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41

For quadcopter designs, you generally want to have around a 2:1 thrust-to-weight ratio. That is, at 100% throttle, you want your combined propeller thrust to be capable of lifting two times the weight of the craft. You then need to determine the amount of power the motors need to generate that thrust (usually given on the datasheet). When you have that ...


14

The best commonly available battery technology when it comes to power density versus weight, and at reasonable cost, is LiPo. I would prbably recommend LiFePO4 batteries. LiFePO4 are somewhat more expensive than LiPo for the same watt-hours, and weigh somewhat more, but they hold the charge better, they age much better, and they can be re-charged five to ...


9

It sounds like you're asking 2 questions: Is an imbalance in motor performance indicative of a failing battery? How would you test for a failing battery? The answer to the first question is "maybe". We had an issue on one of the AUVs I used to work on, where sometimes at the end of the day it would lose all heading control. By chance, we discovered that ...


8

This is one of those questions where if you have to ask, you shouldn't be doing it. There are charge-monitoring boards available for these batteries, and for safety's sake you should be using them. You can still use a solar charger or some other method, but the output of that power source should feed a charge circuit that was built specifically for LiFePO4 ...


7

If the battery cost less than the thing you're powering, then you should probably discard the battery. If you're stubborn (or very strapped for cash) and the battery didn't catch fire when the original damage happened, then it might perform okay, but I'd say there's a moderate chance of fire, especially at high currents. Check battery voltage with a ...


6

I'm not familiar with that platform. But in general, no, you do not need separate batteries for each motor. Also in general, if you need 2-7.5V for each motor, then you probably want one honkin' big battery that puts out 7.5V or slightly more. You could use a 12V battery and take care with your drive commands to never give the motors over 7.5V. Only if ...


6

When taking into account size / weight / Ah, fuel cells and micro power turbines have an energy per kilogram and (with liquid fuels) an energy per liter that is an order of magnitude better than any battery. In particular, I keep hearing that liquid methanol fuel cells are "relatively practical". a b c d e. And I've heard that Hyuk Kim and Seungdoo Park ...


6

The batteries should weigh roughly the same as everything else on the airframe combined. With a given aircraft -- everything known except for the mass of the batteries -- the absolute maximum flight time occurs when the weight of the batteries is twice as much as the weight of everything else on the airframe combined. However, many other characteristics -- ...


5

Lithium Ion Polymer batteries are probably your best bet. They will present the least amount of magnetic interference (followed by Alkaline... NiCD interferes the most). Unlike the regular lithium ion cells (which are usually round), these ones will stack nicely. I hope you'll check the manual before trying this -- many of them are pressure tolerant. ...


5

It looks like your motors can draw up to 2.5A each; there's no way a 9-volt alkaline can sustain that current (plus the other on-board electronics) for any length of time. You'll need to pick a more appropriate battery for this robot. Have a look at the discharge curves for several batteries, and pick one that fits the current draw and desired operating ...


5

Further to @Ian's post, a couple of important comments: Your Battery Management System (BMS) (not just a simple charger!) needs to monitor the condition of each individual cell, not the set as a whole - this applies during the discharge phase, as well as during charging. And cell balancing (keeping all cells broadly level) is probably more relevant than ...


5

There are a few ways to read your question, but in general what you are suggesting is a bad idea. The only reason to do it would be in the extreme case where splitting a large battery into several smaller batteries would help you find space for them in a tightly-packed chassis, and even then it might be more trouble than it's worth -- quadrupling the number ...


5

The battery capacity specification (eg X mAh) tells you that your battery can run for 1 hour providing X milliamps until it is depleted. This doesn't always scale with time, for example you probably won't run for 1/2 hour if you draw 2*X milliamps, but this is another discussion. To answer your question, a greater mAh will allow you to use your battery for ...


4

Basically for charging LiPo/LiFe, you will need charger with balancer which measure each cell voltage level, as they tend to overheat or get damaged or even burst into a flame when handling carelessly. Lipo/life doesn't like trickle charge as NiMh or NiCd and also you will need constant current output at different voltage levels. But there are smart chargers ...


4

You can tell by the voltage. LiPo batteries have a distinct "knee" in their performance, generally around 3.4V-3.6V: It will be slightly different depending on the exact battery, and how you've arranged them in your battery packs (you need to account for the current load when measuring the voltage) -- so it makes sense to characterize your own battery ...


