We have a C500-55 that we use, but don't own. The owner had it serviced as it wasn't holding a charge. The service center installed a new alternator. Owner said it was all set but whenever we go to use it we need to use a battery charger on "start" mode to start the forklift. We installed a new battery as the original was 5 years old. Still not starting without at least a trickle charge on it. Troubleshooting it now, as we should have before, we only get nominal battery voltage of 12.55V at the battery when forklift is running and 12.48V at alternator. Before I blame the new alternator, what else can I check? Anyone have a wiring diagram for this model they could share?