Angelo Posted September 26, 2023 Share Posted September 26, 2023 I believe I have a faulty voltage regulator. It’s a 707b with positive ground and generator. It’s overcharging and burning points and cooking batteries. Anyone ever have issue with theirs. Where is this thing located? I’ve never dealt with generators before. Thanks for any advice Quote Link to comment Share on other sites More sharing options...
Geoff Weeks Posted September 26, 2023 Share Posted September 26, 2023 Got to start by knowing the charging voltage. Voltage reg would be a smaller black box most likely on the firewall. There must be a good connection between the reg and generator and also the ground path between the reg, chassie, body and engine. If the regulator doesn't have a good ground path, it can't compare what the voltage is to what it should be. Some(many heavy duty) regulators are mounted with a rubber mount to protect from rough vibration. They MUST have a ground path to electrically connect the rubber isolated regulator to the chassie. Often it is a thin tab connected to one of the mount screws, but these can either rust or break. If in doubt connect a ground wire between the regulator case and the chassie. I have found the regulators to be extremely reliable and have two that are close to or over 80 years old and still working. 1 Quote Link to comment Share on other sites More sharing options...
Geoff Weeks Posted September 26, 2023 Share Posted September 26, 2023 Also, assuming it has a Delco generator, any short to ground on the field wire between the reg and generator would "full field" the genny regardless of what the regulator tried to do. So look for frayed insulation on the genny wires. Quote Link to comment Share on other sites More sharing options...
Geoff Weeks Posted September 26, 2023 Share Posted September 26, 2023 OK, I just noticed this is in the fire truck thread. Many Fire trucks used alternators long before they became used in trucks. (I have a 6 volt 100 amp alternator) so lets start with some pictures of what you have. Just to be sure we are on the same page. 2 Quote Link to comment Share on other sites More sharing options...
FireSKip17 Posted December 29, 2023 Share Posted December 29, 2023 If someone wanted to swap to a newer 1 wire alternator, any suggestions on an easy drop in? I'd love to get rid of the rectifier and voltage regulator on this Mack Quote Link to comment Share on other sites More sharing options...
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