Please spend time and read entire post as I made several modifications to this Jeep, alot of trial and error, and expense you dont need
15 Years or so ago, My little brother had a 3 Wheeler Cop Bike made by Fisher Price. I believe it was a 6 Volt. I had an RC10 that broke (remember the cheap plastic) I took the Guts out of that and made my Brothers trike RC. The best part about it was that he could still ride on it.
15 Years Later I have a little Girl who's grand parents bought her a New Jeep Wrangler (was supposed to be a Barbie Jeep) but Costco Ran out. So they bought the new model of the Fire Rescue Jeep. 12 Volts of total COOLNESS
I have seen these rinky dink little RC cars that sell at the Swap meet, and knowing what I did 15 years Ago could still apply. The only Difference was 2 Wheels I had to account for.
It started yesterday. I went to Hobby People in Riverside and bought these components:
2 HS-5745MG 1/4 Scale Servos. 2 Cirrus 2 Foot Extension Cables Cirrus Y Cable Servo Tape Xtm Racing 5 Cell Battery 1000mah NiMH (Just for Servos) AirTonics Blazer Radio (comes with Receiver, small servo.) 1 HS-645 for the Gas Peddle. Tubing for the Servo Arms.
The only thing I can’t figure out is what Speed Controller to use. I tried to use the little Servo to engage the Foot peddle but that turned out to be useless. When I rigged up the trike I used my speed controller from the RC10 Car (it was an analog system)
Before the Madness begins.
You can see Below that I drilled holes in the steering arm to accomidate the Servo Bars.
***UPDATED *** See End of Post Below is a shot of the 2 Survos working togeather, I am still unsure on the power of these Servos, they seem to work ok Even with pressure ( 22 pound Cat Litter Bucket (LOL)) but I am thinking of getting larger yet.
Loose one of the links from the servo to the Power Wheels tie-rod. It will just cause binding. The link between the 2 servo arms alone will work perfect. But, you have to put the 2 servo horns on the 2 servos exactly the same so the leverage doesn't change. And make an adjustable link between them so they don't fight each other.
Beef up the other link to the tie-rod. It will not hold up like that. You can buy some pretty beefy ball ends that will screw onto threaded rod.
Add some servo savers. The tires are not only hard to turn because of weight, but the offset from the steering axis to the tire gives LOTS of leverage. Something has to give, would be better if the servo saver gives instead of the servo gears shearing off their teeth! Unfortunately, I don't know of any 1/4 scale servo savers, so it might take some research to find some, or build your own.
In order for dual 1/4 scale servos to get the power needed to run full torque, you will probably need to power the servos directly and bypass the receiver.... the receiver probably won't handle that much power through it. I believe it's semi easy, just ask if you need help with that, I'll see what I can find.
You say a 6 cell battery... 2 questions, what size, and why 6 cell? R/C electric "7.2 volt motors" need a 6 cell for max power. But the ESC then has to provide a reduced voltage (4.8 to 6 volts) to the receiver and servos. Well, you aren't running a 7.2 volt motor, so bypass the BEC (also semi easy), and run a 5 cell pack to power the receiver and servos directly. Keep in mind, you can't run dual 1/4 scale servos from a "Nitro" receiver pack (usually 600mah to 1500mah), the cells aren't big enough, you need a 5 cell "sub C" pack (usually 1500mah to 4000mah, the higher the better). Maybe you can just cut a cell off your existing pack?
I haven't seen a price for a 5745MG, but it's a digital servo, and I'm guessing the analog 805 would be cheaper. And more torque. And digital servos won't last more then a few minutes when "stalled", something very possible when trying to use it on a Power Wheels. I'd see if you can get your money back on the 5745's and get some 805's.
An electronic speed control that will power a "Power Wheels" is going to be very spendy. Especially if it can handle 12 volts. A medium torque servo (645 for example) might push the pedal switch. I'm trying to remember if there is a spring under the pedal on the uni-body Jeeps AND a spring in the plunger switch, or if it's just the spring in the switch.... my uni-body is no where near stock.
Something that might be cheaper then trying to find an R/C speed control is running a scooter controller. It requires running 24 volts, so you'll have to get more batteries, and lock out the high speed switch so you don't burn up the motors. But then use a servo to turn the "twist throttle." Just an idea.
