Brushless, ESC and LiPo #confused

[Problemchild]

hello all..... given that when i ran tamiya the options were 540 then technigold (£50) then dynatech (£75) this whole brushless malarky is sooo confusing!

so i pretty much get the kv then the turns T comes into it (but only sometimes) and although i know what motor turns are i struggle to relate that to speed and power and torque

then when i look at the prices and they range from £30 to £150 

then ESCs start to come into it and another spanner gets thrown into my valve controlled brain

and finally LiPo 2s and 3s start to put things into overdrive  haha

 

so my requirement - for my bashing TT02b MS i'd like to get a lovely 50mph ish beastie like this...

but without too much into apart from 8.5T LiPo i have no idea haha

I have a few ESC

2 x sensored Tamiya ESC (http://www.modelsport.co.uk/tamiya-brushed-brushless-esc-tble-02-sensored/rc-car-products/380755) 

no LiPo (yet) but been advised that 2s would be fine (i already have 4 x 3300nimh but not sure they will be up to the job of brushless)

so some advice/guidance/options would be very much appreciated

ta

 

JJ

[Xeostar]

:-)

[Xeostar]

One other thing, you'll have to ditch those Tamiya battery connectors, they are pants. People used to fit deans but they aren't great either. I'm moving to xt60s or xt90s.

[Problemchild]

how comes?

was looking at this brand of BL 

http://www.modelsport.co.uk/speed-passion-v3.0-competition-bl-13.5t/rc-car-products/36279

JJ

[Xeostar]

Some dam fine advise you've had there hehe ;-)

Those connectors aren't up to the current draw for a brushless setup. IMO they aren't even good for 540s.

[Problemchild]

well connectors are only £1 a pair so not an issue

is the advise good or not? wink is confusing me haha

JJ

[Problemchild]

oh - thoughts.... when a T rating is given on a BL motor is this referring to the pinion??

JJ

[IBIFTKH]

Welcome to the minefield!

I'm no expert but can hopefully shed some light on some of your questions.

The T rating on a brushless motor refers to turns, not the pinion size. Lower turn number = higher rpm.

I haven't used the Speed Passion motor but there are a number of people on here who have, so hopefully someone can give you an informed opinion. I've used a few of the HobbyWing EZrun combos and been impressed. Seems good kit for reasonable money.

2S lipo is generally fine, though you'll need a proper lipo charger, charging bag and low-voltage cut-off or buzzer. (2S lipo is nominally 7.4v, 3S is 11.1v).

Sorry I don't know enough to answer all your questions but I hope this helps a bit!

cheers,

Rob

[Problemchild]

rob - fab!!

i've seen the combos and they also range from £40 to £200 .... aargh!

i've seen the charger bag (fire protection i'm assuming) and modelsport has LiPo chargers from £10

I think the ESC has the low voltage cut off built in (maybe i'm wrong)

JJ

[Jason1145]

First off, that linked Yourube video showing the TT02b is mental... Are you sure you need that much speed lol.

as a general rule I'd guess hitting 50mph would require a 3s lipo over a 2s lipo... Not that a 2s lipo can't hit 50mph but it would usually be at its limits whereas a 3s would be more comfortable ( less heat and amp draw on the lipo)

i think the TT02b has similar gearing options as the TT-02 so that means lots of choice on the pinion gear from 16t up to 25 or 26 iirc. You'll be wanting to use a high pinion on 2s I guess but it all depends on the motor kv.

if you chose a higher motor kv like 4500 up to 5700kv then 2s should be able to hit 50mph.

if you chose a lower kv motor like 3000-3500kv then I'd guess you'd need 3s to hit 50mph as 2s just won't supply enough volts (7.4 vs 11.1) without using extremely high gearing and risking overheating the motor etc.

sorry this might not help a lot but good luck in your quest!

ps, I've just put a 3300kv brushless motor in my Blitzer Beetle on 2s and it's about 40mph... But the fdr between that and a TT-02 makes comparisons irrelevant etc 

[Effigy3]

2 hours ago, Problemchild said:

hello all..... given that when i ran tamiya the options were 540 then technigold (£50) then technisport (£75) this whole brushless malarky is sooo confusing!

