Since helping Jabiru customers with TBI and LCH, we have become aware of the standard permanent magnet Jabiru alternator not supplying sufficient current, resulting in battery charge diminishing over time. This is especially prevalent in cockpits with extra electronic instruments (see Figure 1). Additionally a permanent magnet alternator can only rectify the flux created from rotational motion, not regulate it. Put simply, charging ability is limited to engine RPM.
As noted in the Jabiru Pilot’s Operating Handbook – Section 3.10.
3.10 Power Generation System Limitations
When the engine is turning at approximately 2000 RPM and above the alternator produces sufficient power for all lights to be run continuously. However, below this RPM the alternator cannot produce this power output and power must be drawn from the battery if all electrical systems are running. To reduce the load on the alternator, Jabiru Aircraft recommend only using the Landing Light for takeoff and landing – turning it off during normal cruise operations and wherever safe while taxiing.
This limitation is eliminated with Rotec Aerosport’s ‘Jabiru Alternator Upgrade Kit’.
The most cost effective solution is to replace the standard Jabiru charging system with a fully regulated alternator. This new charging system has the ability to supply 45 amps for the full range of engine RPM. The upgrade is simple with the original coil bracket and magnet fixture being replaced with a new alternator bracket and pulley. The alternator is then mounted, plugged in, and the installation is complete.
- 45 Amps of current at full engine RPM range.
- Run more electronics without the concern.
- Simple ‘bolt on’ upgrade.
- Standard alternator bracket (includes accessory pad).
Jabiru Alternator Upgrade Contents
- 1 x 45 Amp alternator
- 1 x CNC machined drive pulley
- 1 x CNC machined mounting plate*
- 1 x Fan belt
- 1 x Set of required mounting nuts and bolts
- 1 x Set of basic installation and wiring instructions
*For Jabiru 3300 engines only. Jabiru 2200 and 5100 engine brackets may be developed in the future.
Jabiru Alternator Upgrade FAQ
The Alternator Upgrade Kit adds approximately 5 lb (2.2kg) to your total engine weight.
The Alternator Upgrade adds no length to the engine. It meets to the same approximate engine length when the standard Bing Carburetor is mounted to the Jabiru engine.
The alternator drive belt is to be inspected every 100 hours. Check for for any damage or significant cracks and degradation. The alternator drive belt will be more susceptible to failure with improper installation.
Common installation mistakes found with the alternator drive belt:
- Belt tension being too low.
- Improperly tightening the alternator to the alternator mount plate.
In the most unlikely event of alternator drive belt failure (or even an alternator failure), the engine would continue running using the battery power for approximately 45 minutes. The engine could continue to run for as long as fuel is available, as the magneto will generate spark. This should allow enough time for an emergency landing by the pilot.
The alternator is designed to do several hundred thousand kilometers (or miles) in an automobile before servicing is required. The average aircraft engine flies nowhere near the equivalent hours in automobile. Therefor regular inspection intervals of the alternator are not required.
Contrary to conventional wisdom, the alternator is not a critical component for engine operation. A failure would be undesirable and inconveniencing, although not detrimental. The engine would continue to run on the magneto (and electronic ignition if installed) for as long as there is fuel available, if the alternator belt or alternator were to fail during operation. Very little power is required to run the ignition system. The magneto is self sustaining, generating power using rotational energy created by the engine. Instruments relying on power would continue to run off of the battery until it runs out of charge. A charged battery is required to power the starter motor to generate enough RPM to start the engine. There will be far more provision for starting the engine when using the Jabiru Electronic Ignition Upgrade.
Contact Rotec for replacement parts.
While it is possible to read engine RPM from the Upgraded Alternator, it is not recommended due to the potential for the alternator drive belt to slip.
Instead it would be ideal if the Jabiru E-ignition Upgrade Kit were used, as it offers a tachometer pulse wire directly from the ignition module wiring. As viewed on the basic wiring diagram, wire 7 is the tachometer pulse output.
Alternatives (untested by Rotec, contact Jabiru for more information):
- Some Jabiru engines use a proximity switch that count the starter motor ring gear teeth.
- The “P” lead off the stock Jabiru magneto coils can be used as a tachometer source. The tachometer gauge used may need to be calibrated.
The accessory holes on the alternator mount plate are in exactly the same position as the standard Jabiru mount plate. This means any engine accessories that fit a standard Jabiru engine will fit and engine with a Jabiru Alternator Upgrade without modification.
For any other questions please refer to the support page.
|Rotec Aerosport Jabiru Electric Upgrade Kits Installation Guide||Learn what is needed and how to perform the upgrade of both the charging & ignition system on your Jabiru Engine.|
|Wiring diagram of Jabiru charging & ignition system||Wiring diagram of the Jabiru charging & ignition system.|