Does anybody know what kind of connectors these are?
- The size of the holes on the right picture is about 5 mm
- The inner size of the holes on the left picture is about 3 mm
They appear to be Molex "MLX" power connectors (series 42021).
Here is the 6-way variant pictured above, part number 50-84-1065.
They are designed for 2.13mm pins, which fits the ~3mm hole measurement. They have a pitch of 6.35mm, which matches with the ~6mm measurement.
This connector series is also available in the old AMP line that is now supplied by TE connectivity. Their series is called the Universal MATE-N-LOCK.
(Picture source at Digikey Product Page)
In today's use of much lower power in most gadgets and devices these connectors are being used less and less. I still like to use them for power delivery because of their relative low cost and higher current carrying capacity per pin over other 2.54mm contact spacing connectors and headers.