Please help, I don't want to fry anything...

[WRMorrison]

I'm getting ready to re-wire my emaxx and need some help/advice. I spent 2 hours drawing up my diagram, then can't figure out how to upload it (yes I read the sticky, but it still didn't help, I'm computer illiterate for the most part...lol). These are the parts I'm wiring up:

2 - Hobbico 1/4 servos
1 - 12V motor
stock tranny, GD600
(2) 6V - 5 cell batt packs
Novak evx
stock Rx

My reason for running 2 batts is so that each servo will have 6V not 7.2 (I don't want to take any chances on frying the servos.) I plan to use each y-connector that came with the servos to wire directly to each batt. The batts will also connect to the evx like stock. I plan to wire both pos. wires and both neg. wires to the one 12V motor. I think that will give the motor the full 12V it needs. If you're wondering how I'm going to attach 2 pos. and 2 neg. wires to each batt for hook-ups, I'm going to have them ordered that way. Will it be safe to run like that? I know nothing about elec. wiring (as you may or may not know by reading this).

Thanks in advance

[nktrnl]

Originally Posted by WRMorrison

I plan to wire both pos. wires and both neg. wires to the one 12V motor. I think that will give the motor the full 12V it needs. If you're wondering how I'm going to attach 2 pos. and 2 neg. wires to each batt for hook-ups, I'm going to have them ordered that way. Will it be safe to run like that?

If you wire them up the way Im thinking you are trying you are only getting 7.2V to the motor. It sounds like you are planning on running the batteries in parallel. If you want to get 14.4V to the motor you need to run it in series.

So
+ (on batt 1) to esc, - on same batt to + on batt 2. Then - from batt 2 to - on esc. (This will give you 14.4V)

+ on batt 1 and on batt 2 to + on esc, with - from batt 1 and 2 to - on esc will goive you 7.2V.

Safe or not? I dont know. I never ran an EVX.

[WRMorrison]

7.2V? I'm only planning on using 6V packs? In stock config., don't both 14.4V motors receive 14.4V from two 7.2V packs? If they do, running two 6V packs should (if I'm thinking right) send 12V to each motor (or one motor in my case). My two main questions out of this are:

A: Is it safe to run both sets of motor wires to one motor to receive a full 12V?

B: Will it cause a problem to hook each servo up to its own 6V pack, when both of those packs are also used to power the motor?

Too bad you can't build a good crawler with tinker toys and rubberbands, it would be much simpler....lol

Thanks in advance....Please Help!!!

[WRMorrison]

Wait a minute...got to thinking. Both stock motors (Titans) are 14V not 14.4V. Secondly, if both motors receive 14.4V in stock config. from (2)7.4V packs, then one 12V motor should receive 12V from (2)6V packs and I would only need to connect one set of motor wires to the single motor instead of both sets of motor wires, correct? I hope so. All my parts to start this build will be here within 2 - 3 days so I can get started. If anyone notices something obviously wrong with my plan (especially with how I plan to wire these servos), PLEASE let me know soon. I don't have an unlimited bank account to fuel my wild rc ideas...lol.

Thanks

[WRMorrison]

damn....I spend enough time correcting myself that no one else has a chance...lol. What I meant to say above was "two 7.2V stock packs" not 7.4V. I'll get it right eventually.

[BultacoJim]

WRMorrison wrote:

I would only need to connect one set of motor wires to the single motor instead of both sets of motor wires, correct?

Connect one set of motor wires to both sets of motor wires???

I have no idea what you mean by using 6 volt packs to power your motors, but
here is how to wire battery packs in both parallel and series configurations.
If you use 6v, then substitute 6v for 7.2v and 12v for 14.4v

nktrnl wrote:

So
+ (on batt 1) to esc, - on same batt to + on batt 2. Then - from batt 2 to - on esc. (This will give you 14.4V)

+ on batt 1 and on batt 2 to + on esc, with - from batt 1 and 2 to - on esc will goive you 7.2V.

Safe or not? I dont know. I never ran an EVX.

Draw and post your schematic for review.

