batteriesdrone
I bought a drone with a battery and i would like to buy a second one.
Maybe a better one if possible.
I have a charger with wrote :
Li-PO: 7.4V
And the battery:
Full ymax 853480 (i guess it's reference ?)
7.4V 2000 mAh
14.8 Wh
+ 6154*3101
I have seen others battery, but never with same characteristic, Witch one is the most important ?
Does 7.4 V 800 mAh
The identical are only on alibaba, so rather have a better one.
This is a picture of it
The eBay link to the motor did not yield any datasheet. So I will assume for the purpose of this answer that the motors are similar to the Precision Microdrives 106-002 motor, which has nearly identical dimensions and electrical specifications.
The datasheet indicates a starting current of 180 mA at 3 Volts, and a no-load current of 17 mA at 3 Volts. Extrapolate that to the 22 mA current rating from the eBay listing, to a 233 mA starting current for the motors in the question.
If the 4 motors are likely to be started or stalled simultaneously, it helps to design for this maximum current: 233 x 4 = 932 mA = ~ 1 A. For normal operation, this value becomes 22 x 4 = 88 mA = ~ 100 mA.
For a 5 Volt supply, we should thus allow for 1.5333 Amperes current, or at least 1.5 Amperes if we need to cut corners.
- What setup is better?
The second one: Just use a MOSFET (or 4 of them, one for each if you plan to control them separately) to switch the low-side of the 4 motors.
- Is regulating the 7.4V to the 5V max the motor need is a good idea?
Well, you do need to get the supply voltage down to within the motor's specified voltage range somehow. I might even get parsimonious and use 4 diodes such as 1n4007 in series to do the voltage reduction: End result, 4.6 Volts, so the motors will live a bit longer. After that, I'd drive all 4 motors from this rail, with the capacitors and diodes in place of course.
simulate this circuit – Schematic created using CircuitLab
Do I need 1 regulator and split the output
Option 1: Single regulator for all 4 motors:
22 * 4 = 88 mA = ~ 100 mA. For a linear regulator (e.g. 7805) the normal running dissipation would be around (7.4 - 5) x 0.1 = 0.24 Watts, which isn't much for a TO220 regulator package. Option 2: Separate regulators for each motor:
Recommendation: Note that this is a personal view... I would go with a single regulator and add the diodes + capacitors as close as possible to each motor
For the average DIY guy I guess you have these technologies to tinker with:
By specifying it as "portable" you probably don't want the charger to be heavy. Then you can remove Lead acid from your list. The NiMH batteries have quite high energy density nowadays but the charging and maintaining of the cells are a bit more complicated than for Lithium. We assume Lithium for this case.
The nominal cell voltage for a lithium cell can be around 3.6V per cell (depends on make and model). If you're going to charge directly to the USB port you would need 5V input to the phone. So you would be best off using two cells at 7.2V nominal. This would then have to be converted with preferably a DC-DC to 5V.
The Galaxy S4 has a 3.8V cell with 9.88Wh. To double the battery capacity you would need an equal amount of Watthours (cell voltage x Amperehours) in your backup battery. Calculating for 10% loss in your DC-DC you would need a 7.2V cell pack of at least 1.35Ah.
And then you still have the task of doing a charger for your backup battery.
Best Answer
The ampere readings are very important when considering a battery for such usage. Fueling a drone requires a large amount of current flow. I guess it is not possible to power a drone with 800mAh battery. Find some battery that has the same current ratings. And to answer your question both of the Voltage and Current ratings are important.