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Can I have some help clearing up some things?

Old 12-29-2013, 04:34 PM
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-JINGO-
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Default Can I have some help clearing up some things?

Hello RC Universe,

I picked up the DHK Wolf BL:
http://www.rcuniverse.com/magazine/a...rticle_id=1498

Specification of power system:

Brushless 3650 3970 KV motor (power 21 volt / empty load current 2 amp 10 awg cables)
Toro brushless sensor-less 35 amp ESC (10 awg cables)
7.4 v 2S 2300mah 20c lipo battery (10 awg cables)

There's a lot of conflicting information on the web and You Tube videos. These are the current assumptions I'm under:

1) Having a higher C rated battery is better?
- I'm working on the thought that MAH is the size of the "fuel tank" and the C is the "size of the pipe to allow the fuel out". The Motor will only pull what is required up to it's maximum amperage rating. I don't know what the Wolf BL motor wattage is. It's not in the instructions, so I can't work out it's amperage. In the manual there's nothing either, just the above 21 volts.

The wolf came with a basic 7.4 v 2S 2300 mah 20C lipo. I understand you do 7.4v X 2.3a = 46 amps continuous amperage. Possibly a burst of 40 c is 92 amps. Again, C could be a randomly assign "best guess" by the manufacture.

I put in a friends Reedy Wolf Pack 7.4 v 2S 6500 mah 25c lipo and ran the car hard for about 10 to 15 mins. Went on clay and gravel onto tarmac and jumped ramped kerb a few times. There was no "magic white smoke" and the engine didn't feel as hot to touch. I'm going to invest in a IR thermometer to take some readings.

The battery had already run my friends RC for good while before putting into mine. The 6500 mah definitely makes a differences compared to my 2300 mah.

The wolf power system uses 10 awg cables. I noticed the Reedy Wolf Pack has 14 awg cables. Should I be worried about that? The bigger cables meaning they're better suited to the power flow?

2) ESC amperage doesn't worry about C rating?
- The ESC and Motor amperage is the important rating. I've read and watched that you'd want a ESC with about 10 to 20% more amperage than your motors maximum. So a 50 amp motor, you'd match a 55 amp ESC or a 60 ESC. I've read that putting a 80 amp ESC on a 50 amp motor would and could cook and kill a motor?

The Wolf BL has a 35 amp ESC. Using what I've read and watched, it could mean my motor might be 30 amps? (21v X 30a = 630 watts motor? It's a 3970 KV which is 29378 rpm motor (or there abouts))

I'm waiting on an email from DHK. So far they have answered all my emails. My most recent about engine wattage is un-answered. Probably due to Christmas and New Year holidays

But, I got aother conflicting piece of information in another video on You Tube. A guy had a battery which put out 33 amps continuously and was using a 25 amp ESC. He said it's a no no and swapped in a 45 amp ESC and said that's better!? That confuses me...I have a 35 amp ESC with the out of the box 46 amp continuous amp lipo...

3) The RTR power system could be close to it's max already?
- All in all being a ESC at 35 amps with a 20C lipo and a motor I can't figure wattage / amperage of. The set up could be at it's edge already and putting more C through it could push it beyond and cook it?

In the manual the ESC specs has a motor rating column with 35C and 35A side by side. That leads me to believe I could use up to 35C discharge batteries? The next rows have 45C / 45A and 60C / 60A and finally 120C / 120A ESC specifications with batteries and turn ratings.

Having a higher C apparently keeps the power system cooler as well and gives a longer battery life?

Again, conflicting information tells me that a higher C could also damage or cook components. But it's the motor pulling the amps, not the battery pushing. So this confused me as well.

-----

Ultimately what I'm after is a bit more "fun". I'd like my car to last longer when just playing on the tarmac and gravel carparks. I don't want to burn out or cook it. I'm not afraid to try things though and do more reading and learning. I'm actually finding this part of the hobby as fun as the racing. I work in a technical job, so numbers and reading / learning are interesting to me.

If you got this far thanks, I appreciate you spending your time reading this and hopefully you can clear some things up for me.

