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Power Loss Question
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giftacrylic
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Power Loss Question - 03.16.2007, 11:55 PM

I run a X1-CRT geared 9/46 on a 9920/8XL combo on 5s lipo (MaxAmps 6000 mah). The problem of power loss occurs when approaching a long triple jump. The loss is only for a fraction of a second. Now, it only seems to occur when I am actually on the ramp, it does not occur on straightaways under very hard acceleration.

If I ease into the thottle, land the double and roll the triple, it will never occur. My solder joints are good and I am using a Dimension Engineering LVC.

Please help if anyone has experienced this problem.
   
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glassdoctor
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03.17.2007, 12:16 AM

Sounds like you are hitting a current limit on the 9920 or more likely a low voltage cutoff?

It must do it under some other situation also, like landing wide open throttle, or coming off a corner on a high traction area???

Does this mess up clearing the triple? Does it happen when you start to accel toward the jump, or when you hit it?


Jammin CRT MM/Neu 1515 1700kv
Losi 8IGHT MM/Neu 1512 1900kv
Kyosho 777
T4 MM 5700
B4 LRP
XX4 MM 7700
old losi xxcr, MM4600 4s lipo 70mph+
   
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giftacrylic
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03.17.2007, 12:26 AM

Only approaching the takeoff actual ramp (at the base of the ramp under throttle). After the slow turn into the striaght, I yank the trigger to WOT and no problems.

And yes, It will make me land the double and roll the triple.
   
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Cartwheels
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03.17.2007, 12:36 AM

Are we talking about a single 5s lipo or are you running 2 in parallel? If you are running 1p does the battery really heatup towards the end of the run?
   
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giftacrylic
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03.17.2007, 12:42 AM

2s & 3s in series. After 15 minutes under track conditions (hard thottle and hard brake), the batts only heat up 20 degrees above ambient . So I am not pulling on the batts too hard and that is why I am confused.


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glassdoctor
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03.17.2007, 12:50 AM

Sounds very odd... I would look very close at all connections/solder joints and try taping all the wires in place so they can't bump around and see if that makes any difference.

Try using a capactior on the reciever, like the $6 Spektrum one.... just in case it's the rx seeing a voltage drop.

Can you tell if it's a total loss of power, or just a "bogging"?


Jammin CRT MM/Neu 1515 1700kv
Losi 8IGHT MM/Neu 1512 1900kv
Kyosho 777
T4 MM 5700
B4 LRP
XX4 MM 7700
old losi xxcr, MM4600 4s lipo 70mph+
   
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giftacrylic
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03.17.2007, 12:59 AM

It happens so quickly, it is hard to tell. All I know is that my acceleration is greatly dimenished, and then kicks back in (my trigger pull remains a constant).

I will take your advise and make sure that all wires are shielded and secure.

Maybe I will take some video tomorrow.


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glassdoctor
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03.17.2007, 10:38 AM

I have seen simple things like a bad on/off swtich mess things up... but this happens at the same point in on the track which is weird...


Jammin CRT MM/Neu 1515 1700kv
Losi 8IGHT MM/Neu 1512 1900kv
Kyosho 777
T4 MM 5700
B4 LRP
XX4 MM 7700
old losi xxcr, MM4600 4s lipo 70mph+
   
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Patrick
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03.17.2007, 10:50 AM

Is it a radio thing? I sometimes had glitching problems at certain places in the track. Where I stood on the rostram affected it too. Since I got a spectrum it hasn't happened (was only using the stock traxxas radio before).
   
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