E.L.. Shapiro Loc: Ottawa, Ontario Canada

This may be a bit off-topic but I gotta tell you that Lumadyne gear is the best! I have a drawer full of "Speedlights" but compared to my Lumadne system, the Speedlights, even the best of them are "tinker toys"!

Replacing the old Nicad batteries with sealed lead-acid batteries, AKA Gel-Cells is a fine idea- I have 6 units operating that way. There are two models that will fin in those empty battery modules- approximately 5 and 7 Ampere/Hours, The smaller cell weighs less and still will deliver a couple of hundred full power flashes per charge, The larger one is heavy but it will go 400 or more. In TTL or Auto flash a reduced power they will yield even more.

I realize that some of the young folks kinda make fun of "old school" gear. Lumadyne gear ain't all that old- it is still currently manufactured and the latest editions are expensive!

I like using available light as much as the next guy but sometimes there is not enough light available to stop action, garner enough depth of field without shooting at some insane ISO setting which can become rather noisy. With a couple of Lumadynes, I can light up a grand ballroom, shoot at f/11 and freeze action at a fast-paced chaotic ethnic wedding a deliver crisp, clean noiseless images.

I'm 76-years old and I still haul around the rig in the attached picture. My assistant mans the remote light on a monopod and on certain venues I can hang more Lumadynes around the room on light stands or up in a balcony or gallery. Those power supplies pack 200-watt.seconds, the heads have interchangeable reflectors, bare-bulb capability, user changeable flash tubes, some have built-in modeling lamps.

Also- I make my own homemade external power packs for my little Speedlights with 6-Volt Gel Cells. a 7aH battery will power a Speedlight for weeks on a single charge. The battery is small and light enough to put in a pouch and carry it as a belt pack, the charges are not expensive, will automatically switch to trickle charge when the batteries are fully charged and no pesky "A" batteries. All you need is a length of 2-conductor coiled cord, some wooden dowels the same dimensions as the "A" batteries, electrical tape, and some basic soldering gear.

Strengthen up your weaker assistants- tell theme when it comes to muscles if you don't use 'em you lose 'em. Lumadynes and gel-cell are better than barbells!

davesit Loc: Media, PA

If they are a few years old, it's time to replace them. Rechargeable batteries typically are good for just a few hundred charge cycles. Additionally, the technology has gotten better in the last few years. Eneloop and Amazon Basics are two of the brands I use.

aellman Loc: Boston MA

In addition it can be extremely dangerous to try to recharge non-rechargeable batts.

Old Dutch

I have used Eneloop exclusively for everything for a number of years, as they are the most reliable and long-lasting. I maintain them in a LaCrosse Model BC9009 charger, which has a low charge setting, (or high, if you need them right now) and a "Restore" cycle that is very effective at restoring the batteries to like new condition. Most "one hour" chargers over-charge batteries, shortening their life. I have a set of Eneloops (Sanyo) in use for nearly 10 years and they still charge and hold their power as they did when new, as they have been charged nearly exclusively on the LaCrosse. If you use a lot of NiMh batteries, the Lacrosse is worth the investment of $40.00 or so on Amazon. And Eneloops are too; they are the best. And the LaCrosse will tell you the voltage available in the battery as well, answering your problem. Again, stay away from "quick charge" devices; they are harmful.

John9912

A really professional battery analyzer is made by www.westmountainradio.com in Waukesha, WI Phone (262) 522-6503. I have one since 2013 to keep track of condition of about 75 AA NIMH batts and about 40 D cells. It works with your computer via a USB connection. Has features such as programmable discharge rates, stop discharge at a a programmable voltage setpoint and is compatible with all the different chemistries. Sores history information on your computer and you can print a voltage versus time during the discharge period.

Widely used by Drone, Amateur Radio Folks and other applications. The one I have is a model CBA IV Computerized Battery Analyzer. About $ 200 dollars.

And yes Eneloops have a much lower self discharge than conventional NIMH cells.

sajones

Samuel A. Jones, Jr.
In my experience the best battery charger is the MaximalPower. I have used mine for years. It a "Smart Charger". Ie, it does an analysis on each battery to check their condition. It is a multi-function tester able to charge AAA to D size rechargeable. Of course I use mainly Eneloop batteries.

Hanson

Eneloops good choice for flash?

dsmeltz Loc: Philadelphia

Eneloop PRO have a fast recycle rate good for flash. The Eneloop basic is not as fast.

frankraney Loc: Clovis, Ca.

To each his own I guess. but you can buy a whole lot of batteries for $200. And that's an extensive toy for techies of which I'm one but I wouldn't do that. The batteries are old only two things can be wrong. The batteries are bad for the chargers bad. Put another set of batteries in your charge him and see if they work if they do it's not the charger throw the batteries away. that's simple and a lot less money.

But good information for for techies but doesn't solve the OP's problem.

tjw47 Loc: Michigan

I have a charger that also tests the capacity of the battery ( if desired ).
To test the battery, the battery is first charged ( you can set the charge rate )
Then the battery is the discharged ( you can set the desired discharge rate )
The battery is then charged so it can be used.

When all done it displays the Milliamp hours of the battery!

If the battery is rated at 2000 milliamp hours and it tests at 1950 you are ok.
If it tests at 1500 then yes the battery is starting to go bad.

In many years, I still have not thrown out any of my mimh eneloop batteries.

Just sitting on the shelf they self discharge at the rate of 15% per year!

dsmeltz Loc: Philadelphia

There are plenty of less expensive chargers with readouts that allow you to know the current capacity and charging status. That can address the OP's issue. But the OP has had the batteries in question to near the end of their natural life, so those batteries are probably history.

frankraney Loc: Clovis, Ca.

pottermr

My chargers that came with my eneloops that I bought at Costco, tell me when the batteries will no longer hold a charge well, they blink, at that time I think it is time to toss them and buy new ones. With good use and care, your eneloops and similar long discharge batteries should last for a number of years. I find 5 years or more use from my better batteries. I use them primarily for flashes and radio controlled devices. I've retired all of my non long-discharged batteries as they all stopped holding charges after just a year or so, while the long discharge batteries seem to last 5 or so years. I like the idea of writing the dates on your batteries when you first buy them or put them into action.

rehess Loc: South Bend, Indiana, USA

I make heavy use of AA batteries, mainly because I have noticed that stores have them in stock even when they run out of the other types {times like Hurricane/Storm Sandy}. I can purchase alkaline variants even when my rechargeables are totally ‘flat’. I have found that my K-30 camera, which can be operated off them, is hardest on them. My electronic flashes are easier on them, and my LED flashlight {yes, I carry a small one in my pocket in case the power goes out}, clocks, and remote control units require very little be left.

dsmeltz Loc: Philadelphia

Side note:
Rechargeable batteries are much better for the environment than single use, if....
1) They are recharged and used enough times to balance the downsides of the charging process. It works out, according to studies, to be about 50 cycles. Since most rechargeable have a 500-2000 cycle lifespan this should not be difficult.
2) they are properly recycled once they are no longer useful. Lowes, Home Depot and Staples all accept rechargeables for recycling.