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daddycool

DF03 - how to get more top speed

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Hi I have a brushless 13.5t motor and esc (trackstar) with 29/78 spur/pinion which seems to be the lowest final drive I can get. The motor barely gets warm so there’s potential. I have a new 5000nimh battery. Is there anything I can do with the spur/pinions? I have a programmable ESC but no card so perhaps I can open up something there? I’m reluctant to go to LIPO as I only use my cars once every couple of months and storage sounds like hassle, not to mention the associated fire hazard.

Thanks, Kris

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You should reconsider LiPo - I use mine very rarely (like over a year between runs) but the packs never seem to give me any problems.

Get a charging bag and a proper balancing charger and you should be fine. Full disclosure - I have had a LiPo fire - but it was because I was being stupid and not charging it properly (trying to cut corners).  It hasn't put me off though.

Higher power + lighter = more speed. Longer run times too...I would never go back to nimhs now.

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Just now, Gruntfuggly said:

You should reconsider LiPo - I use mine very rarely (like over a year between runs) but the packs never seem to give me any problems.

Get a charging bag and a proper balancing charger and you should be fine. Full disclosure - I have had a LiPo fire - but it was because I was being stupid and not charging it properly (trying to cut corners).  It hasn't put me off though.

Higher power + lighter = more speed. Longer run times too...I would never go back to nimhs now.

While I second this suggestion, a word of warning: Most lipos won't fit in the DF03 battery enclosure, because it's tight and curved. You'd need to find LiPos that are shaped like NiMH batteries.

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I use a 3s Floureon on my brushless

the speed increase is bonkers 

this HAS to be your next step for next speed

motor rpm can go up 20% with a LiPo 

they are able to deliver power so much quicker 

A charger can take the pack to storage voltage or disposal voltage as well as balancing 
 

a LiPo alarm is £1 

2 x 3s LiPo is £25

 

JJ

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It’s tempting. How does the capacity work with LIPOs? For example equivalent of a 5000nimh. 

Do LIPOs lose voltage in storage?

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Same - it’s the amount of leccy it can deliver in an hour 
 

each “s” is 3.7v so a 2s is 7.4v and a 3s is 11.1v

the C value is about continuous draw so a 5000mah battery with 20C would be 5000x20 = 100,000 mA = 100amps

this is also considered for charging 

charging is easy and balance charging just means the charger charges all 3 “cells” to the same level so you plug the battery connector in and the balance lead 

it’s really easy tbh but not quite as easy as nimh BUT you will not get the speed you want unless you go LiPo 

my tt02b wheelies on 3s LiPo and rips tyres from the rims haha


watch this vid for proof that you need 3s

JJ

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3 hours ago, Problemchild said:

I use a 3s Floureon on my brushless

the speed increase is bonkers 

this HAS to be your next step for next speed

motor rpm can go up 20% with a LiPo 

they are able to deliver power so much quicker 

A charger can take the pack to storage voltage or disposal voltage as well as balancing 
 

a LiPo alarm is £1 

2 x 3s LiPo is £25

 

JJ

3s 11.1. 4500? 

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Also get the program card, dynamic timing is like magic. You need lipo if you do though, NiMH will get to the point where it just can't deliver the required power

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75/32 is the tallest gear set I've been able to get for the Dark Impact.

Next step for taller gearing is wheels, I've gone with Dboots Hoons, and needed a 12-17mm spigot adapter (don't use the 17mm hex ,with a 12 cut out,  they foul, and there's only a thread to get a nut on) 

Current top speed record - with the old, Maverick,  wheels/tyres is 103kph, but had to back off ,because the tyres ballooned and became difficult to control. Hopeing these new boots will help, rated to 115mph.

 

2020-05-14_05-59-14

 

Just adding a Lipo will transform any car, just going from a 7.2 nimh to a 7.4 Lipo will add another volt to the mix, as nimh's volts drop like a stone, aswell as being able to give the Amps a motor need a for power.

As technology progresses, there's less and less fires with a Lipo, and 99% of the time, if there is a fire, it's when they're getting charged.

In the early days battery tech and people's lack of knowledge ,caused fires, people letting them drop below 3v per cell, but it's ok- just charge it on nimh for a bit, or even ,Parellel charging a few at once!

If you get a decent charger, a decent New battery, a decent charge bag ,bought from a reputable supplier (ie,not eBay!) plus maybe an, ammo box (seal removed) ,you shouldn't have any issues.

 

 

 

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Now, what about changing the pinion/spur combo to Mod 0.6? A TB05 63T spur on a Hi-Speed Gear Centre from a TT02 and a 28T pinion may fit under the gear cover and would give an FDR of 6.88, better than the current best FDR of 7.16. It's got to be worth a try to get a handful more kph. 🤷‍♂️

Just trying to think outside the box...

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3 hours ago, Jonathon Gillham said:

Also get the program card, dynamic timing is like magic. You need lipo if you do though, NiMH will get to the point where it just can't deliver the required power

I was looking at the motor and see timing marks, tempted to advance it a couple of steps and see what’s what. I did read theres a balance between speed and power (too much timing will use power without giving you any more speed). Think that may have been one of your posts!

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4 hours ago, daddycool said:

I was looking at the motor and see timing marks, tempted to advance it a couple of steps and see what’s what. I did read theres a balance between speed and power (too much timing will use power without giving you any more speed). Think that may have been one of your posts!

Yeah definitely worth advancing timing on the motor endbell. While you dont have the program card put it up to about 3/4 of max and check the temperature of the motor after a run. It should be able to go even higher. When you get the program card then dial back the endbell timing and program it in the ESC

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On 5/17/2020 at 1:27 PM, daddycool said:

I’m reluctant to go to LIPO as I only use my cars once every couple of months and storage sounds like hassle, not to mention the associated fire hazard.

LiPo lasts about a year before you need to do a "storage charge." By then NiMH would die.  So LiPo is actually easier to store.  

Also, if you are using 13.5t, it uses 2A steady, 5-6A burst. Most NiMH can barely do 2A. But LiPos don't have trouble supplying 10A.  It's not about how many mAh you have. It's how quickly the battery can discharge. You can have 8,000mAh battery that drains only at 1A.  Or you can have 2000mAh battery that drains at 10A.  

Right now, your motor and ESC want to use more current, but the NiMH is simply not giving out as easily.  Especially on acceleration.  If you switch to LiPo, you will notice the oomph.  It's not earth shattering, but you are currently bottle-necked at the battery/connector. Which is one of the reasons why things are cooler. Think of running it at 4 volt. It will stay cool.  It's the same with current. Weak current = less RPM = less heat.  Tamiya connectors are also rated for 1A, but actually do about about 2A.  If you switch to LiPo but don't switch to XT60 and Deans the connectors will overheat. The motor and the ESC want more, the battery will give more, but the connector is narrowing the path.  

I would try larger pinion like 28, 30 or 32 after LiPo.  If you are running on clean flat surfaces, taller gearing with larger pinions like 30 or 32 would do fine.  If it's rough and hilly, you might stay at smaller pinions like 26 and 28.  

 

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10 hours ago, martinjpayne said:

Now, what about changing the pinion/spur combo to Mod 0.6?

Good option, as long as you don't want to enter the, speed run ,competition on here. The rules state only gears available for that chassis.

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