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Why is my motor shutting down with a full charge?

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Why is my motor shutting down with a full charge?

Old 09-14-2003, 06:14 PM
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jc4me2
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Default Why is my motor shutting down with a full charge?

Pardon my ignorance, but I know next to nothing about electric motors. My settup is a Sig Racsal, with a Mabuchi 380 motor from a Firebird XL.
(The original S 400 burned out for the previous owner, not sure how) I'm using the original ESC with the 7.2 900mAh NiMH battery pack from the XL. I'm using the biggest gear that came with the Rascal, and turning an APC 9-7 real well. Lately, when I advance to full throttle, it quickly
slows down and stops, and when I keep the low, it does the same thing, but takes a while longer. And this is on a full charge. I'm sure theres a simple solution, I just don't have a clue what it is. Little help? Thanks, Jordan
Old 09-14-2003, 09:06 PM
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rogwabbit
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Default RE: Why is my motor shutting down with a full charge?

maybe your pack has one bad cell.. at 7.2 v minus 1 cell = 6v... speed control shut off is 5v probably.. won't take long to loose 1 volt...
Old 09-15-2003, 07:49 AM
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Matt Kirsch
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Default RE: Why is my motor shutting down with a full charge?

The batteries from your Firebird may not be up to the task of powering the new system. Cells are not all created equal, and there are a few factors that determine how much current a cell can produce without losing a lot of voltage:

1. Cell size. In general, bigger cells can produce more current.
2. Cell quality. It's hard to tell by price, but a "cheap" cell, that is one that is of poor quality, will not produce as much current as a good quality cell. Because your Firebird XL was a low-cost, prepackaged unit, I would expect that it came with the cheapest cells they could source at the time, which means that they are probably of mediochre quality.
3. Cell diameter. Shorter, fatter cells can generally produce more current than longer, thinner cells with the same mAh rating.

Actually, I suspect that factor #2 is the cause of your trouble. Get yourself a quality battery pack, and you'll be fine. Battery packs made with HECELLs (www.edogfight.com) or KAN1050s (various sources) would be great for this application.

I forgot to mention, the new power system setup undoubtedly draws more current than the old Firebird XL.
Old 09-15-2003, 08:10 AM
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jc4me2
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Default RE: Why is my motor shutting down with a full charge?

Could you please poast the optimum pack?, as I have no clue which one to get![&:] Thanks, Jordan

EDIT: I tried a new 9.6 I found, and it did the same thing. I think it might be the ESC???
Old 09-16-2003, 06:07 PM
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Jim Finn
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Default RE: Why is my motor shutting down with a full charge?

Seems like you may not have enough cells. You said 7.2v pack ..that is six cells. With Nihms you need 8 cells for that motor.( seven with nicads.) When your batt. pack voltage drops at throttle advance the ESC cuts the motor off to reserve power for the RX and servos. A 9X7 prop on a 380 motor without a gear is way too large. You may be over amping your system. That motor should use a 6.3x3 Prop max. This would explain how the last guys motor died.
Old 09-16-2003, 06:37 PM
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Dr Kiwi
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Default RE: Why is my motor shutting down with a full charge?

What is the make and amp rating for your ESC? According to ezcalc that motor/prop combo is sucking over 12amps. That's way too much for a 280 - so its brushes are probably burned, and its way too much for any ESC rated at less than about 15amps.

Cheers, Phil
Old 09-16-2003, 06:51 PM
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Dr Kiwi
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Default RE: Why is my motor shutting down with a full charge?

I realize that Jim and I both misunderstood - your 380 is GEARED! What is the ratio? If it is 3:1 your amp draw drops to about 3.5A so your motor should still be fine. Possibly your battery pack is bad, but your ESC could also be bad. You need to check each component by substitution, to find the real answer.
Cheers, Phil
Old 09-16-2003, 07:46 PM
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jc4me2
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Default RE: Why is my motor shutting down with a full charge?

I tried a 9.6v nimh and it still hapened. I just got a APC 8-4, would that prop be better? And yes the gearing is 3:1 I believe. It think the ESC was damaged in the engine burnout, it was the standard Sig 20 anp ESC. Thanks, Jordan
Old 09-25-2003, 03:47 PM
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whanderson
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Default RE: Why is my motor shutting down with a full charge?

If the ESC allows control of motor speed even for short periods of time, it is probably OK. This sounds like a bad cell in the battery pack to me. If the ESC doesn't get hot, the problem really points to the battery. I have had several Firebird XL packs with bad cells. The Firebird people don't make any profit by putting quality batteries in their airplanes.
Old 10-01-2003, 07:05 PM
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Bill L
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Default RE: Why is my motor shutting down with a full charge?

