Rotax Battery/Electrical Help

Chuck Groat · Joined: 04 Apr 2002 Posts: 60 Location: Salt Lake City, UT

I'm at a loss on what to try next. I have two batteries, both relatively new with one battery only having 1 race, but can only get 1 or 2 starts out of each (10-15 laps in each session). The batteries are charged approx 5 hours past the green light & always charged after use. I did a connectivity & resistance test on all the lines and nothing appears to be broke, replaced the starter thinking there was a large amp draw, purchased a new charger, but batteries still fail to start the kart more than twice. The batteries have just over 13 volts after a full charge and fail to start the kart when voltage drops to 12.5 volts. Has anyone else had these types of problems with the batteries, could it be something else within the electrical system, or is this a case of two new batteries already gone bad???

George Grenier · Joined: 23 Jul 2001 Posts: 105

Try replacing the starter switch (button). To test just touch the two wires together and see if it will start. If it does, you found the problem.
Good luck.
George

Stephen Buckley · Joined: 18 Jul 2001 Posts: 861

Does anyone have access to the actual wiring harness schematic?

George Jounakos · Posted: Thu Jul 25, 2002 7:20 am Post subject: Rotax Battery/Electrical Help

Chuck, do you discharge your battery before charging it? If you do, STOP! Lead acid batteries do not like to be discharged. It is best to keep the battery charged by connecting it to the charger when you come off the track.

Chuck Groat · Joined: 04 Apr 2002 Posts: 60 Location: Salt Lake City, UT

George, I'm not sure I'm understanding your question about discharging the battery. During a race I will hook up to the generator between heats, but still had the same problem. During a practice night, I started the kart once, ran 12-15 laps, came in made some changes to the kart went to start and it would not turn over the motor.

George Jounakos · Posted: Thu Jul 25, 2002 8:45 am Post subject: Rotax Battery/Electrical Help

Sounds like your doing the right thing. What I meant was that some people have been misinformed about the proper care for these batteries. Someone in the past made a post stating that the batteries had a 'memory' and that charging it without fully discharging it would shorten its life. This is not true. These batteries are happiest when kept fully charged, even if it means connecting to the charger after every run. If you can measure the battery voltage (at the battery) when pressing the start button, it will tell you if the battery is dead or the wiring is bad. You said 'fail to start the kart when voltage drops to 12.5 volts', does this mean doesn't crank or doesn't fire?

Chuck Groat · Joined: 04 Apr 2002 Posts: 60 Location: Salt Lake City, UT

The battery without attempting to start has 12.5 volts. Voltage while attempting to start drops to approx 9.

Chuck Groat · Joined: 04 Apr 2002 Posts: 60 Location: Salt Lake City, UT

Forgot to add - the motor doesn't crank. The starter will spin, but I guess it doesn't have enough power to engage the gear to turn it over.

George Jounakos · Posted: Thu Jul 25, 2002 9:53 am Post subject: Rotax Battery/Electrical Help

That confirms that the battery is the problem. But why?!?! The said something about hooking up to the generator between heats. Do you mean that your charger is plugged into an AC generator and you are not using a standard AC outlet? If this is the case, it may be the problem. When the battery works fine for the 1 or 2 starts, was it charged from a wall outlet? Please let me know. I am currently running some tests on the Rotax charger and battery.(I'm an engineer) The more info I get the better.

Mike Moya · Joined: 18 Jul 2001 Posts: 213

Hi Chuck, you mentioned that the starter spins but doesn't engage on the flywheel. Is this correct? If yes, then you might need to just clean out the starter bendix with some brakeclean cuz it gums up with chain lube and just does what you described. It's underneath the black cover forward of the clutch. BTW, email me, Bye.

Oscar Aguilera · Joined: 18 Jul 2001 Posts: 1614

The great battery mystery. At least you guys aren't tuening into a Rotax Problem as do the infamous Chain throwing Rotax posts.

Here is what I do and have never had a problem on the kart I use or any of the rentals or any kart purchased through us.

1. Charge the battery the first time for 5 days straight. Yes I have heard someone melted one but it must have been due to something else like charging it on a concrete floor?

2. As soon as the kart leaves the track be sure to undo the kill switch. So if the motor dies on it's own you have to hit the the kill button or it will run down your battery.

3. After leaving the track, put the battery on the charger again until you go back to the track.

4. Charge the battery for at least 2 days before the next race.

If you run the battery to complete dead, usually due to leaving the kill switch on, then you must do the 5 day deal again. Other wise 2 days is good enough.

The green light in my opinion means nothing.

We have come across one charger that wouldn't charge, it was faulty. The sign was the battery didn't charge at all nor did any color light come on.

Oscar

Stephen Buckley · Joined: 18 Jul 2001 Posts: 861

Chuck,
Are you using the correct Rotax-specified battery? In tests, we have found that many other like-batteries won't work for very long. I'm not absolutely positive but it might have something to do with the vibration factor and the internal plates shorting together. Our theory is that the Rotax-spec'd battery has the plates secured somehow or at least in a different manner than other batteries.

Chuck Groat · Joined: 04 Apr 2002 Posts: 60 Location: Salt Lake City, UT

The battery is charged via the supplied Rotax charger through the use of an outlet on the generator. Two of us have used this generator, I'm the only one having this problem. The majority of the time, the battery is charged at home via the wall outlet. My thoughts of it being something other than the battery was because this has happened to me twice so far. Just coincidence or a bad batch of batteries???

Stephen Buckley · Joined: 18 Jul 2001 Posts: 861

Just curious, Chuck, but have you tried another charger? If the rectifier inside the charger is bad, it can cause several things... one of which is a "half-charge".

Chuck Groat · Joined: 04 Apr 2002 Posts: 60 Location: Salt Lake City, UT

Stephen-The battery used is supplied directly by the local Rotax dealer at $37.00 a shot.