Sanity check my upgrade plan

[Theutrich]

I have an old Wraith 2.2 that's been dead in a closet for 4-5 years and I recently got working again. I was still on the stock electronics but I had worked through replacing a lot of the linkage and suspension with metal, by way of breaking something plastic every single time I took it out. As I was about to buy new NiMH batteries I thought "lets convert to lipo" which has led into a plan to revamp most of the stock electronics it has.

What do I want out of it? I'm into this theoretically for rock crawling but in practice it's comparatively rare that I put it on rocks and more trail bashing actually happens, so I want low speed control, but I also would have a lot of fun if I could make this thing quick. I want to be able to drive it through tire-deep water without being scared about it (since that killed it last time).

First I need a new ESC that can handle >2s lipo. I am eyeing the Holmes BR-XL for low speed control. I also want to upgrade my stock servo to one with atleast 300oz of torque. The BR-XL has a 5A BEC, but a 300oz servo is said to be right in the vague inflection point where an external BEC may be needed. I decided to just go ahead and get one and be done with it, and I'm looking at the CC 15A waterproof BEC. Then I thought, well if I'll have this beefier external BEC anyway might as well get a more OP servo, and I'm looking at a waterproof savox .11/500oz @ 7.4v (which stalls at ~8amps). Since the ESC can handle up to 6s, and with this CC BEC, I think I want to try out 4s lipo in hopes of making it fly, and I'm looking at a 2pack of 4s 6500mah LiPos.

Part list
ESC - BR-XL Waterproof - https://www.rpphobby.com/product_p/hh-210100002.htm
BEC - BEC 15A Waterproof - https://www.rpphobby.com/product_p/cse010-0153-00.htm
Servo - Servo 0.11 sec / 500oz @ 7.4V Waterproof - https://www.savoxusa.com/collection...-be-waterproof-premium-high-volta#spare-parts
Batteries - 14.8V Lipo 4S 6500mAh 60C - https://www.amazon.com/dp/B07PD2CNQM/

Plan
I know some dont, but I like a power switch, so I want to put my own SPST cutoff switch on the positive lead to the battery for turning ESC and BEC on and off together.
I'm thinking of running the servo off the CC BEC, but running the receiver off the internal BEC of the ESC, since it's low current. That way I can run the servo at high voltage (when I want to) and not overvolt the receiver.
For now I'm probably sticking with the traxxas 21T brushed motor I have since I just bought that.
I'm also probably going to stick with the stock gears/transmission, until I break them (the way this goes that will prob be soon anyway, running out of other things to break).
I don't think I really need 500oz of torque, but I thought maybe undervolting an over-powered servo (at 6V or even 5.25V compared to it's only advertising stats at 7.4v) would be better reliability wise, if the torque will just scale down linearly with the voltage. Also I like the idea of being able to adjust the CC BEC voltage to change this when I want to.

Questions
Does this setup make sense to run on 4s?
Will I be able to tune the ESC with stock gears to have good lowspeed control and also the speed to fly off jumps at full throttle? Or is that an impossible contradiction?
Is it safe to undervolt the servo advertized at 7.4v to 6v or even 5.25v? Asking in case my assumption I can just scale down the torque with lower voltage is somehow naive.
Is there anything grossly mismatched here?


Thanks

 

[revin9k]

I dont think that 21t motor will last more than a battery pack at 4s, especially if you run a whole 6500mah at one time. I would go brushless after that motor is toast. The holmes puller pro v2 on like 2800kv would be awesome on 4s. I run all my rigs on 4s with direct power 4s capable servos and eliminate the need for a bec. Its just much simpler and you get tons of torque. The holmes servos or the g13/14 from 3brothers would work great for that.

Also id go brushless if you want to play in water and have long trail rides, they just take more abuse and survive water so much better. If you want to stay brushed try a holmes trailmaster sport 5 slot. They are cheap throw away motors but preform amazing for the price and on trails

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[Ninomaniac]

Oof... a 2.2 Wraith will need a lot of upgrades for what you want out of it. I had one and the plastic gears in the tranny, plastic lockers, cheap metal diff gears, it all got wrecked. Only thing that can take some power are WB8 axles and front CVDs (mine was a Spawn kit, maybe you'll have to upgrade those too).

Servo torque and speed scales with voltage, you're right.

