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Old 08-03-2017, 09:40 AM   #41
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Default Re: Stock electronics on 3s?

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Originally Posted by Mountainsofbeer View Post
Why are the temps lower on 3s? For reference the 2s battery I was using before was an Onyx 4000mah 25C 2s hard case battery.
Someone will likely ring in with a more thorough explanation but the short answer is this:

On 3S your motor will use more Volts at less Amps to generate the required rpms, on 2S the Volts are lower, so the Amps go higher to get the same rpm's. Amp flow is what generates most of the heat, drop the Amps = drop the temps.

At least that's my understanding of the basic overview on this issue.
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Old 08-03-2017, 12:01 PM   #42
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Default Re: Stock electronics on 3s?

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Originally Posted by QuesoDelDiablo View Post
Someone will likely ring in with a more thorough explanation but the short answer is this:

On 3S your motor will use more Volts at less Amps to generate the required rpms, on 2S the Volts are lower, so the Amps go higher to get the same rpm's. Amp flow is what generates most of the heat, drop the Amps = drop the temps.

At least that's my understanding of the basic overview on this issue.
Thanks, I did dive deeper into this and there is some good math behind it but that's why I like electricity the forumulas never get too crazy.

Now I have also had many runs on 3s since this post and basically the temps are still good under the light/medium load conditions going at a walking pace on an easy trail, even uphill. But stop at any technical spot for longer than 10 minutes and the temps spike up a reasonable amount but everything works still just fine after many 3s packs and its taken some hard falls and crashes too. My steering servo has mostly taken a dump though and seems to be even weaker. but I was lucky to have it last this long.

edit*knock on wood

Last edited by Mountainsofbeer; 08-03-2017 at 12:03 PM.
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Old 08-03-2017, 01:48 PM   #43
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Default Re: Stock electronics on 3s?

I'm not sure it's something that can be easily predicted in this situation, but from a purely electro-mechanical point of view, the truck is more powerful on 3S. More power = more heat.

If you really want to know what's going on electrically in the model, get one of these:

LCD RC High Precision Watt Meter Power Volt Amp DC Analyzer 60V 100A
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Old 08-03-2017, 06:09 PM   #44
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Default Re: Stock electronics on 3s?

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Originally Posted by NickelPlate View Post
I'm not sure it's something that can be easily predicted in this situation, but from a purely electro-mechanical point of view, the truck is more powerful on 3S. More power = more heat.

If you really want to know what's going on electrically in the model, get one of these:

LCD RC High Precision Watt Meter Power Volt Amp DC Analyzer 60V 100A
ah cool, its actually not expensive either
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Old 08-03-2017, 08:26 PM   #45
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Default Re: Stock electronics on 3s?

Heat is an electric motors worst nightmare.

You can reduce the heat by (generalities):

1. going to 3S. Higher voltage, lower amps
2. buying a mini fan for the stock motor to cool it under load. helps when adding all the weight people are adding on the stock motor but will still not help the servos.
3. reducing the load on the stock motor which means reducing the weight of the vehicle. it's funny because most people are upping the weight be it static or dynamically rotating weight. this is also one of the reasons for destroying the stock steering servo.
4. alignment/ proper gear meshing
4. put the traxxas sensor in that monitors the temp
5. going to a larger motor if you are increasing the load on the motor ie: going nuts on adding weight.

Last edited by mobgma; 08-03-2017 at 08:32 PM.
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Old 08-04-2017, 01:53 AM   #46
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Default Re: Stock electronics on 3s?

Running 2S will be cooler for the motor and ESC. I did some testing and 3S always meant more motor and ESC heat for a given load.

When using the right gear for the job, the motor shouldn't get too hot but the ESC is so underspec'd that it almost has to cook being slow crawled in hot weather. You can only push 18A so hard and it's not like it even has a fan to help out.
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Old 08-04-2017, 04:02 AM   #47
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Default Re: Stock electronics on 3s?

Good information I like this discussion!
I've worked first hand with giant DC electric motors on many ski lifts you guys would love it, they even make giant brushless ones. They responded to load more than anything else with regards to heat, the biggest load they faced was usually getting things moving from a stop kind of like the "rollout" on an RC car. They could operate around 200F but much over that wasn't acceptable because you can damage the magnet in the motor. I find it all interesting

I just switched my stock motor out to a 550 30T so far temps no issue not that I expected it would be.

My stock Titan motor never got too warm even on 3s, the esc was always the hottest then the steering servo, then the motor.

Last edited by Mountainsofbeer; 08-04-2017 at 04:04 AM.
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Old 08-04-2017, 04:56 AM   #48
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Default Re: Stock electronics on 3s?

The standard ESC is pretty poor as it only has an 18amp continuous rating.
Even the cheapo Hobbywing 1060 is rated at 60amps. Even if the 60amp rating is over estimated / overly generous it will be more than 18 for sure.
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Old 08-04-2017, 10:03 AM   #49
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Default Re: Stock electronics on 3s?

Run it on 3S and have fun, carry spare Hobbywing WP1060, WP1080 or whatever you prefer, or sell stock esc and install something else now.
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Old 08-04-2017, 10:18 AM   #50
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Default Re: Stock electronics on 3s?

