Gearing and 3s lipo..I am sooo confused!

Hi All,

Recently I have been trying to get a straight answer on this and everything I read contradicts itself.

I need to know what is the ideal gearing for 3s lipo on the savage flux using the Tork 2200 and the blur esc.

Castle say use a lower than std pinion i.e 18T
Many on this site say run a 25T..as they have blown the esc at 20T on 3s
HPI customer support say lower than 20T as its easier on the esc and motor (see below response)

"Thank you for contacting HPI and Hotbodies customer service. I would recommend gearing the car down if you are going to be running the 6s lipo power, but for the 4s application stock is fine. If you use any optional pinion at 25t that will draw even more current and run hotter than the stock gearing. If you have any other questions feel free to contact me."

I h ave no clue who to believe...Does anyone really know?? Is the ESC really that fragile that is blows when teh car is geared differently ??

Or is it just poor quality control at castle??

My batteries are 45-90c 5000mah 3s lip (Turnigy). I will be using 6.5 mm connectors bullet style. Car is used for bashing not speed runs.

All words of wisdom are appreciated :)

Cheers

my youtube · Last edited by Mr.Snuggles on Wed Aug 18, 2010 3:29 pm; edited 1 time in total

well as for your lipo and bullets, you are really good.

personally i would recommend to start out with smaller pinion to lessen the amperage drawn through the esc, and if taking heat measurements and your motor/esc/lipos/wires and plugs are all fairly cold then you are good to go for bigger pinion.

what one guy says is ok could very well be a disaster for another. we all have our own driving style so as one does not have heat problems as his throttle style is calm and easy, another guy with the same setup is heating his stuff up to self destruct heats.

so start with smaller pinion and go bigger if the heat say's its ok.

x1 with snuggles

Agreed with the smaller pinion. Starting to get the heftyy Flux going with the taller ratio will draw a lot of amps also, once you have your temps in check you can easily bump up a couple teeth or more.

Hi all,

Thanks for the advice. OK I will start off by using the standard gearing 20T (but I will buy an 18T and 22T pinion) and I will monitor the temps.

What is a good termp for the motor and the ESC ?? I think I read 160F and below is OK for the motor and the esc... Is that right Smile

?

Thanks heaps guys it is greatly appreciated :)

Cheers

The ESC has a thermostat that will kick the fan on @ 150 degrees, if your geared correctly the fan should never come on. Then your definitely in the right area for max efficentcy.

The motor should never get above 160 degrees, if the motor gets warmer than this the gearing should be reconfigured and lowered. The motor will handle higher temps but it's strongly ill advised and not efficent, chances of doing damage rises quickly over 160.

Obviously, the cooler the better ?! ! !
You may sacrifice some top speed by gearing conservatively but the motor and ESC will be much happier and last indefinitely, provideing bearing maintinance and cleaning are done.

I would start off with a 20T and go from there. The thing I'm not sure about is running 3s with a 12lb MT ? I feel strongly that it'll run much more efficent on 4s power than 3s, but it's obvisously your truck and bank account.

Results from a Top speed Calculator
Differential Ratio: 3.2222222222222223
Transmission Ratio: 2.215277777777778
Other Ratio: 1
Spur Tooth Count: 44
Pinion Tooth Count: 22
Total Voltage: 11.1
Motor KV: 2200
Tire Diameter (inches): 6.0
Tire Ballooning (inches): .25
Motor Current Draw: 0
Motor Coil Resistance: 0
Spur/Pinion Ratio: 2 : 1
Total Ratio: 14.27623 : 1
Tire Circumference (inches): 20.42 inches (518.68 mm)
Rollout: 1.43:1
Total Motor Speed: 24420 RPM
Vehicle Speed: 33.08 mph (53.13 km/h)
Effective KV Value: 2200
KT constant: 0.61 oz-in/A
Motor Torque: Amperage not specified...
Final Torque: Amperage not specified...
Final Power: Amperage not specified...

if it's any help, I ran my 5.8 KG desertboy-17 with 6s and stock 20/44 gearing and had NO issues, fan never came on, BUT the 2 wires from the battery going into the esc were getting considerably warm. That's with big bullets like you have. The esc wires were the weak point on mine... which is otherwise stock electrics etc. I had no problems with the electrics on 6s, but for my all around bashing I use 5s, just because the 6s is SO MUCH POWER!!

I think your speed calc there has only one 3s battery in it.....I'm sure the fella is looking at dual 3s packs.

Hi Guys,

Thas great advice :)

How do you run 5s ??? Do you simply use 1 2s battery and 1 3s battery ??? Provided that the discharge C and mah values are the same ??

Sorry if that it is a lame question.. :)

Cheers

my youtube

yes that is how you run 5s the individual sell have to be the same in both packs.

only difference is that one pack uses three of those sells and the other two of them.

and it would be so much easier if people would refer to the total sell count of the running setup, instead of pack sell count when referring to the setup.

as the flux has two boxes, everyone knows that a six s setup is dual three and four is a dual two.

Thanks Snuggles,

Great advice from all of you. I will start of with 20T, I will keep temps below the fan cutoff point for my conditions and driving style and i will run the truck on 5s.

OK looks like I will buying 2 more Turnigy batteries 4s 45-90c 5000mah for the 5s setup. :)

I love my savage flux money pit :)

Cheers everyone


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