Stig, can you provide us with the battery model number, as a larger/stronger battery requirement is an ongoing saga with these 500's.
Here you go...
I don't know how hard it is to measure the battery box on your big scooter, or to see what you have in there for a battery.
I took out my battery, measured it, measured the space it fits in - then went to this YUASA site to see what my battery specs were - and what I could up-grade to that would still fit the space in my scooter. Found this more powerful one that fit with just a quick trim to the battery hold-down pins on the battery cover.
http://www.kymcoforum.com/index.php?topic=11456.msg114986#msg114986The YUASA site is where I found the better/bigger battery - with the same mounting type for the posts, etc., etc.
There was nothing listed for my scooter - I just used the info from my OEM Yuasa battery and searched out same sized one with more grunt. Back and forth to my scoot to make certain the new battery would fit - then ordered it from Amazon. Do some reading there and hopefully you can find a more powerful battery that will work in your scooter.
Regards, Stig (I noted that the same big battery I put in my little LIKE is the same battery that came in my bigger Honda Forza)
YUASA specs and charts ....
http://www.yuasabatteries.com/pdfs/Yuasa_Specs_Apps_2014.pdf