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Run it on 3S and have fun, carry spare Hobbywing WP1060, WP1080 or whatever you prefer, or sell stock esc and install something else now.
Hey Natedog talk me out of this, or rather.. do you think I could fit a HW QuickRun WP esc in the trx 4? It seems like the only place is at stock esc location in between the rock slider mount and the transmission servo. I think this thing is a big square but it didn't say dimensions in on HW website or I didn't see them in the specs.

Cont./Peak Current: 80A/400A
Input*Voltage: 2-3S Lipo/5-9 Cell NiMH
BEC Output -Switch *Mode: 6V/7.4V@3A
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Old 08-04-2017, 10:27 AM   #51
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Default Re: Stock electronics on 3s?

The problem isn't Amps or Volts, it's watts. Watts are simply amps x volts, but it's how heat output is measured. Think about electric heaters, they are always measured in watts.

In the world of physics, nothing is free. If you are making more power, you are using more watts, which is more heat.
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Old 08-04-2017, 08:10 PM   #52
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Default Re: Stock electronics on 3s?

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Originally Posted by Mountainsofbeer View Post
Hey Natedog talk me out of this, or rather.. do you think I could fit a HW QuickRun WP esc in the trx 4? It seems like the only place is at stock esc location in between the rock slider mount and the transmission servo. I think this thing is a big square but it didn't say dimensions in on HW website or I didn't see them in the specs.

Cont./Peak Current: 80A/400A
Input*Voltage: 2-3S Lipo/5-9 Cell NiMH
BEC Output -Switch *Mode: 6V/7.4V@3A
I think the Hobbywing 1080 is the perfect replacement for the TRX-4
It has a 6v, 3amp BEC, lots of adjustability via the programme card and runs very cool, almost all of the time. Really smooth driving as well.

1060 is good as well but it only has a 5v, 1amp BEC so if running the 1060 on the TRX-4, i'd want to add at least a cheap 6v 3amp BEC

Both the footprint of the 1060 and 1080 is very small.
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Old 08-04-2017, 08:28 PM   #53
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Default Re: Stock electronics on 3s?

Mountainsofbeer, Hobbywing Wp1060 will fit, iirc wp1080 will too.
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Old 08-13-2017, 10:41 AM   #54
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Default Re: Stock electronics on 3s?

Hey all, I have a new TRX4 and on 3s it felt a little warm(no temp gun) the little harness plug on the side of esc, Traxxas said 6 volts, but I am installing a 25mm esc fan on to help cooling. I will measure voltage to be sure, but is live when batt plugged in. I personally don't like body cause it is top heavy, so I am going with a Proline 66 Chevy body. The weight of a fan is next to nothing and will help a lot, when I raced dirt oval we used fans all the time to keep heat down so we could gear up. Not to beat a dead horse but electronics love cold. God Bless Ya Dave
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Old 08-13-2017, 05:34 PM   #55
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Default Re: Stock electronics on 3s?

If I was going to buy a $15-20 ESC fan to cool the kind of pathetic 18A stock ESC, I'd simply reach for a HW WP 80 (1080) for $41 and be done with it. You don't have any issues where the fan is going to short out in water and cause problems for the BEC and you don't have to load an already super stretched 1A BEC in the stock ESC. If you upgrade your steering servo you're going to need another BEC too so once you add up an aftermarket BEC, fan, lack of waterproofing etc the HW is a bargain and runs cool under pressure (80A cont, 400A peak).

The HW 3A BEC is really solid and takes a decently strong Savox without any issues (no cap I run two full sized Savox servos with 277 and 208 oz/in specs plus I run BEC powered LED lights - 35 LEDs - per truck with this ESC).
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Old 08-14-2017, 03:36 AM   #56
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Default Re: Stock electronics on 3s?

Hey, after I checked the voltage it is battery volts too much on 3s for fan, I had fan already and CoolRunning, you are right, forgot about water. Hey it was worth a shot though. Traxxas was wrong about voltage. Best Idea is just upgrade stock esc when it fries. God Bless Ya All Dave
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Old 08-14-2017, 08:12 AM   #57
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Default Re: Stock electronics on 3s?

to buy a $15-20 ESC fan who is paying that much?
u don't need an special esc fan.... get a cpu fan in the size not more than 2$ or open your old unused pc
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Old 08-14-2017, 08:53 AM   #58
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Default Re: Stock electronics on 3s?

My questions is why do they sell residential/ commercial DC and AC electric motors and rate them by kW/HP but in the RC world they are rated by kV? Why no just give them a HP/kW rating?
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Old 08-15-2017, 04:03 AM   #59
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Default Re: Stock electronics on 3s?

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Originally Posted by mobgma View Post
My questions is why do they sell residential/ commercial DC and AC electric motors and rate them by kW/HP but in the RC world they are rated by kV? Why no just give them a HP/kW rating?
In the RC world rpm is more important.
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Old 08-15-2017, 08:03 AM   #60
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Default Re: Stock electronics on 3s?

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Originally Posted by Hardcoretam View Post
In the RC world rpm is more important.
But the RPM varies. Are you talking Max RPM? Then why are the motors rated in kV like Castle Creations? Why don't they just state the kW/W and Max RPM? I guess they do states how many poles it is so that tells us. Just curious because AC and DC electric motors again for residential, commercial and industrial usage are sold in watts/kW/HP and RPM.

Last edited by mobgma; 08-15-2017 at 08:06 AM.
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