How to calculate clipper new battery charging time

Question

I'm replacing batteries on a hair clipper following this tutorial. New batteries have higher capacity than the original ones :

• old batteries : 2x BYD AAA NiMH 1.2V 600 mAh
• new batteries : 2x Eneloop AAA NiMH 1.2V 800 mAh (5th gen, BK-4MCDE)

My questions is : What is the impact of this capacity difference on the charging time ?

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The clipper manual is not clear about the charging time of the original batteries :

To obtain and maintain the longest battery autonomy possible, allow it to charge for 16 hours before using it for the first time and then approximately every three months.

And 16 hours seems to be a very long charging time for these small cells.

Details

AC/DC power adapter

MODEL NO : HKA-024100EC-230
PRI. : 230V~50Hz 40mA
SEC. : 2.4V DC 1000mA 2.4VA

Despite what is written on the adapter, I measured 4.5V on the output jack using a cheap multimeter, not 2.4V. I don't know if this measurement is relevant however.

Clipper

You can see the clipper internals here :

• https://a.allegroimg.com/s1024/0c64e1/d0c4a6554c439c19f1bbe966978a
• https://a.allegroimg.com/s1024/0ca896/f6aca8134308bc966f8d2d8a898b
• https://a.allegroimg.com/s1024/0cd096/8cf663ba404880ffc5e9c9299ce0

And I also tried to draw the whole circuit, I think it's accurate :

Thanks

Answer 1

The capacity of the new battery is (800/600 = 1.33) 33% larger. So the charging will take about 33% longer. This calculation only works when charging at low current, say less than 0.5C but that is likely the case here.