RC10 was an analog speed control? I'm lost. You mean it was a mechanical speed control? If it was an electronic speed control, the newest ESC's are the same technology they used back then. All the parts from your old RC10 should work with any new parts. Though the RC10 parts won't handle the current or voltage of that Jeep.
Ok, so instead of buying a Speed Controler I just got a larger Servo to pull down the peddle. I just went down to Hobby People because they dont sell the Dual Speed Control units anymore and I do not want to spend $$$ for dual Speed Controllers.
Just got a HS-645 MG BB for the Peddle. Hooked all the batteries back up and everything works! I will post some pics and a video soon.
Not sure what a Servo Saver is. Do you have a pic showing what I need to do? I did a search for servo savers and see what they are but not sure how they will fit into my application.
As for the quesitons from swhenrik, I bought a seperate 5 Cell 1000mah NiMH Just to power the Servos. Nothing ties into the 12 Volt System. I dont want to fry anything.
RC10 was an analog speed control? I'm lost. You mean it was a mechanical speed control YES that is what I ment sorry for the wrong terms.
The Servo Extensions are .062x36 Cut to size and placed inside 600MM Tubing to add Strength. I would Imagin that if I remove a link that it would maybe need stronger extensions.
And THANK you for the Tips!! They are Very Much Appriciated.
I have done some research on the Servo Savers, I called 2 places Hobby People and HobbyTown USA they dont even know about who would sell 1/4 Scale Servo Savers.
I understand the concept now and would agree I need something. If I dont remove the second link to the Tie Rod would that keep from possibly killing my servos?
Perhaps a link to someone who might sell a good Servo Saver?
You could run dual standard speed controllers, tied into the receiver with a "Y" cable like you did for the servos. But most ESC's won't handle 12 volts. A servo pulling the pedal is probably easier.
Servo saver: http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXS444&P=7 But that is for a standard size servo, not a 1/4 scale servo. I'm sure it's gonna be too soft/flexible in your application. Like I said, I don't know of any for 1/4 scale vehicles. They usually have something built in to the steering bellcranks of the vehicle itself.
Making something can be tricky too.... I can't think of anything that is easy to build.
I didn't imagine you would tie into the 12 volts, unless you bought a voltage regulator, which are expensive.
I don't think a 1000mah pack is enough to power those servos. Those are probably the 2/3A size (mini-T's and Nitro receiver packs). I'd get a 2000mah or bigger, made of "sub-C" cells.
For links, something like this would be better: http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXDDY3&P=M At least for between the 2 servos. Right hand thread on one end, left on the other, so spinning the middle adjusts the length. That would be great to have make sure the servos aren't fighting each other.
Though it maybe still is not strong enough for the link to the PW tie-rod.
OK, I can't find a harness that does what I think it should do, so here's how to power your stuff....
Start with a battery... you can cut open up a 6 cell pack (2000 mah or bigger), remove one cell, and resolder the wire on. Or, buy a 5 cell like this: http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXMUU4&P=7 And add your own connectors. Maybe talk to the hobby shop about it.
Take your "Y" harness. Strip a spot on both red wires without cutting them, solder them together along with the red wire from the Tamiya plug. Strip both black wires, solder them together along with the black wire from the Tamiya plug. Tape up the connection well. Do NOT cut the blue/yellow wire.
Plug the steering servos (5745's) into the "Y" harness, and the "Y" harness into channel 1. Plug your 645 into channel 2. Plug the tamiya plug into the battery. And you are set.
I am sad to say that one of my Servos died. Not sure why at this point but I can tell you it was VERY hot, yet the other was fine. Is it possible that it failed in some way? When I plug it in all it does is turn till it cant turn and then keeps running without even trying to control it.(no wonder why it is overheating)
I am beginning to wonder if these are not providing enough Torque. So the question comes up, what next? Larger Servo? is there such a thing?
How could we get this Jeep to drive on the Grass and steer without any issue?
I'm guessing the servo failed because of the additional weight of the kids and running on grass. That would certainly add some strain to the steering The vid looks great though! Looks like it works well.
