Not happy with Brushless Jato :(
 

Well, converted my Jato to brushless last night in a few hours.

For the innitial attempt I used:
-Mamba Max speed controller
-Mamba Max 7700Kv motor
-17t pinion
-55t spur
-Venom 7.2v 3300mAh pack

All of the above was brand new..

Anyways, I got everything setup and ready to rock, calibrated the ESC... Went for the first test spin around the shop, first thing I noticed was the motor sounded very weak and was obviously not getting anywhere near the RPM that my 18th scale Mamba's were getting.

Continued driving, still not impressed. I was probably getting 25-30mph top speed, if that.

After a total of about 30 seconds of driving, the truck stopped dead. No response at all......

After some looking into the problem, the BRAND NEW, 30 seconds of use speed controller is completely DEAD! :mad:1

I fired off an email to Castle Creations in regards to warranty. I am expecting it to be replaced no charge!

Anyways, I'm hoping someone can re-assure me that this thing WILL be faster than the 25-30mph I saw during the innitial test drive... I'm really hoping the bunk ESC was severely limiting performance, and that I didn't waste $300 on a slow ass setup..:031:

In all reality, I only make changes if I expect them to make the truck/car faster... I'm really hoping for this thing to be faster than my Jato 3.3 was.



Also, just reading Castle's website last night, the 7700Kv motor will not do 3s lipo, which was my plan. The 7.2v pack was really just for testing purpose untill I can spend $200 on a phenominal lipo pack...

In all reality, I am aiming for a minimum of 70MPH with the BL setup... I my 3.3 did 110km/h or roughly 65mph being chased down a highway in a car...

If I can't run 3S lipo on the 7700, what other motor can I upgrade to to get me to my minimum of 70mph goal on 3S lipo?

Yeah, I always try to do my research before I buy, not after. ;)

It's not surprising that you aren't getting the RPM of what you get out of the 1/18th scale stuff. An 8000Kv on 3S will hit 88,000 RPM. The Mamba Max motors are limited at 65,000 RPM, which is in their online information. They also say that the fastest motor isn't the 7700, but the 5600. Also, with a high Kv motor, you need a pack that's up to the task, bare minimum GP3300's. I'm not sure what's in the venom packs.

When you noticed the motor seemed very weak, that was your cue to stop, not to keep driving! I've had hands on 3 Mamba Maxes, and i've never been able to make them die in 30 seconds. Your experience is very atypical.

Yeah, that's very atypical.

I'm using the 4600 and it is insane! I tried 14 cells a while ago and destroyed the rear tires. On my typical 2s, it is quite strong, but only goes 45-47mph. I've never had it thermal on me either...

After more research, I'm going to buy the 5700kv motor as well... Seems like with more voltage, it's the more logical choice for speed..


Just for the record, the ESC, motor or battery were NOT even warm, so they definatly did no overheat!


I've got a spare ported and polished XTM 457 laying around, maybe that should go in the Jato instead :p

I think your batteries are not up the task.

I would personally take a less high kv motor to do the job.

I think you are overgeared and like Serum said, the batteries are probably a weak link. I'm assuming they are the stick packs....

Try gearing it much lower and see what happens. The 7700 is very fast so if it's only hitting 25-30mph then it's bogged down bad or the batteries are junk.

And if this is the case, then that would also explain the esc suicide...

Even with NO load on the motor (just free spinning), it just didn't sound right.. Nowhere near the RPM that my 18th's are getting..... Like, not even half, I'd be surprised if the motor was passing 20k rpm...

By gearing it down, do you mean smaller pinion gear?

well ur batteries are just about the most crappy pack u could have, so get some ib or gp batts and there will be a big difference

and then to reach youre insane speed u will have to use a 3 cell lipo and the 5700kv mm and then u should be good

@fiero_silva: I think I also posted a response over at the Traxxas forums.

You can gear down by going with a smaller pinion or larger spur. If you divide the tooth count of the spur by the pinion, you get a ratio. Larger ratios are lower geared and lower ratios are geared taller.

According to my calculations, you should be able to reach ~50mph in first gear and 66mph in second with 6 cells, and no tire ballooning. So, something is definitely wrong.

Generally, it is advisable to use a lower KV motor and higher voltage. The current requirement would be less. Some vehicles are difficult to use anything more than 6 cells, but since the Jato is custom, it shouldn't be difficult to use 3s-4s.

And yes, battery quality is a big factor in performance. So, get high quality GP cells or good lipos capable of ~100A continuous for best results.

Will the 5700kv mamba and speed controller take 4s lipo?

Where are you getting those numbers from? Using the link in your sig, I'm getting 55mph as top speed in 2nd gear with my current setup. I think the only thing that could be different is tire diameter... I don't have my truck in front of me, so I used 3.5".... What are you using?

4.2" tire. Maybe that's not right...

It sounds like a definite problem some where. Just finding it is the key.
Is the battery pack still good?

Battery pack checks out fine with a multimeter. As I said, it was brand new for this setup...

I'm strongly suspecting the ESC was bunk... Even on the 3300mAh battery pack and the gearing I was using, performance should have been far better than it was...

