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View Full Version : 2x3 stack of 8858's?


SkylineLvr
02-25-2009, 06:27 PM
I've heard that doing a 2x3 stack of 8858's aren't a good idea and I should just do a 2x2 stack. Is this true? I heard that a 2x2 will handle just about any motor out there.

I just don't wanna do a 2x2 stack, then end up frying them when I could have just done a 2x3 in the first place. Any advice would be appreciated, since I don't know much about fets

TripleXmodder(akaXXX)
02-25-2009, 06:38 PM
If you go to Atomicmods.com and click on motors, every description says what stack is prefered. They have just about every motor you'll come across and they are GREAT about including specs like that with everything.

http://www.atomicmods.com/Categories/Radio-Shack-XMODS/XMODS-Evo-Car/Motors.aspx

They also have comparison charts for motors and just about everything else.

xmodzracer
02-25-2009, 07:51 PM
i have heard that the higher the stack, the more twitchy or jumpy the motor will become.

SkylineLvr
02-25-2009, 07:58 PM
I've heard that too. Atomic Mods say that the Atomic Chili (the motor I might get) needs a minimum 2x2 stack, but prefers a 2x3. They are talking about stacking the 4562's. I've read that the 8858's are a little more better then the 4562's. I just don't wanna fry my fets and possibly damage my board

xmodzracer
02-25-2009, 08:04 PM
hey better safe then sorry eh?

2wdpancar
02-25-2009, 09:20 PM
2x2 is for the 2wd cars... some of the 4wd cars need one more fet layer due to more strain on the motor. (driveline in the ma010 increases amp draw)

SkylineLvr
02-25-2009, 09:35 PM
I am leaning towards a 2x3 stack. I will wait until tomorrow when I get off of work to do it. I wanna get some more input from others. Either way, if it is too twitchy or I am having problems, I'll just take a layer off

TripleXmodder(akaXXX)
02-25-2009, 09:56 PM
2x2 is for the 2wd cars... some of the 4wd cars need one more fet layer due to more strain on the motor. (driveline in the ma010 increases amp draw)


Completely wrong. The stack height is determined by the motor. That simple. I am running a chilli a PN S04 in a mini-z with only a 2x2 and it is suggested a 2x3. I have had no problems. You should be fine unless you abuse it and ignore stopping running when the motor is hot.

SkylineLvr
02-25-2009, 10:10 PM
I wanna run either an Atomic Chili or an Atomic T2. I'm pretty sure 2x2 would suffice enough, but I know they would run hot, so I wanna be as safe as I can. Not positive if I will run either of these. I do like the Chili though, at least what I have read about it.

TripleXmodder(akaXXX)
02-25-2009, 10:28 PM
I wanna run either an Atomic Chili or an Atomic T2. I pretty sure 2x2 would suffice enough, but I know they would run hot, so I wanna be as safe as I can. Not positive if I will run either of these. I do like the Chili though, at least what I have read about it.

You will be fine with a 2x2 if your running AAA, I would go 2x3 if running Lith/Lipo. Good to Go.

2wdpancar
02-25-2009, 11:46 PM
XXX: S04 and a chili in a 2wd or 4wd car? I don't know how I am wrong but put a chili or an s04 in a ma010 w/ 2x2 FDS8858CZ.
Modified motors can run faster w/ a 2x3 fet stack in a 4wd..... there is more strain on the motor in a 4wd driveline causing more amp draw. The lower the stack will not allow a motor to function at its full potential.
You would think that a guy who winds motor, stacks fets, and drvies long times with modified motors has some sort of a clue...............................

Skylinelvr: The chili has an advanced endbell so unless you don't want to mess around with it... get the T2. You should really see how fast a stock-r is on 2x2 of 3010 fets and the right gearing. You have to move your way up.... you'll see when you get a decent-fast motor. Don't jump to the mod motors yet... I did that and I went back to a base of running the stock-r.

TripleXmodder(akaXXX)
02-26-2009, 01:52 AM
Well your definatly right about a 4wd being more strain on a motor. But it will not be any major difference and it will basically come down to what motor. And I DO have a miniz AWD w/ a 2x2 running a chilli and it is just fine. You can check my miniz thread and confirm that with bigez. Not basho g you or anything, I'm sure you are very knowledgable in this area, I'm just speaking from experience and I usually consult and verify my info from good sources, usually Christian from reflex or soeone like that if I'm not sure. I back my answer still and wouldn't expect you to feel that I'm saying your not knowledable in this area, as I'm sure you are.


XXX: S04 and a chili in a 2wd or 4wd car? I don't know how I am wrong but put a chili or an s04 in a ma010 w/ 2x2 FDS8858CZ.
Modified motors can run faster w/ a 2x3 fet stack in a 4wd..... there is more strain on the motor in a 4wd driveline causing more amp draw. The lower the stack will not allow a motor to function at its full potential.
You would think that a guy who winds motor, stacks fets, and drvies long times with modified motors has some sort of a clue...............................

