to maintain their rated voltage (usually 1.5 volts each for non-rechargeables). The light, which expects to consume a given amount of power (watts) to recharge itself, may be forcing the batteries to deliver that power by increasing their current flow. (Remember that watts = volts x amps.) The batteries should be able to resist that demand, forcing the light to recharge more slowly (or not at all). But if they can't, they will overheat.

Fill disclosure: I'm not an electrical engineer. So the first person who identifies himself as one should probably be listened to instead of me.