Manifold Pressure

[onetrack]

A damaged, sulphated battery with low voltage can damage an alternator. The alternator will run at maximum output continuously, trying to recharge the battery, which is in effect, shorting out the alternator output.

The alternator will overheat, and more than likely suffer from damaged stator windings, or suffer from damaged rectifier diodes, or suffer voltage regulator damage.

New replacement alternators often come with a warning to ensure your battery is in good condition, otherwise the alternator warranty may be voided.

[Moneybox]

There's no way of telling if the generator/alternator ever worked since I got the plane. It hasn't been used enough to tell and the generator light operates as if it's charging.

[onetrack]

Quote

I bought the battery new so about a year old but until completely flattened over several days it remained fully charged. It recharged fully after that so I'm hopeful the battery is ok. It may even improve with constant use.

I've had near-new batteries that were flattened to a very low voltage, and which showed full charge after extended charging - but they would not sustain substantial starter cranking effort - in effect, they were stuffed from being totally drained, and they showed all the signs of being sulphated.

 

However, the AGM batteries are recognised as being much more capable of handling deep discharge, than the regular flooded cell batteries. But a battery load test is the best way to tell a batterys health.

[Moneybox]

24 minutes ago, onetrack said:

I've had near-new batteries that were flattened to a very low voltage, and which showed full charge after extended charging - but they would not sustain substantial starter cranking effort - in effect, they were stuffed from being totally drained, and they showed all the signs of being sulphated.

 

However, the AGM batteries are recognised as being much more capable of handling deep discharge, than the regular flooded cell batteries. But a battery load test is the best way to tell a batterys health.

I can carry out a load test once charged however that is not going to fix the alternator/charging problem. I have no doubt the battery may have lost some of its ability to supply a full discharge however it did fully charge after it was flattened.

 

After I'd left the master on and found the battery flat it was fully charged. I left it at the door of Northam Air Services with a note requesting to have it charged. I picked it up a month or so later and it cranked the engine as if fully charged, not the sign of a stuffed battery.

Edited 18 hours ago by Moneybox

[skippydiesel]

I assume your aircraft is fitted with the usual Rotax (Ducati) VR - if so it may be worth checking it out.

 

The Rotax Owners Forum is full of discussion on this topic however you may find the following helpful;

 

https://pointsforpilots.blogspot.com/2012/12/testing-rotax-912914-generator-and.html

 

😈

[Moneybox]

2 hours ago, skippydiesel said:

I assume your aircraft is fitted with the usual Rotax (Ducati) VR - if so it may be worth checking it out.

 

The Rotax Owners Forum is full of discussion on this topic however you may find the following helpful;

 

https://pointsforpilots.blogspot.com/2012/12/testing-rotax-912914-generator-and.html

 

😈

 

2 hours ago, skippydiesel said:

I assume your aircraft is fitted with the usual Rotax (Ducati) VR - if so it may be worth checking it out.

 

The Rotax Owners Forum is full of discussion on this topic however you may find the following helpful;

 

https://pointsforpilots.blogspot.com/2012/12/testing-rotax-912914-generator-and.html

 

😈

Great article Skippy. That capacitor looks like a must-fit item because the rectifier certainly has a short life expectancy. Blueadventures suggested I might keep a spare rectifier so I'll order one right away and after a few checks most likely fit the new one anyway. If I'm to keep a spare it can be a used one if it still operates. If I had a 19 rego I'd be fitting one of the aftermarket options, preferably something not made in Europe.

[Moneybox]

Ok guys, your attempt to assist has been helpful although you caused me way too much stress for a Sunday morning.

 

I followed the instructions, resistance in the stator was fine at 0.1 ohms and the wiring and terminals look good. The battery charged up nicely, I forgot to give it a load test before installing it but I'm not concerned about the condition of the battery.

 

All went well until I couldn't get any AC voltage from the alternator. I even tried willing it to work because I really don't want to start digging into the back of the Rotax. Eventually I worked out I had to press a Select switch on the multimeter to change from DC to AC and my blood pressure dropped about the same as the voltage came up. I got 19v at a high idle and 22v at 3000rpm so now I'm happy. 🙃

 

Now I just need to buy a regulator/rectifier and a capacitor. It looks like the Rotax rectifier is going to come in at something over $300 plus the capacitor and is known to be unreliable. Then I have to option of fitting one of a Japanese machine, most likely made in China but likely to last a lifetime for $50. What a tough decision?

[Blueadventures]

31 minutes ago, Moneybox said:

Ok guys, your attempt to assist has been helpful although you caused me way too much stress for a Sunday morning.

 

I followed the instructions, resistance in the stator was fine at 0.1 ohms and the wiring and terminals look good. The battery charged up nicely, I forgot to give it a load test before installing it but I'm not concerned about the condition of the battery.

 

All went well until I couldn't get any AC voltage from the alternator. I even tried willing it to work because I really don't want to start digging into the back of the Rotax. Eventually I worked out I had to press a Select switch on the multimeter to change from DC to AC and my blood pressure dropped about the same as the voltage came up. I got 19v at a high idle and 22v at 3000rpm so now I'm happy. 🙃

 

Now I just need to buy a regulator/rectifier and a capacitor. It looks like the Rotax rectifier is going to come in at something over $300 plus the capacitor and is known to be unreliable. Then I have to option of fitting one of a Japanese machine, most likely made in China but likely to last a lifetime for $50. What a tough decision?

Good news, just buy the Rotax one (it'll be plug and play, ensure earthing connection is good, I fit dedicated negative from reg / reg to battery, don't rely on air frame)  Yep the Rotax ones can be a bit sus but you want to be flying now; so sort an alternate one later if you want.

[Moneybox]

Now you can call me a tight-arse if you like but the Italian part is certainly not reliable.

 

 

Lets see what the Chinese can do. It should mount on the same screws and directly plug into the harness.

 

Edited 34 minutes ago by Moneybox

[Blueadventures]

27 minutes ago, Moneybox said:

Now you can call me a tight-arse if you like but the Italian part is certainly not reliable.

 

 

Lets see what the Chinese can do. It should mount on the same screws and directly plug into the harness.

 

Did you sort an answer to this question so you get a suitable one?  (Compatible Vehicles: Different motorcycles have different magneto output voltage, power, and other parameters. When ordering, you will need to select a voltage stabilizer that matches your model.)  Let us know how you get on.