Need Alternator Help

[rtpn60]

Help... My 78FC35 has the original Motorola 8SC2007Z-R 160a alternator and external regulator. I'm replacing this ASAP with a newer setup but currently leave on a trip in the morning.

Problem - It charges at 17v !!!! I cannot seem to get that down. I changed out the regulator with a known good one. Then swapped out the alternator with a known good one.

I'm questioning the wiring. The exiter has a wire coming from inside the alternator and hooks up externally. Also on this terminal is a wire harness wire (not sure where it goes). The only other terminal is the Indicator light. The regulator plugs in at the top with 3 conductors.

Does anyone have a picture of the rear of the alternator?

Thanx,

[warbucks13477]

Michael keep the motorola alternator. Prestolite bought motorola some time ago and now produces them under the leece-Neville line. You can go to www.prestolite.com and get the information on the 8SC2007ZR alternator. Its on a 6.5" frame and you can use an internal regulated Leece-Neville alternator but you LOSE something. The external regulator was used to compensate for the large line losses due to the long distances between the batteries, chargers and alternator.

Take your alternator go a good leece-neville alternator/starter shop in Mesa and have them check it out and repair it. Its a lot less then replacing it. Take along the regulator with it that is installed just over your batteries. Its a prestolite (or should be) regulator in a small metal package. You might try
chandler Alternator and starter at 795 E. Chandler blve,chandler,Az 480-814-2864 they do both motorola and leece-neville. There are a couple in Mesa but I do not know if they do Leece-neville.

good luck

[rtpn60]

Great info Tom! I'll do that but will probably have to wait till after my trip. Might boil some batteries on this one. I verified the wiring and it seems correct. I've gone through two alternators and 3 regulators now with the same results. Some thing strange is going on for sure. Good thing this is only a 300 mile trip.

As far as the new alternator, if they can't locate the issue with hardware then I'm going to break down and get an all-in-one and just eliminate the wiring. I understand about the remote sensing, but I've got two battery banks under both front seats with the alternator between them so I should minimize that issue.

I'm thinking about putting my new ProSine 2000 in with the batteries under the passenger seat if it will fit. That would keep all the wiring as short as possible. If not then I'm going to try it under the couch which is only a few feet further. If that doesn't pan out I'll try the small inside storage near the steps, but that's about 15' away. I want to keep it secure, ventilated, and dry.

Regards,

[warbucks13477]

Michael I dont mean to be harsh but it appears that you do not understand the severity of the problem. If you are truely reading 17VDC at the battery terminals when the engine is running AND (this is important) you are not plugged into shore power or have the generator running where the chargers are also running then you have a serious problem and should not be driving on a 300 mile trip with your coach. You will not only ruin the batteries but are in danger of frying some wires that will leave you stranded somewhere. I have seen this happen before on these forums where someone has had a serious problem like this, ignored the advice and ended up with a more serious problem stranded somewhere where it cant be fixed. Get it fixed before you leave home.

[giderich]

Michael: The problem could be that one or more batteries are already bad...check with a hydrometer and or individually load test the batteries if you have time.

Under no circumstances would I start a trip with that high voltage level.

While the batteries are out for testing, clean the cables and grounds. Just my opinion, but start with the basics first. Your alternator won't last long under those conditions.

[warbucks13477]

Michael have you actually checked each one of the batteries, their specific gravity? Actually the quickest way to check each battery is to disconnect the positive cables to them and then open up the vents in each battery and then using a voltmeter check the voltage of each cell. Positive on the positive post and the negative into the first cell until it touches the plates. Should read 2VDC. You will need a piece of wire attached to your voltmeter probe so as not to screw up the probe. Then put the positive probe into the first cell until it touches the plates and the negative into the second cell until it touches those plates and you should again read 2VDC. Then move to the next cell etc. This should tell you if you have a bad cell quickly.

Another question. When you changed the alternator did you use another externally regulated alternator? If not that is why you had the problem. When you changed the voltage regulator, did you use a Prestolite 8RH2024 voltage regulator and connect it correctly. Just a couple of things to check. But again dont leave with the coach in that condition or you will be asking us again what to do but from somewhere where it is much more difficult to help you.

good luck

[rtpn60]

Tom/Dick, Thanx for your help. I took the spare Alt & regulator (that I removed previously) to Turbo & Electric... They were very helpful. A bench test showed both were in fine shape. They suggested looking for a bad battery also, or a bad ground. I can throw each battery on a load test for quick down and dirty test. If they all pass I'll start with the grounds.... Thanx for your bringing the urgency to my attention. I had so much on my plate I really didn't think this through..

BTW.. I did look at the new28SI Heavy Duty Delco Remy alternators while I was there. Lighter, smaller, open framed and puts out 200 amps with self exciter. They are asking $339 for the 200 amp and $271 for the 180 amp. I'm adding an electric drive shaft retarder with spare battery so the 180-200 amp would be ideal...

Back to trouble shooting.. Again, Thanx...

[rtpn60]

Interesting results.. but problem persists. I removed all 4 batteries (12v in parallel) and tested them. One was bad. I removed the second bank and just ran on the two 12v batteries under the driver's seat to keep it simple. I then cleaned all the connectors in the charging system as well as the batteries. Once complete I fired it up and same results.... 16.5 volts at idle.

When I tested the regulator voltage I found the ignition volts just around the alternator output voltage, but the field voltage swung back and forth from 2.5v to full 16v almost like a sign wave? It was very irratic. So for now I've disconnected the regulator and everything settled down to 13.5v. I'm thinking I may pick up that new alternator as a spare and simply run the generator when needed to charge the batteries. It's only about 5 hours to my destination to full hooks up then back Monday.

Strange deal.. so, do you think the 28SI is the way to go if I go with an internal regulated, self excited alternator?

Regards,

[warbucks13477]

Michael it appears that you have a partner in crime in the name of Bruce Morris the webmaster on the Wanderlodge.us forum. He had exactly the same idea that you have when his alternator went out and he wanted badly to attend the Rally in the Vally last year. We all advised him what to do but he decided to run the generator all the way to Ft Vally and back to Raleigh to power the chargers which would provide the 12VDC he needed. Bad idea

I remember vividly Bruce stopped somewhere between Raleigh and Ft Vally entirely down and hollering for help when his generator quit and help took a long time in coming for everyone was busy then. The generator is not your back up alternator its for power when you have no shore power and power to run your chargers when you have a true emergency when your alternator quits on the road. But remember if something happens to the generator you are up the crick without a paddle literally.

I am still confused what you have for a setup in your coach. How many batteries and what voltage? Are there cables you cannot identify connected to the batteries? You still have not told us if you substituted a remote regulator alternator for the Motorola? You said you have wires you cannot identify on the back of your alternator? Do you have a tachometer driven by them?

good luck anyway. I know from experience that rushing to get somewhere when you dont carefully plan can be a

[rtpn60]

Well.. Back from our Mexico trip. I ended up disconnecting the regulator all together and just running on battery power. Since we had no charge we ran down during the day so the only current draw was the fuel solenoid really. The voltage held steady all the way. Remember, an older 78 Wanderlodge doesn't have all the fancy current drain issues the newer ones have.

Now I'll have to return to my trouble shooting and trace some wiring so I can measure resistances on all the connections. If I cannot locate the issue I'll upgrade to the new internal regulated models. I did note that the new 28SI has a smaller diameter and will reguire a longer belt to keep it away from the bypass radiator hose coming up off the block.

But thanx for the concerns and comments... it's good to have all the facts before making those decisions.

Regards,