I have an older model E-Z-GO electric golf cart. I have changed the resister coils, new batteries, all electrical cable (between batteries), and put new brakes on it, it is still extremely slow, and only has a 20-25 minute run time, doesn't seem to accept a charge. I have tried three different chargers and no help. Everything seems to be in order and either new or good working condition. Any ideas on where to look next?