You'll have to shave off a piece of a link mount on the skid to install a 550 motor or add spacers to raise the tranny. I did the former. But a brushed system in a Wraith that'll go fast will make your motors *very* expendable. Go brushless, esp since you don't seem to be on a tight budget

Oh, and there's a reason you've never seen a switch wired from ESC to battery - it'll have to be a huge switch. Don't think you'll find a switch that can take say 50+ amps and doesn't weigh more than the rest of your electronics! It's good practice to unplug your battery after running anyway.

 

[MOguy]

I have an old Wraith 2.2 that's been dead in a closet for 4-5 years and I recently got working again. I was still on the stock electronics but I had worked through replacing a lot of the linkage and suspension with metal, by way of breaking something plastic every single time I took it out. As I was about to buy new NiMH batteries I thought "lets convert to lipo" which has led into a plan to revamp most of the stock electronics it has.

What do I want out of it? I'm into this theoretically for rock crawling but in practice it's comparatively rare that I put it on rocks and more trail bashing actually happens, so I want low speed control, but I also would have a lot of fun if I could make this thing quick. I want to be able to drive it through tire-deep water without being scared about it (since that killed it last time).

First I need a new ESC that can handle >2s lipo. I am eyeing the Holmes BR-XL for low speed control. I also want to upgrade my stock servo to one with atleast 300oz of torque. The BR-XL has a 5A BEC, but a 300oz servo is said to be right in the vague inflection point where an external BEC may be needed. I decided to just go ahead and get one and be done with it, and I'm looking at the CC 15A waterproof BEC. Then I thought, well if I'll have this beefier external BEC anyway might as well get a more OP servo, and I'm looking at a waterproof savox .11/500oz @ 7.4v (which stalls at ~8amps). Since the ESC can handle up to 6s, and with this CC BEC, I think I want to try out 4s lipo in hopes of making it fly, and I'm looking at a 2pack of 4s 6500mah LiPos.

Part list
ESC - BR-XL Waterproof - https://www.rpphobby.com/product_p/hh-210100002.htm
BEC - BEC 15A Waterproof - https://www.rpphobby.com/product_p/cse010-0153-00.htm
Servo - Servo 0.11 sec / 500oz @ 7.4V Waterproof - https://www.savoxusa.com/collection...-be-waterproof-premium-high-volta#spare-parts
Batteries - 14.8V Lipo 4S 6500mAh 60C - https://www.amazon.com/dp/B07PD2CNQM/

Plan
I know some dont, but I like a power switch, so I want to put my own SPST cutoff switch on the positive lead to the battery for turning ESC and BEC on and off together.
I'm thinking of running the servo off the CC BEC, but running the receiver off the internal BEC of the ESC, since it's low current. That way I can run the servo at high voltage (when I want to) and not overvolt the receiver.
For now I'm probably sticking with the traxxas 21T brushed motor I have since I just bought that.
I'm also probably going to stick with the stock gears/transmission, until I break them (the way this goes that will prob be soon anyway, running out of other things to break).
I don't think I really need 500oz of torque, but I thought maybe undervolting an over-powered servo (at 6V or even 5.25V compared to it's only advertising stats at 7.4v) would be better reliability wise, if the torque will just scale down linearly with the voltage. Also I like the idea of being able to adjust the CC BEC voltage to change this when I want to.

Questions
Does this setup make sense to run on 4s?
Will I be able to tune the ESC with stock gears to have good lowspeed control and also the speed to fly off jumps at full throttle? Or is that an impossible contradiction?
Is it safe to undervolt the servo advertized at 7.4v to 6v or even 5.25v? Asking in case my assumption I can just scale down the torque with lower voltage is somehow naive.
Is there anything grossly mismatched here?


Thanks

To simplify things I would go direct power servo. This way you don't have to worry about an internal or external BEC.
The ESC you mention above is brushed only. There are great bushed motors but when I hear trailing and bashing it seems to me that brushless may be a better choice, but that is just my thoughts.

I had a $50 3Bros G11 that out performed my 500 0z 1230 Savox (using an external BEC so it had all the amps it needed). I have had a few Savox servos and they are never as powerful as other servo I have had that claim to even have less power. As I used the Savox servos I experienced power and speed fade. I have had a couple 1212s get stiff one died and the other still moves but has lost power an speed. Under volting or under amping wont hurt the servo, it just won't work as well.

