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-   -   Making an esc better? (https://www.rc-monster.com/forum/showthread.php?t=6588)

GriffinRU 05.18.2007 03:09 PM
Quote:
Originally Posted by AAngel
Griffin,

Two mamba boards in parallel? Would this be similar to just soldering on a bunch of FETs in parallel to those already on the board? Forgive me if that is an ignorant question. It's just that I was thinking about it as I was sitting in court today. I wondered what the effect would be if I just soldered a bunch of FETs in parallel to those already there. Wouldn't that almost double the esc's ability to handle current? If this is just plain stupid, let me know. If it is a possibility, let me know that too. I'll source some FETs and maybe get lucky.

I don't know if this tells you anything, but I got back a couple of MMs that I sent to Castle for repair. The repair receipt says that the cause of the failure was "FET Failure." It also says, parts used:

6-BSC022N
2-F320
6-ISL6700
2-BAT54A
2-TL750
4-BAW56LT1
2-LM2665
2-LM3394

Obviously (I think) the prefix number preceeding the hypen is the number of components used to repair my two escs, but the rest of the stuff might shed light to someone that knows what they are doing.
Thank you, I will check on parts...
As far putting FET's on top each other, you can do that, but MAMBA MAX ESC is not the best one to try that. I need to do some homework to understand why they didn't install resistor in series with FET's gates, but that might be just mistake or trick which I need to find out. If you add more FET's then you definitely need to add resistors and maybe replace boost caps. Another thought what is working great with TO-220/D2-pak packages doesn't work great with SOIC/SO-8, I am afraid that in addition to soldering you need to use some bonding compound to hold chip in place and provide good heatsinking.
And, fundamentally, YES it would increase current handling and decrease internal resistance.

AAngel 05.18.2007 03:22 PM
Griffin, thanks. I understood SOME of that.

With regard to the FET "gates," I'm assuming that the gates are actually traces on the pcb, or are they a component. Now adding resistors, where? What values would I need? I have a pretty good selection of SMT resistors, but would just as soon glue them to the heatsink, because I have no idea. I'm like a backyard mechanic. I can replace parts because they've gone bad, but don't necessarily have a full appreciation of the internal workings of an internal combustion engine.

As for the "boost" caps, are you referring to those cap mounted next to the heatsink? I believe that those are of the 220uf 25v variety. Would the 330uf 35v caps that I got suffice?

It's really going to kill me if I suffer through all of this, provided that I can get a clue, and Castle releases the MMM.

GriffinRU 05.18.2007 03:40 PM
Quote:
Originally Posted by zeropointbug
6s...300A....:027:

How are you going to go about doing this? (package setup) What kind of FET's are you going to use?

GriffinRU: If you have look at my Quark case design, I am wondering how cooling all FET's very well will change current capability? I know it will probably ALLOW it to run to it's rated continuous current (most likely), do you think it could run a 2250 (with a bunch of added caps) in say a heavy 1/5, 1/6 scale on-road car?
I am looking at IRF1324S-7 with 12 FET's total.

If you can keep temp low and under control then I do not see any problems with driving any scale model. But there is one thing which you need to consider, with every today's speed controller (with SO/SOIC) only one side has good heatsink, that means that only these FET's can be used in calculation for rated power dissipation (at elevated temp) and use derating factor as well. So if your quark has enough FET's to dissipated power of losses associated with 2230 motor at your working temp, then you should be Ok, otherwise that's would be your limiting factor.

AAngel 05.18.2007 03:44 PM
Artur, does it hurt having all of that info in your head all of the time?

GriffinRU 05.18.2007 03:51 PM
Quote:
Originally Posted by AAngel
Griffin, thanks. I understood SOME of that.

With regard to the FET "gates," I'm assuming that the gates are actually traces on the pcb, or are they a component. Now adding resistors, where? What values would I need? I have a pretty good selection of SMT resistors, but would just as soon glue them to the heatsink, because I have no idea. I'm like a backyard mechanic. I can replace parts because they've gone bad, but don't necessarily have a full appreciation of the internal workings of an internal combustion engine.

As for the "boost" caps, are you referring to those cap mounted next to the heatsink? I believe that those are of the 220uf 25v variety. Would the 330uf 35v caps that I got suffice?

