Refreshing rechargeable batteries

Refreshing rechargeable batteries allows you to give a second life to weak and damaged Ni-MH (nickel-metal-hydride) batteries, i.e. Eneloop.


Refreshing rechargeable batteries is a topic that reminded me during quarantine. A lot of people photographing parties and events began to wonder how to store and what to do with the batteries in their flash units, whether to leave them discharged, fully charged or full?

Andthe accumulators should not lie unloaded for a long time, so it is worth checking it and recharging them. Even the cells that were once charged slowly lose their voltage and sooner or later are slightly discharged. In the case of good cells, i.e. Eneloop , discharge up to 70% can take up to 5 years, but this does not affect them well, increasing their internal resistance and even damage.

It is worth refreshing the batteries once every 6-12 months, which by discharging and charging them several times will improve their condition and reduce internal resistance. You do not have to do this every time you come back from photos (discharge and charge), in the case of Ni-Mh rechargeable batteries (nickel-metal-hydride), which are not as susceptible to the memory effect as Ni-Cd cells (nickel-cadmium), which had to be refreshed before use and much more often refreshed.

Battery charger

Anyone who shoots with a flash, illuminates with LED lamps / panels or uses another device using AA or AAA batteries must replace them with new ones every now and then. Sooner or later, such a person will be interested in buying a charger along with a set of rechargeable batteries. Such a set not only gives convenience, when we can charge the discharged batteries repeatedly, instead of going to the store for another package of batteries, we can also save a lot of money in the long run.

porownanie eneloop do baterii - Urbanflavour.pl
The Eneloop BK-3MCCE has up to 2100 charging cycles!

Rechargeable batteries also work better in extreme temperatures. It is true that this reduces their performance, but not as much as ordinary batteries.

eneloopy zima - Urbanflavour.pl

The most obvious and proven choice is to buy a set with a Panasonic BQ-CC51 charger (formerly Sanyo MQR-06 ) and Eneloop R6/AA rechargeable batteries with a capacity of 1900-2500 mAh. Such a set allows us up to 2100 cycles of charging the batteries that are included. It takes about 10h, that due to the output voltage AA 250mA x 2 / AAA 120mA x 2, which is safe for rechargeable batteries, but which can not be changed.

In the case of the Panasonic charger – 4 rechargeable batteries will be fully charged all night so that they are ready for operation. You also need to charge them in pairs of 2 or 4 pieces. It is not possible to change the charging current or check the condition of the cells. The only information we get is whether the charger is charging or whether it has completed the charging process.

In the case of such simple chargers, charging only in pairs of the same cells can be a problem. Cheap chargers can also lead to long-term overcharging of batteries, which leads to an increase in temperature to up to 60 degrees, damage to cells, and in extreme cases to explosion.

What is the best way to charge rechargeable batteries?

To take care of the batteries, a good microprocessor charger is the basis. The battery charger should have independent channels, the ability to charge and discharge the cells, measurement functions as well as a number of press and thermal protections.

everActive NC-3000

Then a charger such as the everActive NC-3000 can come to our aid, which not only can charge the batteries faster with a higher voltage, which can be adjusted for each battery separately, but also gives us the opportunity to check the capacity and refresh the cells. It also detects which rechargeable batteries are in poor condition or are damaged.

The NC-3000 charger also has as many as 6 temperature sensors that protect the charger and batteries from losing.

Advantages of the everActive NC-3000 charger

If someone has not yet dealt with the everActive NC-3000 charger, it will briefly summarize its most important features, and later I will tell you how they differ.

  • Support for the most popular AA (R03) and AAA (R6) rechargeable batteries
  • 4 independent charging channels
  • 6 modes – charging, discharging, refreshing batteries, capacitance measurement and internal resistance test
  • Adjustable charging current 200, 400, 600, 800, 1000 mA
  • Adjustable discharge current 100, 200, 300, 400, 500 mA
  • Overheating protection, detection of damaged or incompatible rechargeable batteries

Having such charger capabilities, we can use one of five modes

Charging – compared to the popular Panasonic/Sanyo charger, which charges with a current of 120-250mA and takes an average of 10 hours, EverActive charges with 400mA by default, which almost 2x reduces the charging time. We have the ability to adjust from 200 to 1000mA (when charging only two cells also 1200, 1400mA).

With a maximum charging current (1000mA) 4 AA 2500mAh rechargeable batteries will be charged in just 3 hours!

Discharge – Can be used to minimize the lazy effect of the battery by discharging the batteries to a voltage of 0.9V. Remember to fully charge the batteries after this process so as not to damage them.

Battery pack refresh – this is a sequence of charging and discharging rechargeable batteries to eliminate the lazy battery effect. By the way, at the end of this process we get the maximum capacity of the cells expressed in mAh.

