New TRX-4 Sport & TRX-6 Intro & Questions

[TRX-4-Baker]

Howdy RC- Crawlerpeople!

Fellow American abroad with new TRX-4 Sport and... since last week proud owner of a TRX-6. My trucks are primarily used on trails and walks with 1-2 hours total runtime. Offroading basically limited to whatever is encountered or looks manageable. Speeds are "normal" walking pace, between 6-8 miles total per day.

Both trucks are electronically stock, upgrades planned for later are HW 1080 + Holmes, however likely a fall/ winter project. Weight is of significance due to trying not to limit range.

Not being sure about the battery story, I went with normal 3000 MAh NIMH from Traxxas and I am seeing 1.4 - 1.5 hours from the Sport and about 1.1-1.2 hours from the TRX-6. Thats about half of what I would like to see. I use the EZ Peak ID charger from TRX.

Questions: Could you guys share which battery would bump my endurance to roughly 3-4 hours? I know there is a perfect setup for every situation. TRX Support tells me to go 2S 7400 MAh Lipo (2869X) others tell me to completely dump TRX- ID, which I would rather not do at this time. Buying both trucks was approved by the "finance department" spending hundreds more on hopups and stuff will cause consternation...

While the sport with its single speed transmission seems very balanced (slow enough, yet fast enough for intended use) the TRX-6 seems as if its in wrong gear all the time. In second gear, cruise control on, it shows its lack if flexibility.

IOW: First gear not enough speed, in second gear the trucks motor isn't running at optimal torgue. Not at all a LiPO expert, means the more special terms and abbreviations are used in your response, the more confusion happens.

I have watched every single video from Mr. Holmes on such topics as he has a style of explaining which manages to work well with my level of understanding. Quite unsure. Should one just go and buy the biggest MAh Lipo with the lowest 25C discharge rate? Could the TRX-6 motor struggle less in second gear with a better battery?

Thankful for any and all tips or pointers.

Greetings,

Jason

 

[OSRC]

The 6 is a heavy truck, and the gearing spread between first and second gears is quite wide. It's working pretty hard on a NIMH battery. You can certainly go with much bigger batteries in each truck, though at the cost of some performance. It's a lot of weight up top and is very noticeable, especially in the sport.

Personally, I'd recommend going with a 3S battery in a 3-4000 mah range, and lowering the gearing on each truck. Without going into all the details since there's a million threads on it, the old axiom "volt up/gear down" applies. The 6 especially will benefit greatly from it - more power, speed and efficiency. A 9t pinion and a 3S battery will really wake it up.

 

[TRX-4-Baker]

Hi OSRC,

thanks for your response. Range is of much more significance than performance in this case. The 6x6 sees very limited bad terrain in comparison to the Sport. At least, I havent arrived at tossing this brandnew 750 Euro RC Truck around like something I could replace for mishanfling it...... :mrgreen:

I am regularly out for 3-4 hours (sometimes more) and two 3000 NIMH's will cut the cheese on the TRX-4. I assume it would easily do 2+ hours on a 8.4V 5000 pack.

But, I'd prefer not having to flip batteries and just keep going, though and I'd like a setup which powers both trucks. That same battery pack/ or packs have a few hours to charge between rigs, before being thrown in the other one.

The spread between gears is tremendous on the TRX-6. It runs quite nicely, but on the small battery it feels like a car with a manual transmission being driven one gear to high for optimal torque. The motor turns too low RPM to match my walking pace and it doesn't seem to actually lack power, its just not getting the juice? I'd get two 5000 NIMH's if that would solve for X, but Holmes Volt Up, Gear Down video sticks.

Gearing down would mean taking the motors gear down from whatever is stock to 9 teeth? So more RPM on the motor for same speed, if my brain follows. That would allow for better cooling (6x6 Stock Motor is quite warm after extended travel in second gear).

'd like to better understand the theory behind higher voltage on the motor and its subsequent ability to perform quite a bit better than on 8.4V. So whats the golden ticket? 2S or 3S with the highest possible capacity? 2S is 7.4V, 3S is 11.1. There goes the Volt Up part....

But Range/ Runtime is allegedly dependent on MAh capacity, first.
Logically one would run out and buy the biggest pack available, just to find out that it doesn't work like this.

I drive most of my tours with the lights off, just to make sure not to task the battery with range limiters. Mx hope is to read from someone who has been successful at getting 2-3 or more hours of runtime with the 6x6.

Until the search feature an I are better friends, I hope for some help.

 

[Raptor_Jesus]

I don't know useful this will be for you but i have a TRX6 that i have upgraded with a mamba x esc, castle slate 3800kv motor, 9t pinion and i get about 3 hours out of a 8400mah 3s pack. now i drive my truck HARD see nasty trails and full throttle if i was easier on it i could probably get 3h out of 5000mah pack

 

[TRX-4-Baker]

Hey RJ,

I suppose a BL setup is overall more efficient, so I am not sure what the situation is. Totally different use-profile. The perfect mix is somewhere in the details, which - at this point
- remain hidden to me.

I'll start with the LIPO, then work my way into the HW1080 and finally see to install a Holmes Trailmaster or something.

 

[OSRC]

Hi OSRC,

The spread between gears is tremendous on the TRX-6. It runs quite nicely, but on the small battery it feels like a car with a manual transmission being driven one gear to high for optimal torque.

