How do you discharge your batteries?

[Houndpup Rc]

How? Over voltage definitely but never heard of under voltage hurting electronics, usually just quit working.

Here's what google AI said:
Yes, running a DC brushless motor at a significantly low voltage can harm it by causing reduced performance, potential overheating due to increased current draw, and may even lead to motor failure in extreme cases, as the motor will struggle to produce sufficient torque under heavy loads while trying to compensate for the low voltage with higher current draw.

This is what I thought.

 

[bisco]

that sounds messed up. run it at half throttle til it dies. but there may be more left in the battery, idk.

 

[Houndpup Rc]

that sounds messed up. run it at half throttle til it dies. but there may be more left in the battery, idk.

Could be, I am no professor at electronics

 

[bisco]

me neither. maybe i'll switch to the shoot it with a gun method

 

[Houndpup Rc]

me neither. maybe i'll switch to the shoot it with a gun method

I want to try that!

 

[Houndpup Rc]

I want to try that!

Maybe a 12ga. 1oz slug?

 

[LitterBug]

I have a chipper shredder we could play with.......

 

[AIRFORGE]

I have a chipper shredder we could play with.......

Oooooh! VIDEO!

 

[Bricks]

Here's what google AI said:
Yes, running a DC brushless motor at a significantly low voltage can harm it by causing reduced performance, potential overheating due to increased current draw, and may even lead to motor failure in extreme cases, as the motor will struggle to produce sufficient torque under heavy loads while trying to compensate for the low voltage with higher current draw.

This is what I thought.

. Think about using an electric drill and low battery running until the motor stops does the drill get damaged?

 

[Houndpup Rc]

. Think about using an electric drill and low battery running until the motor stops does the drill get damaged?

It probably has a built in low voltage protection, because if it didn't wouldn't all your lithium batteries be junk from getting drained down to zero?

 

[Houndpup Rc]

It probably has a built in low voltage protection, because if it didn't wouldn't all your lithium batteries be junk from getting drained down to zero?

Think of a starter in a car, you don't want to sit there trying to start it when your battery isn't full enough because you are likely to burn something out.

 

[Houndpup Rc]

Though if there is no load on it I think the danger of burning something out is minimal.

 

[Foamforce]

I think brushless motors are counterintuitive because when you increase voltage, that also increases amp draw. Normally, if you increase volts, you can decrease amps to maintain the same watts, but with brushless motors, increasing volts also increases kv, and that increases amps.

I’ve seen that if you take a motor and prop that is running at 3s and you hook it up to a 2s battery, it will draw fewer amps, not more. You can confirm this on any motor thrust chart. So even if the low voltage cutoff didn’t kick in, I don’t believe it would damage the electronics by drawing too many amps. Perhaps by some other mechanism, but I doubt it.

Anybody want to try though?

 

[Houndpup Rc]

I think brushless motors are counterintuitive because when you increase voltage, that also increases amp draw. Normally, if you increase volts, you can decrease amps to maintain the same watts, but with brushless motors, increasing volts also increases kv, and that increases amps.

I’ve seen that if you take a motor and prop that is running at 3s and you hook it up to a 2s battery, it will draw fewer amps, not more. You can confirm this on any motor thrust chart. So even if the low voltage cutoff didn’t kick in, I don’t believe it would damage the electronics by drawing too many amps. Perhaps by some other mechanism, but I doubt it.

Anybody want to try though?

That makes sense.

 

[LitterBug]

I think brushless motors are counterintuitive because when you increase voltage, that also increases amp draw. Normally, if you increase volts, you can decrease amps to maintain the same watts, but with brushless motors, increasing volts also increases kv, and that increases amps.

I’ve seen that if you take a motor and prop that is running at 3s and you hook it up to a 2s battery, it will draw fewer amps, not more. You can confirm this on any motor thrust chart. So even if the low voltage cutoff didn’t kick in, I don’t believe it would damage the electronics by drawing too many amps. Perhaps by some other mechanism, but I doubt it.

Anybody want to try though?

This is not exactly the case. I have plenty of experience running 3S motors on 4S and 6S with telemetry. Get a quad in a hover, and compare current at the different voltages. You will find E=IR still applies. Watts = Volts * Amps. At a higer voltage it takes less amps to hover but same watts to hover.

 

[Foamforce]

This is not exactly the case. I have plenty of experience running 3S motors on 4S and 6S with telemetry. Get a quad in a hover, and compare current at the different voltages. You will find E=IR still applies. Watts = Volts * Amps. At a higer voltage it takes less amps to hover but same watts to hover.

I think you’re comparing different things than I am. It takes the approximately the same watts to hover, whether you do it with more volts or more amps, so it applies there. In other words, in your case, the watts are a constant, so yes, more volts will reduce amps and vice versa. But if you take the same motor and hook it up to a 3s vs a 6s and run it at full throttle, the 6s will take more amps, not less.

Take this SunnySky 2212 thrust chart as an example.

SunnySky X2212 KV980 Brushless Motors - Multirotor Version No Accessory

Specifications Warning: this version does not come with any accessory. It is used for props with built in nuts as shown in the following photos. X series of motors are processed by CNC milling, the hollow-designed appearance not only guarantee good heat dissipation, but also greatly reduce motor...

sunnyskyusa.com

At 11.1v, it draws 11a at full power (122w). At 16.5v, it draws 19.5a (322w).

So in relation to the question of whether you can burn out an ESC by running at lower voltage due to higher amp draw, I don’t believe that’s true. In the case of this example motor, if you’re running at full throttle at 11.1v, you’re already far under the maximum current for that motor, and if you reduced the voltage further, the amp draw would also be reduced.

I think? I might be wrong about this, in which case I’d appreciate being corrected.

 

[LitterBug]

I am talking about power ratings of the same motors, SunnySky 2212 KV980 on several multirotors I have. Both a quad 450 and a hex 550.

Yes Maximum watts and amps does go up with more voltage. I don't find it odd at all. Nor do I find it odd that max watts and amps is lower with lower voltage.

Quad Multirotor:

Hex multirotor:

 

[Andrew]

I have read that, especially for larger batteries, soaking in salt water is not the best option. The reasoning is that the connections can corrode away because of the salt water long before the battery is fully discharged. If you test it, it shows 0 volts, but the actual cells can still have energy stored. Some kind of bought or built battery discharger is supposed to be the more reliableoption.

The problem with the salt water method is "Chinese Whispers" and people taking short-cuts, resulting in eroding battery tab's off completely and now a lipo discarded with lot of energy still in it. About 20 year's ago BMF, had a good article on how to safely destroy a lipo for disposal.

 

[Merv]

...increasing volts also increases kv, and that increases amps...

Not to quible, but increasing volts increases RPM, not Kv.

 

[Mr Man]

Not to quible, but increasing volts increases RPM, not Kv.

And Amp Draw of course.