Battery isolator solenoid- legal requirement in 19 reg aircraft?

[facthunter]

It can only go there Danny IF the  electromagnetic part is supplied with more current to UP the voltage and make the electro magnetic field stronger. Thats controlled by the regulator .If you lift one brush off the slip ring, Nothing happens at all. NO current. Nev

 

 

[danny_galaga]

30 minutes ago, facthunter said:

It can only go there Danny IF the  electromagnetic part is supplied with more current to UP the voltage and make the electro magnetic field stronger. Thats controlled by the regulator .If you lift one brush off the slip ring, Nothing happens at all. NO current. Nev

 

 

Slip ring is on a rotor. Yes, if you open circuit a rotor you stop making the electrickery. That is a powered rotor commonly seen on stand alone alternators. And the regulator only has to govern the rotor voltage to regulate total output.On a lot of lighter machines, and my Rotax the rotor is a permanent magnet. The regulator has to control the output voltage. Not ideal, but on the Rotax it's 17 amps instead of say 4 amps for a rotor. Which isn't leaps and bounds different.

 

Only the stator side going open circuit is going to cause a problem. For instance, disconnecting the battery while the alternator is operating.

Edited July 3, 2023 by danny_galaga

[facthunter]

Permanent magnet stuff is another matter. .  I don't know how it can be satisfactorily done. AS the drivespeed rises the output increases. , You'd have to waste it. I'm limited there to what I've seen on  motorcycles.   Nev

[danny_galaga]

Like I say, you regulate the output instead. If it's some sort of linear regulator, it will dump excess energy as heat through diodes (not the rectifier)

Edited July 3, 2023 by danny_galaga

[facthunter]

. I know it's crude and wasteful.. Nev

[RFguy]

There is a limit of the voltage produced without load. Regulators and alternators will survive it if load is disconnected. Dont worry about that.

 

Danny have a look at a mid 70s schematic of a Piper Warrior or something, that will show the right way to do things in terms of battery and alternator disconnect.

As for standards- in GA  you will not satisfy the criteria unless there is a battery isolator. GA is driven by criteria to meet to ensure reliability and safety.  There are generally two types of criteria that would apply- there may be a specific requirement in AC43  AND there will be the catch all 'thought shallt make every possible fault remote' elsewhere.

As for 19/24, I doubt there is any requirement at all, (it would be in the ATSM) since Jabiru factory airframes have  unfised, uninterruptable hot battery wires that are not particularly thick going through the firewire through metal grommets - a fire waiting to happen- (the only problem with Jabiru airframes IMO- otherwise they are excellent)  .
RAAaus doesnt make technical specifications, it refers to them.

 

 

 

 

Edited July 3, 2023 by RFguy

[danny_galaga]

That's the conclusion we have come to. My battery is on the inside of the firewall. Cables go through a fibreglass firewall with grommets. Even if it rubbed through nothing would happen. Negative goes straight to the back of the starter. Positive to the starter solenoid which is mounted on the outside of the firewall pretty close to the starter and battery. The kit has you put the solenoid WAAAY over on the left side- quite a long cable run and more chance of a short.

[BrendAn]

On 03/07/2023 at 10:58 AM, danny_galaga said:

I only ask because an LAME apprentice was in the hanger and we were talking about it. He was pretty confident you HAVE to have on in GA, but wasn't sure about 19 rego...

my xair is 19 and does not have one. my jabiru was 55 reg and that had a master solenoid near the battery. 

[kgwilson]

The solenoid in the Jab is for the starter motor.

[BrendAn]

7 minutes ago, kgwilson said:

The solenoid in the Jab is for the starter motor.

not mine . all the power went through it.  the battery was behind the fuel tank and the solenoid was directly in front of it and 1st position of the key energised it and powered everything up. 912 not jab motor.

[RFguy]

yeah, there is variation across Jabs, especially early types.  but in general, they have hot wires through the firewall, and no alternator disconnect from the battery.  Both I am sure may lead to fires. But, in factory built LSA ' the manufacturer knows best'  and there isnt any recourse to changing anything without leaning on the airspace regulator. 

 

The manufacturer of a factory built LSA  having the last word is a feature of LSA. Someone help me understand WHY this is a feature ? 

I guess is does work for most LSA manufacturers, they respond to industry best practice more than J.  appear to me to do.  

[facthunter]

That's how LSA was designed. A quasi VH and I have never liked it. It got around the 51% RULE.  Nev

[danny_galaga]

A bit of an update. I had put a little motorcycle battery isolator in, but of course that's not easy to reach. Fine if I'm on the ground. But if I happened to need to use it in flight, I'd probably 'John Denver ' myself. 

