Voltage Regulator Failed

[danny_galaga]

  On 22/05/2025 at 5:30 AM, facthunter said:

They don't use just a simple relay. It includes windings reacting to the voltage as well as Current flow, all spring tension adjusted, and it  modulates  by opening and closing the Points . Some times a  resistor is also across the Point  to minimize the current change. A cut out was used as well to prevent reverse current on shut down. Later Diodes do the same thing. They need cooling.  Nev

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I used to be an auto electrician 😉

[Geoff_H]

Another technique is the same as inverter technology.   It uses switching using Mosfets.  If you use resistance for control a large amount of heat will be produced.  In essence the .Mosfet will switch on and when the output reaches the desired voltage the Mosfet will switch off.  It does this as often as the time for the outlet voltage to drop to a predetermined value.  On and off will be very quick at low power and very long at high voltage. Efficiency low at low power settings. 

[skippydiesel]

Hi All,

 

To assist with decision making, I urgently need need feedback on the following;

 

Seems that the easy options have narrowed to;

• B&C AVC1/XB199-2 - An external 14V shunt type VR, designed for use with single phase permanent magnet alternators up to 20A. Claimed to be a drop-in unit including wire connections. Adjustable. Appears to require the retention of the Capacitor. https://bandc.com/product/avc1-advanced-voltage-controller-14v-homebuilt/

 

• Schick GR6b-OVP 12V  is a compact AC rectifier-regulator, believed to be MOSFET, useable for Rotax-, Hirth- and Solo aircraft engines with lead and LiFePO4 batteries. It has been designed to provide a stable power supply minimizing interferences on the aircraft main electrical bus. It has a built in overvoltage monitoring device (OVP) that inhibits ignition of the thyristors if the battery voltage exceeds 15V. Adjustable. No mention of any need for a Capacitor. Will require a bracket adapter be made and changes to wiring. https://www.aeroakku.com/REGULATORS/Schicke-Regulator-GR6b-OVP-12V::1901.html?language=en

• CARMO CARR5115 MOSFET  Claimed to be more effective, generate less heat than original, leading greater reliability - suitable for lithium ion batteries 14.6V / 39A. No Capacitor required. Local supplier. Will require wiring changes & fabrication of an adapter bracket     https://www.vectriqparts.com.au/product/rotax-voltage-regulator-carr5115/

 

 

I await your responses with anticipation😈

 

[skippydiesel]

• B&C AVC1/XB199-2 - An external 14V shunt type VR, designed for use with single phase permanent magnet alternators up to 20A. Claimed to be a drop-in unit including wire connections. Adjustable. Appears to require the retention of the Capacitor. https://bandc.com/product/avc1-advanced-voltage-controller-14v-homebuilt/

The "An external 14V shunt type VR" statement is not correct.

B&C 's initial advice was to use one of their VR's with this operating system.

They changed their advice to the AVC1/XB199-2  which is a modern MOSFET system. Unlike other MOSFET systems, the need for a  Capacitor appears to remain.

The web page will give you the correct information. 

My apologies for making a misleading statement😈

[skippydiesel]

Wow! I had expected a thunder of advice/opinions - the silence is deafening.

 

Where have all the sparkie's gone? Long time off-line😈

[Geoff_H]

  On 23/05/2025 at 9:45 AM, skippydiesel said:

• B&C AVC1/XB199-2 - An external 14V shunt type VR, designed for use with single phase permanent magnet alternators up to 20A. Claimed to be a drop-in unit including wire connections. Adjustable. Appears to require the retention of the Capacitor. https://bandc.com/product/avc1-advanced-voltage-controller-14v-homebuilt/

The "An external 14V shunt type VR" statement is not correct.

B&C 's initial advice was to use one of their VR's with this operating system.

They changed their advice to the AVC1/XB199-2  which is a modern MOSFET system. Unlike other MOSFET systems, the need for a  Capacitor appears to remain.

The web page will give you the correct information. 

My apologies for making a misleading statement😈

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I expect that the Capacitor is to give the MOSFET a voltage level at which to switch off. When the Capacitor discharges into the aircraft electrical system iits voltage will start to drop, the control circuit will see this and turn the MOSFET on.  When the Capacitor reaches the voltage of the set voltage for aircraft operation the control system will turn the MOSFET off.  This cycle continues as required.

[skippydiesel]

Hi Geoff,

So why don't the other MOSFET VR's use a Capacitor?😈

[Geoff_H]

 

Not totally sure but I expect that it has to do with the on/off control circuit.  The battery is one huge Capacitor.  I expect that the others have a amperage demand circuit and use that to control.  I think that the Capacitor one uses a simpler control circuit using the Capacitor and the resistance of the cables to the battery in an RC delay circuit that would give the frequency of the on/off operation.  Why the control doesn't have an inbuilt Capacitor is don't know, but I am guessing it is to do with the size of the box 

 

[danny_galaga]

  On 23/05/2025 at 11:15 AM, Geoff_H said:

I expect that the Capacitor is to give the MOSFET a voltage level at which to switch off. When the Capacitor discharges into the aircraft electrical system iits voltage will start to drop, the control circuit will see this and turn the MOSFET on.  When the Capacitor reaches the voltage of the set voltage for aircraft operation the control system will turn the MOSFET off.  This cycle continues as required.

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The battery is already doing that. If not, the capacitor would be internal otherwise your whole system is relying on the installer dong that correctly- for instance if people are leaving them off because the Carmo doesn't need it, then B & C would be getting a bad rap. I feel either they are playing it safe by recommending you use one (if it's not needed it won't make any difference) or else maybe their design makes the same amount of noise as the Ducati 🤷‍♂️

Edited May 24 by danny_galaga

[skippydiesel]

In the absence of qualified / "sparkie"  advice have decided to purchase the CARMO CARR5115 MOSFIT.

