Where can i get portable backup charge for mobilty scooter?

Most scooter batteries take 5 to 8 hours to charge correctly the only backup methods are the following
if you have a detachable battery box .pride gogo ect a spare battery box can be purchased and kept charged.
there is no quick way emergency charge if you run out of power
just charge it evrey time you use it and for a min of 8 hours to keep your batteries in top condition,have them tested if you think low range.