[JohnRobHolmes]

he is using an evx, so he will just plug in two 5 cell packs instead of two 6 cell packs.

just hook up one of the motors. cap off the other two motor wires. they are in parallel on the circuit board so you dont have to worry about it.

here is an idea, use the BEC for one servo, and use the 6v pack that has its ground connected to the evx for the other servo. if you used the second batt pack you would send 12 volts to the servo since the batteries are in series. only the first battery pack in the series will work.

you are on the right track, but you can only use one battery to power the servos, as the second battery will have the first battery's power going through it and would thus have 12 volts on the last positive terminal in the series.

[WRMorrison]

Thanks a lot for the post, John, that makes sense. But I do still have some questions though. You said to connect one of the servos to the "BEC". What is that exactly, a power source? Is that the empty slot on the stock Rx that says "B"? If that is correct, then the Y harness that comes with the servo, one goes to the BEC and the other goes to one of the channels on the Rx? At least that's what I'm understanding.

Also, I understand now that the batts are wired in series, and that only one set of motor wires needs to be hooked up, but does it matter which set? It shouldn't if I understand you correctly.

Another thing, you said to connect the other servo's power source to the 6V pack that has its ground connected to the EVX. Which pack would that be? Both of the batt packs' neg wires run to the EVX. I understand that I shouldn't wire the second servo to the second pack in the series, that makes sense as well. But is there a way to tell which pack is the first in the series?

I'm sorry for all the newbie questions, but I'm a machinist, not an electrician...lol.

Anyway, thanks a BUNCH for the help. I really appreciate it.

[JohnRobHolmes]

aye, crap.

http://www.traxxas.com/products/acce...df/evxaddm.pdf
the instructions just in case.


i just realized that you will need a voltmeter to tell which battery is first in the series chain on that esc. i dont remember which wires are which and i dont have one to look at. i think its the one just labeled batt in the drawing, but i suggest you get a multimeter anyway. they are pretty cheap and you can test resistance, polarity, amp draw, and voltage.

for future reference, red is the live (positive) wire, and black is the ground (negative). it almost always works that way. sometimes brown is used for negative, especially on servos.
___________________________________________

B on the EVX stands for battery input. its for a reciever battery that you dont need since you have BEC

BEC stands for Battery Eliminating Circuitry. it elliminates the need for a seperate receiver/ servo battery. the EVX has a 1.5 amp BEC, which is enough power for most single servos-- but your 1/4 scale servos are too big.


what you are wanting to do is essentially substitute a 5 cell sub C pack for a 5 cell AA reciever pack.

to pull power directly from your 5 cell pack (the one that is first in the series chain) you will need to make a harness that goes between the rear servo and the reciever. cut the red (positive and power) wire in the harness so that the BEC current isnt sucked into the rear servo. then wire the positive and negative to the first battery. keep the negative connected to the reciever as well- the more ground the better. the third wire not touched (probably orange or white) is the signal wire and tells the servo what to do.




i think that will cover it. this took me a while to plan out! im doing the same with my super rooster. my servos overpower the 3 amp BEC

the way i have it drawn, the EVX's BEC powers the reciever and the battery directly powers the servos. you could get rid of the BEC and power everything directly from the battery. it might be easier for you that way. pic in next post.

[JohnRobHolmes]

this will work better for you since you are running dual 1/4 scale servos with the evx.




notice the arrows. the power wire is cut from the EVX, so the BEC is disabled. both servos will use the Y harness to power themselves and the reciever as well. because of high amp draw i would recommend that each servo get a seperate harness off the first battery pack in the series. your "reciever" pack will have main power wires, and two sets of y harness jumper wires emerging- one set for the front servo and one for the rear.

i would also suggest you put these jumpers on the EVX side of the battery plug. that way it is always on the right side of the EVX and you get the right voltage.

i hope i didnt over-explain it.

[WRMorrison]

First off, let me say thanks (again ) for taking the time out to deal with this. Some people would have stopped posting after I didn't understand the first time.

I'm pretty sure I get it, but let me double check with 'ya before I get out the side cutters:

!. The power wire from the EVX (blk/red/white) that used to connect to Ch. 2 on the Rx, now is going to be plugged into the "B" slot on the Rx, but the middle (red/power) wire is cut before it reaches the Rx.

