Best controller for 12-16 cells?

[Rtsbasic]

Hi, decided I'm going to go high voltage with my Emaxx, I plan to run a 540C 7XL or 8XL motor on 12-16 cells. Both of these motors should be fast on 12 cells, but killer on 16 cells?

Now I need a new ESC as my Mtroniks Truck only handles 12 cells. What would you guys recommend? A 9920? Whats the low speed control like on this? Should I get a UBEC to run with it? Mostly I'm concerned about cogging at low speeds, and reliability. I'm used to the very smooth feel of the Mtroniks controllers and would hate to spend $200 on something that stutters at low speeds or at pullaway.

If I purchased a 9920 from Mike and it encountered a problem, would I return it to Mike or BK? Approx how long will it take to get a replacement? Its for this reason I've not purchased a BK unit before, I think to be honest its rediclious to wait 2 months for a replacement.

Oh and will Mike be stocking the 540C-XL motors, or just continue with the Wanderer's? I think I'd rather get a 540C so I don't have to worry about it falling apart, and it saves the cost of a heatsink clamp (even though they do look sweet).

Thanks.

[Serum]

Hi RTS;

yes, both the 7XL and 8XL would be killers on 16 cells. The 8XL is one nice motor, 14 cells is a nice balance, if you smelled the power of 16 cells, it is hard to go back to 12 again.

The 9920 is a smooth controller. The startup will go with a little cog, nothing to worry about imo, you can go about .5 mph running cog free. You need to know that the controller can't determine the possition of the rotor in the motor, and it starts with a rather soft rotation. once the rotor is moving, the magnets of the rotor give feedback to the controller and the possition is known, to run cogfree.

So with less words; the cogging would take a .1 seccond. Allmost if it's not there. Imo nothing to worry about. Every sensorless controller does this. It is minimal.

The 9920 is a problem free controller, if however you have got a problem you can't fix, you can post it here on the forum. If we can't help you out, Mike will tell you if he thinks that he can fix it or if it's better to sent it back to BK. Mike will use the option that is the fastest for you. It should take a small month to have it fixed. It's good to consider a thing like that, but service is better than NO service..

I haven't seen a 540C-XL? got a link?

[Rtsbasic]

Hi Serum, thanks for your reply. I am farmilar with the slight cogging you speak of, my Mtroniks sensorless ESC does the same sometimes. Normally it can pull away without even this though, something to do with how they pulse it I think.

Starluckrc is the place getting the 540C-XL's in stock, as Mike gets his 380C and 540C motors via Starluckrc I figured maybe he'd be able to get them in stock, so I only have to place one order for all the kit.

Which motor would you suggest for 12-16 cells? 16 is the limit as I will be getting the FLM chassis and don't wish to stack cells up. Would the runtime be good with the 7XL? I'd like to be able to gear high (40-50mph) and have a good setup, but also be able to gear down for 30-40mph and get killer runtime. My Mtroniks/8L setup is giving me the sort of top speed I'd like (35-40mph), but it gets too hot and runtimes are not as long as I would like.

Pleased to hear the service isn't several months long normally, I'm used to a 3-4 day service with Mtroniks which is why I'm very concerned about the service with a BK. Whats the warranty like? Like say if I buy one from Mike and 3 months down the line it lets its smoke out, will it be replaced free?

Looks like its definately going to be a 9920 and XL combo..what drivetrain upgrades will I need to worry about? Its all stock except for some steel universals in the middle and a Robinson Racing slipper kit.

Sorry for all the questions, this larger scale stuff is all fairly new to me still :)

[Serum]

40-45 mph is the topspeed you might get on 16 cells

you can keep the same gearing and tune your radio down to 60-70 percent. This gives a longer runtime as well.

About the warranter, you act like you are going to ruin it, just run it, use it with sense, gear it with sense and the warranter from BK is good. Much better than from schulze.

The 3-4 day is very quick, i love the service from Castlecreations as well. It is by far the best i know of. They don't have got the mamba maxx out yet, unfortunately.

