Front Alternator 8V92

[GARY MINKER]

Most DC alternators can be spun up without a load with no problem unless they are self excited. Running these without a load can result in wild voltage swings that could damage the regulator or on external regulator units result in several hundred volts of output which makes them very dangerous. With a load or battery attached of some kind, even if there is a run away voltage, it will be limited until you notice things have gone sour. AC alternators for 120 VAC production must never be started up with a load. The load on the unit causes severe currents to be bourne by the regulator which will struggle to provide a proper voltage even though the frequency is terribly low. Many appliances can suffer excess current draw when supplied with low frequencies and low voltages. The impedance of motors skyrockets with even 50 cycles and will burn up many motors and electronics that are not rated for 50/60 Hertz usage. Shutting down an AC alternator while under load is a huge reversed no no. the same damage criteria exist only in reverse. --- On Wed, 10/14/09, Wayne Kotila wrote: From: Wayne Kotila Subject: Re: [WanderlodgeForum] Re: Front Alternator 8V92 To: WanderlodgeForum@yahoogroups.com Date: Wednesday, October 14, 2009, 5:13 PM Hi Greg: I don't know about no load on an alternator being harmful but it is hard on an alternator to start up with a full or very heavy load on it. It is also hard on a generator to start up under a heavy load, that is one of the reasons for the delay in the auto changeover after the generator starts. Frequently starting a coach with the house batteries very week puts an immediate heavy load on the alternator and this practice will shorten the life of the alternator. Wayne kotila 96 PT42 From: gregory O To: WanderlodgeForum@ yahoogroups. com Sent: Wed, October 14, 2009 9:06:06 AM Subject: [WanderlodgeForum] Re: Front Alternator 8V92 I dont know, may be that is where they are failing more often in motorhomes, by being run with the battery bank turned off? or up against a battery bank being charged via a shore wire at a higher than 13 amp? If the rectifying diodes are that burnt it would suggest your claim. I have a battery/alt test device that make a heat coil load I think it was about $30. from harbor freight not a very good instrument but one more test to help make a decision. I was unaware that running an alt without a load would cause harm to the alt Greg of Tim&Greg 94ptca --- In WanderlodgeForum@ yahoogroups. com, "Donald Watson" wrote: > > I appreciate your posts Greg, especially since you have a pretty diversified > experience with heavy equipment. > > That being said, did you really mean, "Check the output when output wire is > disconnected from bus batteries." ?? > > Without a battery or batteries to act as a load, I believe the rectifying > diodes would burn up in an instant. Greg's suggestion of lifting the > alternator output cable on both ends , checking continuity as well as > resistance to ground is a reasonable one. I have a friend who drives over > the road with a 60 series Detroit. He goes through alternators quicker than > he should and I wonder if it is simply the quality of the rebuilds that is > questionable as Greg suggested. > > Donn > '76 FC33 > South Kingstown, RI > > From: WanderlodgeForum@ yahoogroups. com > [mailto:WanderlodgeForum@ yahoogroups. com] On Behalf Of gregory O > Sent: Tuesday, October 13, 2009 9:12 PM > To: WanderlodgeForum@ yahoogroups. com > Subject: [WanderlodgeForum] Re: Front Alternator 8V92 > > alternators require many working parts any one part that fails will not > allow it to work. when a bearing goes out it still pumps amps but the heat > can screw the windings and vr. if the prior rebuild didnt repair the bearing > or other cause for resulting failure replacing a burnt electrical component > will be short lived, like in your case. The other possibility is something > is burning out the electronics and replacing the alt will only prove that > point with a third failure. > > Check the output when output wire is disconnected from bus batteries. I > would then take the alt to a good rebuilder. > > one other test is to remove both ends of the charge wire, insulate the > battery end, then check for continuity with ground at the alt end. there > should be no continuity, if there is, 'continuous path' will show a ground > fault which will always demand amps. > > You can usually find a referral of a local parts re builder from a local > salvage yard. WHen ever I am forced to buy a Pepboys reman alt or starter I > drop it off at my favorite rebuilder in Riverside Ca. they ship > http://riversidealt ernatorstarterac .com/ > Greg of Tim&Greg > 94ptca > > --- In WanderlodgeForum@ yahoogroups. com > ups.com> , "SteveQ" wrote: > > > > I had the front alternator rebuilt in 2007 right after buying the coach, > and have about 25,000 miles +/- since then. After testing it today it is > dead again, there must be an underlying problem. Any ideas? > > > > Steve Quandt > > 1993 PT40 > > Iron Mountain, MI >