2. First batt. pack in the series has the reg. power wires that connect to the EVX. and two sets of jumper wire leads (that plug in to each servo)

3. The double servo jumper leads are actually on the EVX side of the batt. connection (I assume this is for when I take the batts. out to charge them, I don't accidentally plug it in on the wrong side and cook something)

4. Ch 1 on the Rx (formally for the front steering servo only) now gets plugged into the servo reverser, which splits (or doubles) the signal to both servos now.

So far so good?

If so, then I have yet ANOTHER question for 'ya...lol (bear with me)

I want to be able to turn the rear steering servo on/off so that if I don't want to use it, I don't have to. Is there a way to install a toggle switch on the line that goes between the output of the servo reverser and the rear servo? If this would work, will a normal toggle work, and what terminal do I solder the three wires to? (If there is a way to describe such a thing)

Much thanks for the help and especially for taking the time to draw up the diagram. Sometimes, you just need a picture of it. (Thank God I don't still have crayons or my walls would look terrible...lol...hmmm....maybe I could get a chalkboard....anyway...)

Thanks, and I hope I'll be able to quit buggin' you soon and let you get back to your normal life.

WR Morrison

[JohnRobHolmes]

my time is well spent helping you out now. not only do i need to figure out my next project, but you might be able to help me later.

now for a few corrections.

1. the blk/red/white wire on the EVX still plugs into channel 2. its still the ESC and needs to be on the correct channel. the middle (power) wire is cut. you can actually take the red wire pin out of the connector and just tape it back, so that if you want to use your BEC later you just plug the red wire back in.

2. you are correct. your first reciever/main battery will plug into the EVX and have two jumpers going to the servos (and the reciever too, the second diagram shows it with an arrow)

3. you are correct. putting the servo jumpers on the EVX side ensures that the correct battery in series (so you dont overvolt everything) is always the servo/receiver batt. also, you dont have to deal with the jumpers when you go to charge your packs.

4. for 4 wheel steering on just one channel, you are correct in plugging in the reverser. the bad part is that you have to live with it all the time. the only way to effectively get rid of 4ws is uplugging the servo, and having a seperate linkage that bolts to the axle that will lock out the steering.

the only other option you have is a 3 or 4 channel radio so that the rear is independent. definatly my choice if you can spare the cash.

im sure there is another way to lock out the rear servo, but it would involve a switch that would divert the servo signal to a microchip that put out a centering pulse (440?). it would be easier to just buy a new radio and reciever.

im gonna be on the road a few days, but ill be online occasionally.

[WRMorrison]

Thanks a million. I'm gonna get to work on this in the next day or so when my parts finally arrive. I'll post again afterwards and let you know how it works. On your current project, If you need any custom pieces, let me know. I'll help you out if I can.

WR Morrison

[JohnRobHolmes]

its no problem at all man. i love electronics. i hand wound a 65 turn that will be pumped 12 to 14.4 volts on my maxx crawler when it is done. if i need any parts, i will keep you in mind, but i am pretty handy with hand tools. do you have a lathe or cnc available? i doubt i will need something, and all i could think of right now is aluminum beadlock wheels- but i know that would be very expensive.

good luck on the build!

[WRMorrison]

I have almost everything at work, but I'm a CNC Lathe operator and have no clue how to run a CNC mill. We do have manual mills, lathes, and of course drill presses, etc. If it can be made on a lathe, I can do it. I'm getting ready to make my own beadlocks. When I get them done, I'll email you a pic. (I still can't figure out how to post pics on here imageshack just doesn't seem to work for me) If you like the way I make the 'locks, I'll make and send you a set (you pay for postage, I'll take care of the material and labor)

Thanks,
WR Morrison

[JohnRobHolmes]

8O 8O your kidding right?? i would be infininatly indebted to your service for some beadlocks. even if you just made faceplates for me, that would be awesome.

[WRMorrison]

Sure, when I get my 'locks done, I'll send a pic. If not, draw up what kind of plates you want and I'll see what I can do.

[JohnRobHolmes]

i think it would be easier for you to just make two sets of your design. im bad at measuring and i have never messed with lathes. are you making your 'locks for your maxx? i cant wait to see some pics of your build.

[WRMorrison]

Yeah, they're for the maxx. It may take a little while though. I can only work on my stuff on my days off, and that's only when someone else is gonna be in the shop. But, I'll let you know.