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Tennis Tutor charging problem
I recently found my old tennis tutor and changed the old battery to new 12V7A. I have been charging it for almost 2 days. The indicator light is still red.
Should I keep charging it or is there any problem with the light or the battery?
or the charging circuit?
Maybe I should just charge the battery directly instead of thought the motherboard or make a external battery pack??
here's an old post with possibly some info that may interest you: http://www.tennisw.com/forums/showthread.php?t=287
also, i would say that 48 hours of charging should be more than enough. if it doesn't work by then, there's definitely a problem. and it certainly wouldn't hurt to charge it directly so yeah, try that. let us know how it goes.
I charged the batteries directly and it works fine.
Sure there is problem with charging circuit.
You might need a new machine
This site is good for learning about machines.
No sales pitches, just reviews from customers and owners.
I'm kind of late to the party on this one, but I've looked at the charge circuit on the tennis tutor. There's not much to it, and little that you would expect to fail over a period of ten years. Most likely the problem is the wall charger itself. I've heard other complaints of these units failing, and the active circuitry in these inexpensive adapters are prone to failure. As a quick test, you can put a voltmeter on the output of the charger. Nominally, mine says it puts out 12VDC at 1A. With no load, I measure close to 17V. If yours is not behaving similarly, it's time to replace the charger.
My output says 18V and I thing that it is the problem not charging my battery anymore. The device says 'operate 120V - output 12VDC". So it is 50% addicional voltage and probably over charged the battery and decrease its life. What do you think?
Originally Posted by TennisWidower
I know this is an old thread but I thought I would take a shot. I bought a used Tennis Tutor which did not come with a charger. I have several chargers that have the correct voltage and amperage but I would like to be sure of the polarity on the plug. On the charger, is the outside of the tip negative and the inside of the tip positive? There are several posts in the thread above that state the output voltage of the charger. To get the voltage, do you insert the red (+) probe into the tip and touch the outside of the tip with the black (-) or is it the other way around? Thanks in advance.
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