 

I hope it will not be too difficult to fit and will last a very long time.😈

[danny_galaga]

Just for sh*ts and giggles, I'm going to temporarily install the capacitor on my set up. I have an MGL radio, which is not highly regarded around the hangar, and since it seems to be getting worse without anything else seemingly changing, I suspect it's a bit dodgy. But it can't hurt to put that capacitor in the circuit and see if the radio improves. Ill report back on the results. Could be a week or two.

[skippydiesel]

  On 25/05/2025 at 12:09 AM, danny_galaga said:

Just for sh*ts and giggles, I'm going to temporarily install the capacitor on my set up. I have an MGL radio, which is not highly regarded around the hangar, and since it seems to be getting worse without anything else seemingly changing, I suspect it's a bit dodgy. But it can't hurt to put that capacitor in the circuit and see if the radio improves. Ill report back on the results. Could be a week or two.

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I was thinking to do the same. My VR is difficult to access - leaving the Capacitor in place, just reduces the number of times I need to go there (assuming removing it would require another difficult job) 😈

[skippydiesel]

VR OUT!!!

 

Anyone know of tests that I can do on the VR to confirm in situ failure findings?????😈

Edited May 27 by skippydiesel

[Underwood]

  On 27/05/2025 at 6:45 AM, skippydiesel said:

VR OUT!!!

 

Anyone know of tests that I can do on the VR to confirm in situ failure findings?????😈

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While its unplugged check the Stator output, its an easy check

 

[danny_galaga]

If you do underwoods test, you'll know your charging system is working. If it's working, that is how you test your regulator 🙂

[Underwood]

Sorry forgot tos say, you are looking for something like at least 28 volts ac coming from the alternator at 3500rpm and resistance across the 2 yellow wires of between 0.1 - 0.8 ohms.

 (this is from memory please check these figures they are in the manuals somewhere)

Mine measured 30v ac at 3500rpm and 0.2 ohms

[skippydiesel]

IF my in situ tests were correct the alternator is working - I am hoping there may be some continuity/resistance checks that can be done on the removed VR???😈

[Blueadventures]

Alternator???  If getting specified ac volts from engine then stator is good; if rec/reg not giving specified dc volts then it’s US and replace. Specs in Rotax manuals.  Very straight forward to check with multimeter.

[skippydiesel]

 "Specs in Rotax manuals"

 

Fair enough BUT which one of the four manuals?😈

 

[danny_galaga]

  On 28/05/2025 at 1:39 AM, skippydiesel said:

 "Specs in Rotax manuals"

 

Fair enough BUT which one of the four manuals?😈

 

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You only need a ball park figure to get an idea if it's working or not. Battery at rest voltage is about 12.4V. If you see more than that when the engine is running, it's charging. It should if course be significantly more. We used to see so much variation when I was an auto electrician we drew a line at about 13.2v . Between that and about 14.4v is fine. I don't know that you'll easily test it off the plane. A dedicated workshop might have a suitable AC output to hook it up to. For you, your best source is the running engine 🙂

[Blueadventures]

  On 28/05/2025 at 5:11 AM, danny_galaga said:

You only need a ball park figure to get an idea if it's working or not. Battery at rest voltage is about 12.4V. If you see more than that when the engine is running, it's charging. It should if course be significantly more. We used to see so much variation when I was an auto electrician we drew a line at about 13.2v . Between that and about 14.4v is fine. I don't know that you'll easily test it off the plane. A dedicated workshop might have a suitable AC output to hook it up to. For you, your best source is the running engine 🙂

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That’s right, and done with engine running, with safety care.  Will do him world of good to find the specs in Rotax manuals. Maintainers must be familiar with the different Rotax manuals, their use and info.

[Underwood]

  On 27/05/2025 at 10:53 PM, skippydiesel said:

IF my in situ tests were correct the alternator is working - I am hoping there may be some continuity/resistance checks that can be done on the removed VR???😈

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What tests checks did you actually make? and what where the symptoms of you're apparent failed regulator?, It looks like you never said what lead you to this conclusion.

[skippydiesel]

  On 28/05/2025 at 6:47 AM, Underwood said:

What tests checks did you actually make? and what where the symptoms of you're apparent failed regulator?, It looks like you never said what lead you to this conclusion.

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Symptom -Voltage dropped from 14.2 to 12 V and negative amps being delivered at engine start  - no improvement during run up.

My eldest Son, Electrical Engineer, CPL and occasional helper and way way more flexible than his old man, did the checks engine off & running - diagnoses' VR has failed.

Since last post have realised I do have some the VR out of aircraft checks on the the unit; https://pointsforpilots.blogspot.com/2012/12/testing-rotax-912914-generator-and.html

😈

[skippydiesel]

  On 28/05/2025 at 5:26 AM, Blueadventures said:

That’s right, and done with engine running, with safety care.  Will do him world of good to find the specs in Rotax manuals. Maintainers must be familiar with the different Rotax manuals, their use and info.

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The whole point of a Forum like this is ASSISTANCE so that the wheel does not have to be reinvented every time a hurdle is encountered - I doubt you actually  know which Rotax Manual addresses my question.

 

Next time you seek assistance, I hope the answers are full and helpful ie not so arrogant 😈.

[BurnieM]

How much is a new rec/reg ?

 

Buying a new one and trying it would save a lot of time and 'pointsforpilots.blogspot' recommends Rotax owners carry a spare regardless.