Continuous flat battery - poor charging - Rotax 582

[Microwave]

I have recently replaced the battery on my trike as it was just not delivering the power to drive the starter motor. I assumed that it was just old age setting in. However, after some hours I smelled a rat after I realised that the new battery was also going flat. I checked the voltage of the battery with the engine off and with it on and it was clear that the battery is not being charged since the voltage is the same for both.

How does one go about testing to see if the problem is with the coils or with the regulator? The engine and coil are essentially new with approx 100 hours only. The regulator is reasonably old. Does anybody have a test to check the coils, presumably a resistance reading between the two yellow wires from the engine or and AC output? My system does not have a fuse. Does anybody have any pointers for me regarding possible reasons for the problem and possible solutions?

[RudiGreyling]

I am also interested to know, so if you find out, post here please!
Kind Regards,
Rudi

[Morph]

You can use this Rotax document which takes you through the whole testing procedure. It takes a while to download. Right Click and select FIle save as....

http://www.wcmc.co.za/Downloads/chargin ... oke101.pdf

[Microwave]

Hi Morph,

I could not get into the page at all. Are you sure the address is correct???

Sounds just what Ineed though. I will try again tomorrow.

[Duck Rogers]

You've already done this bit according to your post but I'll mention it anyway for others to see.

Multimeter on DC volts scale. Test across the battery WITHOUT the motor running. If your battery's good the reading will probably be around 12.5 - 12.7 VDC.
Start the motor and test again across the battery.About 3000 rpm should be good. Make sure all accessories are off. If the rectifier and lighting coil system is good, then the voltage will probably be around 13.5 - 13.8 VDC (I've seen them higher also) If the reading's the same, it's time to check the voltage regulator and the lighting coil.

Disconnect the thick yellow and yellow/black wires from the lighting coil that connects to the yellow input wires on the regulator. We will be testing these wires only...NOT THE WIRES FROM THE REGULATOR.

Do a continuity test between these two wires without anything else touching them. You'll probably see about 0.1 -0.3 ohms (I hope) Make sure you have a good, accurate digital multimeter. If you get the reading Ok then you'll know that there's no broken wire in the coils.

Next, take one of the yellow wires and connect to one lead of the multimeter. Take the other lead of the multimeter and touch it on the casing of the motor. There must be no continuity, the meter reading MUST be zero. You don't want the lighting coil wires to be shorted to ground. If you had continuity between the 2 yellow wires in the first test, then its not necessary to do a ground test with the other yellow/black wire as the are essentially the same wire then. Do it anyway just to keep everyone happy. Again there must be no continuity between ground and the yellow or yellow/black.

Now put the multimeter dial to AC volts 'cos the lighting coil puts out AC and not DC and connect the leads of the multimeter to the yellow and yellow/black wires.

Start the engine and let it idle at the normal speed of about 2200 rpm. You should get about anywhere from 27 - 32 volts AC reading.

Push the revs up to 4000 rpm and you should get about 50 - 55 volts AC. Revs at 6400/6500 should give you about 75 - 85 volts AC. Note these numbers are not absolutes but it will probably be reasonably close. What you're actually looking for is an increase in AC voltage as the rpm increases, but it should be more or less around these numbers.

DO NOT LET ANY OF THE WIRES SHORT TO GROUND. YOU ONLY MEASURE BETWEEN THE YELLOW AND YELLOW/BLACK WIRES FROM THE LIGHTING COIL.

If you're not getting an AC voltage output from the lighting coil or if the numbers are substantially lower, then the lighting coil/stator has to be checked out. It may have a short or partial connection to ground or high resistance etc.

If the lighting coil circuit is working, I would suspect the voltage regulator. Before you chuck it out, make sure ALL connections are clean and/or soldered and there's no rustiness of sorts on the connections. Make sure terminals are tight. If this is all OK, then chuck the voltage regulator.

Hope you come right.

Duck Rogers

[Microwave]

Thanks Duck for the comprehensive response, its much appreciated. I will go back and check now again and see what I have to chuck. I will also check to see if the grounds between the regulator and airframe and the engine airframe are sufficient as well.

[RudiGreyling]

Thanks for the link, wrt the rotax document..how do you know if you have single phase or 3phase voltage regulator?

[Duck Rogers]

..how do you know if you have single phase or 3phase voltage regulator?

The difference is not too difficult to spot.
If I remember correctly, AND THIS IS PROVIDING YOU HAVE A GENUINE ROTAX PART INSTALLED, the single phase RR (rectifier regulator) has only 2 wires coming out the output side and the 3 phase has 3 wires.
Also the single phase used to be different looking than the 3 phase. Single phase has no cooling fins (I think) and the 3 phase has a lot of them. Reason being that the 3 phase doesn't require a 1 amp load to draw current away from it, so it will get a lot hotter than the single phase.

The single phase used to have slotted "ears" on the ends where the screws (bolts) go so it is adjustable when its bolted on. The 3 phase has fixed holes for the bolts and cannot be adjusted in position. That means you gotta drill the holes exactly where you want to fit it.

It's been a long time since I dabbled with the Rotax RR and I hope the above info is still valid. Perhaps Niren wants to help me out here?

There is an exception to the above RR descriptions and that is if you have a RR from Amptronics. It doesn't look anything like the Rotax RR's. It has a large heatsink with cooling fins and there should be a large capacitor on it that is cast in some sort of epoxy. This is a 3 phase RR.

Hope this helps with your question.

Duck Rogers

[Aviation Engines]

If the battery is fully charged and the load at a minimum, it is possible that you will measure a charge rate as low as 5VDC. With the engine at 2500-3000rpm and full load (switch everything on), you should measure a minimum of 13,5VDC at the battery. Maximum 14.5 VDC.

The most common cause of low charge rates, in my experience, on the 2-stroke systems using the genuine Rotax regulator is inadequate earth/ground connections.

Far too often I've found connections on painted/coated surfaces - you have to ensure that you have a metal-to-metal earth connection and remember that Aluminium may not alwaya be an ideal conductor.

Check that you have a good earth/ground connection between the engine body, regulator body and battery negative terminal.

The primary charging circuit from the engine can be checked by measuring the resistenance between the yellow and yellow/black cables which originate from the inside the engine casing. Should read 0.3 - 0.35 ohms.

DO NOT confuse these with the ignition switch wires, they are also yellow in colour, but they originate from the electronic boxes (secondary coils).

If you check for the AC voltage from these cables with the engine running it will ready anything between 5VAC and 30VAC.

Quite often I find that operators are unaware of a fuse in the charging circuit from the regulator to the battery, check this?

Most common causes of failure of the regulators is overheating caused by inadequate earth/ground connections and/or insufficient airflow over the regulator for cooling during normal operation.

If you haven't got a clue about what I'm talking about, you shouldn't be working on your aircraft wiring without professional help!

[Duck Rogers]

If the battery is fully charged and the load at a minimum, it is possible that you will measure a charge rate as low as 5VDC.

Niren, if a lead-acid battery is fully charged it should read 12.6VDC. If you're getting as low as 5VDC then either the battery is VROT or the voltage regulator and/load is pulling it down to this voltage. Either way you've got a siriaaaz problem :D

If you haven't got a clue about what I'm talking about, you shouldn't be working on your aircraft wiring without professional help!

I agree...call The Duck :D :D