Duracell 15min charger CEF15 UK

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Duracell makes both batteries and chargers, here I am looking on a four channel super fast charger.

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I got the charger in a blister pack. As can be seen on the pack the charger needs 15 minutes to charge batteries, but is this correct?

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The pack contained the charger, a power supply, four batteries and a instruction sheet.

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The power input is placed on the back of the charger and requires 15V from the supplied power supply, i.e. it is not rated for car usage.

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The only user interface is four leds, one for each channel:
Red while charging,
Flashing green when partially charged (When the charge current is reduced).
Green when finished.
Flashing red on error error.
Off when slot is empty.

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Below the batteries is air vents and a fan to keep them cool. The fan is only on when the charger is working.

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The charger has the typically two level slots used for AA and AAA batteries.

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Measurements charger


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The charger is rated as a 15 minute charge, but the charge time with one cell is closer to 30 minutes. The termination looks like -dv/dt and after termination it switches to a trickle charge with around 15mA.

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The 3 other slot looks the same.

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The high capacity cells has higher internal resistance and requires nearly an hour to charge.

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A high speed charge must be fast at detection a full cell, this charger does it in 2 minutes.

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With AAA cells the current are reduced to 3A and this time it charges in 15 minutes.

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The charger can easily handle 4 cells, but at reduced current and longer charge time.

Temp3803

M1: 37,7C, M2: 37,2C, M3: 36,0C, M4: 35,4C, M5: 36,5C, HS1: 64,7C
There is some electronic inside the charger that gets a bit warm, but the fan is very good at keeping the batteries cool.

PowerOn

The charger needs a bit above 1 seconds to initialize, before it turns the current on.

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With 3 or 4 cells the current is halved, but it do not use time sharing.

ChargeReducedCurrent

The charger reduces the current when the battery is nearly charged. During this phase the led will flash green.

ChargeTrickle

The trickle charger is a 1 second pulse every 82 seconds, i.e. 1.2% of about 1A or 12mA, this is a nice low trickle charge.



Testing the transfomer with 2830 volt and 4242 volt between mains and low volt side, did not show any safety problems.



Conclusion

This charger is not the right solution for long battery life, but it is very useful if you need batteries charged fast and dont mind replacing them frequently.

As a general purpose charger I will not recommend it, but for people needing very fast charging it is useful, but as usual the announced charge time is rather optimistic*.


*It is probably correct, for the specified condition (2x1300mAh cells), but the conditions will usual not match real usage.


Notes

Here is an explanation on how I did the above charge curves: How do I test a charger