Gearing down would mean taking the motors gear down from whatever is stock to 9 teeth? So more RPM on the motor for same speed, if my brain follows. That would allow for better cooling (6x6 Stock Motor is quite warm after extended travel in second gear).

'd like to better understand the theory behind higher voltage on the motor and its subsequent ability to perform quite a bit better than on 8.4V. So whats the golden ticket? 2S or 3S with the highest possible capacity? 2S is 7.4V, 3S is 11.1. There goes the Volt Up part....

Yes, focusing on the 6 for the time being, I know exactly what you mean. Chugging along the trail in second gear the motor is just loafing along barely turning any RPM. It's working hard though and pulling a lot of amps, hence the heat.

I'm not an electrical expert by any means, and not sure I can explain this but here goes. By putting the smaller pinion gear on, the motor is spinning somewhat faster for the same speed of the truck, but not working quite as hard as the lower gearing takes some of the load off the motor. Thereby, it's working more efficiently. More efficiency=more runtime. Gearing down does lower your top speed of course, which is where the extra volts come in...gets your top speed back where it was. Plus it's more tractable, better throttle control, etc. Really, there should be a sticky on this issue, it comes up all the time.

I swapped in a 9t pinion on mine, and now first gear is more of a creeper gear but second is now much more usable on the trail. Traxxas geared it for a balance of trail speed and basher speed. If your'e not bashing around, it's well worth the investment to gear down for dedicated trail use. I run on 2S since I drive slow anyway and get about 2-2.5 hours on a 4000mah 2S lipo pack. I don't know that I gained more runtime per-se, but it is far more drivable in second gear with that gearing. Don't think I lost any runtime though either. Honestly, the spread between both gears is sometimes a pain, sometimes I think it would be easier to take out the 2 speed and just gear it for trail use with a single speed and go from there. That's not as much fun though...

I think 3-4 hours of constant trail time is a big ask for a heavy truck like the TRX6... I can go 3+ hours on just a 3000mah pack on my smaller trucks depending on where/how I'm driving, but they are far lighter. Regardless of how efficient you can get it you'll need a pack with higher capacity. Traxxas may be right with the 7400mah pack - if your not looking for pure performance, that should do it.

 

[TRX-4-Baker]

Hi OSRC,

Great and helpful post, thank you kindly for taking the time!

The 7600 2S Lipo is on the way. Its approved equipment in both trucks, so my assumption is that the Sport will get well more than 3-4 hours. If I get the 6x6 into the 3 hour range, I will be happy.

A fellow TRX-4 Land Rover owner took his truck up a huge mountain, on a nearly 3.5 hour hike. He is running the 2S, has two of them along for long trips and states that he ran out of power on the way back, some 250 feet from the parking lot.

I had the same idea, slap the sport transmission in and go walk, however the truck has way too much potential to just chuck the tranny.

My assumption is that the motor will require less throttle to get into good running speeds. I thought about the gear down option, but will take it step by step. My local buddies think the same, battery first, see how it works out. slight gear down second, see how that works, HW1080 and different motor last. Its not like I am planning to drag 5 pounds of hopups around, expecting the truck to run 10 hours...

I got an hour and 15 minutes out of the rig today, the 3000MAh battery was dead and drained 7 minutes after arriving back at the farm.

This rig is pure fun and definitely a highly capable rig right out of the box. I am no Mercedes Benz fan by a long shot, but the body is neat and a sight to see when it works its way through terrain.

I was hoping to meet John Holmes here one day. He is 50% responsible for this new addiction and willingness to learn, the other guy at fault is RC Review on Youtube.

Greetings,

Jason

 

[OSRC]

Glad to help! I agree with you on all counts, the 6 is a unique and fun truck. I think you'll find the truck has much more punch on a lipo as well, even 2S. Second gear especially.

Good luck!

 

[TRX-4-Baker]

A Traxxas 7600 2S will comfortably extend the trucks runtime to 2 hours and 45 Minutes. 90% Trailrunning, a lot of it in second gear (inefficient). I have not yet used the truck extensively, but longer trips are definitely possible.

2nd gear is the vehicles downfall. First is too slow, second is with too low motor rpm, hence I will put a 9T in and see what that does.

 

[Inspector86]

I have both the Traxxas 5000mah 3s and 7600mah 2s ID batteries, the trucks just run better on 3s in my experience with fairly close total run times of between 3 to 4 hours. In the TRX6 I would recommend going to a 9t pinion and a 5000mah 3s. Gear down, Volt up! I would add that the slow 1st gear issue goes away with a 3s battery. Everything just works better on 3s.

 

[mass-hole]

Agree’d you are gunna regret not going to the 3S battery now if you decide to gear it down later.

 

[TRX-4-Baker]

Time has marched on and so have all these Traxxas vehicles.
I've been having a bunch of fun with both, the TRX-4 Sport and the TRX-6 and have finally given in to the urge to put a MAXX into the fleet, as well.

Been messing with Youtube for a bit as I enjoy capturing these things in action on video. Both TRX-s have now run on 3S as well, a worthy investment. Not sure if Youtube vids embed here, but here goes the latest one.

https://youtu.be/wyygHfBVEBA

Both are going to get a Hobbywing Brushless set, in time.

Greetings from way over there in Europe