You're only young once, but you can allways be immature
I know why your servo died.... digital servos don't like to be stalled, and burn up in a matter of seconds. Digital servos also "hum" when trying to correct. Once to the proper position, the humming should stop, or be intermittent. In the video, they were humming constantly. You NEED a way to adjust it to get rid of the servos fighting each other. And going with non-digital servos would help them last longer when they are stalled.
So now the control board burned up, and that's why it won't find it's own center. Been there, done that, $100 lesson learned (Hitec 5925)!
The "gearbox" in your link, uses a 5955TG, which is a digital servo again... only this time a VERY expensive one! Also, being it's a gearbox, it's gonna be kind of slow. 0.75 seconds doesn't sound that bad, but when you are waiting for it to steer while driving, it may seem like an eternity.
Tying the wires into the servo is something I'd let them do. Even though it's $30 extra, it's kind of a lot of screwing around, and an expensive lesson if you do burn it up. Hitec's warranty is fairly good, but not THAT good!
You need a 3rd channel servo to run forward/reverse duties LOL.
So how did the 1000mah 5 cell hold up? Dead after being on for a few minutes?
Well the 5 Cell is still working without a charge, pretty decent really.
I know the reverse was killing me, it was funny too because if you noted in the one video the kids kept clicking the unit into Reverse after being trusted back. So something may be done, but I dont want to spend the money on the Speed Control. Perhaps since I have an extra servo I can use that to figure out reverse, however only 2 channel radio will not give me the control.
The Gear box will replace the 2 Servos, So I will not have to worry about servos fighting. I wonder if the Hobby Shop will return the one working.. (probably not) Do you think HiTec will replace the burnt up one, no scratches on it so it dont look abused. You would think when they stall that there should be a safty unit to keek it from burning up the motor.
So you think the gearbox might be to slow? If we are only going 2-5 Mph I dont think it would be that slow. I went ahead and orderd it, but I did not pay the extra 30 bucks (dont think it will be that bad to hook up)
I believe the way it works is that you just hold the brakes for a minute, and then it will tell the 3rd servo to go into reverse.
Going with a single servo will get rid of the binding issues... as long as you go with only one link to the PW tie-rod.
For returning the working servo, you'll just have to ask, they might take it back.
Hitec warranty for the burned up one.... again, ask.... call them, the number is (858) 748-6948. They will probably want to just send you a new one, not a refund. Though you may be able to return the new one to the store.
If I were to make a guess, I'd think the steering speed would be fine in low speed (2.5 mph), but possibly an issue in high speed (5 mph). For R/C's, a transit time of 0.20 seconds for a 645 seemed like forever, but 0.13 seconds for a 5945 seemed perfect. Though I'm talking about something capable of speeds closer to 40 mph.
Did you read the info about connecting the external pot on that site?
quote:Note: Since the motor in the HS-5995TG servo is soldered directly to the circuit board, extreme care is needing when disassembling the servo to reach the internal potentiometer wires. If the motor wires are damaged, they cannot be repaired and the servo will be ruined. We HIGHLY recommend having our technicians assemble this unit for you. * We highly recommend purchasing this unit assembled by our factory. If you are not accustomed to using a soldering iron or handling delicate parts, please order this product assembled ready to plug into your receiver or servo controller. It is money well spent. Thanks
Ok so I just called and talked with Tom at Servo City (great guy) He was telling me that he has had a handful of customers buying this exact gear box for this application. He also mentions that it is easy to solder (only if you know how, which I do otherwise pay 30 bucks) the connections in place. The unit comes with pictures and detailed instructions oh how to put the unit togeather.
He also mentions that there is really no need (yet) for a servo saver besides the unit itself has no room for one. All the customers that have ordered have not called back because of a broken tooth, you can also order if you like a metal gear system from them. They only have it though for the 5:1 unit.
That Reverse Mixer is awesome! I will have to look into that one. I assume you plug this into one of the channels (the one that opporates the servo for the gas peddle) then you plug the 2 servos into that unit.
Reciever CH1 to Reverse Mixer to Servo for Gas Peddle (forward) Servo for Gear Shifter (reverse)
What's odd about the mixer is that it looks like it has plugs for 3 servos, yet only one male... so not sure what the 3rd is for. Otherwise, I assume you are right about plugging the throttle and reverse servos into the mixer, and steering straight to the receiver. HPI directions are usually pretty decent, I'm sure they'll answer any questions you have once you get the unit.
