Model Boat Mayhem
Technical, Techniques, Hints, and Tips => DC Motors (Brushed) and Speed Controllers => Topic started by: dogbone on January 16, 2009, 06:11:24 pm
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well i've come to an abrupt halt and just ca'nt work it out. in other words help!!!!!!!!!!
i am mid way through a scratch built motor cruiser, fiberglass hull and wooden deck. 43" long , 15" beam .
12v torpedo 800 motor
EL Model ESC-110A 5-10 cells ( i know way over the top but it was free, and you ca'nt turn them down.
acoms 4 ch Rx Tx with BEC.
i want to run the boat on 1 12v 7Ah battery.
i have been fitting the motor/ prop tube and electrics and testing with a 6v battery because i have been waiting for the 12v.
prop turns free and true, and servo works the rudder fine.
now heres where the fun starts. guess what arrived today, my 12v 7Ah battery. i could'nt get it off the postie fast enough.up staries into
work room, red to red black to black, Tx on, power on. nothing, only the servo for the rudder. no motor. not even in reverse.
check battery, 12.69v .
put 6v back on, all works.
put 12v battery straight to motor, ok, spins like a good un. connect 12v back into ESC only rudder servo works.
help. need help before the hull gets launched, big time. i've missed somethin i'am sure ,but what?? {:-{
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Hi,
try these things.
reverse the servo reverse switch as some speed controls need forward signal for forward operation.
check battery on load.
has speed controller have switch
are you using a reciever pack
hope this helps
ro88o0
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hi
another thing you battery is over 12v charged.
is the max voltage 12v
ro88o0
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hi ro88o
no reciever bat pack
no switch on esc
batt fully charged as far as i'am aware. do'nt all batts say about 12.7v when fully charged?
reversed the servo.
still nothing
only other thing is the heat sync on the esc is getting warm. i think this is down to the fact that it only need 5v so the rest is dispersed as heat by the gubbings inside.
dogbone
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Hi,
have you tried it on a smaller voltage battery eg.7.2v or 8.4v or 9.6v
if it works on these then the battery must have to much voltage but not sure why.
ro88o0
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Hi
looked up the controller and web says 6v-12v
12v lead acid must be to much voltage
ro88o0
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hi
yea shall have to run it on maybe 2 6v in parallel or get another esc
thanks
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hi,
two 6v in parallel will be slower with longer endurance.
I would try anothe speed controller if you have one and use the above one for a 6v model
ro88o0
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or go for a viper marine 15 esc
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hi
have used the esc because it was free, "never look a gift horse springs" to mind.
yea may as well go for the viper i'll need the 12 power to move her any way
i wanted the 12v because i've got a smit nedderland to build and was going to transfer batts from one to another
there i go again saving money
thanks to all
off to remove the so called esc
dogbone
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Check your pm dogbone
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Perhaps the BEC in the ESC is not up to the job. That is probably what is warming things up and possibly triggering a thermal shutdown. It could also be why it was donated. 10 cells is a nominal 12 volts (quite a bit more, really) so it should work.
The other thought is that the battery is not as charged as you thought at first. Check the voltage under load.
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had batterys on the battery charger, and its drawing no amps.
whats the best way of checking under load ?
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dogbone.
I dont think you have the right motor either.
The MFA 800 revs at about 4000 rpm on 12 volts.
The MFA 850 revs at 9000 rpm on 12 volts.
Bob
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dogbone.
I dont think you have the right motor either.
The MFA 800 revs at about 4000 rpm on 12 volts.
The MFA 850 revs at 9000 rpm on 12 volts.
Bob
What are you thinking?
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Its a motor cruiser 43 inches long.
The MFA 800 will only let it plod along.
The 850 is the old Marlin which used to power the MFA Avenger which is likely to be far lighter.
Bob
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I thought the 800 was introduced to replace the Marlin and the 850 came later but that is academic when the stall currents are about 35 and 80 amps respectively.The blurb for the esc states a 110 amp rating.
I just wondered what the actual overcurrent trip level was and whether swapping motor wires and servo reverse would help make the combo work on 12v 7Ah.
I thought a high inductunce ferrite on one of the motor leads might help or the trip threshold raised.
It 's all guesswork when you can't see the esc instructions
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The 800 was introduced to replace the Marlin, but was rewound to give lower rpm and current consumption.
The 850 was a "hotter" 800 very close to the old Marlin figures.
I have tested all 3 and the 850 is very close to the old Marlin, but this could be that the Marlin I had was an old one.
Bob
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Possibly right on the Marlin but it's a real bummer when you get a gizmo promising amps++ and at can't even start a torpedo 800.
Dogbone,if you are a boat club and know a knowledgeable member with a soldering iron you could get the overcurrent level adjusted but if there is a reference to frequency control like the Electronize esc then it should be turned to maximum.
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had batterys on the battery charger, and its drawing no amps.
whats the best way of checking under load ?
Hi there connect the battery direct to the motor, meter across the battery terminals this will give you the voltage . Try with the boat in the water and out of the water. A 12v 7ah full charged not under load will read about 13.5v ish, under load i would expect 11 to 12 v on a fresh fully charged battery.
As for your ESC problem the answers you have give rule out all the normal problems. Try an email to the manufacture stating all you findings and they might have a answer. One question is your ESC programmable ie 3 sec delay before revers etc, If so do a factory reset and see what happens.
There is another test you could do is to by pass the bec. On m-tronics you remove the red lead from the cable that plugs in to the receiver and then use a 4 aa battery pack to power the receiver.
john
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With this particular esc, is not only normal it is déjà vu.
