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

[hoovhartid]

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

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....

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

[ogrfre01]

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

[Sammus]

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.

[tc3_racer_001]

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 ;)

[Sammus]

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.

[hoovhartid]

Originally Posted by tc3_racer_001

whats this about pulling the red wire to program?
to run a castle bec, you remove the red wire from the esc;


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?
yes, not a dumb question.
there is a simple solution tho. You buy one of these (servo extension wire) to run between the esc and the Rx;



cut the red wire on the servo extension.

when you need to reprogram, just unplug the esc from the extension, do whatcha gotta do, and put it back.

i too like to know everything - or as much as i physically can -

me too!

hope that helps...

[Sammus]

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.

[hoovhartid]

Originally Posted by Sammus

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.

Thanks for the heads up on this! I'll use some elect tape or something to secure it.

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.

I havent the slightest clue! in fact, I cant even claim to have come up with the extension idea myself. I was only parroting what I had read somewhere else

PS 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. .

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
ha ha

[ogrfre01]

[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

[ogrfre01]

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?

[JerryF504]

Originally Posted by ogrfre01

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.

[Sammus]

Originally Posted by coolrunnings

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.

Ahh dissing castle again . 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.

[BrianG]

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.

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