Rotax Batteries-When they go bad?!

Jim Emerson

Has anyone seen a battery go bad while on the track in race conditions? I have a feeling my engine problems last week at the Rock were caused by a battery going bad or losing voltage. The engine was missfiring acted like loss of fuel. Yesterdays testing should a different battery resolved the misfire at higher RPMs. Does this sound correct????

I have seen the posts, but if a charger has been left on for a 24 hour period will the battery become damaged? The initial battery I swapped out yesterday was a one that had a long green light period, which I normally only go 3 hours after the light switches from red to green.

-Jim Rotax #77

Blake Newson

Jim:
What was the voltage of the battery when you came off the track after the race? If you don't have a voltage meter, you should invest in one. They are only $20 or $30. I made up a test plug using a 2.5mm jack (like the one on the Rotax charger. This way I can plug my meter into the battery very quickly to test the voltage. Great tool.
A lean jet can also cause misfiring at high RPM.
Using the Rotax supplied charger, you will not damage your battery by leaving it on the charger. The Rotax charger is designed to limit the voltage to about 13.5Vdc even when the battery is full. With other cheap "chargers" or AC adapters that you can buy for $8.00 at Radio Shack, the voltage will start to creep up as the battery gets fully charged. For example, when the battery has reached a full charge, the voltage could be as high as 22Vdc coming from the "charger". That will damage the battery over time and THAT is why we only use the charger supplied by Rotax. Another good quality charger could be used, IF and only IF you are sure that it's charging characteristics are appropriate for this kind of battery. I have looked at such chargers, and they are just as much, if not more money than the Rotax charger. So stick with the Rotax charger. I hope this helps.

Jim Emerson

More to add....

The voltage was at 13 volts as it came off the kart at the Rock. I have only been using the rotax charger so no overcharge on my two batteries. It definately was not jet because I was 2-3 sizes bigger than other guys and my plug was dark.

The next issue I am considering is the current draw on the track and what is the voltage dropping to while at the higher RPMs.

Nick Weil

Jim,

I have experienced a low battery MANY times.

In the beginning it can resemble a bad jetting situation. The kart will 'pop' in some cases, and it may not rev in others depending on what sort of conditions you are in, and how low the voltage is. One thing that I found to be a constant in these situations is that it seems almost as if the motor completely shuts off for a split second. The reason being, as best as I can explain it is the battery supplies as much power as it physically can, and then when it reaches the point of no return it drops the voltage suddenly. In some cases this will cause a backfire due to loading of the carburetor and then igniting the fuel. While in others it may load the carb and no longer have the necessary voltage to ignite the fuel and thereby cause a bogging situation. Neither situation is good obviously, and both are extremely hard to diagnose without the aid of the voltmeter. Hope this helps you and others identify battery problems.

Nick Weil
SpeedQuest Karting
SpeedQuest Karting Webstore - All your Rotax parts in one place

Blake Newson

Jim:

If your battery was at 13 VDC when you came off the track, then I would say it's highly unlikely, you are experiencing battery problems. These ignition systems will work well below 13 V. I don't recall the "minimum" voltage required, but I know it is quite low. I had a new Panasonic battery fail during practice, and it failed. I had to push back to the pits. The battery would no longer charge or discharge at all. If your backup battery gives you the same result then I would be tempted to look for something else causing your woes.

Bruce Woodrow

If the battery plates have come loose due to vibration (seems fairly likely), could a voltage drop be occuring when on track and not show up during a static test?

Bruce

P.S. Time to velcro your 'works' Fluke to your steering wheel, Jim

[ September 10, 2002: Message edited by: Bruce Woodrow ]

Chad Hartzell

Just bought a "Deltran Battery Tender" junior for $39.99 from Batteries Plus. It states it can be used for a 12V battery. It has the clips easily marked red & black for both connections. The nice thing about this is you can take the battery off the kart and charge easily.

The operating instructions state the following:

Status Indicating Light- This light will display red, or green depending on the status of the charge.

Red- When the light is glowing red the battery charger is in the process of fully charding the battery. In order to properly charge the battery, the charger may remain in this mode for several days on some battery models.

Green- When the light is glowing green, the battery charger is in the storage mode of charge. In this mode the charger will maintain the battery at full charge. If the battery becomes partially discharged due to an external current draw or excessive internal battery losses, the charger will automatically switch itself back to the charge mode of operation.

Based on the above information, should be safe, correct?

Chad Hartzell

Blake Newson

Chad:

What is the charging current of your charger?
The Rotax charger is 1 Amp. If your charger is less than this (say 500 mA) then that's OK, it will just take twice as long to charge the battery. If your charger is charging at 2 Amps or more, then this would be considered a "quick" charger, and these are harder on batteries. Other than these things to watch for, it sounds like this should do a good job.
Just curious, but why didn't you opt for the Rotax charger? Is it a lot more than $40?