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Model Forum / Radio Controlled / Water Models / February 2005motor upgrade
Hi, I have one of these "toy" twin 380 motor speed boats. It's fun, but I want a little more out of it. What motor can I replace the stock, cheap, 380's with to give it more speed? I don't understand what 380, 400, 480, 540 etc is. Thanks in advance, Nick  Signaturehttp://www.lake-district.info the number is the length of the can a 380 is 3.8cm long a 540 is 5.4cm ETC but as they get bigger numbers the diameter of the can increases and also the shaft size and also the amount of current the motor takes so the battery life decreases and you might need a bigger speed controller and to get the same run time a bigger battery so you need to work out a way of mounting a bigger motor and if it will connect to the prop shaft Kevin > Hi, I have one of these "toy" twin 380 motor speed boats. It's fun, but I > want a little more out of it. What motor can I replace the stock, cheap, [quoted text clipped - 4 lines] > > Nick > the number is the length of the can a 380 is 3.8cm long a 540 is 5.4cm ETC > but as they get bigger numbers the diameter of the can increases and also [quoted text clipped - 4 lines] > connect to the prop shaft > Kevin Tnx for that. Would I be correct in assuming that I can get better quality (ie faster) 380's? Also, would a 400 be close enough to fit (with perhaps only minor modification), not much more draining on the battery, but at the same time - that little bit quicker? tnx, Nick >>Hi, I have one of these "toy" twin 380 motor speed boats. It's fun, but I >>want a little more out of it. What motor can I replace the stock, cheap, [quoted text clipped - 4 lines] >> >>Nick >> the number is the length of the can a 380 is 3.8cm long a 540 is 5.4cm >> ETC but as they get bigger numbers the diameter of the can increases [quoted text clipped - 9 lines] > (with perhaps only minor modification), not much more draining on the > battery, but at the same time - that little bit quicker? Actually, what is confusing me is that the 380 is rated for 26,000 rpm (no load) whereas the 400 is rated at 16,400 rpm. I know this is "no load" but I want a motor that will turn the prop quicker... >>> the number is the length of the can a 380 is 3.8cm long a 540 is 5.4cm >>> ETC but as they get bigger numbers the diameter of the can increases and [quoted text clipped - 13 lines] > load) whereas the 400 is rated at 16,400 rpm. I know this is "no load" but > I want a motor that will turn the prop quicker... I must admit I am more of an electric plane modeller than boats and the difference a 480 makes over a 400 is quite a big step, 1 thing that will boost the speed is running on another cell so if you are running a 6 cell pack try running on 7 as 1.2volt increase make a big difference as well but it could damage the electronics in the boat so be warned > Actually, what is confusing me is that the 380 is rated for 26,000 rpm (no > load) whereas the 400 is rated at 16,400 rpm. I know this is "no load" but > I want a motor that will turn the prop quicker... The trick is that under a given load, the 400 will turn faster. As someone else suggested, you can get a bit more out of your existing motors by adding a cell (maybe two) to the battery pack (that drives the motors, if the electronics are also driven from this pack, you'll have to do some rewiring). The danger is overloading the speed controller so watch for overheating there. Of course if you upgrade the motor, then the speed controller is going to be carrying a bigger load anyway. Another element is the battery chemistry. Alkaline cells - non-rechargeable - give about 1.5 volts, but it degrades quickly under load and as the battery warms up. NiCds or NiMh batteries have a lower cell voltage but maintain it better and can provide more power. Sealed lead-acid batteries (I'm partial to the D-sized "Gates" cells) can give a lot of power (and at 2V per cell) but do add weight. -Wm "380", etc. is the diameter of brush-type motor "can" in millimeters. Most motors are by Mabuchi.They are also rated as 6-volt or 7.2 volts. A 6-volt motor will turn up higher rpm than a 7.2 on the same battery pack. A larger diameter motor will pull more amps and deplete your battery pack quicker than a smaller one. You can get more power with same motor by using a battery pack with one more cell but that will probably shorten the life of the motor.Brush motors usually cost about $10 so you can replace them as needed. Brush-type motor brushes overheat and wear down quickly when run at higher than intended voltage/current draw. To properly upgrade, you will need to mount a larger motor and probably a larger amperage/capacity battery pack with maybe one more cell.. You might need to increase the size/pitch of the prop. If you install too big/heavy a motor and battery pack, the boat will ride lower in the water and may not run as nicely at lower speeds. Hobby Lobby sells some easy to install geared 400 and 600 motors with stuffing box and prop. Gearing allows using smaller motors with bigger props. HL also sells coiled brass tubing to be installed on the motor can for water cooling which may help longevity of motors. Brushless motors can tolerate higher voltages ( more cells) and produce much more power for a given size. Brushless motors are much more expensive and require much more expensive electronic speed controls. I am an electric plane flyer and haven't heard much about use of brushless motors in boat models yet. |
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