I have a MambaX that I like. If you do want to go with a BEC/ESC powered servo it does have a legit internal BEC that is programable and it can put out all the voltage and amperage (up to 8 amps I think). It is waterproof and can handle up to 6s I believe. The MambaX is great but bigger and more expensive than other ESC. Space shouldn't be a problem in a Wraith. Not sure about you budget?

I have an older Wraith 2.2. I had the MambaX with a Trailpro Holmes Hobbie 3800 sensored motor and it was fast and fun but not the best motor for crawling but the old Wraith 2.2 really aren't that good for crawling anyway. Ihad a Savox 1212 in that lasted a short period of time before it became stiff and useless. I but the MambaX in another rig and the Wriath and the Trailpro just sit on a shelf with a worthless Savox servo.

It seems that allot of people like the Holmes Hobbie Puller pros for trailing / crawling. I have never tried one. I just crawl. The motors I have I like are my Revolvers, My Tenkin HD brushed and my Tenkin ROC. I have some HH sports and they are fine but don't have as much low end torque and not the best drag brake but if you are looking for inexpensive, at $15-20 they are the deal.

 

[twade984]

Considering the path you’re going down, skip the brxl and bec, and just get a mamba x.

It’s 6s capable, has a beefy bec, can be used brushed or brushless, and you could use it with the stock motor until it quits.

At that point a puller pro is probably going to be one of the best options for all around power/torque, low speed control and high speed buffoonery.


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[DRED805]

I’m doing a flat rail chassis wraith build. The electronics I got were:

Mamba x
Castle 2850kv slate motor
370tbl protek servo
4s 5200 tattu batteries

If I didn’t get a great deal on that servo, I would have looked more into direct power servos.

 

[MOguy]

I’m doing a flat rail chassis wraith build. The electronics I got were:

Mamba x
Castle 2850kv slate motor
370tbl protek servo
4s 5200 tattu batteries

If I didn’t get a great deal on that servo, I would have looked more into direct power servos.

With the MambaX you can set the volts up and it will deliver the needed amps and it should work great. Make sure your receiver can handle the added power voltage.

 

[Voodoobrew]

$20 brushed motors are great for water and on 4s they have some power. They might not last as long but you should get a few runs. mostly the brushes just wear faster. If it burns up then you are geared too high. People run their ride on power wheels with these motors at 24v all the time. The brushed motors won't handle the wide rage of speeds as well as brushless motors though. Brushless motors can get wet inside and rust just like brushed motors but are more expensive to replace.

For water I only recommend cheap brushed motors.
Water can kill any electronics, there is always a risk. So my advice is keep it inexpensive if water is expected.

 

[DRED805]

With the MambaX you can set the volts up and it will deliver the needed amps and it should work great. Make sure your receiver can handle the added power voltage.

It will be a standard spektrum 3 channel. I don’t know the specs on it, but I’ve been using the 5 channel equivalent in my UMG10 at 7.4v with a 170tbl with no issues.

 

[MOguy]

It will be a standard spektrum 3 channel. I don’t know the specs on it, but I’ve been using the 5 channel equivalent in my UMG10 at 7.4v with a 170tbl with no issues.

I have had a few Spektrums and I think they will be fine at 7.4. (I think 7.5 on the MambaX)

 

[Voodoobrew]

Spektrum receivers are good to 9.6v

 

[Theutrich]

Oh, and there's a reason you've never seen a switch wired from ESC to battery - it'll have to be a huge switch.

You convinced me on this. I was not thinking of the amount of DC current that would be going through it. Only the appeal of not having to bother with disconnecting the battery.... and a cool lever switch sticking up from the center console like a gear shifter.


Other than that, thanks for all the responses. A lot of really good perspective and info. My main takeaways are
1. Brushless would mostly be better for my usage

2. Servos exist that can run on 4s worth of voltage directly
3. Speed controllers exist which can handle brushed AND brushless motors (I did not know that!)
4. The mamba x is a crowd favorite
5. Savox servos are not a crowd favorite. I don't know why i thought they were like the name brand but that's not the first time I've heard someone say they lose power and wear out fast.

I just got the 21T motor a week ago to save the crawler from the closet and barely put 2 packs through it, so I didn't want to immediatly get rid of it. But otoh buying a $100 brushed speed controller to save a $25 motor is probably not wise. I also was worried about losing fine speed resolution at the low end with brushless but with more research it seems this is less of an issue with newer sensored ones.

just get a mamba x.

It’s 6s capable, has a beefy bec, can be used brushed or brushless, and you could use it with the stock motor until it quits.

