External Alternator Over Voltage
in 912 / 914 Technical Questions
7 years ago
Hi All,
Just wanted some advice about my external alternator setup on a new Rotax 914 build please.
I have the Rotax 40A external alternator in addition to the standard 18A internal generator in my 914 system. Both are controlled via relays connected to the main bus through a 3 way switch so both cannot be on at the same time. Plan was to start the engine on battery to minimise starter load, then once running, engage the alternator and leave the internal generator as a backup.
System was working perfectly for the first few hours and the alternator was charging the battery well. then I noticed at high operational revs, that the over voltage warning light on the alternator would coming on and the CHT and oil pressure sensors would stop working (presumably because of the over voltage). Now the over voltage light is on all the time, anytime I switch the alternator on, even at low revs. However, If I switch over to the internal generator at any time, then everything is fine again, the sensors all work again, and the battery begins to charge as normal.
I presume that if the 18A internal generator is working at charging the battery, then the Ducati regulator must be ok, and that the problem must be at the alternator. Is this correct? Maybe the alternator's internal regulator has blown or it is something to do with the capacitor or wiring? If it worked before why would it suddenly fail? How do I confirm this and fix it? Does the capacitor help to regulate the voltage from the alternator, or is it just to filter noise from the alternator?
Many thanks in advance for your replies
Amer
Just wanted some advice about my external alternator setup on a new Rotax 914 build please.
I have the Rotax 40A external alternator in addition to the standard 18A internal generator in my 914 system. Both are controlled via relays connected to the main bus through a 3 way switch so both cannot be on at the same time. Plan was to start the engine on battery to minimise starter load, then once running, engage the alternator and leave the internal generator as a backup.
System was working perfectly for the first few hours and the alternator was charging the battery well. then I noticed at high operational revs, that the over voltage warning light on the alternator would coming on and the CHT and oil pressure sensors would stop working (presumably because of the over voltage). Now the over voltage light is on all the time, anytime I switch the alternator on, even at low revs. However, If I switch over to the internal generator at any time, then everything is fine again, the sensors all work again, and the battery begins to charge as normal.
I presume that if the 18A internal generator is working at charging the battery, then the Ducati regulator must be ok, and that the problem must be at the alternator. Is this correct? Maybe the alternator's internal regulator has blown or it is something to do with the capacitor or wiring? If it worked before why would it suddenly fail? How do I confirm this and fix it? Does the capacitor help to regulate the voltage from the alternator, or is it just to filter noise from the alternator?
Many thanks in advance for your replies
Amer