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hi
did a little research work on the esc and found out it came from ebay via china. Bought myself the bigger MFA 850 motor.
decided to ditch the esc ,put the motor on the shelf for something else and bought a viper 15.
rewired everything and bobs your uncle. Runs like a dream.
Moral to the story
don't trust ebay and take the advise of the more experience of others
thanks to all
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you will still have to see how she performs on the water.
Bob
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Oh Gawd!
I couldn't fathom it for a moment there. I took "runs like a dream" to mean everything was just spiffy and the boat sailed well.
Dogbone,there is a distinct possibility that you may blow a few fuses and/or go back to the Torpedo 800.
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Oh Gawd!
I couldn't fathom it for a moment there. I took "runs like a dream" to mean everything was just spiffy and the boat sailed well.
Dogbone,there is a distinct possibility that you may blow a few fuses and/or go back to the Torpedo 800.
Just out of interest I have a Torpedo 850 in a 42 inch long fast motor yacht. I am using 12 cell packs to drive an X40 prop. This combination draws about 18A. Looks good on the water though! Be sure to fit a suitable fuse.
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stallspeed- its still a bit cool here up north for a trip on the water so i will finish off the deck and cabin in warmth first.
max power- what would you say for the fuses? go straight in with a 15a, os start lower, do'nt want to go for a paddle you know
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stallspeed- its still a bit cool here up north for a trip on the water so i will finish off the deck and cabin in warmth first.
max power- what would you say for the fuses? go straight in with a 15a, os start lower, do'nt want to go for a paddle you know
I would go for the 15A fuse, assuming that the speed controller can take short bursts in excess of 15A. Best of all would be to borrow an ammeter, if you do not have one, and check the current with the boat in the water before releasing it. I did it in the warmth of my own home by placing the boat in a bath full of water O0
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Dogbone,if you had a scrap telly or computer you'd have a ferrite to make a 15+ amp ,100uH choke which might just have prevented the shutdown feature in the first esc.Remember the amp rating it quoted?
If it was a high frequency esc a choke would almost certainly have done the trick.
You are now using a 15 amp esc and a motor that will draw twice the current.
I think it would be a wise investment to purchase a multimeter and do some skiddling about with a basin of water.
Pull the curtains and watch the room light up with a glass encapsulated ten amp fuse.I would do that with the prop immersed in water and the motor connected to a battery.
A £6 meter would not be damaged by 30 amps but it can't give a reading beyond ten amp.To measure your current so you need to use a low resistance and measure volts generated by the current passing through it.
By the way,I'm staring out at snow capped peaks closer to Max power than Arrow5.That probably makes you down south. ;D
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The first speed control was probably shutting down as the BEC would struggle to handle 12V and a servo. A better BEC would be about 3A or you could go to a switching BEC for higher voltages. (I am coming to this from aircraft and cars.)
Receivers and servo run on perhaps 5V. The BEC has to take the 12V of your battery and step it down to a voltage that won't fry the radio equipment. That 7V differential is disposed of in heat. If you add multiple servos, high drain servos, (and the small ones are often higher drain than we might expect), or a binding linkage, you are adding more current, creating more heat which has to be dissipated by the BEC. Usually, speed controllers can deal with up to 4 servos on 6 NiCds, (7.2V), 3 servos on 7 or 8 cells, (8.4-9.6V), 2 servos on 9 cells, and 1 servo on 10 cells. Better controllers are more tolerant of stretching these guidelines, and cheap controllers often don't.
Martin
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The rudder was working. :-))
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Martin.
Standard BECs are rated at 1 amp.
Sub BECs are rated 1 1/2 -2 amps.
For 3 amps you would need a stand alone BEC.
I amp is plenty to run 1-3 servos and receiver.
Bob
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"The rudder was working. :-))" Missed that!
Bob, Castle Creations ESCs have 3A BECs, but that is more a plane controller.
That's why I'm here - to learn boat stuff! :embarrassed:
Martin
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The rudder servo worked, so the RX must have been working, so both had power. If I understood the problem properly, the motor battery supplied all of the power via the BEC in the ESC, so the ESC should have worked. Therein lies the mystery. I suspect that at 12 volts the ESC BEC was warming up, and warming the ESC protection circuit as well, beyond the point where the ESC would shut down. At 6 volts, it didn't do as much work, ran cooler, and everything worked.
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The rudder servo worked, so the RX must have been working, so both had power. If I understood the problem properly, the motor battery supplied all of the power via the BEC in the ESC, so the ESC should have worked. Therein lies the mystery. I suspect that at 12 volts the ESC BEC was warming up, and warming the ESC protection circuit as well, beyond the point where the ESC would shut down. At 6 volts, it didn't do as much work, ran cooler, and everything worked.
EL Model ESC - 110A (Rds =0.0076 ohm omitted from this Ebay listing)
Yes,agreed: the esc couldn't maintain 110 amp continuous unless it had a Pentium heatsink+fan but it has two smartfets which trigger it seems from a Torpedo 800 stall current.
Well almost déjà vu as last time it was a Torpedo 850 and possibly on 10 or 12 cells.
This is a new ESC only taken out of the package for picture. The El Model 110 ESC when connected with motor, it is capable of supplying up to 110 Amps (forward) and 40 Amps (reverse) of continuous motor current. Its integrated Battery Eliminator Circuit (BEC) powers the receiverfrom the motor battery, with automatic cutoff of the motor power to preserve receiver power as the battery becomes depleted. It is small, powerful and waterproof..........
This ESC is for Brushed Motors ONLY.
Due to the nature of this Hobby item is sold AS-IS