Introduction: 24v Grave Digger - Electronic Speed Controller (ESC) Upgrade
In this Instructable, I'm going to be installing an ESC (electronic speed controller) into our 24volt Grave Digger Power Wheels. If you haven't been following along, I've done a bunch of other requisite modifications to this beastly BPRO. This should be our final upgrade before I go and just fully convert it into an electric go-kart.
Why do I need an ESC? It's the best way to prevent mechanical failure of gears, motors and wiring when you run 24+volts of DC power to a kid's BPRO (battery powered ride on). The ESC provides soft start, variable throttle and soft braking. These are the main features that allow you to go to 24v and beyond without shredding your gearboxes and melting your wires. The stock throttle pedal is just an on/off switch. Larger motors on higher voltages can put out a lot of torque. Applying all that torque instantaneously is a recipe for breaking things. The ESC allows you to softly ramp up your throttle, which not only prevents breakage, but has better acceleration vs stock (because you're not just doing burnouts until the wheels grab, they will start soft, grab and go).
Plus you also can get cool features like remote parental kill switch, backup beeper and easy 12v accessory wiring.
I got my ESC from www.EastCoastPowerUp.com . The 1000w DIY kit is an awesomely fun wiring project (for those that like that sort of thing) and the man running the show there is super helpful and willing to answer any questions you might have. Some of the best customer service I've ever experienced. Can't recommend them enough. (No, I wasn't paid to say that... and Yes, I happily paid full price for the kit. It's an excellent value.)
Step 1: Disassemble the Hood and Trunk Pieces
The 24vGD doesn't have an easily accessible hood and trunk like the older GD model does. To gain access to the areas we need to run wires, we'll have to remove some screws. On the underside of the vehicle, there are about a dozen screws holding the hood onto the main tub. They're mostly located along the edges, but there are a couple up near the headlights and a couple way up in where the dash and hood meet. Easiest way to find them all is to start in one corner and work your way around while gently prying the hood up. If it's getting stuck, look for a hidden screw. It will pop right off easily once you have found them all.
The trunk is a bit easier. With the seat off, there are three screws that attach the rear lid to the tub. Then there are four screws hidden beneath the rear window sticker. If you look closely, you can see the outline of the holes they are sitting it. This will require damaging the rear sticker for access.
Step 2: Board Layout
For this step we're simply following the directions on the wiring diagrams that came with the East Coast ESC Kit.
I started with mounting the ESC and relay groups to my board. I tried to mount them in in positions that would make wiring to the terminal block and other accessories as simple as possible. After the large components were mounted I test fitted the board in the truck to make sure it would fit. Then I just went wire by wire, making each connection as shown on the diagrams. I made sure to double check each connection before cutting wires. I used my crimpers to secure the terminals on each wire.
Once I had the heavy wiring completed, I connected the bench side of the light gauge wiring diagram. There are a lot of wires to connect, but don't be intimidated. Just go one by one and it'll get done. It took me a few hours to complete this step, but I was meticulous about double checking each connection before I cut/crimped. I really enjoyed this part of the project, something about making so many wiring connections was satisfying.
Step 3: Test Fit the Board
After I had everything connected, I unscrewed it from the board so that I could paint the board. I would recommend painting the board first if conditions permit... but it was freezing here when I started, so I had to wait for a sunny day to paint my board. The board I used is just a piece of 5mm underlayment / luaun plywood. You could also use a piece of plexiglass or any other non-conductive material. Some people mount their ESCs directly to the vehicle. Since the compartment in the 24vGD is vertical, I figured mounting to a board would be the easiest method.
Once I was confident that everything would fit inside the rear compartment, I reattached all the components to the painted board and set it aside for a bit.
Step 4: Remove Stock Wiring Harness
Almost all of the stock wiring needed removed for this install. After all, a big positive of using an ESC kit is to have properly sized wiring for the amperage that a 24v system like this can draw.
I started by removing my batteries and the previous connections I had made to them. I unscrewed the wire raceway on the underside of the vehicle and followed the wires to each end, disconnecting everything. I pulled the plugs off the shifter and foot pedal. I also disconnected the quick connects to the motors, leaving the leads on the motors for the time being.
The only stock wiring that I left intact was related to the sound board and LED lights. It was all a rat's nest from the factory, but I'll clean that up shortly.
Step 5: Clean Up Stock LED Wiring
The jumble of wiring for the stock lights and sounds was appalling. Literally just tossed in there and all knotted/tangled up. They were clearly in a hurry to get this out of the factory.
Anyway, each light had its own lead tied into a circuit board. There's one circuit board in the front hood compartment and one smaller circuit board in the rear trunk compartment. The front connects the speaker, headlights and sound switches. The rear connects the side and rear lights. Each lead had a quick connect plug to the circuit board, so I just disconnected each wire, untangled it, pushed it through a length of heat shrink tubing, applied heat to shrink the tubing, then routed them in a neat bundle. For this entire project, I tried to run everything in the heat tubes to keep the wiring as neat as possible.
I left the front circuit board mounted in the stock position and relocated the rear circuit board onto the board I created in step 1.
Using my multimeter, I could see that the front board was taking in 24v from the batteries and putting out 1.8~v to each LED. Often times when installing an ESC kit, you'll need to use a stepdown converter to apply proper voltage to your stock circuit boards. This model was 24v stock from the factory, so it did not require a stepdown. If your model was stock 12v, you'll need to use a stepdown converter to keep the magic smoke inside your circuit boards. 12v circuit boards do not like running at 24v.
Step 6: Mount Throttle and Brake Pedals
Next I needed to mount the new foot pedals. This kit uses a separate brake and throttle pedal. Stock BPROs have automatic braking when the driver releases the throttle. That instant on/off action puts a lot of strain on the gearboxes. This kit features variable throttle with soft starting and stopping, which greatly reduces wear on the drivetrain. We also noticed a boost in acceleration with the soft start, as there is much less wheel spin at startup.
