Mgm esc help

[Rc4me]

I have a mgm x2 series 250a boat esc. I have the esc in a 51 rio i built. Motor is a tp 1150kv 5670. Boat ran very well, but it thermals after about 4 saw laps. I hooked up esc to computer and motor is pulling 7500 watts. The question i have is what is the continuous amp reading. There are pulse amps and input amps which are 250a. And then there are peak amps which was in the 900s im thinking ill just need a bigger esc but im going to play with stinger adjustments etc. Any help is greatly appreciated.

[rol243]

when you say the esc Thermals after 4 SAW laps, are you giving some stop time between each saw leg ? normally it is wise to let things cool for about 1 minute before going for another quick saw run. maybe try this before doing anything else.

[Rc4me]

I did not take any breaks. That's an option though. I was hoping the esc would not heat up that fast. Temp wise only the esc was hot. Motor was 120f and batteries were 107f. 4 4s packs 8s 10000mah total.

[RandyatBBY]

How big is the prop?

[Rc4me]

The prop is s+b octura 48x1.5

[CraigP]

[QUOTE=Rc4me;697686]I have a mgm x2 series 250a boat esc. I have the esc in a 51 rio i built. Motor is a tp 1150kv 5670. Boat ran very well, but it thermals after about 4 saw laps. I hooked up esc to computer and motor is pulling 7500 watts. The question i have is what is the continuous amp reading. There are pulse amps and input amps which are 250a. And then there are peak amps which was in the 900s im thinking ill just need a bigger esc but im going to play with stinger adjustments etc. Any help is greatly appreciated.[/QUOTE

Usually there is a running baseline, showing the boat hooked up good. This would be your Continuous amps. The spikes should not exceed the motor's max amps. Many do, but many burn things up too. In competition, you have to push lines, it's the nature of the game... This is where experience tells how much you can push.

[RaceMechaniX]

Which MGM do you have? The 25035 or 25063? 7500W on 8S per side is quite a bit of current. The peak amps are phase currents which give you some indication the ESC is working rather hard pushing those motors. The 63 series ESC's tend to very thermally safe and limit current quickly to protect against failure. I have a lot of experience with these and know the 28026 and 25035 will actually push harder than the larger 25063.
Although the current limiting is inevitable with these ESC's, providing extended cooling will help. I would recommend an additional electric water pump that can circulate coolant when you pause in between runs.

TG

[CraigP]

No doubt! I believe most people hurt their stuff as components heat soak after running. I'm building a cooler now because of the alarming temps I data logged while the boat was on the beach, after a run. With a good data logger, you'll see rpm drop and amps clip off as the current limiter kicks in. If you have throttle position charted, that can also help identify those occurrences.

[RaceMechaniX]

Although these are very expensive, they are just the ticket for cooling. They can be run off the BEC circuit when the appropriate voltage is selected or you can use a simple inline voltage regulator.

http://www.micropumps.co.uk/

Picture of the small pump in a SAW rigger with closed circuit tank. I recommend just using a normal pickup to the lake water instead of the tank. The tank heated up pretty quickly.


DSC_6219.jpg

[CraigP]

I'm making an external unit. Just a bucket, high enough to cover the rudder intakes. I have plastic polyline that will fit into the ports of the discharge block that come from the pump discharge. The pump just sits in the bottom of the bucket, like a water fountain pump. Then I run the water backwards... There's little Chinese pumps that are much less expensive. Your system starts cooling right away, a nice advantage. But that's a bit too much weight to put in the boat. I can see that tank will heat up very quickly. Anyway, we see it the same, prevent heat soak. I was amazed how high the temps shot up. It runs at speed around 105-110 deg F. It went up to 150-155! That's hot!

[Rc4me]

I have the 25035. Thanks for the info. I never knew they made electric water pumps. I have water pumps on my gassers. I know the boat was running wet. At 100% throttle the input current peaks at 251 same with pulse. Should i not worry about the peak amps? The boat would run at half speed for a couple ten seconds then id be able to take off again. Is the half speed mean the esc was limiting thw current? This is my first mgm controller the caps were the hottest items @ 190. I also have a kill mode rc 8800uf cap pack that was at 130.

[CraigP]

Sounds like both the current limiter and the over temp limiter are kicking in. Your running amps are too close to the ESC's limit. Your cap temps are way over temp! I can't comment on the reasons. Either too much prop or set up is way off.

[Rc4me]

Thanks for all the info. I got the boat to run drier by removing two packs and raising the stinger. The boat is now pulling 5000w and peak amps are at 380. Continuous amps maxed at 180. It still was running a little too wet. Batteries were at 125 after 3mins. I guess not bad for only 5000mah of 8s.