4

I find it's always cleaner to use connectors rather than soldering directly to leads, no matter what component you're trying to attach to your robot. You have to think about things in terms of maintenance. If a battery goes kaput (technical term :D) and you soldered directly to the leads, you'll have to desolder and solder again. If you used a connector, you ...


4

There are two main ways to power an Arduino: with 5 volts and with 6.5 to 12. Since your case falls under the 6.5 to 12 option there are two main ways you can get power into an arduino. The barrel jack can be plugged into a 6.5/12v source which works well. I have a habit of chopping the connectors off wall warts then I use the power supplies for other things ...


4

Typically, with LiPo batteries, they don't have a hard case. The hazard comes when the battery internals get dented, which causes the battery to short out internally. LiPo batteries can dump enough current when shorted to cause a fire and/or explode when shorted. The deformation that causes a dent in the battery is generally caused by a high local ...


4

I agree with @Greenonline 's recommendation regarding LiPo batteries along with his warnings on battery care. It seems you will need a fairly small battery, considering your current requirements (about a 1000-2000mAh 2S LiPo). However, you also need to add 2 5V BECs (5V regulators in RC lingo) to power your circuits; The 7.4 or 11.1V provided by the battery ...


4

You are approaching the problem from wrong side. Current capability of a battery (25C) has nothing to do with that how much current will it actually source. It is the load (motors in that case) what defines the current, not the battery. You could use 10C, 25C, 50C battery, and the current flowing through the motors would be (approximately) the same, as long ...


4

You aren't being specific enough. Some chemistries would possibly allow this but others would not. If the batteries have the same nominal voltage than theoretically they should work fine in parallel with no issues. The problem is when you start discharging them. See the graph below: (source: mpoweruk.com) Batteries with different capacities would ...


4

You should check your driver specifications and get the battery accordingly. The driver specs you need to check: Voltage Rating The voltage range that the motor is designed to operate. Within the range you can select a voltage value that suits your needs best. No Load Current The current drawn by the motor when its running free with nothing ...


3

Total current that can be drawn from a battery depends on discharge capacity (C) and ampere-hour (Ah) rating of a battery. Maximum continuous current that can be drawn from batter can be given as follows Maximum Current (A) = discharge capacity (C) x ampere-hour(Ah) For example, in your case if you are using 5000mAh, 25C battery, then you can draw ...


3

In process of selection of components for multirotor, one should start from motor as it is the driving component. Maximum current drawn by your motor is given by manufacture which is 15A. Now your ESC should have maximum current rating more than maximum current rating of motor. This is satisfied in your motor-ESC combination so your selection looks good. ...


3

250mA states the maximum output current to drive the load. So check what the current rating of the 5V regulator is. Check whether there is a voltage drop before reaching the motor. It might be that the motor is not spinning because of insufficient supply. Change the adapter you are using. If it is marked 21V, the output from adapter will be around 20.5V to ...


3

Roombas move slowly, below a walking pace, right? If that's so, then you probably want a geared DC motor. I'm guessing that on concrete you can get away with a motor that's 100W or less, particularly if it's geared down a whole bunch. You might want to figure out the highest incline or steepest step that you want to negotiate, figure out what force you ...


3

A linear regulator has a major drawback: it dissipates the power it doesn't deliver. Using the well-known 7805, the output voltage is 5V, your input shall be at least 7V to allow a good regulation (2V dropout voltage), if your load requires 1A, your 7805 dissipates 1A * 2V = 2W. This makes your Linear regulator hot. The best efficiency you may expect from a ...


3

Lots of robots safely use LiPo batteries, see almost all multicopter setups. There are plenty of batteries designed for the RC market that are capable of high sustained amperage, along with a plethora of pre-made chargers for LiPo batteries and plenty of options of chips designed to be integrated that do all of the charging logic for you as well. What ...


3

Power Law: Power = Current x Voltage The voltage of the batteries plays a huge difference in whether electronics function properly. Each of them is built to run using a particular voltage - 3.3V, 5V, 6V, 7.2V, 11.1V, 12V, 19V and 24V are some common operating voltages for electronics. Some devices have a voltage regulator that shift input voltages to ...


3

The best way to manage power redundancy for autonomous systems is a really interesting topic. There are two classes of power needed. Flight and processing. Often the power required for flight is much higher than what's needed for processing. Issue number 1 is that as soon as you introduce redundancy (2 batteries instead of 1) you incur a penalty of extra ...


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