so i pretty much get the kv then the turns T comes into it (but only sometimes) and although i know what motor turns are i struggle to relate that to speed and power and torque

then when i look at the prices and they range from £30 to £150 

then ESCs start to come into it and another spanner gets thrown into my valve controlled brain

and finally LiPo 2s and 3s start to put things into overdrive  haha

so my requirement - for my bashing TT02b MS i'd like to get a lovely 50mph ish beastie like this...

but without too much into apart from 8.5T LiPo i have no idea haha

I have a few ESC

2 x sensored Tamiya ESC (http://www.modelsport.co.uk/tamiya-brushed-brushless-esc-tble-02-sensored/rc-car-products/380755) 

no LiPo (yet) but been advised that 2s would be fine (i already have 4 x 3300nimh but not sure they will be up to the job of brushless)

so some advice/guidance/options would be very much appreciated

ta

 

JJ

So many questions!  What I think you're ultimately asking is how can you replicate the performance you saw in the video with your TT-02B.  I'll do my best to explain the points and questions you listed with an eye to your ultimate goal.

There are a number of variables that comprise an R/C power train and resultant performance.

1. Battery
2. ESC
3. Motor
4. Drive-train

These all factor into resulting performance but there are couple of overarching concepts that must be simultaneously considered:

1. Durability
2. Drive-ability

Battery

I think of the battery as my rigs potential energy (measured by voltage).  The more potential energy you have on tap the better.  NiMh batteries are heavy when compared to LiPo which impacts power-to-weight ratio. NiMh do have a higher peak output when used off a fresh charge but they drop voltage quicker resulting in a more variable driving experience.  Battery connector can be an issue.  Tamiya connectors are not rated to withstand the amperage associated with newer motors.  As a result they can, and do melt.  Personally I won't use a Tamiya connector but if you choose to, I suggest that you do so only on a 7.2V NiMh and a silver can.  Deans connectors are probably the most popular but I think the XT60 (and XT90 for 1:8th scale) are probably the best choice.  Castle connectors are also interesting as are Traxxas.

ESC

I think of the speed control as the flood gate valve (measured by amperage).  It controls how much of the batteries power is sent to the motor.  A lot now happens in this stage.  How much power is lost in the form of heat?  How well does the ESC disperse this heat?  MSCs had resistors, ESCs have heat sinks and sometimes fans.  How smoothly does the ESC deliver the power?  How well does the ESC manage the brakes?  Old school MSCs were a two or three stage affair with reverse.  VERY basic.  ESCs do so much more! There is modulation, boost, an an infinitely larger number of stages and power delivery curves.  They also have BRAKES!  You can change all of these variables on the best ESCs.

The TBLE-02S is a decent but basic speed control.  Some power is lost to heat compared to other speed controls but the TBLE-02S is buttery smooth which is all most bashers really notice.  The biggest drawback IMHO to the TBLE-02S is that it does not have a low voltage cutoff that is compatible with LiPo batteries.  The low voltage cutoff is designed for LiFe batteries common in Japan.  If you run a LiPo down to a LiFe cutoff level you will destroy the LiPo.  The only solutions are a ) not run LiPo with Tamiya ESCs  b ) get a LiPo battery checker/alarm and connect it to the battery during operation.  The alarm will sound when the voltage has hit bottom alerting you to cease operation or risk damage.  They are cheap: <$10.

Motor

I think of the motor like a guy pedaling a bike.  It's taking the potential energy that the ESC has passed on from the battery and converts it into kinetic energy.  There are two types of kinetic energy that you must keep in balance: torque and RPM.  Since a cyclist has the luxury of changing gears that our R/Cs do not this balance is super important.  Too much torque and you sacrifice top speed.  Too high RPM and your acceleration will be abysmal.  Gearing is your best friend to achieve the performance you desire but many rigs have as few as only two gearing options.  Use temperature as your guide.  Get a laser thermometer and check the end bell and can every few minutes.  Keep the temperature between 140 F and 160F.  Any cooler and you're leaving performance on the table.  Much hotter and you risk damage to the motor.  Excessive heat can and will demagnetize the motor.

