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Old 09-24-2014, 07:09 PM   #1
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Default brwnouts... should have plenty of power

Not really sure whats going on . Have my 1/8 scale car set up with a castel 10 amp bec. I am using 2 savox sb2274SG servos. These are high voltage high speed servos that i choose for reaction time with the AVC. Power is fed into a spectrum 4210 RX. I do also have the 2 fans running from the extra ports on the rx. I had a bec on the car, set at 5.5volts. Everything worked, but ater i got done tuning, i bought a second bec and the hobby shop set it at 6.5 for me. This is under the voltage limit for everything on the car. At 5.5volts, no brown outs. At 6.5 it cuts out and comes back fairly rapidly

My first thought is to just run the fans and servos power directly off the battery. 7.4v 2400mah 18 wh.. not sure the c rating but it is a trak power battery so maybe im just not getting enough juice.. idk.

Any suggestions?

Included a picture of the setup....sorry for the mess, still in the build phase.
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Old 09-24-2014, 07:18 PM   #2
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I think this woul be more suited for the radio/electronics section. Sorry for misposting. Can a mod move?
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Old 09-25-2014, 03:42 AM   #3
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Anyone?
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Old 09-25-2014, 11:13 AM   #4
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I'm no specialist, but i think you need a spektrum brownout capacitor

Here's someone who had similar issues
http://www.rctech.net/forum/rookie-z...ssue-help.html
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Old 09-25-2014, 11:30 AM   #5
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savox servos......
super common issue, run a glitchbuster cap
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Old 09-25-2014, 01:18 PM   #6
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Spektrum receiver + Savox servos = brownouts!!!

Heard it a million times.

Most people struggle to get the Spektrum receivers to work with 1 Savox, let alone 2.

As already suggested, a power cap (aka glitch buster) plugged into a spare port on your receiver will fix it.
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Old 09-25-2014, 01:40 PM   #7
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Lol I don't have a spare port ...how about if I power the servos directly off 7.4 from the battery? Where would the ground go? I assume I'd need to make sure the servos don't get above 7.4 volts right ? Meaning cell voltage of 3.7
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Old 09-25-2014, 02:32 PM   #8
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Run the fans straight off the batteries. This will help. You get brown outs from too much mah draw, that drops the voltage. You need a higher mah bec not a higher voltage one. I run savox with sectrum and have for a while. Never had issues.

Also is the mechanical brake system needed? That just adds weight. Even in 1/8 e-truggy most motor brakes are enough, even with those huge tires. dropping a servo would help. Did you also make sure your rx is capable of outputting more than 6 volts?

Its hard to tell what you got going on with all that spagetti. You might want to clean it up so something doesnt get caught where it shouldnt. Also, what do you have holding your battery down?
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Old 09-25-2014, 10:51 PM   #9
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All that spaghettit wont be there when im done. Like i said its still in the build phase. There is still alot left to do Yes the mechanical brakes are mandatory. Im already running a castle 10 amp bec. Thats why my original post was "should have enough power" the fans max voltage is 7.4. The batteries fully charged are 8.4. I would prefer to run the servos directly off the battery and the fans off of the bec. I think the problem is just rying to pull that much power throught the spectrum internals. Either that or the battery just isnt up for it (which i highly doubt. Even at 2c it should be plenty)

I bought some mini deans plugs tonight. Im going to do so wiring and make myself a bus bar tommorrow since im off work. If the problem doesnt go away im sayin screw it and buying futaba servos
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Old 09-26-2014, 12:03 AM   #10
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You should be able to run that without a BEC...the high voltage servos and that receiver can take the higher voltage of your receiver pack. I'm not sure how the ESC will handle it but if you want to be safe just remove the red wire from the plug on the ESC so that only the main battery powers it. I run my 1/8th nitro car with Spektrum receiver and 2 Savox high voltage servos from a 7.4v LiPo receiver pack with no problems.
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Old 09-26-2014, 07:40 AM   #11
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The wire is pulled on the esc.imgoing to mess with it today. Let you know how it goes
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Old 09-26-2014, 07:49 AM   #12
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Your still better off running the fans straight from the batt. That voltage will drop pretty quick. Which is also a problem for running the servos straight from the battery. Can your servos handle higher than 8.4??? And even if they can as voltage drops your servos will slow and torque will decrease..

Also, your running an 1/8 scale at 2s??? You should be running atleast 4s.
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Old 09-26-2014, 08:02 AM   #13
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im running minimum 3s. With a 6400 35c battery for testing. Car is getting all carbon fiber and titanium parts so its plenty light and plenty of power . The 2s is for the electronics only. After im done building it will be run either 4 6 or 8 s
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Old 09-26-2014, 08:25 AM   #14
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Why are you using 2 servos? You can use the electric motor as the brakes, since there is no clutch anymore now that you removed the Nitro engine. And then you can remove the 2nd 2s battery as well
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Old 09-26-2014, 05:50 PM   #15
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I have a clutch and a 2 speed transmission. 1 way gears = no brakes. Id have mechanical brakes anyways since you cant trail brake with the motor.
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