Before I get ripped off...subject is Busch alternator output

Gentlemen,

My '78 "B" with electric fuel pump got a new battery and a Bosch alternator but I don't seem to be getting enough voltage out of the Bosch (12.1V at best). The battery reads 12.0V. The does not seem to be any drain when all swithces are off and the key is in the "off" position.

The effect is many unexpected sudden stops along the side of the road when the motor shuts off... Trying to restart on the battery is out....the best I get is a weak effort by the starter to crank.

I thought it was related to the electric fans, cowl fan, or headlights but they are not the source of the low alternator output.

My local "B" repair guru, told me $550 and he'd change out the alternator and brackets....seems about 2X too much, and since the Bosch conversion went beautifully, I think he's just taking the "easy" way. I've put the work on hold and come to the fountain of knowledge for advice.

When I pulled the Lucus alternator there were three wires and the Bosch had four pins on the $23 connector, but the conversion document that I worked with indicated I only needed two of the wires so I carfully tied off one of the "B" wiries (it has 12V on it whether the car is running or not) and two brown wires on the alternator plug.

Which Bosch alternator did you use? Voltage output should be 13.5 volts. What wires did you connect to the alternator? How are the terminals marked on the alternator? Can you post a picture of the connections to the alternator?

A healthy battery , especially a new one should show at least around 12.5 to 12.7. on its own when fully charged, When engine started the input to the battery from the altrnator should be as kimberly stated 13.5 to 14 something .First i would charge up the battery and check its satus with a volt metre, you might have a defective battery even though its new , a bad cell , it happened to me. then check voltage from alternator at the battery again after you start it again with the volt metre. should be as above , Also apon installation of the new alternator , or the battery if not being carefull you might have blown the diode in the alternator by a short circut. Just hooking up the battery and grounding the wrench to the cars body can blow the diode

Kimberly, the alternator is a CS130 and the documentation with it indicates that the output should be 14.5V.

Ron, the diode that you refer to...if it were blown, would the alternator have any output? When I measured the output it was 12.1V. The was a spark when a wire touched the body of the alternator during final installation...had everything wired up inclusing the battery and then took the battery lead off the alternator when it touch the alternator housing.

I'll be able to get pics but don't have them now.

Thanks

Seth

Seth, If you checked at the battery and only were getting 12.1 , first the battery is not up where I said it should be, yes it sure sounds like the diode is fried, just take it to an alternor shop , and they will be able to fix it, but make sure you do not have the battery hooked up when you re-install the alterntor again.

Ps the battery must be re-charched again up to where at least 12.5 or better is showing. you need to have a fully charged battey when the alterntor is re-installed

Regards

Ron

Your quote isn't clear to me.

(When I pulled the Lucus alternator there were three wires and the Bosch had four pins on the $23 connector, but the conversion document that I worked with indicated I only needed two of the wires so I carfully tied off one of the "B" wiries (it has 12V on it whether the car is running or not) and two brown wires on the alternator plug.)

Tell us which wires you have on the new alternator battery post. Describe them by color and location. From your quote it's isn't clear which wires were tied off. Which wire did you connect to the brown/yellow ignition wire? Tell us which wires are not connected to anything and tied off.

Yes, get the battery charged but don't drive the car until you have the alternator working. When you say the alternator is putting out only 12.1 volts, I think you are reading battery voltage and the alternator isn't charging.

Clifton

All,

Thank you for the input....I travel a lot so my time with the "B" is sporatic. I won't be near the car again unitl next weekend. I'll get the wiring info then and rejoin the discussion.

Thank you all.

Seth

What kind of output does that Alternator provide..in amps? That's a lot of dang money. I switched from the OEM alternator on my 69 to the Ford Fiesta conversion which works great and is practically a bolt-in. Doubled my Amps from 20 something to 50 amps. Just had to buy an inch longer belt and file a bit on the front mounting ear on the alternator so it fit straight and I am no great mechanic. I bought two of the Fiestal alts for just over $100. Don't know what your OEM alternator was putting out, though on your year car.

Why did you put the Bosch alternator in?

You could just have a dead battery, had you thought about that?

Even if you buy an 8 year battery, they still only last about 3-4 years.

I don't know if anyone covered this before me, but make sure that the battery is disconnected when you install the alternator again.

I'm not sure what the diode being burned out would register as far as voltage is concerned. I don't know if it reads low or nothing.

Did you test the alternator at idle???? You should test it at least at 2000 rpms for an accurate output. If you have a bunk battery and are testing a good alternator at 800 rpms you could very easily get a reading of 12V instead of 14.5V

Brian