Skylinelvr: The chili has an advanced endbell so unless you don't want to mess around with it... get the T2. You should really see how fast a stock-r is on 2x2 of 3010 fets and the right gearing. You have to move your way up.... you'll see when you get a decent-fast motor. Don't jump to the mod motors yet... I did that and I went back to a base of running the stock-r.

Action B
02-26-2009, 10:28 AM
I've been running 2X2 stack for awhile. It handles the T2 motor without a question. I also run lithium on occasion, this is also fine. Trust me, the extra power will NOT be an issue. The T2 is so fast I can't even use it on the track.

Everyone can speculate whatever they want, I'm doing it.

Though, I'm not against throwing another layer on and reporting my results with the throttle response.

SkylineLvr
02-26-2009, 11:13 AM
I shot the guys at Atomic Mods an email and they said that a 2x2 will do, but a 2x3 will not hurt performance and it will only make it more efficient. I asked about the 8858's, but their response was about the 4562's. I think I will do a 2x3 stack and see if there is any noticable problems with that

TripleXmodder(akaXXX)
02-26-2009, 11:51 AM
you'll be good either way but a 2x2 is completely safe. Have fun with it.

Action B
02-26-2009, 01:16 PM
I shot the guys at Atomic Mods an email and they said that a 2x2 will do, but a 2x3 will not hurt performance and it will only make it more efficient. I asked about the 8858's, but their response was about the 4562's. I think I will do a 2x3 stack and see if there is any noticable problems with that

The 8858 is a superior FET. They don't sell that FET thats why they suggested 4562. Also, Atomicmods is not the most valid source to contact. Try shooting an email to reflexracing.net . The guys there are world champion Mini-z racers. Christian Tabush will probably get to you himself. There are far better references to contact. Much of atomicmods information is marketing influenced, also, I can't begin to list the amount of false information provided on their website.

Also, I still don't suggest such a poweful motor. I bought the T2 and still don't use it because its too fast to control on most typical RCP tracks, and I'm a pretty experienced racer. Though, if you have a fully programmable transmitter that could help (like the helios) becuase you can cut the throttle down to make it more manageable.

I'd suggest the atomic standard motor. Great price, great efficiency, perfect for medium tracks.

Here is an example of what I was talking about regarding atomicmods marketing. Trust me there are plenty of posts validating this argument. - http://www.minizracer.com/forums/showpost.php?p=297209&postcount=19

SkylineLvr
02-26-2009, 08:09 PM
Well I lifted a pad when I took of the stock fets. I thought I fixed it, but when I soldered the new fets on, I didn't have any power going to the motor. Looks like I'm gonna have to sell my Xmod now just to buy a new board. Man this sucks. Should of had Action B do it for me for $10. Now I'm out $50-$100. I'm so ****ed at myself right now

Action B
02-26-2009, 08:14 PM
Well I lifted a pad when I took of the stock fets. I thought I fixed it, but when I soldered the new fets on, I didn't have any power going to the motor. Looks like I'm gonna have to sell my Xmod now just to buy a new board. Man this sucks. Should of had Action B do it for me for $10. Now I'm out $50-$100. I'm so ****ed at myself right now
If you want I can take a look at it and try to fix it.
What technique did you use to take them off? I know the feeling sucks to have your Z down.

Don't get down on yourself man, its part of the learning process. I've not seen a board yet that was unusable after a failed FET install. It can probably be fixed.

SkylineLvr
02-26-2009, 08:17 PM
I was heating it up w/ an iron and using a hobby knife to pry it off. It worked fine except for one of the pads. If you could that would be great

Action B
02-26-2009, 08:25 PM
Well I lifted a pad when I took of the stock fets. I thought I fixed it, but when I soldered the new fets on, I didn't have any power going to the motor. Looks like I'm gonna have to sell my Xmod now just to buy a new board. Man this sucks. Should of had Action B do it for me for $10. Now I'm out $50-$100. I'm so ****ed at myself right now


I know the feeling sucks to do something like that though, I've done stuff to my real car like that before.

Usually these things are repairable. How did you go about fixing the lifted pad? While I've never lifted one I know how to fix them.

SkylineLvr
02-26-2009, 08:28 PM
I scraped away some of the board to expose some of the connection and soldered a small piece of wire to it. I don't think it worked, or maybe I didn't solder the fets on right

Action B
02-26-2009, 08:30 PM
I scraped away some of the board to expose some of the connection and soldered a small piece of wire to it. I don't think it worked, or maybe I didn't solder the fets on right

This is where a multimeter would be very helpful. You need to check for continuance to see where your issue is. Not only can you make sure there is no bridging, but you can test to see if the FETs leg is properly connected to the board.

If you have any questions let me know, if you don't feel comfortable messing with it further you can send it to me and I'll do my best with it.