Happy New Year
Old 12-29-2013, 06:04 PM
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Originally Posted by -JINGO-
Hello RC Universe,

I picked up the DHK Wolf BL:
http://www.rcuniverse.com/magazine/a...rticle_id=1498

Specification of power system:

Brushless 3650 3970 KV motor (power 21 volt / empty load current 2 amp 10 awg cables)
Toro brushless sensor-less 35 amp ESC (10 awg cables)
7.4 v 2S 2300mah 20c lipo battery (10 awg cables)

There's a lot of conflicting information on the web and You Tube videos. These are the current assumptions I'm under:

1) Having a higher C rated battery is better?
- I'm working on the thought that MAH is the size of the "fuel tank" and the C is the "size of the pipe to allow the fuel out". The Motor will only pull what is required up to it's maximum amperage rating. I don't know what the Wolf BL motor wattage is. It's not in the instructions, so I can't work out it's amperage. In the manual there's nothing either, just the above 21 volts.

The wolf came with a basic 7.4 v 2S 2300 mah 20C lipo. I understand you do 7.4v X 2.3a = 46 amps continuous amperage. Possibly a burst of 40 c is 92 amps. Again, C could be a randomly assign "best guess" by the manufacture.

I put in a friends Reedy Wolf Pack 7.4 v 2S 6500 mah 25c lipo and ran the car hard for about 10 to 15 mins. Went on clay and gravel onto tarmac and jumped ramped kerb a few times. There was no "magic white smoke" and the engine didn't feel as hot to touch. I'm going to invest in a IR thermometer to take some readings.

The battery had already run my friends RC for good while before putting into mine. The 6500 mah definitely makes a differences compared to my 2300 mah.

The wolf power system uses 10 awg cables. I noticed the Reedy Wolf Pack has 14 awg cables. Should I be worried about that? The bigger cables meaning they're better suited to the power flow?
Ok to calculate the max current the battery can output....
7.4v 2S 6500mah 25c lipo
first u devide the mah by 1000, then times it by the c rating
6500mah / 1000 = 6.5a
6.5a x 25c = 162.5a.... Meaning that battery can supply 162.5 amps continuously

mah = how long ur run time will be
c = its a multiplier thats used with the mah rating to calculate the max current draw
Old 12-29-2013, 06:26 PM
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Ok so ur battery can supply 162.5 amps

And ur ESC can supply 30a continuos... They don't list the burst current tho.... But I would assume its around 190a

there is absolutely no way it's going to draw over 100a in any situation, so u are safe there (the little 25a toro puts out 90a burst)

that at motor will pull....
3970kv x 7.4v (2s lipo) 29,378rpm
i would need the motor specs to calculate the maximum amp draw it can handle
Old 12-29-2013, 06:31 PM
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Here is a video I made a while back, its a very similar setup.
It should give u an idea of the watts, volts and amps do under load.

http://youtu.be/xbQcM_qJ5C4
Old 12-30-2013, 12:42 PM
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Hi phmaximus,

Thanks for all the information.

The motor wattage and amperage are the unknowns to me. In the manual it has motor specifications as:

21 volts power
11 ohms resistance
2 amp empty load current

I've emailed DHK asking for the wattage of the motor.

So basically the ESC and Motor will have amperage ratings. The ESC will need to be higher, but not by too much, amperage than the motor to support it's draw. The C of the battery doesn't matter. That's just how much current it can supply and the mah is for how long it can supply that.

In your video I've seen that small in-line device which does the measurements. I wouldn't mind one of those to check. This is the hobby I want to get into so I'd like to build up a tool kit.

Cheers

Jingo
Old 12-30-2013, 06:06 PM
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I have a Raz-r, same thing with a truggy body and truck wheels. Three of us have them. All of use use the 25c 5000mah 2s batteries. When we get together we do run them pretty hard. Never had an issue with the motors or ESC yet. We went through 5 of the 5000mah batteries and a couple of the 2300 batteries in a short time. Never did let them rest. Changed the batteries, handed the Tx to some one else and they ran it. The setups in this car are not going to pull enough to need a 50c battery. For giggles I ran mine with my 1300mah 50c battery. Nothing changed except run time.

When we changed the rims and tires to a new set of Gladiators, we did see a small rise in motor temps. The tires do not slip or slide, they grab like velcro.

You can get a watt meter that will not break the bank. Seems they are out of stock

http://www.hobbypartz.com/aeo-p0-watt-meter.html

Or here

http://www.hobbyking.com/hobbyking/s...eter_100A.html

http://www.hobbyking.com/hobbyking/s...Analyzer_.html

Sounds like you have it pretty much figured out.