So I picked up a panel mounted isolator from Whitworth marine. Much the same as the ones with the red plastic key, but these look tidier. Might as well have form AND function if it's available. Installed it where my USB outlet was, which I moved over. Looks tidy there and it's just about the shortest amount of extra cable at the location 🙂

[facthunter]

Good idea but how much "Live wire" is involved?  You could eliminate that by using a hollow rod (tube) to actuate something nearer the battery.  Nev

[danny_galaga]

There will be an extra 550mm cable..it's still less cable overall than the kits master solenoid idea. And WAY less than some aircraft where they've had to put the Battery rearwards for C of G purposes 🙂

[facthunter]

I'd rather a manual switch than a solenoid..  Nev

[danny_galaga]

9 minutes ago, facthunter said:

I'd rather a manual switch than a solenoid..  Nev

Agree, that's what I've just put in my panel 🙂

[danny_galaga]

1 hour ago, facthunter said:

Good idea but how much "Live wire" is involved?  You could eliminate that by using a hollow rod (tube) to actuate something nearer the battery.  Nev

I do like this sort of idea, and I think oldkorelah did something like that. It's the lightest way to go since a light aluminium tube extension to a switch close to the battery is going to be lighter than copper cable. I thought of doing something like that with my little motorcycle battery isolator. But I have to weigh getting the plane actually flying against experimenting with homemade gadgets. I've been building this too long. 

[skippydiesel]

On 03/07/2023 at 11:03 AM, Blueadventures said:

 

 

It's also like fuel systems and weather to fit a gascolator or not;  I did and always would.

 

 

I have a gascolator in my current aircraft and consider it to be inferior to a quality inline gauze filter in several ways

• heavier
• less filter gauze area - will block quicker
• it's the only contamination "protection" in the whole system ie all fuel goes through it - if it blocks you have no fuel flow
• checking for contamination/blockage requires removal of the bowl & gauze screen
• very easy to damage the gauze
• sealing is by compression of a flat rubber gasket - prone to leaking                      
• the one posative, is it will separate (to some degree) water from fuel

Quality inline gauze fuel filter eg

Hengst H102WK, H103WK  https://www.hengst.com/en/products/1155-fuel-filters

Baldwin BBF7863,  BF7850, BF7725, BF9906https://ph.baldwinfilters.com/baldwin/en/product/baldwin-in-line-fuel-filters/bf7725

• light weight
• very robust
• will not leak - subject to correct installation
• easy to view condition
• compact - can be fitted on every fuel delivery line. Main line contamination blocks filter - switch to  bypass and keep going to land safely.
• cheap - can be cleaned but better to retire to mower duty and fit a new one
• carry  spare(s)

[spacesailor]

With two ' hose spigots ' double the leakage ' .

I tried two inline filters with two taps . ( and Y joiner)

making twelve hose clips .

Now, I'm back to " gascolator " that has a fuel drain / tester .

Just double " mr filter " all the fuel going into your tank .

spacesailor

[skippydiesel]

"With two ' hose spigots ' double the leakage '"

 

I stand to be corrected - Every fuel delivery system MUST have an in & out facility ("two spigots"). This won't change whatever filtration system you prefer/use.

 

"I tried two inline filters with two taps . ( and Y joiner)making twelve hose clips  "

 

Trying hard to imagine what's happening here and failing. Need more detail.

 

"Now, I'm back to " gascolator " that has a fuel drain / tester ."

 

I too like the fuel drain feature but the rest of the design is so bad, I wonder how they can be fitted to certified aircraft.

 

"Just double " mr filter " all the fuel going into your tank ."

 

Not sure what you mean by "double". I have always filtered my fuel into the tank.

 

With my last aircraft, this meant my in line fuel filters almost never trapped contaminants (even after 100 hrs they were clean but replaced anyhow). My new home built plane is a diffrent matter - only has 68 hrs,  despite flushing tanks several times,  filtering all fuel in, I am still getting quite a bit of crap (scientific term) on the gascolator gauze. As far as I can tell it's mainly paint & sealing compound . The crap is diminishing, so I hope will drop to zero in the near future.

Edited February 18 by skippydiesel

[cscotthendry]

On 3/7/2023 at 10:48 AM, facthunter said:

You are only Isolating a battery. Why does it matter which terminal is OPEN? Nev

Rotax reccomend a capacitor between the output of the regulator and ground. An isolator on the positive terminal of the battery shouldn't be placed between these two or it negates the benefit of the capacitor.

The capacitor provides a small load to the regulator to stop it from overvoltage damage if the connection between the regulator and the rest of the system is lost, most likely from the isolator switch being turned off, or a master relay failure, while the engine is running.

[facthunter]

A peculiarity of the Rotax electrical supply.   Nev

Edited February 20 by facthunter

[danny_galaga]

1 hour ago, cscotthendry said:

Rotax reccomend a capacitor between the output of the regulator and ground. An isolator on the positive terminal of the battery shouldn't be placed between these two or it negates the benefit of the capacitor.

The capacitor provides a small load to the regulator to stop it from overvoltage damage if the connection between the regulator and the rest of the system is lost, most likely from the isolator switch being turned off, or a master relay failure, while the engine is running.

Good to know, but the one aftermarket thing I spent more on than the 'original' is the regulator. I bought a Dutch one, name eludes me right now. They've been making regulators and rectifiers to replace hard to find motorcycle parts for years. And Rotax. And of course to replace any crappy Italian electronics 😄

 

Upshot is mine doesn't need a capacitor (either better design or a capacitor built in or I don't know what) and has one less wire. It just has AC in and DC out, and a warning light. Simples ☺️

Edited February 20 by danny_galaga

[skippydiesel]

Hi Danny_G

 

 Would be great if you find that regulater name/supplier and put it on your  "Started Spare Parts List"