I'm surprised they don't suggest a servo saver. Aborbing impacts with something flexible (servo saver for example) is a whole lot easier then having the gears take it all with no give.
Did you ask him about getting a setup with non-digital servo to prevent "burned out due to stalling" issues? Can you get it attached to a single 1/4 scale servo with a little less reduction to get some speed back?
Alright the moment all have been waiting for... Well at least I have. I got the new Mega Servo and wow was my first impression. I rigged up a new mount and mounting hardware.
I also took the liberty to figure out a new solution to the Gas Peddle. Took off the assembly and made the survo pull a cable that way if a kid decided to press the gas it will not kill the servo.
Ok Need some advice, I just bought a Speed Controller (EVX3014) Need to figure out how to hook it up.
I have 2 Motor Connections and 2 Battery Conntections. What I would like to do is connect the Single Lead from the 12 Volt to the Speed Controller (So do I take the 2 Bat leads and spice them?) How about the output to the Motors? Splice them too?
What I tried was to take the leads from the Battery, Twist the Red-Red and Black-Black from the EVX Connect the leads to the Battery. Then wire up the 2 Motors (Like was intended) but I did not get any power to the wheels. I was able to program the EVX I see it getting signal but no wheel movement. Is it possible that the EVX is not getting enough Power to drive to the motors? I know its intended for 2-14 Volt Batts but was willing to take a chance thinking it would power what ever it was given.
I also found out the Specs of the Motors in the PW's They currently use Johnson HC683LP Series motors (Code PT03007, Type PMDC, 600 Size)
A Side note: I feel its kinda funny that I thought the Steering would be the most difficult to engineer however I seem to have more problems with the gas peddle more over everything else. All the while I am trying to keep the integrity of the powerwheels for the use of Kids. (No cutting of wires, only minor drill holes)
What you want to do is connect the battery to only one side of the battery connections of the evx and use this jumper on the other side. http://www.buytraxxas.com/product_info.php?products_id=2696&osCsid=nt59206o7qknd99gaqcnp9vte0 This allows you to use 1 battery. This esc is designed for 2 battery packs in series which should equal 14-volts, without the jumper I assume it is an open circuit, what the jumper does is complete the circuit. What I do not know is if that one side can handle 12 volts since it was designed for 2 batteries. You could just get 2 6 volt batteries and hook each battery to each connection.
As for the motors one motor would connect as normal and the other motor would have to be connected in reverse because the motor is facing the other way.
The link for the "manual" goes to the same page....
The EVX is set up to run the batteries in series. Twisting the reds together, and the blacks together, forced it into parallel. I'd be surprised if it didn't burn something out.
To connect a single 7.2 volt battery to the EVX, you have to connect to one terminal, then diconnect and reconnect to the other terminal, and see which set of wires powers it up. The set that powers it up, is the set you connect to. The other set needs to be shorted together (with that jumper, or by connecting the red and black together).
This also allows the BEC to work (it will power servos and the receiver). If you are using a receiver pack, you need to NOT connect one of the wires from the ESC to the receiver.... either the red or the black, I'm not sure which. Again, if you connect all 3 from the ESC to the receiver, and plug in the 5 cell, it will probably burn something up.
Next issue... can the EVX handle 12 volts into one set of wires, where a 7.2 volt used to go? I'm not sure!
The motor output wires, I'm pretty sure are just in parallel with each other. You can connect to just one set, or twist the reds to each other and then the blacks to each other, and power that way... I "THINK". Or a motor to each...
If you want a person in the vehicle to be able to "Drive" it with the normal pedal, you will probably need to physically disconnect the motors from the ESC.
OK so I just called Traxxis and the most that box can handle is 8 Volts each lead. That means even though a Jumpered lead you still can only run 8 Volts. Dang it will not work.
I was reading somewhere about possibly using a dimmer switch for variable speed, what is the probability of that solution?
I was reading somewhere about possibly using a dimmer switch for variable speed, what is the probability of that solution?
Pretty much zero! But here's an idea:
quote:Originally posted by swhenrik
Something that might be cheaper then trying to find an R/C speed control is running a scooter controller. It requires running 24 volts, so you'll have to get more batteries, and lock out the high speed switch so you don't burn up the motors. But then use a servo to turn the "twist throttle." Just an idea.