Now that I know I can get an ESC that can handle both motor types, that's a no brainer to me. I can have fun wrecking this 21T motor while letting my wallet cool off, and then go for a hefty brushless. I'll just have to be disciplined about maintenance after water (bearings etc) since it's not exactly disposable. Or heck just swap on a cheapo brushed motor if I want to submarine. But the mamba X is the same price as the BRXL+BEC, and to have less things to break under the hood, more capability, and the option to use either motor type... no brainer. Only drawback is I'm not thrilled about having to run fans, but I'll get over it.

 

[Theutrich]

The MambaX is great but bigger and more expensive than other ESC. Space shouldn't be a problem in a Wraith. Not sure about you budget?

I wouldn't say "budget isn't an issue" but I held back to enjoy what I had for a years ago, then it died on me and spent 5 years in a dark hole, so it's overdue for a fancy haircut and some new shoes.

Funny you say that about there being plenty of space in the wraith, I don't have much experience to compare but my perception is the opposite. I do keep the interior in it and I guess that hugely reduces the available area. It seems like the remaining area in the front and back of the cage is pretty limited. I expect to have to do some problem solving to fit things. I'll probably move the battery to the front for weight, and put the ESC in the back, which will get it a little higher to protect the fan from getting wet as much.

... but the old Wraith 2.2 really aren't that good for crawling anyway.

Interesting. What about them makes them not great for crawling? Stock weight distribution or something else?

 

[Ninomaniac]

Yeah, you'll have to do a lot of Tetris with electronics in a Wraith. Now that I think about it, I barely managed to get a 5000 3s under the hood (sideways). A 4s 6500 may fit in the back but the whole thing will handle like crap!
ESC can go in the front where the stock Rx box/faux motor goes.

 

[Steve g]

I have a few crazy wraiths. I also run 4s, but small hv packs. They fit perfectly where the rx box sits up front. The bigger the battery, the heavier it is, and the more broken parts you will end up with. I started off with large packs, and one day bought a small drone battery on sale for like 11 bucks. Made such a big difference in both crawling and higher speed handling that I bought 11 more. I get up to an hour crawling, about 45 minutes trailing, and 20 minutes geared up snow bashing out of a 1600 mah hv pack.
The thing is with these, on higher voltages, you'll dump alot of money into to make it last a battery pack. There's not a single moving part left stock on all of ours, everything had to be replaced with high end parts. Honestly probably have over a grand in each. Problem is, not many quality aftermarket parts available anymore. Vanquish and Dlux and everyone else gave up on these a couple years ago.

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[Voodoobrew]

instead of a switch you can make a plug that when disconnected interrupts one of the battery leads. then carve out a scale accessory and glue it in there, to make a Deadman's switch. just pull the scale accessory off the disconnect the battery.

 

[MOguy]

I wouldn't say "budget isn't an issue" but I held back to enjoy what I had for a years ago, then it died on me and spent 5 years in a dark hole, so it's overdue for a fancy haircut and some new shoes.

Funny you say that about there being plenty of space in the wraith, I don't have much experience to compare but my perception is the opposite. I do keep the interior in it and I guess that hugely reduces the available area. It seems like the remaining area in the front and back of the cage is pretty limited. I expect to have to do some problem solving to fit things. I'll probably move the battery to the front for weight, and put the ESC in the back, which will get it a little higher to protect the fan from getting wet as much.



Interesting. What about them makes them not great for crawling? Stock weight distribution or something else?

About savox and what was said above about them being popular, Hobby stores sell them so that is how they get pushed, other are.

The big wraith is big and awkward I think it big chassis tube thing gets in the way if it suspension working. I also don't think the Capra is all that great either, it seems to want o always raise a wheel but that could probably be fixed. I but my esc up in the interior behind the seats, double sided tape and zip tie. There is also room u front under the hood, depending on the size of the battery you run if you run it up front.

 

[Theutrich]

The bigger the battery, the heavier it is, and the more broken parts you will end up with. ... Made such a big difference in both crawling and higher speed handling that I bought 11 more.

Sounds like shooting for 6500mah at 4s is too much. Good to know. I only superficially picked 6500 cause I saw it early and thought big is good. But for the sake of handling and fit, I can go smaller, no problem. Esp with a more efficient brushless system. I'll have to do some research and figure out what I can physically fit where anyway.

