TO BEc or NOT TO BEc...not just for Patrick
 

I'm sure Patrick could answer this best, but I cant expect the guy to spend all his time tooling around the threads...i'm sure he has enough to do :whip:

Anyway...

I have a MMM V2 that should be here soon. I also have a spankin new CCBEC sitting here as well. After hearing hints that some V1 failures came from the MMM internal bec, I thought this would be the safest bet. But now that the MMM has been revamped, is using the BEC warranted/needed/suggested?

Ideally, I would prefer to use the MMM the way it was designed...stand alone

...But I do have the BEC....:neutral:

what would you do?

and more importantly....why?

thanks in advance,

Jarrad


PS, in case it matters....

this will be run in an e-revo. (12lbs?)
Using a tekno Neu 1515/1Y , with
1)two TRC 15C 8000'mAh 7.4 run in a series
2)two Zippy 4300 3s 20-30C run in a series

I will not be using an external BEC when my MMM gets here.... i dont know if the problems with the fan are solved, if the fan shortens, will the internal BEC work? if not i will probably do the "open case mod" and run it without a fan. Yesterday i was on a local track and there where 2 guys that had converted 1/8 buggys. Both of them had the MMM, both of them had done the "open case mod", none of them uses fan..... i felt on one of the controllers just after they had raced..... no problems whatsoever running without a fan..... i estimate that it was app 40-45 degrees centegrade. The car was a Xray XB8 EC with a Hacker motor (around 2400kv), MMM, 12/46 gearing, and 2S2P Orion platinum edition...... The way i see it is that using a fan in a MMM is only an extra source to problems..... BUT one have to keep in mind that you cannot "overgear" your car.... then there will be allot more heat.....

IMHO

Jarrad: I don't own one, but want to, and have been reading every tidbit of information as it becomes available. I think you should be fine with no BEC. The reg in the MMM is switching regulator anyway, so theres no efficiency gain, its just a PITA to remove and replace the red wire in the ESC lead everytime you want to look at/change the programming.

orfre: In a buggy I reckon it'd be fine to do that mod - in my HB Lightening 2 Pro I run a stock standard Mamba Max (brand spankin new, just got here today) on 4s1p A123 and a 3000Kv L-can $25 inrunner geared 14/46 and it doesn't get too warm

Are you sure they were running 2s2p. A 2400kv motor on 2s geared 12/46 will be barely crawling! Maybe two 2s packs in series making it 4s1p? Sounds like a much more ideal setup.

Anyway, the point is that in a Revo or other Large vehicle there will be a lot more stress on the ESC, I'm not sure hacking up the case and running without a fan in anything bigger than a buggy is a great idea. Maybe if your running 6s exclusively it would be OK.

yes, thats what he means... im not aware of a 2s2p orion pack...

also sammus, whats this about pulling the red wire to program? do you mean if you ran without the inbuilt bec he would have to replace it to program and then remove it again to run it?
sorry for the dumb question, i too like to know everything - or as much as i physically can - drives my parents crazy being on forums 90% of my spare time :D

but without them id be broke with some useless pile of junk i paid way too much for in the beginning ;)

[QUOTE=Sammus;200388]

Are you sure they were running 2s2p. A 2400kv motor on 2s geared 12/46 will be barely crawling! Maybe two 2s packs in series making it 4s1p? Sounds like a much more ideal setup.
QUOTE]

ooops, i ment 2 orion platinum 4800mah in series making it 4 Cells

To run without significant load on the internal BEC you remove the +ve (red) wire from the ESC->Rx connector. This is the same connector you use to program the ESC with CastleLink.

I've always just assumed you need that +ve wire in place to program it, and always replace it before programming. I've never tried not doing it come to think of it - it could work.

hope that helps...:mdr:

Yeah... and theres always that lol. Last time I tried that it wiggled itself free somehow and I lost control and nearly killed my car :( ever since then I like to use as few extensions as possible.

hoovhartid: do you know if you even need the +ve wire in to program it? I imagine it needs full V to power whatever it needs to, and uses the signal lead to program stuff, but my imagination has been known to be wrong.

PS I still dont think you need an ext bec for the new monster :) The only reason the first one failed is because of dodgy componentry or design or whatever - its either fixed or it isnt. If it's fixed you have nothing to worry about, if it isn't, your just delaying the inevitable. The BEC will have load on it no matter what - its used internally to power the brain of the esc.

good point there.


its just that I have had my e-revo collecting dust for 3 months now.
I want a chance to break something that isnt out of my control:diablo:
ha ha

Like hoovhartid posted buy yourself a servo extension lead and remove the red wire from this .
Then use the extension from you esc and reciever .
When it's time to programme remove the extension and you still have the red wire attached to your esc for programming .

I did the same for my R1 Pro :wink:

As I mentioned elsewhere, I don't think it would be wise to handle the MMM with kid gloves.
If anything, considering the known issues with both versions, I'd say it would be wiser to stress the thing as much as you can without voiding the warranty as soon as you get it.
No external BEC and no fan modding. These things should kick major booty right outta the box.
I mean, that's why we pay more for them as opposed to the tried and true MM setup...right? I don't think that is asking too much.