I also experienced faulty Firebird Packs, but Horizon Hobby made them good.
Jordon, can you put a simple volt meter in parallel with your battery pack, in other words a voltmeter with the + on the + side of the pack, and the - on the - side of the pack, then turn it on with your transmitter, through the ESC. Watch at what voltage the motor stops. I'll bet the guys with "bad cell" information are correct. It shows 1.2 volts, untill a load is put on it, then it drops to "0" or very near it.
Good luck. I have a beautiful Rascall in purple and white, which I'm afraid to destroy but it has great thrust with a 2.5 : 1 geared Max speed 400, and a Master airscrew 8/6 electric prop. It gets 7.5 oz of thrust on a 7 cell 600mAh Nimh battery pack, for a 0.31 thrust to weight ratio.
Old 02-07-2004, 01:22 PM
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jc4me2
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Default RE: Why is my motor shutting down with a full charge?

OK, I had to resurect this thread because I just got a new motor(GWS400G) and battery(8.4V Ni-cad) and it STILL does it. I'm really ticked, I thought the new stuff would help. The prop is a GWS 11-8. It must be the ESC at fault, I don't know what to do! Jordan
Old 02-07-2004, 03:12 PM
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Default RE: Why is my motor shutting down with a full charge?

Go out and buy a decent ESC - Castle Creations Pixie 20P - and all your troubles should be over. An added bonus with this ESC is that it has programmable LVC so when you turn to LiPoly batteries you'll be good to go!

Cheers, Phil
Old 02-08-2004, 12:57 AM
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clively
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Default RE: Why is my motor shutting down with a full charge?

I second Phil's suggestion. Dump your ESC and get a Pixie. There are so many garbage ESC's being produced, but Castle's are quality.

chris.
Old 02-09-2004, 10:25 AM
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Matt Kirsch
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Default RE: Why is my motor shutting down with a full charge?

What SIZE 8.4V NiCd? Batteries have limits as to how many Amps can be drawn from them. Use a battery that's physically too small, draw too many Amps, voltage drops, and the ESC shuts down the motor.

You need to run at least a 600mAh NiCd, 2/3A cell. No AA cells, period. They don't work in anything but digital cameras and toys.
Old 02-16-2004, 06:05 PM
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Default RE: Why is my motor shutting down with a full charge?

yo,

I have an e-starter,a 300 motor, an ICS 100 ESC, and a 8.4v 730 mah battery. I have the same problem, the motor turns off after a few minutes. Should I use a 1080 propeller or will it pull too many amps.? People say I should try a 9070, should I? If I want more thrust than should I use a 1080 but get a better ESC to handle the amps? Will the motor burn out soon with a 8.4v? I NEED HELP!!!!!! AAAAAAAHHHHHHHHHHH!!!!!!!
Old 02-17-2004, 08:58 AM
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Default RE: Why is my motor shutting down with a full charge?

Your problem is exactly the same as the one earlier in this thread. It's your battery. You're trying to draw more Amps from the battery than it can produce. The voltage is dropping, and the low-voltage cutoff is kicking in.

Luckily, yours will improve with use. After a few cycles, that NiMH battery will start working better.

You can improve things by switching to a 9x7 propeller. This will reduce the load on the motor so it won't draw as many Amps. You can switch back to the 10x8 prop after 3-4 flights, but keep your full throttle flying to a minimum.

Above all, don't sit there running the motor at full throttle on the ground for extended periods. The forward motion of the plane through the air causes cooling air to flow over the motor. Prop blast does very little to cool the motor, because most of the prop blast is toward the outer edges of the prop. Extended static runs will cause the motor to overheat in many cases. Best not to chance it.

Those 700mAh-ish AAA NiMH cells max out at around 7 Amps. The EPS300C drive in your E-Starter normally draws a little more than 7 Amps on 7 cells. Even properly broken in, you're pushing the battery pack to its limits.
Old 02-17-2004, 11:37 PM
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efurche
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Default RE: Why is my motor shutting down with a full charge?

Have a twin speed 400 with a 2 cell 1500 mah Li-Poly pack. and a WATTAGE IC-30 controller. Everything worked fine with a Nicad Pack (7 cells 800 mah.) Now controller cuts out after 5-6 seconds of full throttle.
Using 5.5x5 props on both motors.

I went to Li-Polys to save weight (6 ozs).

Thanks, Ed

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