There's not a single moving part left stock on all of ours, everything had to be replaced with high end parts. Honestly probably have over a grand in each. Problem is, not many quality aftermarket parts available anymore. Vanquish and Dlux and everyone else gave up on these a couple years ago.

Years ago, I managed to break nearly every non-electronic stock part, it literally broke every time I took it out even with stock electronics. I took it as "the substance of this hobby is continually finding the next weekest link every time I take it out". So my steering and suspension linkage, c hubs, knuckles, axle lockouts, driveshafts and servo horn, are all metal. The skidplate, tranny, axles/diffs are still stock. I do see that all of my old bookmarks to upgrades are broken links now or discontinued out of stock. That's sad.
At first I thought everything had to say COMPATIBLE WITH X on it and came around to realize a lot of stuff are interchangeable. What parts are "proprietary" to a certain rig type, or only compatible with specific other rigs? Is it most things other than the electronics?

I'm kinda lost with the KV. I know endless has been written about this, and I've read/watched a lot and get the theory but have nothing to anchor the numbers to. I know I can't have perfect crawling and huge speed. Speed is fun, but I really enjoy smooth slow movement. I'd sacrifice some speed for smoothness while doing mild crawling (going up and down street curbs, smooth slow hill climbing, watching articulation p0rn while driving over my foot nice and slow, etc). I guess I want something kinda in the middle. After reading about this I'm more apt to pick something in the lower kv range like 2200 (atleast i think that's "low"?) but I'm not sure. Should I basically just pick something, and then try it out, and adjust the transmission/throttle curve until I like it?

 

[23drumerboy]

Sounds like shooting for 6500mah at 4s is too much. Good to know. I only superficially picked 6500 cause I saw it early and thought big is good. But for the sake of handling and fit, I can go smaller, no problem. Esp with a more efficient brushless system. I'll have to do some research and figure out what I can physically fit where anyway.


Years ago, I managed to break nearly every non-electronic stock part, it literally broke every time I took it out even with stock electronics. I took it as "the substance of this hobby is continually finding the next weekest link every time I take it out". So my steering and suspension linkage, c hubs, knuckles, axle lockouts, driveshafts and servo horn, are all metal. The skidplate, tranny, axles/diffs are still stock. I do see that all of my old bookmarks to upgrades are broken links now or discontinued out of stock. That's sad.
At first I thought everything had to say COMPATIBLE WITH X on it and came around to realize a lot of stuff are interchangeable. What parts are "proprietary" to a certain rig type, or only compatible with specific other rigs? Is it most things other than the electronics?

I'm kinda lost with the KV. I know endless has been written about this, and I've read/watched a lot and get the theory but have nothing to anchor the numbers to. I know I can't have perfect crawling and huge speed. Speed is fun, but I really enjoy smooth slow movement. I'd sacrifice some speed for smoothness while doing mild crawling (going up and down street curbs, smooth slow hill climbing, watching articulation p0rn while driving over my foot nice and slow, etc). I guess I want something kinda in the middle. After reading about this I'm more apt to pick something in the lower kv range like 2200 (atleast i think that's "low"?) but I'm not sure. Should I basically just pick something, and then try it out, and adjust the transmission/throttle curve until I like it?

Ill say this...un-sensored BL HW 4276 can 2200kv 1/8th scale motor in my rustler 4x4, can run damn-near 1:1 gearing, allll day at near 100 mph, and hardly get warm....idk if this helps as the only BL crawling ive experienced is my SCX24 B17 Betty....BL outrunner and Furitek TEGU... that setup has been incredible! But no idea whats what in 1:10 yet...still Brushed HH TM Sport 550 27t, w/ HW 1080

Read-Up! Mod-On! Crawl EXCESSIVELY!

 

[23drumerboy]

Ill say this...un-sensored BL HW 4276 can 2200kv 1/8th scale motor in my rustler 4x4, can run damn-near 1:1 gearing, allll day at near 100 mph, and hardly get warm....idk if this helps as the only BL crawling ive experienced is my SCX24 B17 Betty....BL outrunner and Furitek TEGU... that setup has been incredible! But no idea whats what in 1:10 yet...still Brushed HH TM Sport 550 27t, w/ HW 1080

Read-Up! Mod-On! Crawl EXCESSIVELY!

Kv means RPM per 1 volt of "juice" there's a formula for it, and im sure you've read the description of lower vs. higher kV......just know it IS NOT KILo-Volt!

Read-Up! Mod-On! Crawl EXCESSIVELY!