Charger Panasonic BQ-CC51





Panasonic has a line of NiMH chargers, some are fast and smart, others dumb. This one here is a very slow and very dumb charger.
I found this charger on ebay from buyer_holic.



I got the charger in a blister pack. There was no extras, only the charger and a instruction sheet.
The instruction sheet specifies charge time for different cell capacities, from 5 hours for a 1000mAh AA to 12 hours for a 2500mAh AA.



The charger is designed with a EU plug.



The only user interface is two leds, one for slot #1 & #2 and one for slot #3 & #4, i.e. the charger can only charge two or four batteries at a time.
The leds is green while charging and will flash on error. When charging is done they turn off.




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







Measurements charger

• When not powered it will discharge the battery with 0.04mA
• If the charger detect an error the green led for that channel will flash fast.
• Steady green light is charging.
• Charge will restart charging after power loss, or battery insertion.
• Can only charge in pairs.
• Power consumption when idle is 0.23 watt

The two cells is fully charged and a bit more, using about 12.5 hours. This looks like the charger uses a fixed charge time.



There is no surprise with the second channel, it uses exactly the same time.




Using higher capacity cells fills the batteries and will not change the charge time.



Charging AAA cells will reduce the current and use the same time.



Starting with two full cells is not a good idea, they get another full 12.5 hour charge.



Four batteries do also take 12.5 hours to charge.



M1: 40,5°C, M2: 42,3°C, M3: 42,6°C, M4: 40,7°C, M5: 44,8°C, HS1: 54,5°C
The charger uses a low charge current, but the batteries is warmed a bit from the charger.



M1: 46,4°C, M2: 49,8°C, M3: 49,8°C, M4: 46,1°C, M5: 41,3°C, HS1: 52,8°C
When the charger is finished, the batteries will produce some heat.



The charger needs about 0.5 seconds to start. I wonder about the pulsing, the charger do not measure any voltage to terminate the charging.



The first chart was with two cells, here I tries with four cell, it looks exactly the same, i.e. no time division of a single charge circuit, the charger has two charge circuits.



With AAA the current is reduced.

Testing the mains transformer with 2500 volt and 5000 volt between mains and low volt side, did not show any safety problems.



Conclusion

This charger do always need 12.5 hours before it says done, this makes me wonder why the instruction sheets list shorter charge times.
It is not a good idea to charge full or half depleted batteries on this charger, it is best to charge only empty batteries.
I do generally not like this type of charger, it is hard on the batteries, because it always overcharge, but it may charge old mostly worn out batteries.



Notes

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