I mounted the new throttle in the same location as the stock throttle. The new pedal has much more physical range of movement than the stock, so I mounted it recessed inside the nook that previously housed the stock wiring. I used a screw/shim to adjust the height of the pedal. I wanted it to be just above the floor at full throttle, without the floor inhibiting the pedal from being fully depressed. The screw split my shim (found this out when I snuck my camera in for a picture, I couldn't actually see this). So I pulled the shim out and left the screw to act as a bump stop.
The brake pedal was super easy to mount, just marked its spot and put a couple of screws in. I ran the wires for both pedal into the rear compartment via the raceway on the underside of the vehicle. I made sure to put lengths of heat shrink tubing over each set of wires as I ran them. This will help with wire management later on.
I needed to use my multi-tool/vibrating saw to remove some material for proper fitment. I have a few of these multi-tools of various brands and they're so incredibly versatile. By far my favorite power tool for my tinkering projects!
Step 7: Extend the Motor Leads
I'm using Traxxas 5675 motors in this build and they have performed wonderfully so far. The stock leads on the motors are only a couple inches long with bullet connectors. There's two 14awg leads for both positive and negative. I removed the bullet connectors and connected both 14awg leads into one 10awg wire to extend the leads into the rear compartment. I made sure to use heat shrink tubing over my connections to prevent them from shorting out against each other.
Step 8: (Optional) Install Gauges for Monitoring Voltage / Amperage / Watt Hours
This step is optional but I really recommend it. I went and added a gauge for monitoring different aspects of the electrical system. I used one of these onboard multimeters to monitor the voltage, current, power and energy. I was mostly interested in watching the voltage to know exactly how much battery life is left during playtime and the watt hours measurement to use as an odometer that tracks total power consumption over time. Being able to monitor amp spikes is also nice. Plus it's a cool little LED screen in the dashboard and kids love stuff like that.
Install for this was simple as well. I just followed the included wiring diagram and used 18awg wire to make the connections. It basically involves wiring in a 100A shunt on the negative line between the batteries and the load. Then 4 light gauge wires measure differences on either side of the shunt to give you the readings. I connected the light gauge positive wire into the new on/off switch so that the gauge is only powered on while the entire unit is powered on. If you wire it directly to the battery, it will stay on 24/7 and drain your batteries.
I used my multi tool to cut a hole in the dash and inserted the gauge unit. It snaps right in place and secures itself with push tabs on the back. Definitely a good addition to the setup as it allows me to monitor everything with the electrical system during play sessions.
Step 9: Replace Stock On/Off Switch
The stock on/off switch only controlled the lights/sounds. Flipping it to the off position did not prevent the vehicle from moving if the pedal was stepped on. I fixed this by removing the leads to the stock switch and connecting them together. Then I drew power for the stock circuitry from the terminal/accessory block of the new ESC kit.
The switch that came with the ESC kit fit perfectly in place of the stock switch. I wired it up as detailed in the ESC wiring diagrams and pressed it into the dashboard. Now when you flip the switch, the entire unit powers on/off. The ESC kit came with a choice of colors for the switch, we chose the light up green switch and it looks really cool with the green Grave Digger color scheme.
Step 10: Mount Batteries, Make Final Connections, Test
Whew! We're finally getting somewhere!
Now I went and installed everything in its final spot in the vehicle. The ESC board was mounted securely in the trunk. The vehicle side wiring was all connected to the proper locations as depicted in the wiring diagrams from step 1.
The batteries were placed back in their position and connected to the shunt on the negative side and the ESC on the positive side. I used the push-button resettable 40A circuit breaker to connect the two batteries in series. The circuit breaker was located under the driver seat so the driver can reset it during a session without any disassembly required.
I also opted to not use the ESC kit's charge port in favor of using leads for my Noco G4 charger. I attached a set of leads to each battery. This will allow me to balance charge the 24v bank by charging each 12v cell individually. I also really like that the Noco has a cold weather maintenance mode, which is important in my climate.
I also connected my motor leads to the relay group and triple checked my wiring diagrams vs what I had actually installed. Everything looked good so I put it up on jackstands and tested it.
Turning the switch on and the ESC/Relay group lets out an audible click to show that it's powered on without fault. Pressed the pedal and the wheels move.....in opposite directions! Whoops! I needed to have one motor connected in reverse (could probably even use a reverse-timed motor, but had trouble sourcing one). So I flipped a few connections around and it was functioning properly.
Step 11: Wire Management
After I was positive everything was routed properly and functioning, I started to wrap up my wire management.
As I went along, I ran my wires in heat shrink tubing to keep everything neat and separate. Here I just bundled it together with zip ties and coiled excess up neatly where possible. This step is really up to you with how meticulous you want to be. I felt that I did a reasonably decent job, but wished that the underseat compartment looked a little cleaner. Not sure how, as there are just so many wires, but overall I was pleased with the look of the install.
Step 12: Send It!
The ESC Kit install has been a great success! We've been running for over a month now and we've had zero issues. Previously we'd blow fuses frequently and even melted a switch in the stock shifter. Before it could not handle two kids with the upgraded motors, now it handles two kids just fine. My son loves that it has two pedals and has rapidly advanced his driving abilities. The stock gearboxes have held up to the 9~mph speeds and hilly terrain. This kit is good stuff!
Overall, the ESC kit solved all the issues we were having and added more functionality. Can't recommend www.EastCoastPowerUp.com enough! (Wes, if you see this - send me a T-shirt or stickers or something for plugging the crap out of your website!... or don't and I'll still keep buying your stuff because now kiddo wants the other rides to be as fast as Grave Digger)