I own this thing for like 2 wheeks and a gear box is going bad? It keeps slipping now. Is this common? We drive the jeep in the grass with my 1 year old daughter in it. No modifications as you know has been done to the drive gears. Or motors for that matter. If i pick up the rear when the rear right wheel clicks It then goes... but if it hits strain it stops again.
If you have a gearbox going already, I'd call Fisher Price, or where you bought it from, and see what they can do to fix it for you. It should NOT go out that fast unless someone was severly abusing it.
For a radio, I'd recommend a Traxxas TQ3. They are fairly cheap new, and cheaper yet on eBay. The 3rd channel would be handy for forward/reverse. It's also a semi easy radio to modify, you can change the switch for the third channel in it to a 3 position (then you could have high, low and reverse), or even another potentiometer for a variable 3rd channel.
No I did not get a reverse mixer, I have still been tinkering with a better solution for the gas peddle.
What I did this time was buy a ON ON Momentary Toggle Switch. This allows me to hook up a servo to the toggle and mount it somewhere. I bought some more terminal connectors and made a jumper to the foot peddle (disconnecting the switch there) with 1.5 foot extentions to the Hood of the Jeep (12 guage) hooked them up to the new toggle switch and mounted the servo and swith to a mounting bracket in the battery compartment. This seems to work now flawless and less strain on the servo trying to pull down that massive spring in the stock switch.
The Battle switch only has a max Amp of 10. I believe these are running at 20 (have not been able to test)
Just wanted to give an update to the madness. Mostly all the same components are being used with some mods:
1. I got a Momentary ON / ON switch to use for the throttle and mounted it to under the hood. Did this witout harming existing wiring, and disconnected the foot peddle. Photos to come if you like.
2. Deffinatly get the Metal Gears for the Servo box system, the plastic ones only lasted a week. Metal ones still going working perfect.
People have asked how much weight I have put in it. 2 Little Girls (one 25 Lbs the other 30) so 55 Lbs. I even drove it in the grass and all over parks with this config. People absolutly love watching. Moms call the Hubbies to come and see it. People wonder where I bought it and well maybe I sould sell... but I would rather tell people how to do it.
3. I have not got a reverse mixer yet to control the Toggle switch on the Jeep (Reverse, Slow, Fast) I have found it not needed.
Obviously the most money spent here was used on R&D / Trial and error. Please use my knowledge to help guide you, and dont make the same mistakes I did, unless you have the money to waste.
Quick question how did you mount the servo for the steering the holes on the servo for screws are on the top of the servo and the servo needs to be mounted side ways how did you do it.
Quick question how did you mount the servo for the steering the holes on the servo for screws are on the top of the servo and the servo needs to be mounted side ways how did you do it.
I think it would be helpful to look at the site he mentioned to see what he is talking about. http://servocity.com/
Its been a while since I posted.. The more I drive this thing with my daughter in it the more I have fun watching reactions, Take this weekend as an example, There was a couple that had a 9 month old girl, she was strapped in with my little girl in the passenger seat and drove though a crowd, people were pointing and amazed.
My Uncle told a few people in this crowed "You have to watch this this little girl is amazing at driving" lol anyway just wanted to keep in touch.
Update on the linkage The metal gears are stripping a little, but I have had (on several occations) been driving my neice and my daugher in this jeep (about 60 pounds total) in the grassy fields we have. The thing that would make this complete is a Speed Controller.
Adding to what Gameboy posted, get a twist throttle for a scooter controller, remove the spring, and use your existing servo to turn the throttle. That 645 should have no problems turning it.
Well it looks like China is trying to do something to manufacture these kits to make PowerWheels RC. Some guy from China added my IM to his list and started chatting about how the market would be for something like this... I sure would like to see this be made in the USA.
Hey Sourceminer, I just wanted to say thanks for you post. I read all your instructions and applied it to my sons Lightning Mcqueen and it worked great!
I wanted to give another update since I am on the site. Danika has just turned 2 and now can reach the peddles so we disengaged the Radio controls (FOR NOW) until we have another. It’s been so much fun and was worth the efforts entirely.
Fire Rescue Jeep RC Conversion
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Posted - 10/19/2007 : 10:07:53
