Jabiru 12 Pole Alternator modification / upgrade

[Bluboyz]

Jabiru Au - has a modification procedure for their 12 pole alternator upgrading it's useful rpm charging range, and they have released an Engineering Report to this effect.

 

Basically this involves changing the present stator winding's terminations from a parallel connection to a series configuration, and this should produce 12 volts @ 900 rpm instead of 12 volts @ 1800 rpm, and may assist with battery charging during low rpm operations although limited.

 

www.jabiru.net.au/images/AVDALSR087-2_12_Pole_Alternator_Mod.pdf or can be found under:- Manuals, Maintenance Persons Information.

 

Happy Landings

 

 

[frank marriott]

One done locally, and works as listed.

 

 

[Bruce Tuncks]

I wish my regulator was charging closer to 12 volts than it does. With a digital meter connected directly to the battery, the voltage reads 14.49 volts as soon as the charge used for starting is replaced, and this is usually even before takeoff.

 

Now the advice about charging voltages is that 14.2 is a sensible maximum , and 13.8 is better for long flights if you want to maximise the life of the battery.

 

Does anyone know if it is possible to adjust the output voltage of the Jabiru regulator?

 

regards, Bruce

 

 

[geoffreywh]

not adjustable Chinese unit (in the unkindest way) Check with City Auto Electrics in Melbourne, ( Motorcycle electric specialists, Real experts!)

 

 

[Bruce Tuncks]

not adjustable Chinese unit (in the unkindest way) Check with City Auto Electrics in Melbourne, ( Motorcycle electric specialists, Real experts!)

Hi Geoff, I happen to be in Melbourne this week, do those guys know about Jabiru regulators or are they just good at motorbike electrics? Or is there a better regulator from a motorbike ?

regards, Bruce

 

 

[geoffreywh]

no, they are experts in regs. generally. They will know what to use, I believe they had their own made. I never had a failure from any of their bits in 20 years.

 

 

[Old Koreelah]

I want to do this modification on my alternator because long warm-ups often leave me with a bat flattery. I'd like to do it without removing the engine- perhaps I can move it far enough forward for the alternator spider to clear the firewall and engine mounts.

 

Has anyone actually done this job themselves? How much clearance do I need?

 

 

[Bruce Tuncks]

How different 2 engines can be... I still have the original unmodified regulator. It charges the battery quite well at the 1000 rpm idle though.

 

What I do these days is to disconnect the battery from the alternator as soon as the energy taken by the start is replaced. For the rest of the flight, there are a few big capacitors which the alternator thinks is a battery. So the radio works from this.

 

Usually, the battery is disconnected before the plane begins to move. I have a digital voltmeter and switch out at 14.4 volts.

 

The only problem is that my plane is now a bit non-standard. But it has gone for years like this.

 

 

[Bruce Tuncks]

The reason why I disconnect the alternator is because my starting battery is a LiFe type from Hobbyking and it doesn't like being overcharged.It starts the engine just fine and weighs 1 kg. I have had it for 2 years now.

 

There are LiFe batteries out there which come with the charging electronics built in and would be good for non-technical people.

 

I hereby bet a glass of red that in 5 years time lead acid batteries will be considered obsolete in cars and planes.

 

 

[Old Koreelah]

The reason why I disconnect the alternator is because my starting battery is a LiFe type from Hobbyking and it doesn't like being overcharged.It starts the engine just fine and weighs 1 kg. I have had it for 2 years now. There are LiFe batteries out there which come with the charging electronics built in and would be good for non-technical people.

I hereby bet a glass of red that in 5 years time lead acid batteries will be considered obsolete in cars and planes.

Bruce the time is approaching when I may need to fit a new battery. Can you tell us about your setup?

(I'm one of those non-technical people. I did all the wiring for my plane; it works, but that doesn't mean I understand why.)

 

 

[Bruce Tuncks]

The battery is a 13.2 volt 30C , 8.4 amp-hours. Weight 950 gms I think. LiFePO4 which is not flammable. From hobbyking for about 100 dollars.

 

It is rated to have 8.4 times 30 or 269 amps for cranking. All I know is that it belts the motor over better than the Odyssey did.

