What is the minimum voltage requirement to power an ESC Brushless motor? And can I power it using 4 AA alkaline batteries rather than things like NiMh or LiPo?

Help & Support Robot Parts
, , ,
1

Pretty much what it says in the title, i dont usually see people powering their ESC BLDC using anything lower than 7.2 volts, and I dont see why i must using NiMh or LiPo

Thank you.

2

Hello @Mahr758 and welcome to the community
The voltage required is related to the KV of the motor and the rpm you want it to reach … for example
if you have a motor with 1000kv and you want the rpm to reach 7400 rpm you will have to use 7.4v battery the relation is
RPM = KV x Voltage

This video will answer all your questions

1 Like
3

Hi @Ebram, yeah I saw that video but the thing is, i connected 4 AA NiMH batteries (4 x 1.2 = 4.8 V) to the ESC that was connected to the motor but the ESC didnt even start up. So I was wondering if there was some minimum voltage

Thank you

4

Hey @Mahr758
Of course there is a minimal voltage for every motor.
Can you provide us with the motor model ?

1 Like
5

Yes @Ebram, of course. Im using an Emax Brushless Outrunner XA2212/1400KV. On the bottom it says “2-3s LiPo” if that means anything. Also will alkaline AA cells work instead of NiMH or LiPo?

Thank you.

6

Hey @Mahr758,
A (LiPo) cell has a nominal voltage of 3.7V. For the 7.4V battery above, that means that there are two cells in series (which means the voltage gets added together). This is sometimes why you will hear people talk about a (2S) battery pack - it means that there are 2 cells in Series.
So in this case the motor can operates with 7.4v (2S) or 11.1v (3S).

As for the alkaline AA cells, you can connect 7 batteries and see if it’ll work or not.

Also you can check the specifications in this link


Hopefully this answered your questions, feel free to ask again if you have more questions :slight_smile:

Sincerely,

1 Like
7

Ah so would that mean about 8 NiMH cells (1.2V each) to get the whole thing running, @Ebram ?

8

Or just 7 since 7 x 1.2 = 8.4v which is enough.

1 Like
9

Alright @Ebram, thanks so much for all the info. Helped a crap load, wish you the best!

1 Like
10

Glad to help, best of luck :slight_smile:

1 Like
11

This won’t work because AA batteries won’t offer enough current.

When it comes to batteries, as well as any electrical power source, you have to remember that they all have an internal resistance. This resistance; called the Thevenin resistance, limits the amount of current that the power source can provide.

When dealing with motors; particularly those that you find in the RC industry, the necessary current to drive them is quite high. The internal resistance of AA batteries, as well as any non-rechargeable battery, like 9-volts, etc., is too high, and will offer too little current.

Of those types of batteries, the one that has the lowest resistance, and therefore would provide the greatest amount of current, is a D battery. You’ll notice that the D battery has the same voltage as a AA, but it has a much bigger diameter. This bigger diameter allows it to have a lower Thevenin resistance; hence more current capability. So, if any type of alkaline battery would work, it’d be that type.

I should also mention watch batteries. Watch batteries tend to have a low Thevenin resistance – possibly even lower than D batteries. They may have the best shot. Just know that, even if they could offer the current, they wouldn’t last long, at all. My guess is that it would be less than a second. They just don’t have the capacity.

Then, of course, there’s a car battery. Car batteries have a very low Thevenin resistance, and, therefore, provide lots of current. A car battery could easily power any RC motor. At that point, you’d just have to worry about voltage, as you’ve all been talking about.

I recognize that this thread is old. However, if you’re wondering why the AA’s didn’t work, that’s why.

1 Like