Brushless motors are the wave of the present.  Brushed motors still have their place in our hobby but IMHO powering a modern R/C is frequently not one of them.  There is so much that can be said about brushed vs. brushless I won't go into it here.  The power output of a brushless can be measured in Kv which is likely the most accurate but it doesn't relay the ratio of torque to RPM.  In off road racing a 17.5T brushless is considered "stock".  A 13.5T is considered "super stock".  In on-road racing a 25.5T or a 21.5T are considered "stock".  10.5T and lower are considered "mod".  Those are just the sensored motors using a 540 rotor (as indicated by the .5 in the turn count).  You'll see whole number brushless motors like 20T.  This motor uses a 380 size rotor in a 540 can.  I suggest that you avoid these.  Keep in mind that ESCs are rated for certain amp draws and turn counts.  Ensure that the motor you choose to use falls within the ESC rated capabilities.

Typically as the turns of the motor go down, the RPMs go up but the torque goes down.  Higher RPMs mean higher top speeds.  Lower torque means slower acceleration.  Find a balance for your car, gearing, and driving conditions.  Note that in the video the dude was driving on pavement.  I would think that an 8.5T motor in a TT-02B would be a bit much in dirt, on a track, or in grass.

Drive Train

This is mostly transmission and gearing.  A ton can bed said of this as well but I'll keep this short and focused on the TT-02B.  First off, as you might already know, the gear box of the TT-02B is plastic and can't really handle much more power than the Torque Tuned motor that comes with the kit.  I ran a Super Stock BZ in my daughters TT-02B Pink special edition.  The teeth of the gears were shredded within a dozen battery packs.  The BZ was also outside of the TBLE-02S range.  Once the ambient temps went above 75 degrees the ESC would thermal lock to protect itself.    I replaced the gears, swapped out the BZ for a 13.5T brushless and it works like a champ!  If you plan on ramping up the speed in your TT-02B you really should consider upgrading the rear gearbox with the DF-03 mod (as detailed in a number of threads here) or the GPM metal gear hop-up.  You also should use the metal motor mount and a steel pinion.  The aluminum drive shaft would be good but many people find that the stock one holds up just fine while others report flexing under power which can result in chassis slapping during hard acceleration.

Conclusion

Anyone can strap an insane motor and massive battery into their rig and have a rocket.  IMHO that's an inelegant solution which results in a completely unbalanced rig which will most likely be uncontrollable and prone to break downs.  If you want a suggestion for your TT-02B based on my personal experience that will result in a fun, balanced and seriously quick rig, here it is:

• LRP Spin Super ESC
• Speed Passion 10.5T Competition v3.0 MMM motor
• Any decent brand 2S, 5000 mAh LiPo with Deans connector
• Do the DF-03 gear box mod or install the GPM metal gear hop-up

Good luck with your TT-02B rocket project.  May it not go the way of Elon Musks Space-X recent launch attempt. 

 

[Problemchild]

jason thats all excellent info

i want fun - 50mph isn't essential 

the TT02B is currently running the 3300nimh and a firebolt 15Turn brushed and its fast but not quite there

i have a 20T pinion on its way, yeahracing motor mount and a highspeed spur 

the speed passion is slightly tunable - thoughts??

JJ

[Effigy3]

2 minutes ago, Problemchild said:

the speed passion is slightly tunable - thoughts??

JJ

All sensored brushless motors have adjustable timing on the endcap.  The nominal boost often set at the factory is 30 degrees advance timing however my Atomik Redline motors came set to 0 degrees.  You need to be careful with adjusting the timing.  If you advance too far you will really build heat exponentially and can even start cogging because the timing is off.  There are ways to set optimum timing to get max power out of each motor.  You see, the optimal timing point varies from motor to motor.  So while 30 degrees is a nice rough estimate, some may reach peak  power output at 20 while others might need to go all the way to 40 or 50.  This dude has it down to a science!

 

[Problemchild]

god thats complicated haha! i remember my dynatech motor was the same.....all i knew was the battery died really quickly if fully rotated ha

JJ

[Effigy3]

I'm charging up my daughters TT-02B right now.  Her car has a 13.5T motor with timing set to 0 degrees, a TBLE-02S ESC, Duratrax Onyx 5000 mAh NiMh battery.  Stock plastic gears.  I have the GPM metal gear hop-up in my parts box that I'll install if/when the stock gears shred again.  I'll do a short run time video of it with a full speed fly-by so you can see what her buggy looks like running with this configuration.

[Problemchild]

21 minutes ago, Effigy3 said:

 

Conclusion

 If you want a suggestion for your TT-02B based on my personal experience that will result in a fun, balanced and seriously quick rig, here it is:

• LRP Spin Super ESC
• Speed Passion 10.5T Competition v3.0 MMM motor
• Any decent brand 2S, 5000 mAh LiPo with Deans connector
• Do the DF-03 gear box mod or install the GPM metal gear hop-up

Good luck with your TT-02B rocket project.  May it not go the way of Elon Musks Space-X recent launch attempt. 