The XL will eat his way through your diffs and make pritzels from your driveshafts.. on 14 cells, it will hold up a bit. but it will wear out much faster. Unless you are easy on the throttle.

[nitrostarter]

I run a 7XL/BK18120 combo, geared at 16/51 and on 16 IB3800 cells. I just radared it at 44mph, and it gets there pretty quickly.

Runtime is prett decent, I can get about 15 good minutes of hard running. I haven' raced yet with the IB3800's yet, our track is being overhauled for some airtime.

CVDs, Steel Idlers, and diffs upgrades are going to become a necessity when you start running it hard.

[coolhandcountry]

If you going with a maxx of 16 cells what about the mgm 16016 esc.

[Rtsbasic]

After reading from a few people about how long MGM take to resolve issues, I am staying as far away from their units as I can. Which is a shame, I come very close to buying a 16016 when they came out with the cube design last year.

Serum, the reason I act like its going to break is because every brushless ESC I've owned has broken in some way with the exception of 2, generally it'll fall apart or let its smoke out. I treat my equipment as carefully as I can, but I bash my truck hard and except components to fail eventually. Its nice to know that if they do fail the warranty is there to fix it.

nitrostarter, whats the temperature like on your setup with that gearing? Sounds pretty much exactly what I'm looking for - top speed in the 40's and good runtime.

Whats the most cost efficent way of upgrading the diff's? I see the "bulkless" gearboxes on RCM for 1/8 buggy diff's, but I simply cannot afford it. What other options are there? I will be picking up the steel idlers when I purchase the 9920.

For the min I may get the 9920 and run a 540C 9L on 14 cells (been offered a direct trade for my 540 8L, simply because its a tad faster than my mates truck with his 9L). Then when budget allows get the 7XL. What would the power difference on 14 cells be between the 9L and 7XL?

Thanks for all the help so far, very informative :)

[coolhandcountry]

Well to my understanding it took a while on some peoples esc to fix cause mgm was in process of changing there escs. Made them better and worked a few buggs out.

[RC-Monster Mike]

I have the xl"c" motors on the way, for those who are wondering. I should have them here mid week next week. 7, 8 and 9 turns.
The MGM controllers are as good or better than any other on the market IMO. Their service is also as good as anyones and better than many. There was a time when they were updating/upgrading, which caused some time for the service, but those who were affected were rewarded with a new, updated controller.

[MetalMan]

I was one of them. What I don't understand is their lack of communication, though.

So far, I have yet to come across a speed control of any sort (brushed or brushless ) that hasn't failed with the exception of the EVX (it never had a large load). Here's my brushless count:
-1 9918 that just stopped working, and another 9918 that had a damaged circuit board (this one I have been waiting for it to be repaired for 5-6 months now!)
-1 MGM 12012 that stopped working in CAR mode and took 6 months for repair, and my current updated one's BEC has died
-1 Mtroniks Truck that let its smoke out, but the repair only took 11 days round-trip from California to England (that's unbeatable service!)

So, I can't say that any single controller is reliable, but so far it seems that the MGMs have lived the longest.

BTW Mike, I don't think I would say that we were "rewarded" with a new controller, but more that we deserved it (IMO). I just wish that BK would do the same since it seems to take so long in its repairs.

[Serum]

Too bad Mtroniks only makes a 12 cell controller.

Castlecretions has got a flawless and quick service as well.

they sent you the new one, with a returning envelope for the old/dead one. It took 4 days, before i got the replacement for my mamba 25.

[Rtsbasic]

Thats good service. Mtroniks service is 90% of the reason I use their speed controllers.

Just a small update, I've since purchased a 9920, 6V UBEC, RC-Monster heatsink/clamp, and a 9XL, connected with the 5.5mm connectors. I plan to run it on 16 cells. I got all the electronics in a trade for an excellent price, my tranny is also getting a few upgrades to handle the power - the UE diff's and housings (not sure if they're 6 or 8 gear versions), all around cvd's, alloy hubs and bulks. I still need to order the steel idlers from Mike, after that my tranny should be pretty bulletproof? Oh it'll have a strobe slipper as well.