Battery Hook up

[Dlr]

Newbie here to rc boats. Went to hook 6s lipo 5000 100c batteries with 8mm bullet connectors to boat. Plug 1st one in sparked, red lights came on esc then sounded like esc running. Is this normal? Didnt even try to hook 2nd battery. Was worried.
please help

[Ron1950]

We used 5.5 mm bullets on electric race boats so your 8mm plugs will have no problems. The spark is normal just make sure u are hooking in parrell or series correctly for your esc