 

fan- -tastic

the gear box mods were on my to do list (just researching it more)

thank you lots

JJ

[Effigy3]

Oh, not sure where in the world you are, but the Speed Passion US direct warehouse has this combo available that would be perfect IMHO.  Since it's Labor Day, you can get 20% off using code:  LD2016

[Effigy3]

OK, here's the video I took.  The battery was minutes off the charger.  My 9 year old was driving it and I was recording.  You can clearly see that it's not as spry as the Neo Scorcher in the video you posted.  IMHO the 8.5T is a bit over powered for this chassis and a 10.5T is as low as I'd recommend going.  On the smooth the 10.5T would be fun but not over powered.  In the rough I think the 13.5T would be a better match for the chassis.  Of course it's all personal opinion. 

 

[Problemchild]

good vid and love the colour of the pink one

BUT

my TT02B MS is already quicker than that with brushed and nimh

 

i'm in the UK - entered the details on my profile when registering - will try again

JJ

[Xeostar]

5 hours ago, Problemchild said:

well connectors are only £1 a pair so not an issue

is the advise good or not? wink is confusing me haha

JJ

Hehe the wink was because its me Pete :-)

I've never used sensored motors, all mine have been sensorless but those speed passion ones are the cheapest censored ones and I think they're ok. Its quite a big jump up for any others as sensored ones tend to be used for racing and people don't mind spending £ on those.

A 10.5t with 2S will be plenty quick, maybe too much for the chassis if what others have said is right. You'll need smallest pinion with biggest spur if you get one.

What charger you using? Do you need lipo one?

 

[Xeostar]

This is my BLACKFOOT with a 5.5T Ezrun which is hilarious but fairly uncontrollable.

[Problemchild]

 cheers pete haha

i do need a LiPo one if I go there BUT they aren't a big outlay

people have been v surprised at the speed of the car already so maybe i'm throwing good money into a few mph more

maybe i should see what speed the car is doing as is..... surely there must be a gps speed app for the iphone (plus a load of bubble wrap haha)

so (on top of all the parts already coming) i think my shopping list currently is.....

1 x 5000kv brushless (£30)

1 x 5000mah LiPo 2s + charger (£40 or same price for 2x on ebay)

1 x LiPo low charge alarm (£3) think i will try the tamiya ESC 

and try and work out this metal diff set up (£30 - or £34 if i get the gpm 8 piece kit specially for the TT02)

JJ

 

 

[Xeostar]

Is it all ball raced too?

[Problemchild]

yeah - its the MS so

• TT-02 Aluminum Propeller Shaft
• TT-02 Aluminum Propeller Joints
• TT-02B FRP Front Damper Stay Set
• TT-02B FRP Rear Damper Stay Set
• TT-02 FRP Battery Plate & Transponder Stay Set
• DF-02 Two-Way Aluminum Rear Uprights
• Full Ball Bearings

JJ

[Jason1145]

I don't think you can beat the cheap EBay combos around at the moment if you want a plug n play brushless motor and ESC... Like these ones here:

3000kv

http://www.ebay.co.uk/itm/SKYRC-13T-3000KV-Brushless-Motor-60A-ESC-5V-2A-BEC-Program-Card-Combo-V4Q6-/262297491681?hash=item3d122618e1:g:m4wAAOSwDuJWxomz

 

 

3930kv

http://www.ebay.co.uk/itm/SKYRC-10T-3930KV-Brushless-Motor-60A-ESC-Program-Card-Combo-RC-Set-C0P4-/272316761218?hash=item3f67580482:g:P1MAAOSwSv1Xkfc0

These come with deans connectors and all motor wires pre soldered so you only have to locate them in the chassis and programme them as you wish ( lvc, punch, drag brake etc)

But these are the smaller 380 sized rotors in 540 size cans so some people don't like to use them, I think they might be ok for these lightweight Tamiya's though, but not in heavier 1/10 short course trucks etc.

just throwing some ideas out there. With of those two systems would be happy on 2s, a GPS top speed recorded and a heat gun are handy tools to have too. ( I've destroyed an Iphone using it as a GPS, never again!)