SkylineLvr
02-26-2009, 08:32 PM
Yeah, I don't have one that works. I should have just waited. I wanted to get so many upgrades for it, now I got to try to get it fixed or buy a new board

Action B
02-26-2009, 08:34 PM
Yeah, I don't have one that works. I should have just waited. I wanted to get so many upgrades for it, now I got to try to get it fixed or buy a new board

Well, if you want to pick one up, I got mine at walmart, its great. Only 20 bucks and it does everything.

I have a spare car too and I could maybe help you out with a new board, lets just see if we can't get this one working first.

SkylineLvr
02-26-2009, 08:35 PM
Can I send it to you? Do you have time to try and fix it?

Action B
02-26-2009, 09:20 PM
Yeah, I don't have one that works. I should have just waited. I wanted to get so many upgrades for it, now I got to try to get it fixed or buy a new board

Hey if you don't mind, which leg did you have a problem with. Consider the front of the board being the front of the car and the FETs labeld A and B. Like this

1234 1234
(A)---(B)
5678 5678

The formatting won't turn out right but
which pad did you have the problem with?

SkylineLvr
02-27-2009, 03:38 AM
It would be on B-3. The side that is closest to the diode

Action B
02-27-2009, 10:24 AM
It would be on B-3. The side that is closest to the diode

Wow, that IS a tough spot. Its okay though, I have an idea.

SkylineLvr
02-27-2009, 10:31 AM
Yeah tell me about it. I'm thinking it might not be repairable

Action B
02-27-2009, 11:15 AM
Yeah tell me about it. I'm thinking it might not be repairable


I found a spot to run a jumper wire on the other end of the board. If you have a camera that is good enough take a picture of your PCB and i can show you where it is. Some other guys have had success with repairs like this. It is taking a chance but it might be all you've got. The repair is similar to the ones in the below link, but different as its a different pad. I didnt' find any specific references to fixing the particular pad you lifted, so I think were about to make one.

http://www.minizracer.com/forums/attachment.php?attachmentid=8202&d=1069593325

I was going to use this picture to show you were YOUR jumper wire could run, but the board is different. So this is just an example.

I ordered 25 more 8858 FETs last night and sent them priority mail. So my FET stock won't be an issue.

SkylineLvr
02-27-2009, 11:24 AM
I've already sent it out to you. Do what you can. If you can't fix it, do you have a spare board you could sell me?

Action B
02-27-2009, 11:34 AM
I've already sent it out to you. Do what you can. If you can't fix it, do you have a spare board you could sell me?

Well.. again, I run into the issue that the extra board I have was given to me. Let me think about this for a bit. Right now I have all intentions of giving your board back to you with a functional 2x3 stack. I feel 80 percent certain I can fix it.

SkylineLvr
02-27-2009, 11:43 AM
Sounds good to me. I wish I knew people that you know, I like free stuff, lol. I hope you can fix it. I'm bummed out that my Mini-Z is in pieces boxed up right now. :cry:

Action B
02-27-2009, 11:45 AM
Sounds good to me. I wish I knew people that you know, I like free stuff, lol. I hope you can fix it. I'm bummed out that my Mini-Z is in pieces boxed up right now. :cry:

Well, these people are my friends. You can meet them too just come down to myrtle beach on the 7th. On the minizracer forums I have personally met a lot of the members. We travel to race with each other and race every now and again. People from all over are going to that Myrtle beach race. So when they have extra parts they aren't using, or when my car is broken, a lot of times they are willing to help me out. Because of this generosity I have seen, I've been doing FETs for free. I can't afford as much parts or cars as some of those guys, but I can offer my services.

You took your car apart?

SkylineLvr
02-27-2009, 12:16 PM
That's awesome. I think the wife and I will make the trip down. It sounds like a lot of fun. I've never seen a real race before. I would offer my fet service, but I think people would want their cars to run after wards, lol. I'll just have to practice more. I think if I didn't lift the pad, it would have worked out nice. I'm pretty good at doing the tight turns and the power switch bypass on the gen 1 Xmods, but those are pretty easy to do. Have you done a power switch bypass on a Mini-Z? Does it really take away power having a power switch.

Just so you know, my wife was the one that wrote the addresses on the package, not me.

Action B
02-27-2009, 12:54 PM
That's awesome. I think the wife and I will make the trip down. It sounds like a lot of fun. I've never seen a real race before. I would offer my fet service, but I think people would want their cars to run after wards, lol. I'll just have to practice more. I think if I didn't lift the pad, it would have worked out nice. I'm pretty good at doing the tight turns and the power switch bypass on the gen 1 Xmods, but those are pretty easy to do. Have you done a power switch bypass on a Mini-Z? Does it really take away power having a power switch.

Just so you know, my wife was the one that wrote the addresses on the package, not me.

Heh, you'll see my girlfriend if you come, she is a great racer!

I haven't removed the switch, does it take away power? I don't really think so.

If you come down, I'll give you a spare board I pracitice on a lot and some spare FETs I have in my box. Then, I'll see if I can give you a couple pointers in person.

SkylineLvr
02-27-2009, 01:07 PM
Sounds good to me. I look forward to it. Is it just on Saturday or is it a weekend thing?