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  #1  
Old 06-26-2019, 05:20 PM
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Default Help with esc

Recently l installed a 10 amp micro brushed esc in a mini z.
Input voltage for that esc ranges from 4-8 nihm or 2s lipo.
4.8 volts nihm applied runs the servo fine, but l have to trim the throttle down to 25% to get a smooth driving motor. Any higher on the throttle trim will cog the motor and render it undrivable.

My question here is what can l expect if l installed a 5 amp esc? Would that allow full uninhibited throttle or should l be going the otherway higher amps?

Keep in mind that 4.8V nihm is the power source.
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  #2  
Old 06-28-2019, 02:36 AM
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You're saying the motor runs fine at low throttle but stutters and cuts out at high throttle?
I would try measuring the battery voltage under both low and high throttle to see if the batteries can't take the load.
I would try another motor to see if it's just gone bad from old age (or maybe lack of lubrication).
The amps shouldn't matter for a mini-z as long as it's more than 3-4 amps.

Another possibility is that it's actually your receiver browning out. That's an issue I had with my conversion tests. at 4.8v the ESC BEC will probably deliver max 4v to the receiver. If the batteries sag to 4v under load, that might deliver a low enough voltage to shut down even a 3.3v capable receiver. You can try powering the receiver directly from the batteries.
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Old 06-28-2019, 01:31 PM
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Thanks again!

I'm thinking brown out based on your desciption.

Here's the measures l got...

Trimmed throttle @ 25% measured at motor =3.03 volts
100% no trim at Tx measured ar motor=4.85 volts

Batteries no load measured at connector =5.15 volts

BEC measured at reciever =4.05 volts

Is there a remedy?
Or will a battery upgrade be the fix here? More supplied voltage to keep the power up to 6 volts at the rx.
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Old 06-28-2019, 04:25 PM
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Both the servo and rx should in theory be fine with both 4 cell and 5 cell nimh directly, without needing a bec, so direct connection between battery and rx and adding another cell are two things you can test.

You could also for testing purposes power the rx from a different source entirely just to be sure you've identified the problem. I use a usb power bank with a cut usb cable for testing rx and servo stuff. Just remember to unplug the red bec wire but keep a common ground connection.

I saw banggood had a 12a esc with a boost circuit for the bec that can keep the bec voltage at 5v even with a 1s lipo drive battery. I'll look for the link later if I remember.

Edit: In my fire truck I'm using a small circuit board that boosts 2s lipo to 9v to drive some LEDs. It's fully adjustable and keeps a regulated voltage. There's also some tiny boards out there for boosting 1s lipo to 5v, the same kind usb power banks use. Could look into the specs for those.
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Old 06-30-2019, 01:07 PM
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So what l have done now is pulled voltage direct from battery wires to the rx. Basically seting it up as an old rc that uses a mechanical speed control would. Im getting 5.3V to the rx now and have removed the power source from the esc to the rx. (Red wire)

Runs much better, but now instead of trimming throttling at the Tx set 25% l can get 50% and then the cogging begins. 50% is fast enough for me but l dont think I'll get 100% with out add more battery power.

I think checking into those micro boards would get better results I'm just not familiar with them. I'm also surprised that this is not 100% functional l never thought this simple Z would be so contained to itself. Maybe thats why they are the way they are

I wont give up on this though...
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Old 07-01-2019, 12:04 PM
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It's an interesting problem, and I guess Kyosho's engineers did a good job with their Mini-z board.

I just tested this: https://www.banggood.com/1pcs-MT3608...r_warehouse=CN Hooked up to a variable power supply. When this board is tuned to output 5.9v it stays at 5.9v output from 2v to 5.9v input.
It had no problem supplying my spektrum receiver, but when I connected a servo to the receiver it couldn't keep up with the fast power spikes and dropped below brownout for the receiver. Probably because it doesn't have any large capacitors onboard. I would suggest testing that board to power the receiver but connecting the servo and esc power directly to the battery.
They also have several alternative step up/boost boards, but that's the one I happened to have.

This ESC also looks like an option. It's got an integrated boost circuit for the BEC. https://www.banggood.com/3_7V-1S-12A...l?rmmds=search

Of course there may be other issues than this one too, but we can only troubleshoot one issue at a time
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Last edited by Wombii : 07-01-2019 at 12:06 PM. Reason: clarification
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