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A have designed a robot to perform tasks in farms. But the problem now is I'm not sure on the best way to supply continuous power to my robot. All the motors are rated at 12V and only Arduino and a few sensors work at 5V or less.

Can I continuously charge a 12V lead acid battery with an adapter (comes with the battery) plugged into the AC output of the generator while the robot is operating? Do I have to worry about overcharging the battery?

Or should I use the generator's DC output which can supply 12V and up to 8.3Amp. Or is there any other suggestions?

Some information about the adapter which are stated on the package: 1. Built-in over-charge protection device. 2. Built-in thermal protection device 3. Output: 6v/12v 2Amp

This is the generator that I have: http://global.yamaha-motor.com/business/pp/generator/220v-60hz/0-1/et950/

This is my first robot which is quite big that requires a lot of electrical/electronic knowledge to power it. I do not have a lot of experience in this field. So any feedback is greatly appreciated.

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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.

If I recall correctly, I think a vehicle 12V bus could swing from dead battery voltage of 11.8 to a charging voltage of 14.4V, so you should check that you aren't violating any ratings on the motors.

For the electronics I would use a 5V DC-DC converter. You should consider a 12V-12V DC-DC converter for power conditioning if the generator output is too noisy.

The only reason I would consider using a battery is if the generator can't supply the peak current you need or if you have to be able to run some functions without the generator on. Remember that the generator must supply more than the average power draw or you'll always wind up running the batteries dead.

Lastly, some generators may require a minimum load for proper voltage regulation, so be sure to check.

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  • $\begingroup$ Thanks for your feedback. All the motors are DC and I guess that is the nominal voltage since that is all I can find on the datasheet. For the DC-DC converter, it has to be plugged in on the generator DC output, am I right? Which do you think is better? Getting the power from AC or DC output? Another concern is I'm afraid that if I'm getting the power directly from the generator without the battery, the voltage coming from generator will fluctuate? The more I think about it and as you said earlier, the battery unnecessary. The purpose of the battery is so that I can get a steady DC voltage. $\endgroup$
    – goddar
    Sep 26, 2015 at 18:17
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    $\begingroup$ Not sure why you would use 220VAC if you're only going to transform and rectify down to 12VDC when there's already 12VDC available. Unless you can get (and need) more power from the AC side. More parts = more money. The DC-DC converter would need a DC input. As I mentioned earlier, I would expect voltage to fluctuate between 11.8-14.4V, as anything in that range is acceptable to an automotive 12V load. Whether or not that's acceptable for you is your choice. $\endgroup$
    – Chuck ♦
    Sep 26, 2015 at 19:54
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    $\begingroup$ If the peak power exceeds the generator capacity but the mean power does not, you need a battery, where the battery capacity is large enough to handle the worst case power excursion plus some buffer. A DC-DC converter is a voltage regulator. If you need one, it also needs to be able to supply your peak power demand, and it also needs to be placed between to battery (if you use one) and your robot or the battery will never get to a proper charging voltage. $\endgroup$
    – Chuck ♦
    Sep 27, 2015 at 10:59
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    $\begingroup$ If the mean power draw exceeds the generator capacity, you need a bigger generator, but remember too that you can pull from the 220VAC side of the generator, you just need a transformer, bridge, and capacitors. $\endgroup$
    – Chuck ♦
    Sep 27, 2015 at 11:01
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    $\begingroup$ I don't know why it would say it's for battery charging only, but it may have to do with either voltage regulation or the DC bus could be so noisy it might damage electronics. I would monitor the bus voltage with an oscilloscope first before I connected anything to it. $\endgroup$
    – Chuck ♦
    Sep 28, 2015 at 11:17

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