The internal resistance test allows you to check whether the battery will be able to give off a large current in the flash. We can do it using the Quick Test option, which lasts 10 seconds. It is worth conducting a test for each of the cells at least 3 times, so that the difference in subsequent measurements is not more than 30%.

How to read the resistance test?

20-80 mΩ – Cells new and in very good condition. Best for devices such as flashes, flashlights, cameras.

80-120 mΩ – Standard result, equally good for most devices.

201-500 mΩ – Low-current cells (lazy batteries), worn or of low quality. You can still use them in undemanding prejudices that do not need a lot of energy – watches, TV remote controls, mice, keyboards. In the case of Ni-MH rechargeable batteries, the Refresh mode can help, which recharges and discharges the batteries several times to start them a little.

>500 mΩ – These are already very worn or damaged cells that should be replaced with new ones. They will charge for a very long time and generate high temperatures, which in extreme cases can be dangerous. Cells with such resistance can be recognized by devices as discharged, even after being pulled out of the charger.

*Lazy battery effect ‘it arises as a result of incomplete discharge, which causes a slight decrease in rated voltage; this effect can be removed by means of a charger with a discharge function.”

How to refresh the batteries in the everActive NC-3000 charger

Refreshing the batteries begins by inserting them into the charger by clicking 5 times on the fashion button until the Discharge Refesh option appears. The value of ma that we will see can be left unchanged. 200mA is the discharge current, which is 1/2 of the charging current. In this case, the charging current will be 400mA (2x the discharge current).

If we want to refresh the selected rechargeable batteries, we can select them using the Slot button.

005 everactive nc3000 odswiezanie 1596 - Urbanflavour.pl

After activating the refresh, it remains for us to leave the charger for a few days until we see the message “Full”.

001 everactive nc3000 odswiezanie 1591 - Urbanflavour.pl

At this point, we have completed the refresh process and we can go to check the capacity measurement expressed in mAh.

Refreshing eneloop rechargeable batteries
Rechargeable batteries 1900 mAh as you can see still in the form.

We also receive information about the voltage, where, as you can see, the batteries are approaching 1.5V.

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You can also see the value of the charging current, which only gently supports the batteries at the level of 14mA.

Battery or Rechargeable Battery?

Ordinary AA zinc-carbon and alkaline batteries have a nominal voltage of 1.5V, and nickel-metal hydride and nickel-cadmium batteries have 1.2V. However, in most cases, there is no question of incompatibility, since 1.2V is the average voltage of the batteries, which when charged exceeds 1.4V.

Good batteries cost about 1-2 zł per piece and you can get them in cheaper multipacks, and Eneloop rechargeable batteries approx. 10 PLN / pcs, to which we have to buy a charger for approx. 100 PLN

So it is easy to conclude that it is a pity to put rechargeable batteries in the TV remote control, watch, mouse, keyboard or other equipment, where we replace them on average once every 6-12 months. By the way, batteries do not suffer from the lazy battery effect and do not lose energy so quickly, so it may turn out that they will last slightly longer than 10 times more expensive Eneloop, which do not like woooolmoo.

The only sensible solution may be to use old rechargeable batteries that have high internal resistance and are not suitable for flash, and in the remote control they will still be able to help us change channels on TV for a long time.

Ni-Mh rechargeable batteries are great for devices that consume a lot of energy and where we replace them often – flash units, powerful flashlights, toys, drones and other equipment that consume approx. 500mA. In such applications, rechargeable batteries can last up to 2x longer than batteries of similar capacity.

akumulatorki w niskiej temperaturze - Urbanflavour.pl

Batteries in the flash?

I also met with the opinion that batteries withstand more flashes, because they can be discharged more. It is possible that this is related to the rated voltage of the battery, which starts from 1.5V and drops to 1V at the time of discharge, and in rechargeable batteries from 1.2V they fall to 1-0.9V.

According to These measurements show that the voltage of 1.2V for rechargeable batteries is the average discharge voltage, which at the beginning may exceed 1.4V and then decreases, but the average 1.2V maintains slightly longer, in the case of power-hungry devices, i.e. Flash. Therefore personally, I do not use batteries, and I have one set only for emergency situations.

Longer battery life

In order for Ni-Mh rechargeable batteries to serve us for a long time, it is worth following a few rules:

  • We charge the batteries with a current higher than 20% of their rated capacity. If we have 2000 mAh, we charge with a current of 400mA or higher, but there is also nothing to exaggerate, because in the case of old rechargeable batteries they can boil
  • We do not leave discharged batteries
  • We do not use rechargeable batteries in devices that consume very little energy
  • We avoid very low (-20) and high (60) for a long time
  • We do not have to discharge them and charge them to the end every time, because it is not needed and takes away their charging cycles
  • AAA rechargeable batteries have a maximum of 1100 mAh and AA 2700 mAh, but on Allegro you can find larger capacities, which is a simple scam

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Fotograf eventowy - Marcin Krokowski