When I needed to change batteries in a final I used Losi EC5s. I think Deans don't quite have a high enough rating for the bursts in 1/8 use.
I now use 6mm gold tubes (6mm Corallys), though they aren't polarity protected, and there are two wires to pull out/reconnect rather than one connector.
Stick with the EC5s, it may be worth plugging them in and removing them loads of times as they will free up over time.
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