It's really going to kill me if I suffer through all of this, provided that I can get a clue, and Castle releases the MMM.
No, gates are pins on FET chip.
Well, there are couple ways how you can achieve that, first we can just add resistor in between gate pins (quick and easy bad) another way (good) would be cut the trace install resistor in place and then install second resistor in star type connection and connect it to other gate. It is pretty simple on the board but sounds complicating in explaining how-to. Also I am not ready to recommend that yet, I need to do some research with Mamba ESC.
Boost caps are not the big ones on the side, they actually small ones responsible for high side FET's drivers. I need to measure them first and then verify if their capacitance sufficient to drive additional number of FET's.

zeropointbug 05.18.2007 04:17 PM
Quote:
Originally Posted by GriffinRU
I am looking at IRF1324S-7 with 12 FET's total.

If you can keep temp low and under control then I do not see any problems with driving any scale model. But there is one thing which you need to consider, with every today's speed controller (with SO/SOIC) only one side has good heatsink, that means that only these FET's can be used in calculation for rated power dissipation (at elevated temp) and use derating factor as well. So if your quark has enough FET's to dissipated power of losses associated with 2230 motor at your working temp, then you should be Ok, otherwise that's would be your limiting factor.

Yes, that's what I mean. It should keep all FET's very cool... the top FET's will have copper heatspreader to case, and the bottom FET's will be directly attached to case, it should work great!

I really am excited to see what comes out of your esc's for performance. What is the bigger problem then? -Getting the heat away from the FET's? -Or the number of FET's handling the power?

430A current capability, that's impressive!

GriffinRU 05.18.2007 04:27 PM
Quote:
Originally Posted by AAngel
Artur, does it hurt having all of that info in your head all of the time?
:) Hobby :)

silentbob343 05.18.2007 05:57 PM
Quote:
Originally Posted by AAngel
Yeah, I thought the Quark would be the ticket. I can live with 5S, but when I started reading about the heat problems, I wasn't so sure. I consider excessive heat to be a sign of a bad design, especially in light of the fact that the esc won't do 6S like it's supposed to. I don't mind doing the mod to help keep it cool, but that would render it a one shot deal. If it blows, you're just about screwed.
and stacking fets is ok with CC?

I see you went with the Quark, good luck with it.

supralover72 05.18.2007 07:56 PM
I just wanted to let you guys know, for the right price castle will build you guys a custom esc. They did it for Tony Phalen.

Aragon 05.18.2007 08:07 PM
That means there could be an opportunity for a bunch of people to all pitch in on paying them to do that...

silentbob343 05.18.2007 08:07 PM
Quote:
Originally Posted by Aragon
That means there could be an opportunity for a bunch of people to all pitch in on paying them to do that...
Group Buy

GriffinRU 05.18.2007 08:44 PM
Quote:
Originally Posted by supralover72
I just wanted to let you guys know, for the right price castle will build you guys a custom esc. They did it for Tony Phalen.
More details and pricelist, please.

BrianG 05.18.2007 09:02 PM
I'm surprised some engineer at Castle hasn't thought of a modular ESC idea. That way, they can use the same brains board, and just feed the signal to as many power boards as needed. Would be a little more pricey at first to come up with a modular unit, but would cut their costs on the long run. That is assuming their firmware/software was totally upgradeable like the MM...

AAngel 05.18.2007 09:23 PM
Artur, again thanks for the information. I suppose that my ignorance is showing with the elementary questions, but I actually did understand what you said about the resistors on the gates. I am quite comfortable soldering on pcbs. I am typically working on pcbs about .5" in diameter and soldering 0603 size resistors to them, among other things. Working on the MM will be a walk in the park, so to speak.

Last question for now...I have 0603, 1206 and 1210 size resistors. Will any of these be of the appropriate size? I just hope that I have the proper values.

GriffinRU 05.18.2007 09:40 PM
Quote:
Originally Posted by AAngel
Artur, again thanks for the information. I suppose that my ignorance is showing with the elementary questions, but I actually did understand what you said about the resistors on the gates. I am quite comfortable soldering on pcbs. I am typically working on pcbs about .5" in diameter and soldering 0603 size resistors to them, among other things. Working on the MM will be a walk in the park, so to speak.

Last question for now...I have 0603, 1206 and 1210 size resistors. Will any of these be of the appropriate size? I just hope that I have the proper values.
Questions are always welcome and there is no bad questions, 0603 are fine parts for ESC mods.


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