Feedback on a project I've been working on

[codrum]

I've been working on a project that uses a phone as an analog and digital gauge for wideband, boost (MAP), oil pressure and IAT/CLT temp sensors. It connects via Bluetooth and is meant to replace physical gauges for these four sensors. It's very fast and responsive, querying the sensors 50 times a second to keep up with changing conditions. I've never liked having physical gauges in my car because I'm afraid of advertising to potential theives. But I also wanted to keep an eye on crucial engine processes, especially when I first tore the engine apart, put it back together, and turbocharged it. It's a small peace of mind when I'm ripping around in the e30 to know that the engine is running as it should be. The project has turned out pretty well and I thought there might be potential for other enthusiasts to use it, so I'm asking for feedback from the community.

Here is what the app looks like. You can download it free from Here
Here is what the device that connects the car to the phone looks like (prototype, no soldermask or silkscreen layers).

I'm calling it "Chariot Gauge" since I've done most of my design and testing on an e30. I've started building out a site to house more in-depth information about it here: www.chariotgauge.com. The app is free and I'm trying to keep the price down for the device. I would sell two kits: a DIY kit for $30 that you can build yourself with instructions on how to do it on the site. Total cost with all components would be around $50. The second option would be a fully assembled kit with pigtail for $100 ready to be installed on your car. The device comes with the MAP sensor on the board, you would need to source your own wideband, oil and temp sensors if they're not already on your car. The app is widely configurable for different sensors and sensor resolutions and most should be connectable.

It's currently only available on Android phones. I'd love to port it to iOS but if there's not much interest I'll probably keep it as a personal one-off project and stop development. The app is lightweight and runs smoothly even on old Android phones which can be picked up pretty cheap if you don't already have a few laying around.

My questions are then:
1. Is this something you would be interested in if I started producing them?
2. Is $30 ($50 total) for the DIY kit and $100 for the assembled kit reasonable?
3. Any other feedback on the project? Anything that needs clarifying?

Edit: Also, here's a short video of it in action:

[Xat1cZ]

1. This is pretty cool, I don't think I would actually use it over actual gauges in a car that's pushing serious HP, I guess I would just feel more "safe" with the good ol' gauges, but in a daily driven below 300hp car that don't need that much supervising it would be pretty cool to have just for fun, while still having some important data covered which is never a bad thing. And if it would be proven to be working real good, maybe the gauges would eventually go ;)

2. I think the price sounds good. I could pay that for it in the future.. when money ain't thight

3. 1 internet cookie for great effort ;)

[codrum]

1. This is pretty cool, I don't think I would actually use it over actual gauges in a car that's pushing serious HP, I guess I would just feel more "safe" with the good ol' gauges, but in a daily driven below 300hp car that don't need that much supervising it would be pretty cool to have just for fun, while still having some important data covered which is never a bad thing. And if it would be proven to be working real good, maybe the gauges would eventually go ;)

Great feedback, thanks. My hope is to produce a more responsive gauge system than analog gauges provide. With more installations on various cars and trucks I'd like to win over your confidence that you can use the Chariot Gauge system to permanently ditch your other gauges.

While I'm trying to present it as a simple product there is fairly serious tech to ensure accuracy of the gauges. All of the data is converted from an analog signal to a 10-bit integer in the onboard ADC on the microproc for good data resolution. The temp gauge uses the Steinhart-Hart thermistor calibration model to interpret non-linear resistance as a temperature. The wideband takes a linear voltage and interprets a lambda value for various configurations (pre-set to 0v=7.35AFR, 5v=22.39AFR). The MAP sensor is a proper MPX4250AP used in various automotive applications for absolute 0-250 KPA readings.

3. 1 internet cookie for great effort ;)

Aw Yiss!

[TurboJake]

I like the idea. Quite good. One little bit of advice would be to make a tablet version or mode, so you can have multiple gauges up at once. Heck, even make the gauges able to be customized and do "Mini-dash" systems.

Add tach signal, introduce datalogging. Etc.


I would be worried about the refresh speed and frequency too, but I don't think this would serve as a good tuning platform. Just as a good monitoring one. And with that in mind, it fits the bill very nicely.

[nokincy]

Displaying multiple gauges and having a night mode would be good features to add later on, but this is a great innovative idea. I'll consider picking up the kit once I turbocharge my car.

[codrum]

I like the idea. Quite good. One little bit of advice would be to make a tablet version or mode, so you can have multiple gauges up at once. Heck, even make the gauges able to be customized and do "Mini-dash" systems.

Add tach signal, introduce datalogging. Etc.


I would be worried about the refresh speed and frequency too, but I don't think this would serve as a good tuning platform. Just as a good monitoring one. And with that in mind, it fits the bill very nicely.

As it sits right now is the minimum viable product so I could move into the current beta testing and research stage. If and when I start producing them I'll begin developing some of the enhancements you mentioned. The first three will be:

1. Two selectable gauges per screen (on a phone). There's two schools of thought when passing the data between the device and the phone: The first passes a token from the phone back to the device to indicate which data should be sent over corresponding to which gauge is currently displayed. The second is to have the device package all four sensor's data and send it to the phone and let the phone decide which data it needs to display. The firmware is currently setup for the latter in order to support multiple gauges at the same time, datalogging and warnings - development for down the road.

2. Configurable warnings for each sensor. Say your oil pressure drops for some reason, regardless of which gauge you're looking at a flashing popup would display what's going on. Or maybe your temps are too high for too long, your boost pressure hits too high etc..

3. Datalogging over some time period.

I really like the idea of a tablet mode that could display all four at the same time, I'll be looking into that once development ramps up again, thanks!

Displaying multiple gauges and having a night mode would be good features to add later on, but this is a great innovative idea. I'll consider picking up the kit once I turbocharge my car.

Night mode is already present (settings -> general) but you're right about the multiple gauges. Thanks for the interest.

[codrum]

Thanks for the positive feedback and votes of interest - once I finish the beta testing on a few local cars in the next few weeks I think I'll produce an initial run of 100 units and reassess interest then. I'll keep the community updated!

One last bit, it was designed to fit in an Altoids tin:

[Wergen7]

This is a sweet idea especially since I haven't put any of these gauges in my car yet it would probably save me a lot of money. I would have to know it works well though. I'm sold on the Altoids can thing haha so sick

[Thizzelle]

can you turn your phone sideways and the app rotates?

[codrum]

can you turn your phone sideways and the app rotates?

Not currently, I'm forcing the portrait layout (has to do with rendering the gauge face and needle positioning). However one of the big three enhancements will be multiple gauges per screen and that'll be forced into the landscape layout.

[OrganicMechanic]

why no iPhone?

[mbonanni]

Great idea to keep boosted people from using their cell phones while driving.

[jaywood]

This is cool...

I am an iPhone guy so I would need an iPhone app...

Good job so far. Looks very promising!

[der affe]

could you do oil temp as well as oil pressure?

[dustyperez]

could this be integrated into a radio receiver with a pop out screen some how? that would be sweet.