Welcome to the
Old Pueblo Engineering Center
OPEC of the West
"OPEC of the West" was founded 2006.05 in Tucson, AZ. to explore Human/Robot Interactivity

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“Drilling Brains for New & Better Use of Technology”

- PreFlighting the R2PV1 Batteries -
Calculating for the Optimal Battery Pack

A couple of nice things about the R2Pv1 Robot is the base has plenty of room to stuff battery packs into it ... such as the simple AA cell battery pack or the super 10,000 mAh LiPo pack.

The computer system can run anywhere between 9VDC to 12VDC ... but the robot does need a little more power than a simple BoeBot so I choose using a 3-cell Lithium Battery Pack. But Lithium batteries can cost big buck’$. Hence you need to find the battery pack(s) that best fits your budget and gaming needs.

Right off, changing out the “AA” cells battery pack for a LiPoly pack reduces the pack weight (really no big deal on the R2PV1 Robot), but more importantly a LiPoly gives you the ability to add more battery capacity per cubic inch … which translates to longer running times between battery changes and recharging.

You can see the in the photograph below the medium size 3200-3S Lithium Poly battery pack I use just over flows the gap in the base plate provided but gives me hours and hours of operation. So it all comes down to how many $’s you can spend for more operating time to play games before having to recharge the battery pack. So who doesn’t want to know how to get the most battery bang for your battery buck?

As you use your robot you should be logging all your run times in your logbook or log file so you can add up all the time the robot used power between the last time the battery was replaced or recharged to when it is drained to the recharging/replacement point. This will enable you to accurately calculate how much battery power it takes to run the robot for the amount of time you want your battery to last. You can also identify if you are having battery problems or not getting the proper recharge.

We’ll assume that you want the battery to last at least 10 hours for a very long day of gaming competition plus add another 10% time to fudge for errors and excessive motoring on occasion. So figuring 11 hours total for operation you will have the ideal battery size for your needs.

So what does 10% mean? Well, lets say you have $1. 1% (called one percent) is $0.01 or one cent. That makes 5% of $1 = $0.05 or five cents and 10% of $1 = ten cents or $0.10.

Looking at the side of the battery you want to look for the mAh’s rating. Not all battery manufactures print this on the battery so you have to start with batteries that you know the mAh’s rating to figure this math problem.

If your current battery is 1.5VDC and 250mAh’s and needs to be charged every hour, then your batteries are only lasting a little less than 11% of the time you need.

To use that mAh’s rating to figure out how big the best battery to last for 11 hours of operation is going to be by simply multiply 11 times those mAh’s and that becomes your target battery capacity.

So if your original battery is 250 mAh’s then you need;

11 hours * 250 mAh’s = 2750 mAh’s

This means your optimal battery would be about 2750-3S but you might not find any battery packs exactly in that size. So you may decide to go a little smaller and save a buck or two, or go a little larger.

You probably can find a 3300-3S for $125 and maybe a 2200-3S for $80 … it’s your choice but now you know about how big a battery will let your robot play all day and you decide how much to spend on the battery pack to optimize your $’s v. robot operation time.

Also, because the “AA” cells are 1.5VDC put in series for 6VDC and your 3S LiPoly will be 11.4VDC you gain a lot more running time just with the bumped-up voltage. Hence, the smaller battery would probably do more than you want.

One big battery could last all day, or you can have two smaller batteries that can be swapped out between matches. Have the second battery on the charger when it’s not in use.

Now it’s your turn to actually test and measure your battery pack and remember to log all your measurements in your logbook or log file so as time goes by, you can see how well your battery is performing and holding out so you can figure other battery optimizing ideas for testing and competitions later.

You may even want to more accurately define your battery requirements by comparing 12 VDC from two “AA” cell battery packs to an 11.1 VDC 3S LiPoly battery pack.

Patents Pending

If you’re bored with all this reading, just go play the game for a while and continue getting familiar with the robot and how it works. Try the AlwaysLeft and AlwaysRight rules to see them in action, to see which is more efficient in the gaming arena you setup. Then come back after your break to learn more about optimizing the robots travel through the gaming arena.

still under construction ...

The Autonomous and Remote Control Robot Gaming systems being developed at “OPEC of the West”
(OPEC = Old Pueblo “Tucson, AZ” Engineering Center)

HOME . . . . . Arts&Crafts . . . . . Preflighting . . . . . Castles & Crosses . . . . . Software . . . . . RoboParts . . . . . Videos . . . . . Contact
R2Pv1.com . . . . . R2Pv1.org . . . . . R2Pv1.net . . . . . LRobotorium.com . . . . . LRobotorium HobbyShop . . . . . ARGA . . . . . RoboToons

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