# Tag Info

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 ...

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

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 ...

4

There are quite a few issues I see with your setup. You are setting up the ESC in your code to use pin 9, but your diagram shows that you've connected to pin 8. Pin 8 won't do anything because the code is writing to pin 9. You are setting up the ESC in the code, but then you are never actually writing to it. You need to use ESC.write() and pass some value ...

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

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

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

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

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 ...

3

Assuming that the motor is in a healthy condition... Voltage is only one aspect, you have to be sure that you battery can supply the current drawn by your motor. The maximum current, according to the link you have specified is approx 10 Ampers. I am not sure how many batteries and in which config you are using, the description I have found is this one. ...

3

A fully charged LiPo battery cell should has a voltage of 4.2 V. Assuming that you have three cells in series, that would give 12.6 V. When you apply a big load, this voltage of course, will decrease instantly but if you measured 11.98 V in open-circuit that means the batteries were not fully charged. I guess your batteries were not charged at all. Here is ...

3

Power (Watts, milliWatts, etc.) is given by: $$P = IV \\$$ where $I$ is current in (milli)Amps, $V$ is voltage in Volts, and $P$ is power in (milli)Watts, respectively. Energy (Watt-hours, milliWatt-hours, etc.) is given by: $$E = P\Delta t \\$$ (assuming constant power output), where $E$ is energy in (milli)Watt-hours and $t$ is time in hours. ...

3

30 minutes is half an hour. 323.344 Watts is approximately 324 Watts. If you want 324 Watts for half an hour, then you want a (324 * 0.5) Watt-hour battery. This assumes, though, that your battery will go from 100% charge to 0% charge after exactly 30 minutes. Discharging a battery down to a state of charge of 0% can physically damage batteries, ...

2

In short, yes, there are a number of robotics companies catering to just your needs. Specifically which apply to you depends on what type of robot you desire. Naturally cost varies with the complexity and durability. For example if you would be satisfied with a differential drive robot for indoor use then the iRobot Create may suit your needs. If you need ...

2

You have to be very careful with those packs as they don't usually have under-voltage protection for themselves. You're pack is likely fine but the charger isn't seeing the minimum voltage required to begin charging and so it won't. I found myself in nearly the same situation not too long ago and managed to bring the battery back to a visible voltage by ...

2

You can detect an IR LED from quite some distance. This is how TV remote controls work. A tiny battery operated LED can send data even when not aimed directly at the TV. The trick is to modulate the LED with some high frequency then the receiver uses an analog filter to pass only that frequency. This filters out room light (which is close to DC.) Homing ...

2

You are right that there are issues in having an "unclean" power supply running into your RaspberryPi. If you are drawing tons of power, things get very hairy very fast. However, there are ways to "convert" and "clean" a supply to isolate the voltage (and therefore making it suitable for input to the Raspberry Pi). How much cleaning will depend on your ...

2

Battery life is generally measured in amp hours. From a PWM perspective, you are pulsing current at a constant voltage, so you could estimate current output to be (duty cycle)*(rated current) where rated current is the nominal current draw at your operating voltage. Remember too that P=IV, so you could get a rated current by dividing rated power by operating ...

2

The alternator in a car is constantly charging the 12V battery while the car is running, which is to say battery-wise you shouldn't have any issues. Several things could be meant when you say the motors are "rated" for 12V. Is that a maximum, minimum, or nominal voltage? I'm assuming they're rated for DC power, but there are some low voltage AC motors. ...

2

Any quality power device should list its load regulation capability, which is typically in a datasheet as a voltage range coupled with a maximum output current. You can expect normal voltage fluctuations to occur within this band. However, when you include a motor in the scenario, you need to be aware that voltage can spike up/down if you suddenly remove/...

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