 

I put the battery in a plywood box so that it would fit where the old battery did, and painted the box grey to make it look more technical.

 

Now the downside of these batteries is that they cannot be discharged too much and they can't be overcharged at all. They have no vents and if they are mistreated they puff up.

 

The Jabiru voltage regulator will overcharge these batteries. It produces about 14.9 volts and the LiFe batteries can't take more than 14.4, although a bit over for a short time doesn't seem to hurt them.

 

So I got a digital voltmeter ( about 10 dollars) and a few big capacitors.

 

The battery is just connected where the old one was. No change to the rest of the plane wiring except that the capacitors were put between the positive and negative bars in the instrument panel and the digital voltmeter on the same bars.

 

In operation, the engine is started as usual EXCEPT that when the voltmeter shows 14.4 volts ( usually before taxying is even started) then the master switch is turned off. This isolates the battery so it is no more likely to start a fire than when it is sitting in the hangar.

 

The alternator now thinks the big capacitors are the battery and the radio works just fine from this.

 

I am well aware that I have made the system non-standard and this is a bit of a worry. It would be quite possible to automate the disconnection of the battery from the voltage regulator. My daughter in law is likely to be flying the plane soon and I would like to make it standard for her. But in the meantime it all works just fine.

 

 

[Bruce Tuncks]

Heres a picture of the battery

 

 

 

[Bruce Tuncks]

here's the box , halfway out from its mounting spot

 

 

 

[Old Koreelah]

Thanks Bruce. I'll show this to my electronically-qualified mate.

 

You mention that your battery gets charged to 14.4 before taxiing. You must have done the Jab alternator job.

 

Mine battery doesn't charge during warmup, so I've learned that I usually only get one shot at starting.

 

Yesterday I tried to remove the spider to do the mod., but it's not easy. Those tiny little 8mm nuts on the front end of the four 1/4" mounting bolts are almost impossible to get at.

 

 

[frank marriott]

Thanks Bruce. I'll show this to my electronically-qualified mate.You mention that your battery gets charged to 14.4 before taxiing. You must have done the Jab alternator job.

 

Mine battery doesn't charge during warmup, so I've learned that I usually only get one shot at starting.

 

Yesterday I tried to remove the spider to do the mod., but it's not easy. Those tiny little 8mm nuts on the front end of the four 1/4" mounting bolts are almost impossible to get at.

Try 5/16" ring spanner on the nuts and a socket on the other end, makes it quick and easy.

 

 

[rhtrudder]

Heres a picture of the battery

How would one of these batteries go with the charging set up on the rotax 914, mine is close to needing replacement

 

 

[Old Koreelah]

Try 5/16" ring spanner on the nuts and a socket on the other end, makes it quick and easy.

That's what I'm using, Bruce. There's precious little room to get at the nuts behind No.4 cylinder- I've removed them before (to fit the cold start kit) and had lots of fun. Now it's worse- there's also an air duct in the way (part of my improved cooling system). Tomorrow I'll cut down an 8mm socket and adapt an extension to fit. Little fingers would help!

 

 

[Old Koreelah]

The battery is a 13.2 volt 30C , 8.4 amp-hours. Weight 950 gms I think. LiFePO4 which is not flammable. From hobbyking for about 100 dollars.It is rated to have 8.4 times 30 or 269 amps for cranking. All I know is that it belts the motor over better than the Odyssey did.

I put the battery in a plywood box so that it would fit where the old battery did, and painted the box grey to make it look more technical.

 

Now the downside of these batteries is that they cannot be discharged too much and they can't be overcharged at all. They have no vents and if they are mistreated they puff up.

 

The Jabiru voltage regulator will overcharge these batteries. It produces about 14.9 volts and the LiFe batteries can't take more than 14.4, although a bit over for a short time doesn't seem to hurt them.

 

So I got a digital voltmeter ( about 10 dollars) and a few big capacitors.

 

The battery is just connected where the old one was. No change to the rest of the plane wiring except that the capacitors were put between the positive and negative bars in the instrument panel and the digital voltmeter on the same bars.

