Hi coolhands,
I normally use the CORALLY type battery connectors. 4mm and 5mm dependant of size in the battery (lipo).
I use this technique when I solder the connectors on the end of the wire.
As can be seen in the pictures I use,
Long nose pliers
Tamiya cross wrench/box spanner
Connector
Wire.
Just put the pliers in the biggest end of the box spanner, then use the other socket for the connector. You will need to rotate the spanner to see what size fits the connector.
This then holds the connector snug and firm and gives you total control when placing the wire and soldering on to the connector.
Hope that helps …...…………...
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