Battery Monitor Project
 

Our team, 5052, is working on a project and were looking for some feedback on the idea. I have designed a battery monitoring system, that can monitor the voltage of the robot battery and display it onto a simple LED bar graph to provide a quick, accurate way of telling how much charge your battery has. The purpose is to know when it is time to switch batteries for the best performance in competition or practice , without having to constantly rely on a multi-meter.
We were considering producing these in larger quantities (batches of 20 or so) to cut costs and to sell as a fundraiser, since being a rookie team, we are in need of money. I was wondering if there would be a demand for this sort of device, and whether anyone had any insight on how to market something like this.

Thanks,
David

Re: Battery Monitor Project
 

The CRE Battery Beak is already a very good existing solution to the problem.

Re: Battery Monitor Project
 

Something like this?
http://www.andymark.com/product-p/am-0995.htm

If it is something like this, I think it would be hard for you to drum up customers, as this is already being sold and many teams like it; unless what you make is functionally similar and cheaper.

Will you test at load? Because, as I understand, voltage without load isn't enough to know if a battery is charged or not.

EDIT: guy above me basically hit the nail on the head.

Re: Battery Monitor Project
 

Timing wise, the best time to switch out a battery is before every match.
That is the procedure most teams (that I know of) try to follow.

Aside:

There are existing solutions to this issue already. Cross the Road already sells a battery beak, but those are quite expensive. In addition, the driver station also already has a voltage monitor on it while the robot is in operation.

However, don't be completely discouraged. A quick, easy to check battery meter might still have a place if you can get it to a low enough price point.

The idea and drive to create a new product is awesome to see. However, as a rookie team, you need to evaluate whether or not time might be better spent trying to establish relationships with local companies as sponsors.

Re: Battery Monitor Project
 

I mean a multimeter works fine for our team for checking voltage.

Every team should have a nice one....we picked up a nice Fluke Multimeter from FIRST Choice. (for free :cool: )

Re: Battery Monitor Project
 

I would have to agree that a battery visual aid system is a good project...

Though the beak from Cross the Road Electronics is a FAR better way of checking a battery state than a multi meter. The beak gives the battery voltage, battery percentage of charge, as well as voltages with a few different loads.
The load voltages are a much more accurate depiction of the battery current "health".
I highly suggest one..

Also if you do VEX there is an adapter to test there batteries as well..

I will say it has saved us potential issues in competitions. Yes, finding a dead cell battery in competition is a pit managers feel good moment!
While the rest of the team is out driving, scouting and just out having a good time, you are there quietly testing what many forget...
Also check your battery cables, many work loose after a few matches with big hitters. :yikes:

Hope your project and season go well..

Aloha!

Re: Battery Monitor Project
 

Aloha!
An easy way to keep battery hardware from coming loose is to add a #10 star washer between the terminals before you assemble. This little addition prevents the wire terminal from slipping around on the battery terminal. Without the slip, the normal battery hardware (#10 screw, lockwasher and nut) cannot loosen.
A search here on CD will give you a lot of posts on battery health. No voltmeter will give you an accurate measure of battery health without monitoring while connected to a load. The terminal voltage of an unloaded battery will show almost full terminal voltage. The Battery Beak does a quick check by switching in resistors to act as a temporary load and then calculates battery impedance. If you are going to design a device like the Beak, my one wish is to have a larger display.

Re: Battery Monitor Project
 

Maybe your team could tweak your project slightly. While the need for a battery checker is already fulfilled by an off the shelf product, there is another application you could focus on.

Our team has found that it is best if the drive team keeps its eyes on the robot, rather than looking down at the drivers station displays for data. But each year, there is usually some piece of data which would be useful for them to know. This year we have a pneumatic catapult. We want to know if the pressure in the system is above the threshold to be good to fire. We have installed a pressure sensor and will turn on a light on the robot if the pressure is good.

Last year, we wanted to know how many disks were in the hopper. We ran out of time to implement that. The year before, we wanted to know if the shooter wheel was at speed to properly shoot a basketball. Even when there isn't some sensor, it would be nice to have a visual indicator on the robot of how much time is left in the match.

Your led display idea could be adapted to provide a useful visual indicator given some sort of sensor input (linear voltage, encoder pulse, timer start pulse etc.). If you were creative, you could make both the input type and the display output configurable. This custom circuit would relieve the robot computer of valuable cycle time. If it were easily configurable, it could be a last minute addition on practice day which did not require potentially bug inducing code modifications.

If it existed as a product, with a reasonable price, we'd probably buy it.

Re: Battery Monitor Project
 

I checked out the battery beak and it does seem like a good product. As far as functionality goes, ours would be simpler since it only shows the voltage equivalent, not accounting for the load drop -unless you could somehow read it while the bot is running (probably unlikely). Ours was also designed for permanent mount on the robot. As far as price goes however, we were thinking of a price point of around $20, which is a fraction of what the battery beak costs on andymark.

Would it be worth it to teams to have a quick indicator of general battery charge, or is the load check the make or break for this sort of thing?

Re: Battery Monitor Project
 

If you're simply looking at creating something to measure battery voltage, either this: http://www.adafruit.com/products/460 or this in a panel: http://www.adafruit.com/products/575 could be used. My team has used the smaller non panel meter on our robot, and it is very useful.

Re: Battery Monitor Project
 

Bonz, The driver's station shows the battery voltage near real time, under load. Are you looking to do something different? The voltage is sensed by the analog module by sampling the voltage at the PD through the analog module power input required under R70.

Re: Battery Monitor Project
 

Our team has small seven segment displays that wire into both the battery terminals and the PDB so we can tell what the voltage is. One of our mentors found them online and theyre pretty cool.

Re: Battery Monitor Project
 

The idea was to be able to tell how charged the battery was without having to be connected to the driver's station. This could keep from wasting time connecting to the robot, deploying/running code, and then finding out that the battery needs to be changed; in which case the robot would need to be powered off, then reconnected etc.

Re: Battery Monitor Project
 

For competition, you should change the battery after every match.

For practice, you are connected to the Driver Station and can see the voltage on the screen.

Re: Battery Monitor Project
 

We added a voltage display to our robot this year and it's actually one of the best additions. The reason it's nice is we can check voltage without having to be at the drive station. When we're testing normally only our drivers are at the laptop and the rest of the team doesn't know the voltage. With the little display everyone can see it. Also we can see if the battery has been changed or not very quickly when at events.

It's basically this but in blue.