 

In operation, the engine is started as usual EXCEPT that when the voltmeter shows 14.4 volts ( usually before taxying is even started) then the master switch is turned off. This isolates the battery so it is no more likely to start a fire than when it is sitting in the hangar.

 

The alternator now thinks the big capacitors are the battery and the radio works just fine from this.

 

I am well aware that I have made the system non-standard and this is a bit of a worry. It would be quite possible to automate the disconnection of the battery from the voltage regulator. My daughter in law is likely to be flying the plane soon and I would like to make it standard for her. But in the meantime it all works just fine.

Very interesting, Bruce. I've been researching and found your battery on the Hobby King site.

 

ZIPPY Flightmax 8400mAh 4S2P 30C LiFePo4 Pack.

 

Some reviewers were really happy with earlier ones, but a couple of newer ones had "poof"ed (whatever that means). They are now out of stock.

 

Another source wasn't convinced that your battery is the ridgy didge LiFePO4, and said that 3.2v cells are the very safe LiFePO4. He said 3.7v cells are LiCobalt, and 4.2v cells are Li Manganese oxide- both of which are known for thermal runaway. He can provide a four-pack of cells that should produce well over 300cranking amps and weigh 2.6 kg. Trouble is the pack is fully charged at 13.8v, so I need to reduce the Jab's alternator output to avoid overcharging. A programmable regulator might cost me my gold teeth, so I need a more inexpensive solution.

 

 

[Bruce Tuncks]

I know of two of those LiFe packs which were poofed. One was mine when I left the master on and it was dead flat a week later and could not be revived.

 

Another was charged on a Li-PO charger ( 3.7 volts per cell not 3.2) and it puffed up.

 

The one I have now is 2 years old and going fine.

 

Yes there are lots of new things coming out at expensive prices. There are some that use " lead acid equivalent" to make them seem worth the money. I dont know what that means but they sure were expensive.

 

But I say again, in 5 years we will regard lead-acid as ancient stuff.

 

 

[Old Koreelah]

not adjustable Chinese unit (in the unkindest way) Check with City Auto Electrics in Melbourne, ( Motorcycle electric specialists, Real experts!)

I just spoke to someone there, and he didn't think a lead battery would be harmed by 14.49v. He doesn't have a regulator that is adjustable.

 

 

[geoffreywh]

AGM batteries have the best energy density, generally available, some sort of development of lead/acid........... A??? Glass Mat

 

 

[Bruce Tuncks]

I agree Old K. The cost of a special regulator was more than I wanted to pay so thats why the battery is manually switched off. The battery could actually be removed from the plane then as it is only used to start the engine

 

As for impossible nuts and bolts, I reckon dealing with them is the big difference between the likes of us and professional mechanics.

 

There was a leaking hose connection under the cab of this Deutz tractor which I could hardly reach with my fingers let alone a spanner. Well the local repair place fixed it without removing the cab and I reckon they must have used black magic.

 

 

[Bruce Tuncks]

The time on charge matters. For a lead-acid on permanent charge, 14.2 volts is the max, but for a plane where it is only on charge when flying, 14.5 volts would be ok.

 

With lithium types, there is a trade-off between life and storage capacity. Longer life results from a lower charge voltage. I don't know the figures on this though.

 

 

[Old Koreelah]

I agree Old K. The cost of a special regulator was more than I wanted to pay so thats why the battery is manually switched off. The battery could actually be removed from the plane then as it is only used to start the engineAs for impossible nuts and bolts, I reckon dealing with them is the big difference between the likes of us and professional mechanics.

There was a leaking hose connection under the cab of this Deutz tractor which I could hardly reach with my fingers let alone a spanner. Well the local repair place fixed it without removing the cab and I reckon they must have used black magic.

They struggle like the rest of us. To make matters worse, my mechanic mates complain that wear and tear just makes their fingers bigger!

 

 

[Bruce Tuncks]

I read about lower charge voltage giving longer life on an electric bike forum and it made sense.

 

Buyers like to see high capacity numbers and the higher the charge voltage then the higher the capacity would be. If, say, ten percent less charge voltage led to double the life, we would not necessarily be told.