ColeNeyhart 1 #1 Posted February 11 I’ve got an 89 520 hc with the onan p20 and was wondering if the dc wire on the rectifyer is supposed to go straight to the battery or through the key switch. i tested the positive wire and i get battery voltage when the key is on and off. was wondering if it is a key issue. 1 Share this post Link to post Share on other sites
cleat 6,884 #2 Posted February 11 The older 520's (like yours) have the charge wire run directly to the battery cable on the starter through a 30A inline fuse. That is the best way and I rewire all Onan powered machines this way. Here is the wiring diagram for your machine. HC wire diagram.pdf 1 Share this post Link to post Share on other sites
WHX?? 50,024 #3 Posted February 11 (edited) Cole What Cleat said. Pay attention to any connections long the way that can get hot and burn out. More than one fuse block been melted out that way. On a 516 but same difference. Edited February 11 by WHX?? 2 Share this post Link to post Share on other sites
peter lena 9,015 #4 Posted February 11 @WHX?? good advise there , pretty easy to change out to a better grade of connector , like the boat waterproof connectors , another thing often missed is the ORIGINAL WIRE ROUTING SET UP , for change improvement , wire chafing , heat stress , etc . like to do a make over with , spiral wire wrap , away from issue areas , lots of stick on / screw on wire attachment add ons available . basically eliminate the original cause of issue . pete Share this post Link to post Share on other sites
ColeNeyhart 1 #5 Posted February 11 1 hour ago, cleat said: The older 520's (like yours) have the charge wire run directly to the battery cable on the starter through a 30A inline fuse. That is the best way and I rewire all Onan powered machines this way. Here is the wiring diagram for your machine. HC wire diagram.pdf 264.03 kB · 4 downloads The reason i was asking, was because the onan rectifyer was charging at 17 volts at high idle. So i threw in a kohler three prong regulator and it charges good at 14.5 volts, but in the morning when i fire it up it has a slow crank. i have yet to try unplugging the battery wire from the regulator to see if that makes any difference. on kohlers, i believe the battery wire on the regulator is through the key switch. so what i’m thinking is maybe onans regulators are meant to have 12v at all time. i’m not sure Share this post Link to post Share on other sites
WHX?? 50,024 #6 Posted February 11 11 minutes ago, ColeNeyhart said: charging at 17 volts at high idle. They are known for overcharging ... even the cheap ones in the jungle right out of the box. Don't go by the voltmeter on the tractor either they can be way off. Use a DMM Maybe cooked your battery? 1 Share this post Link to post Share on other sites
953 nut 56,975 #7 Posted February 11 If the voltage regulator is not properly grounded it can cause it to run a bit higher voltage. 1 Share this post Link to post Share on other sites