Buzz.
Old 12-31-2013, 09:39 PM
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BIG AL HBX BONZER
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Gday phmaximus sounds like you know a but about power systems can you tell me if my HBX bonzer would run a 2s lipo ok with stock running gear?
Old 12-31-2013, 10:11 PM
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Originally Posted by -JINGO-

- The ESC and Motor amperage is the important rating. I've read and watched that you'd want a ESC with about 10 to 20% more amperage than your motors maximum. So a 50 amp motor, you'd match a 55 amp ESC or a 60 ESC. I've read that putting a 80 amp ESC on a 50 amp motor would and could cook and kill a motor?
On this no it doesn't matter if its 10-20% more
most my ESC's are 60A paired with motors of same amperage.
Now going higher on the ESC Amperage is no issue as it will only supply what the motor asks for. Only time you can run into issues is if you do the opposite, and pair a higher amp rated motor with a lesser rated ESC as the motor will ask for more then the ESC can deliver, and smoke it.
Basically if you have a 50A motor on a 80A ESC, and smoke the motor its due to poor gearing honestly if a 50A ESC was used with the 50A motor that burnt up it too probably woulda went up in flames.
Now overkill like that is also not a good thing as you are wasting money for the most part
I will be honest I do run a 100amp motor in my Stampede coupled with a 120A ESC. But that was not done to try an outdo the motor. It was done cause I never heard of a 100A ESC Same thing with say a 50A motor you pair it with a 60-65A ESC cause there are ESCs in that rating there are no 50A ESC's I know of, and you cant go down to 45A without risking smoking it.
I've also ran a 10-15A BL motor on a 35A ESC cause its what I had laying around with 0 repercussions (along with batteries that could deliver 150A's of juice )
Old 12-31-2013, 11:09 PM
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Originally Posted by BIG AL HBX BONZER
Gday phmaximus sounds like you know a but about power systems can you tell me if my HBX bonzer would run a 2s lipo ok with stock running gear?
Yes it will work with a 2s lipo.... but there are 2 issues
1, Finding a battery that will fit without been expensive
2, there would be no LVD, or LVC. So there is nothing to prevent the lipo discharging to much. I would recommend connecting a NOVAK 2s Smart Stop to the receiver.... or u could get a little $3 buzzer with built in display that BUZZES when the lipo is going flat, and plugs into the batteries balance plug.
Old 12-31-2013, 11:21 PM
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Originally Posted by -JINGO-
Hi phmaximus,

Thanks for all the information.

The motor wattage and amperage are the unknowns to me. In the manual it has motor specifications as:

21 volts power
11 ohms resistance
2 amp empty load current

I've emailed DHK asking for the wattage of the motor.

So basically the ESC and Motor will have amperage ratings. The ESC will need to be higher, but not by too much, amperage than the motor to support it's draw. The C of the battery doesn't matter. That's just how much current it can supply and the mah is for how long it can supply that.

In your video I've seen that small in-line device which does the measurements. I wouldn't mind one of those to check. This is the hobby I want to get into so I'd like to build up a tool kit.

Cheers

Jingo
Im using a G.T. Power Wattmeter as far as I can tell, this one is the same...
http://hobbyking.com/hobbyking/store...dProduct=10080

yes ur right the motors to have ratings, but they only really only list maximum ratings, witch are kind of useless

generally manufacture's just list a turn limit.....
is this ur ESC?

