Red 390 motor upgrade

[windmill]

Installed red 390 motors today. Definitely kicks up performance, but also cuts run time in half with 2800 mah battery. No doubt I'll get some 3500 mah batteries to compensate.

Also noticed the motors, and the battery get significantly hotter. I already opened up the radiator shutters on the back deck, but see I need to get the fan installed. I may drill some vent holes in the battery box too.

[windmill]

Go the fan installed, motors are warm rather than hot, but it knocks run time down to around 10 minutes on low power setting. not sure the generic 2800 mah batteries I got on amazon are really as rated, they don't seem to last any longer as the OE 1800 mah battery.

[Hellcat 7]

Go the fan installed, motors are warm rather than hot, but it knocks run time down to around 10 minutes on low power setting. not sure the generic 2800 mah batteries I got on amazon are really as rated, they don't seem to last any longer as the OE 1800 mah battery.

I've read a post by Rubicon99 stating that he rips out the smoke generator which makes room to put a small fan if your willing to remove it.

[Rubicon99]

I've read a post by Rubicon99 stating that he rips out the smoke generator which makes room to put a small fan if your willing to remove it.

This is correct plus it frees up room in the rear next to motors for increased air volume and flow. The T90/72 are horrible for keeping in heat and overheating. I have melted a few parts in them just from the heat produced by 390 motors and having nowhere to go. Just so little internal air volume to move around.

Keep in mind adding a fan also means you need to seal the gap between the upper and lower hulls as the fan will draw in air through the gap which just happens to be where all the dust is kicked up by the tracks. Without sealing the hull you you will get more dust inside the tank while running the fan then you would with the fan turned off.

I have one that is sealed and one that is not. The non sealed tank’s internal hull is always covered in far more dust and dirt sucked in by the added air flow from running the fan. I can mitigated this by turning the fan off when driving and on when stopped. That said the dust/dirt have never effect is performance and or reliability. I clean it out every few months though. Somewhere on the forum I post a thread about this.

[windmill]

This is correct plus it frees up room in the rear next to motors for increased air volume and flow. The T90/72 are horrible for keeping in heat and overheating. I have melted a few parts in them just from the heat produced by 390 motors and having nowhere to go. Just so little internal air volume to move around.

Keep in mind adding a fan also means you need to seal the gap between the upper and lower hulls as the fan will draw in air through the gap which just happens to be where all the dust is kicked up by the tracks. Without sealing the hull you you will get more dust inside the tank while running the fan then you would with the fan turned off.

I have one that is sealed and one that is not. The non sealed tank’s internal hull is always covered in far more dust and dirt sucked in by the added air flow from running the fan. I can mitigated this by turning the fan off when driving and on when stopped. That said the dust/dirt have never effect is performance and or reliability. I clean it out every few months though. Somewhere on the forum I post a thread about this.

I have the fan mounted on a removable bulkhead just in front of the gear boxes, it moves a lot of air, and can feel it blowing out the radiator shutters. I have it hooked up to the fan outlet, but it runs all the time at full speed, I'm considering hooking it up to one of the motors, or both to make it proportional to the load.

[Rubicon99]

I have the fan mounted on a removable bulkhead just in front of the gear boxes, it moves a lot of air, and can feel it blowing out the radiator shutters. I have it hooked up to the fan outlet, but it runs all the time at full speed, I'm considering hooking it up to one of the motors, or both to make it proportional to the load.

Sounds like a interesting idea. Just a word of caution though. The red 390 motors draw a lot of amps compared to the stock 380 motors and the fan might not be able to handle being hooked up directly inline with a motor.

[windmill]

Sounds like a interesting idea. Just a word of caution though. The red 390 motors draw a lot of amps compared to the stock 380 motors and the fan might not be able to handle being hooked up directly inline with a motor.

I believe if I tap into each motors positive, and negative lead with a diode in each line so they don't cross feed through the fan it will be ok.

[windmill]

The fan, and removable bulkhead. Vented battery box. Modified, radiator shutters.

[Rubicon99]

The fan, and removable bulkhead. Vented battery box. Modified, radiator shutters.

Similar layout to what I did.

[windmill]

Similar layout to what I did.

I made an interesting discovery that really enhances the cooling fan function.

As I mentioned, i wasn't satisfied with the fan being hooked up to the fan port on the MFU because it runs as long as the main power is on, and at full blast.. Next I hooked it up to the wifi port which allows turning it on and off with the transmitter. As the wifi port is 6v, the fan ran a little slower which reduces its draw, but pushing the 2 keys was awkward.
I then unhooked the smoke unit, and tried the heating element port since it only needs a single key to control, but again it was running full blast when on.
Finally I hooked it up to the blower port. It puts out less voltage, and the fan runs fairly slow. I figured I'd give it a try, and see if it provided sufficient cooling at the reduced speed.

I was testing it with the sound off so I could hear the fan as I turned it on, and off. Much to my surprise I could hear the fan spool up spool when I gave it throttle, and spool down when the throttle is cut. It seems the smoke unit fan speed is proportional to throttle settings. A few test runs have demonstrated it does an excellent job of cooling the motors in this configuration, and has a minimal impact on run time.

The vent holes in the battery box have also produced positive results, although a bit less dramatic, I may add a couple more rows of holes.

[Rubicon99]

I made an interesting discovery that really enhances the cooling fan function.

As I mentioned, i wasn't satisfied with the fan being hooked up to the fan port on the MFU because it runs as long as the main power is on, and at full blast.. Next I hooked it up to the wifi port which allows turning it on and off with the transmitter. As the wifi port is 6v, the fan ran a little slower which reduces its draw, but pushing the 2 keys was awkward.
I then unhooked the smoke unit, and tried the heating element port since it only needs a single key to control, but again it was running full blast when on.
Finally I hooked it up to the blower port. It puts out less voltage, and the fan runs fairly slow. I figured I'd give it a try, and see if it provided sufficient cooling at the reduced speed.

I was testing it with the sound off so I could hear the fan as I turned it on, and off. Much to my surprise I could hear the fan spool up spool when I gave it throttle, and spool down when the throttle is cut. It seems the smoke unit fan speed is proportional to throttle settings. A few test runs have demonstrated it does an excellent job of cooling the motors in this configuration, and has a minimal impact on run time.

The vent holes in the battery box have also produced positive results, although a bit less dramatic, I may add a couple more rows of holes.

The smoke power ports are usually where I recommend drawing cooling fan power from as it can be turned on and off easily. I was under the impression you were still using the smoke system so I did not mention this.

I have used both power ports and like the heater power output more. But then I run a full sized sub “c” 9.6v 5500 mah NiMH battery in my T72/90s. Yes I removed the battery box and airsoft motor/gearbox. This allows for far more space and power options which provides for longer run times. With Red 390 motors I see about 35mins of peak performance or a half day of IR battling with fan operating continuously.

Side note: My batteries are semi hard mounted and are charged via the stock battery access hatch on the bottom of the tanks. Being NiHM it is “safe” to store and charge them inside the tank vs Lipo or Li-ion which are questionable to be stored or charged inside the tank. I prefer the use NIMH batteries for their ability to be run to an almost empty state with no ill effects, higher heat tolerance, heavier weights and stability with rapid charging.