Bike draining battery

Hi folks
New to the site
Can anyone help me I removed a set of spot lights from my bike as the mot mechanic said he would fail the bike because it was draining my main beam.
My bike is now back firing and spluttering and it totally drained the battery. I tried a second battery in it and it ride ok for 15 mins and then started the same behaviour.
Is there a chance there could be a sort circuit or is it the altoniter or something else. Any help would be appreciated 
Thanks

Sounds strange, have you tried reconnecting the lights to see if it goes back to as it was before?

Rectifier/regulator problem maybe!!

Thanks for the info
simbo I will try and reconnect them and see what happens

Bad earth?