http://www.agmhobby.com/toro-one-cel...112-p-618.html
[TABLE]
[TR]
[TD="width: 228, bgcolor: #ffffff, colspan: 2"]Controls, TORO 1/10 1/12 Scale[/TD]
[TD="width: 580, bgcolor: #ffffff"]Fwd/Rev or Fwd/Brk[/TD]
[/TR]
[TR]
[TD="width: 228, bgcolor: #ffffff, colspan: 2"]Input Power (Cells)[/TD]
[TD="width: 580, bgcolor: #ffffff"]1-2S LiPo/LiFe, 3-6 NiMH (8.4V Max)[/TD]
[/TR]
[TR]
[TD="width: 228, bgcolor: #ffffff, colspan: 2"]Motor Type[/TD]
[TD="width: 580, bgcolor: #ffffff"]Sensored and sensorless Brushless Motors[/TD]
[/TR]
[TR]
[TD="width: 60, bgcolor: #ffffff"]Motor Limits[/TD]
[TD="width: 156, bgcolor: #ffffff"]1S LiPo or 3-4S NiMH)[/TD]
[TD="width: 372, bgcolor: #ffffff"]≥3.5T (1/12 on- road) [/TD]
[/TR]
[TR]
[TD="width: 156, bgcolor: #ffffff"]2S LiPo or 5-6S NiMH)[/TD]
[TD="width: 372, bgcolor: #ffffff"]≥4.5T (1/10 on-road), ≥6.5T(1/10 off-road)[/TD]
[/TR]
[TR]
[TD="width: 228, bgcolor: #ffffff, colspan: 2"]BEC Output[/TD]
[TD="bgcolor: #ffffff"]6.0V 1A, Built-in BEC with set-up DC/DC booster for 1 cell LiPo racing[/TD]
[/TR]
[TR]
[TD="width: 228, bgcolor: #ffffff, colspan: 2"]Status LED (2 LEDs)[/TD]
[TD="width: 580, bgcolor: #ffffff"]White LED, 3 color LED (Red, Green & Orange)[/TD]
[/TR]
[TR]
[TD="width: 228, bgcolor: #ffffff, colspan: 2"]Thermal Overload Protection[/TD]
[TD="width: 580, bgcolor: #ffffff"]Yes[/TD]
[/TR]
[TR]
[TD="width: 228, bgcolor: #ffffff, colspan: 2"]Compatibility[/TD]
[TD="width: 580, bgcolor: #ffffff"]Sensored Brushless Motor or Sensorless Brushless Motor[/TD]
[/TR]
[TR]
[TD="width: 228, bgcolor: #ffffff, colspan: 2"]Dimensions(L*W*H/without fan)[/TD]
[TD="width: 580, bgcolor: #ffffff"]36.5*42*18mm(1.44*1.65*0.71in)[/TD]
[/TR]
[TR]
[TD="width: 228, bgcolor: #ffffff, colspan: 2"]Weight(Without wires)[/TD]
[TD="width: 580, bgcolor: #ffffff"]34g(1.20oz)[/TD]
[/TR]
[/TABLE]
Old 12-31-2013, 11:27 PM
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just looking.... I suspect that motor is a 380 size motor in a 540 housing....
meaning it would be aroung a 10t motor
Old 01-02-2014, 12:06 PM
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Just my 2 cents: The C rating of a battery is only "important" if you know your motor system is going to pull large amounts of current (amps). OR if you notice that the 20C packs you're using are getting HOT under normal running conditions. If the motor and ESC temps are normal (ESC <125F , motor <170F) but the battery is getting over 110F, the battery pack could be getting stressed by the system trying to pull more current than it can deliver. In that case, going to a higher C-rated pack will give you a pack that will have a longer useful life because it won't be getting so hot. Electronics + Heat = Bad
Old 01-02-2014, 02:02 PM
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Happy New Year eveyone.

Thanks for all this information all of you. Really appreciate it.

This is my manual:
http://www.hobbypeople.net/media/upl...L_Raz-R_BL.pdf

Mine is a Toro Brushless / Sensorless 35 AMP ESC with built in linear BEC (5 Volts / 2 Amps) and a fan on top.

2S Lipo On Road ≥ 10.5T Off Road ≥ 13.5T

Last night I just blasted up and down an empty new housing section road. ESC limiter kicked in at about 15mins as battery ran down. I checked the temp, hot to touch on motor, but not pull away burning. ESC was cool as the fan was on and 20C 2300mah 2S lipo pack fine.

I'm going to invest in a IR thermal gun soon.

I think I'll be OK with a 6500 mah 25c 2s lipo pack.
Old 01-02-2014, 03:08 PM
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Wow, 15min of run-time from a 2300mah battery is pretty good. Sounds like it's setup pretty well. If you can hold you finger on the motor for 2-3sec, you're certainly in the ballpark.

Two things to keep in mind: All temp guns are not created equal. Try to buy the best you can afford, preferably with a good recommendation. And check that your battery compartment can fit the 6500mah pack. The higher 2S lipos get from 5000mah it seems, the THICKER they get. You can buy 2S packs of 10,000mah, but it's as thick as a 3S. Have fun!!

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