I am currently working on a new robot and I will soon have to choose a way to feed it with power.
I've been reading about LiPo batteries, but I am still confused about how to integrate this kind of power supply in a robot. Here are a few questions I have in mind :
Can I use a LiPo batterie exactly like a standard NiMH batteries ? (guess not, because of the discharge limit). For instance, can use one of OddBot's configurations for voltage regulation (https://www.robotshop.com/letsmakerobots/node/3880) directly with a LiPo battery ?
I read about ESC, BEC etc. Is a mandatory component to integrate with LiPos or it is just needed to create PWM signals to motors ?
Is there a simple way to prevent a LiPo battery to go under the discharge limit ? (zener diode ?)
Oh yeah, important one : to your opinion, is it worth it to use LiPo on a classic robot (with wheels or tracks, and DC/Servos motors)
I can answer the last one: “is it worth it to use LiPo on a classic robot (with wheels or tracks, and DC/Servos motors)”: No
I freakin love LiPo’s, have some the size of wall bricks that can zapp enormous amounts of electric stuff, drive a car and all… an I have the tinyest light weight, that can still pack an impressive punch! They are COOL!
But all that special charging and do-not-discharge-completely does not at all add up fr the punch you get - when you just need to drive around
I can recomend “ordiniary RC packs” 7.2V. These are very very powerful, they weigh a lot compared, but one of these with a 5V regulator, and your robot will drive for ever, ever, ever!! And they are easy to charge/recharge.
I am not saying there is anything wrong with LiPo’s, not at all, but if you are starting, you will have enough to think about, and there a standard RC pack is your solid friend - you will not have to think about that part
Or just do normal AA’s / rechargables, they work wonders
I’ve used Li-Po’s many times without any problems, but Gareth is right: Buy good batteries, a good charger and use a voltage monitor (every LiPo has a 3 pin connector for charging and plugging in a voltage monitor). Voltage monitor can be simply a voltage divider, connected to your ADC. If the voltage drops under a given level, a power MOSFET (N channel) will switch off the power supply.
Love LiPOs, small size huge power. However, you need to treat them nicely. GOOD charger is a must. I have use Lipo in most of my robots. Personally, I like to keep battery fully charged and have “low voltage indicator” to check them when you don’t use them for while. It’s a bit tricky to recharge LIPO when they ran out of power.
If you have servos in your robot, I suggest you could use BEC if you are not so sure how to reduce voltage to 6V. I am not professional in here and also not very knowledge in this field but just accroding to my past experience, that’s how I learned. There are 14 servos running on following robot with single 2S Lipo and I use that “UBEC”. So far it works fine(except my poor code not working well :P)
Smaller and lighter than the equivalent NiMH battery, but they’re more finicky about charging. It definitely takes a real charger; you can’t just do a C/10 charge rate. Get a balance charger if you’re going to use 7.4V or 11.1V packs. They can be had for cheap:
Thank you guys for your wise and helpful advices ! It is much clearer to me now
I’ll probably follow fritsl advice for this robot, it already involves enough new technical skills to me (Xbee, comm between picaxes etc.), no need to add more complexity for now !
But I will definitely look into those batteries later, they look pretty cool
Same for me,I realy appreciate educative comments from you guys. I was also questionning myself about those Lipos. Thanks for your advices guys and for asking LordGG.
