A Simple Trick to Revive a Dead Rechargeable Battery

Like many other photographers and filmmakers today, we need batteries for many of our gear and accessories. Many devices today come with their own rechargeable battery but there are still many gadgets and accessories we use that still can take the standard AA or AAA batteries. Keeping many on hand can be a pain in itself, so I tend to keep a set of traditional non-rechargeable batteries as a backup with many rechargeable ones as the main source for these items that need them. What happens with the rechargeable ones will not recharge anymore?

There are a few tricks out there to try to give you rechargeable battery life again, and it takes less than a minute to try to restore your battery with this tip from Lensvid. It’s worth a try and saves you from possibly throwing away several rechargeable batteries that can still be used. In this video, simply using a barbeque clamp and 30 seconds, the rechargeable battery may be able to accept further charging.

My personal favorite rechargeable battery is the popular Panasonic Eneloop batteries and I carry a few sets of both with me in one of my bags. Which is your preferred brand of rechargeable batteries? Do you have any tips to prolong their life? Do you use another method to try to bring them back to life? Leave your answers in the comments below.

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Deleted Account's picture

This works for batteries that seem dead but are just deep discharged so a "smart" charger doesn't pick up on them, but still have viable chemistry and such good capacity. You can deep-discharge modern NiMH rechargeables and even lithium cells once or twice and they won't be worse for it, but don't make it a habit or they will become truly dead. Once they are, only use them in an emergency, especially when they go in a pack together with others, don't leave them in a device, and get replacements.

A dead NiMH or dying cell (very) quickly goes to low voltage—it can even flip negative—, and can put additional load on other cells in a pack. If you recharge such a pack as one or use it for demanding applications like speedlights, you will end up putting excess load across the other cells and kill them too. There's also an increased risk of leakage which can quickly damage or destroy your equipment.

So when you have rescued a "dead" cell and you have a charger that can measure cell capacity, put it through such a cycle to see if it's still reasonably close to "normal" capacity (what's normal would be determined by measuring a bunch of fresh cells of a given make). If it measures up, I would still mark it as "maybe bad" and keep an eye on it; if it comes up significantly below normal, get a replacement.

michael buehrle's picture

i like to put mine in the microwave to get them warmed up first...........

Justin Berrington's picture

Why does this work?

ron fya's picture

Because what your are doing is connecting a voltage source (the functional battery) to a load (the dead battery cannot produce voltage and is therefore a load). It's that difference in potential that revives it. The reason it doesn't work with a regular charger is that battery chargers are current sources, not voltage sources, which start slow and ramp up.

Justin Berrington's picture

Great explanation. Thank you

Deleted Account's picture

The problem is that smart chargers won't "see" deeply discharged cells or refuse to charge them for safety reasons. What you're doing is get the cell up to a voltage where the charger will recognise it as something it can handle.

Damon Loomis's picture

I use the rechargeable Eneloop AA & AAA batteries but they are made by Sanyo. Great batteries!

Justin Berrington's picture

Has anyone tested the Amazon Basics AA High Capacity batteries in the field? There are several people in the comments ( https://tinyurl.com/yb3r2zll ) saying that they are rebranded eneloop pro's.One of the comments from NLee the Engineer goes into detailed testing using a "La Crosse BC1000 Battery Charger/Analyzer". I'm wondering if anyone here has used them for professional use in the field and had good results. The amazon basics are about $30 less when buying 8 batteries.

Brendan Kavanagh's picture

I put a set of 4 Amazon basics in my speedlight, untouched, as they came from Amazon's packaging and they lasted over six months before the indicator showed a drop; one "bar", in their capacity and it took another couple of months before another "bar" disappeared.
At that point, I figured that it might be time to charge them up.
Having done so, they're now well on their way towards another six month stint.
I'm not a pro. but I do shoot all the time and I use that speedlight in just about every shot, daylight, sunshine or otherwise.
They're definitely worth the money.

Jimmy Taylor's picture

For years I have used older manual charges that don’t analyze a battery’s state, it just shuts off automatically when fully charged. Any battery claimed to be dead or unrecognized by my smart chargers, goes into one of my older manual chargers, and it’s works 100% of the time. This has never failed to work for many years. Even after 1/2-1 hr in there, it gets recognized by any smart charger 100%. I have several old Rayovac Model PS3.