I have a v1 that I used a bec on to take as much load as possible off of the internal bec. I even ran the wires for the internal fan to the external bec. It worked for 2 months with no problems except the fan stopping. I replace it with a Novak 25mm, but now I a v2 so it's collecting dust. I have 14 hours or more on my v2 using the internal bec with no problems. I run it on 5s and 6s in a 3905 E-Maxx with 2 MG995 200oz steering servos so I'm sure there is PLENTY of load on the bec. I think it's safe to say you will not need your CCBEC for your E-Revo. Maybe you should start another project that will use a MM on 4s. lol

My question is, if the fan stops or gets shorted from the known problem with the wires comming out in the bottom and the bow beeing to tight... will the internal BEC break down on the MMM V2?

I doubt if the fan stops but if it shorts I'm sure it would. If you short and external bec it will "break down" as well. I opened my v2 after I read about the first failure and was going to dremel the case to make room for the wires, but my wires had plenty of room to move between the case and the board. There were no marks on the wires at all. I put a piece of electrical tape on them just for added insurance but I had plenty of run time on it so I would think that if they were going to rub through it would have already happened.

External bec's are known to fail as well I had a coolflight ultimate bec go on me and I've also read here on this forum that the castle bec fails and takes the servo with it because they send full battery voltage to the servo, a high quality unit like a hercules or a dimension bec is the only way to go.

The CC BEC is a high quality BEC, it just uses a discrete component design. All the other ones I've seen (barring the DimensionEngineering ParkBEC) use a circuit on a chip where the switching FET is integrated into the package. So, they probably use some kind of catastrophic failure circuit. All of those designs based on the common IC are limited to around 3-3.5A, whereas the CCBEC is rated for much higher.

Ahh dissing castle again :wink:. Upon failure they not only (potentially, depending how it fails) send full voltage to the servo, but to the receiver as well, which will usually kill it.

Yet another reason to stick to the internal BEC. :)

The castle esc is also apparently a little more noisy than the other brands mentioned (koolflight, herc, dimension) and can cause glitching if you have it near enough your antenna or rx.

Yea your right brian...my herc bec says 3.5 amps I'll try and limit myself to 5 servos or less.

Don't be so quick to take the piss, I read an article (and for the life of me cant find it right now) about some guy testing a bunch of newer high torque servos - I think it was the JR series that have super high torque (like figures over 400oz.in) that were drawing 4A or so with minimal load on them. The bright side is that fully loaded peaks weren't much higher - still under 5A...

well, thank you all for the input!:smile:

I set up my MMM v2 w/o the BEC and its kickin @$$! :yipi:

I ran my e-revo with two zippy 4300 20-30c 3s run in a series for (6s)
Lasted about 20 minutes. VERY powerful :surprised:

My zippy's looked a bit puffy tho. They came out at about 135F :no:

doing more testing in a bit.

Charging my TRC 15c 8000's (4s) :mdr:

Whooo!
I'd check your temps a lil more frequently when you run those TRC cells simply because they'll last longer and gone unchecked, you could end up with more than a puff...maybe smoke...or FIRE even! :oh:
j/k: you know I'm just jealous. :yes:
Flog that sucker, Hoovhartid!

Just got back from jammin my TRC's :whip:

:yipi:

The temp outside was 95F. Motor got to 185, batts got to 120
ESC fan turned on a few times, but averaged around 160-140.
Still goin strong. I'm gonna give it hell.:diablo: It seems to like it :yes:

Got the e-revo geared for about 40 on 4S, and 60 on 6S.
Might gear it down a bit to see if it lowers the temps overall :neutral:

I think the temps are just going to be high do to the heat outside tho.

A servo that draws 4amps? My hs-5955 tg 333oz beast is pulling about 220-330 ma (5v/6v) with no load and around .5a (500ma) with load which sounds about right with the dimension sport bec specs that state 6 digital servos.

Mate since when were we making personal attacks? I was just trying to help.

Did you measure your servo current with an oscilloscope? unless you have one your readings won't be accurate at all. Here are some readings of a few servos, 1.8A for an analogue 200oz servo. Or if you want to whinge because that's quarter scale, the one to the left is a regular size analogue 100oz high speed servo. Still not even digital.

OK guys, take it easy.

coolrunnings: What did you use to get those current readings? I've tested a Hitec HS-5945MG (180oz-in @ 6v) and it pulled 2.4A under typical steering load. I wonder if the meter (or whatever) you used had a sampling rate too slow to capture the current peaks?

I got this info from a guy named Randy Moody at r/c dude hobbies, he did not use any testing equipment that I know of, I think it was best guess going by what he read on my servo's spec sheat and from info he's gathered over the years on the dimension bec's...he was supremely confident that my sport bec would handle at least four of the 5955's I mentioned as stated by dimension. No I didnt test anything.