Forums » Ask a Question

Use this forum to post your questions to our experts – you need to be logged on to do it (you can register here ), then scroll down to the bottom of this page and click the blue Post Thread words

If you can help answer the question, feel free to post a reply – you need to be logged on to do it (you can register here ), then hit the reply button on the thread.

 

To go back to the experts page click here>>

AuthorMessage
pdscaz
pdscaz

Posted: Thu Apr 12, 2012 7:14pm

Post Subject: alternator problem

i replaced the lucas alternator onmy perkins engined narrowboat with a higher output magnaelli one but when i turn the ig nition switch to stop the engine the engine fades the alternator light comes on and the engine comes back to life i have put a relay in the circuit powering the alternator from the leisure battery the relay powered from the ignition switch this works but iwonder whats the corect way of solving this problem ?

Tony-B
Tony-B

Posted: Thu Apr 12, 2012 7:40pm

Post Subject: alternator problem

Simply changing an alternator should not produce these symptoms. Also alternators are NOT powered - they produce the power. They are usually be exited from an external source but unless there are two alternators in use I can not see why you need the relay. This is so muddled that I think that you may have made some wrong connections but I will not be able to tell unless I can see the wiring diagrams for the old alternator (including terminal identification), the new one and how the relay is wired. I also need to know if the stop is a power to run or power to stop solenoid. It sounds rather like the latter and you have Managed to connect it to the alternator W terminal so as soon as the alternator output falls the solenoid resets to the run position. If you do not know which you have then describe exactly what you do to stop the engine. Send the diagrams and explanation plus what you think the relay is doing to Tony@TB-Training.co.uk.

pdscaz
pdscaz

Posted: Mon Apr 16, 2012 9:33pm

Post Subject: alternator problem

thank you for your reply the engine stop is power run.if I replace the with the older alternator fine my problem is when the ignition is switch off the charge light glows for a few seconds on the lucas alternator this is not very bright and is no problem on the magnarelli higher output alternator the charge light glow is brighter the current back tracks to the engine stop and the engine revives i put the relay in so when the engine is put to stop the relay brakes the circuit to the alternator and the engine stops taking to another boater with the same engine he fitted a cooling fan this again would feed back to the engine stop he resorted to a manual engine stop my system works but what do grown ups do ?

Tony-B
Tony-B

Posted: Tue Apr 17, 2012 6:05pm

Post Subject: alternator problem

From what you say I must assume that you have a power to run stop solenoid rather than the more usual (for boat engines) power to stop. I still think there is a connection problem. The warning lamp will glow for a short time as you turn the "ignition" switch off because the still spinning and energised alternator will back-feed from the three auxiliary diodes on the rotor (field) circuit. Normally the charge warning lamp bulb glows but limits this current to a value that is insufficient to energise the stop solenoid. So I must now ask what wattage is the warning lamp bulb and if you have any resistors in parallel with it. If the wattage is any more than about 2.2 watts (nowadays I would expect 1.5 watts or less) then change the bulb for a lower wattage one. If that is not possible rewire the stop solenoid so it has its own push to open operating switch. This can still be fed from the ignition switch and really only involves cutting the cable and inserting the switch. Tony Brooks

Most Read

Newsletter Sign Up

Canal Boat monthly newsletter
Sign up to receive our regular email newsletter

Our Privacy Policy

Like us on Facebook



Follow us on Twitter

Cache: Disabled for this object  Total Queries: 43.  Total Objects: 162.  Total Unserialized: 3. Total Runtime: 0.53 seconds.