I have heard of one other Mamba ESC going out in 30 seconds...It was a member here. Here is a link to his thread about it....

You had the change to measure the voltage of the batteries when they had a 60-100A load? a battery pack can deliver 20V on no load and drop in to .01 volt under load.

Rule number one with brushless; The setup is as powerfull as the power the batteries can produce.

Since you bought relative cheap batteries, the setup will not preform as it would with good cells.

If you got the money, buy yourself GP3300's.GP3700's or IB3800's.. they will give you the speed you expected.

You are not able to hear what RPM a BL motor is turning on without a load.

Better yet, pick up some Maxamps 4000mah 3S lipo in conjunction with a 5700 motor. Then, your Jato should hit 60 easy.

Serum, may i ask why you didnt list the IB4200's..? Ive heard great things about the newer WCE at maxamps. And Gp3300 are hard to come by.

What kind of connnectors are you using? If I'm not mistaken, the MM comes with Tamiya, right? I remember somebody saying something about that...

The MM comes wih bare wires so you can use your plug of choice..

If you want the fastest setup, get the 4600 motor and use it on 4s Lipo. You would need to use an external power source for the receiver/servo (like a UBEC or receiver pack), but this would be worth it IMO.

My guess on the not-so-good performance is the quality of the battery pack - it's generic, with most likely weak cells, in a stick format, so it won't be able to supply the current the 7700 wants (and it wants a lot). Although it is rather strange that the ESC died...

My MM system arrived with bare wires, but they (CC) supplied me with 4mm bullet connectors.

Ah. I rememebered something about Tamiya connectors, probably a forum member using them...But I think I remember what I was thinking about...If I'm not mistaken (again), the Orion LiPo's come with Tamiya connectors (adapter of sorts for those who don't want the 4mm bullet connectors I guess). I just remembered something that shouldn't have them, had them...

Tamiya connectors should be outright banned from any brushless system and any high C Lipo packs. Even my kid's Stampede started heating up that connector and the connectors were new with a low powered brushed system.

Leave the Tamiyas for the Tycos and RadioShack R/C wannabees. :)

The tamiyas are good for rock crawlers. The low gearing and low amp draw.
It shouldn't even break a sweat.

Okay, repeat after me;

Tamiya plugs are EVILLLLL

EVILLLL
I'm even having bad dreams about them.. running thru the desert, chased by a group of melted tamiya plugs..

That's right.. The only time a Tamiya plus isn't melted is when they come fresh from the factory, after 1 run it is melted in a form beyond recognition..

check www.tamiyaplugssuckbigtime.com..

The powerpole plugs Leroy is euphoric about deserve a bit more credit in the BL scene. they are cheap, easy to mount and have got a high contact pressure with a low resistance.

Wow. Ant-eater and sock fetishes, dreams being chased by melted Tamiya plugs. You really, really need help! :027: :005:

Yeah yeah.. Rub it in..

('',)

I like the power pole much more. On some rock crawlers they run for like 50 mins on 3300 mah. Not much amp draw there.

I'm a Deans person myself. I like the smaller size. Its a bit inconvenient to put on because you have to solder it, but I love their compact size - when plugged in, the set is smaller than a single female Tamiya. During running, I havent even got a Deans plug above room temp...they are awesome.

Yeah, I like the Deans too. It's just too bad they don't come in 3-position for use on the BL motors...

The deans are ok. They work great. I have a problem trying to unplug them.
The power poles I can wire batts in series with no special adapters.

Yeah, unplugging Deans can be a PITA. Too bad they didn't have some type of gripping texture or something to make it easier.

The trouble I have with power poles (or bullet connectors for that matter) is the physical length needed. Once you snap two ends together, the length of the resulting connector is larger than a Deans set. This is normally not a problem for long-ish wires, but when you only have a couple of inches of wire, it can be easier to unplug the Deans since there is more "slack".

I use Dean's on all my toys...

I didn't realize Leroy was euphoric about Power Poles :017:
I've used Anderson Power Poles exclusively since 2003. I find Soldering a PITA so Power Poles and the Power Pole Crimper are excellent. Since Power Poles are genderless, connecting them in series is simple. My only issue with them is they can unplug too easy sometimes. I have to use a strip of electrical tape to hold the connectors together because in very bumpy races, they can disconnect. However, I am more willing to slap on a little tape then deal with Deans.

Well gives me hope there starscream. I thought I was the only one that liked
them around here. I talked rene into trying some.
Joe got me on them.

I love my deans, they seem so sturdy too, and the connection just feels good.

Problems on 12.24.06, it's now 01.02.07 and I have yet to hear from Castle Creations...

I'm going to assume they were closed for the holiday period and have some E-Mail backlog to deal with... I'll give them a few days more to respond, if I don't hear from them I'll fire off an other email....

If I still don't hear from them, I'm on my way from being a loyal CC customer, to an unhappy one :(

Recieved an email from Joe Ford at Castle Creations today, new speed controller is in the mail :)

Good to hear, hope this one works better