LiPo batteries (Lipo Battery 4400mAh 6S 22.2v 60C EXTREME PRO)

[killer_fighting]

Please refer the battery link from (https://www.overlander.co.uk/batteries-chargers/lipo-batteries/lipo-battery-4400mah-6s-22-2v-60c-extreme-pro.html)

I have bought two batteries (Lipo Battery 4400mAh 6S 22.2v 60C)as shown in subject for my project purpose. Below are my queries about those batteries:

1. When I direct the battery to motor, there is some huge sparks occurred. To prevent this happens again, I have installed a MAXI fuses in between the battery and motor. Does my
precaution allows me to get off from this problem? Does there is any precaution that I can do?

2. Regard with the fully charged battery, if I have 100 % fully charged battery for the battery, how many voltage that I will get back for the battery? It is 22.2 (V) or more than that? This is very important for my project! As I don't want burn out my electronic circuit.

This is rough drawing for my power system, please to the image below:
View attachment 61632

Lithium Polymer battery: (https://www.overlander.co.uk/batteries-chargers/lipo-batteries/lipo-battery-4400mah-6s-22-2v-60c-extreme-pro.html)

MAXI Fuses: (https://uk.farnell.com/littelfuse/0299020-zxocr/fuse-slow-blow-20a-maxi/dp/9943145)

SyRen 10A Motor Driver: (https://www.active-robots.com/contr...lers/syren-10a-regenerative-motor-driver.html)
Input voltage: 6-24V nominal, 30V absolute max.
Output Current: Up to 10A/20A continuous. Peak loads may be up to 15A/30A for a few seconds. These ratings are for input voltages up to 18v in still air without additional heatsinking. For thermal, airflow and voltage rating charts for voltages over 18V see the back inside cover.

 

[Sceadwian]

Typical Lithium chargers charge to 4.1 volts per cell, though you may want to find out the specs for your specific charger, that would mean the battery will show 24.6 volts above any state if charge higher than about 75-80% If you worry... Measure it.

How are you switching the motor on your project sounds like you're using a relay? The battery you stated says it's 60C which means it is rated for 264 amp discharge, this is MASSIVE current, I'm a little surprised to see a Lithium battery rated for 60C thermal precautions better be seriously taken into account or fire/explosion is a very real possibility. The only way to avoid arcs with that much current draw is to use a solid state switch like a Mosfet or Solid state relay rated for DC use (not all solid state relays can be used on DC)

 

[audioguru]

My Li-Po battery cells are charged to 4.2V each. Then the six cells in his Li-Po battery pack will be 25.2V when fully charged.

A fuse does not prevent a spark, instead it blows out if the current exceeds its current rating and prevents a fire.

The size of the spark is determined by how much current the motor draws when it starts. The starting current is much more than the running current.

 

[Sceadwian]

I stand correctred audioguru, 4.23V seems to be the standard for Lithium Polymer, though I do err towards the lower voltage because it increases cell life, the two worst possible cases for a Lithium cell/pack are over and under charge

 

[killer_fighting]

What is the meaning of discharge rate? Does the battery will give out max current (264 A)?

 

[audioguru]

What is the meaning of discharge rate? Does the battery will give out max current (264 A)?

The maximum allowed output current is 60 x 4400mA which is 264A. It can do that for a portion of 1 second. The datasheet will say the allowed duration of a 264A current.

 

[killer_fighting]

The maximum allowed output current is 60 x 4400mA which is 264A. It can do that for a portion of 1 second. The datasheet will say the allowed duration of a 264A current.

I am using LiPo battery to power a DC motor (required 22 V and 2.5 A) with a motor controller (up to 24 V and 10 A). Does this will make my motor and controller short circuit?

 

[audioguru]

If your motor runs with 2.5A then it might draw 25A when it starts and when it is stalled.
Your motor controller is rated for only 10A so it might burn out.
Look at the starting and stalled current ratings for your motor.

The battery does not "force" a current of 264A. Your motor takes only as much current as it needs.

 

[killer_fighting]

If your motor runs with 2.5A then it might draw 25A when it starts and when it is stalled.
Your motor controller is rated for only 10A so it might burn out.
Look at the starting and stalled current ratings for your motor.

The battery does not "force" a current of 264A. Your motor takes only as much current as it needs.

Below is the specs for my motor controller:
•Up to 18V in: 10A continuous, 15A peak.
•24V in: 8A continuous, 10A continuous with additional heatsinking/airflow, 15A peak.
•Synchronous regenerative drive
•Ultra-sonic switching frequency
•Thermal and overcurrent protection
•Lithium protection mode
•Input modes: Analog, R/C, simplified serial, packetized serial

To prevent the burn for my motor controller, I am actually install a MAXI fuses rated at 20 A. Does this will prevent the short happen in my controller?

 

[Sceadwian]

Yep, the motor driver is only 10A and rated for 15A peak, please note additional heatsinking and airflow is required for 10amps.

You need to determine the stall current of the motor you're using, this can often be done easily by simply measuring the DC resistance of the motor coils and using the voltage and resistance to figure out it's maximum draw. You also need to consider how much load you'll place it under. 2.5amps is probably it's no load current rating after starting, and it's stall current will be worst case scenario, if you can approximate the percentage of it's full rated load you'll be using this will be an important number as well.

If the stall current is above 15amps, or your average expected load is going to be at or near 10 amps you'll want to consider a new driver.

No the fuse will not prevent shorts from happening in the controller, first of all the 20A fuse is 5amps over it's rated max current, so even once it gets to the point where the fuse will trip the motor driver will likley already be fried.

So determine the stall current and you can proceed from there.

 

[killer_fighting]

Yep, the motor driver is only 10A and rated for 15A peak, please note additional heatsinking and airflow is required for 10amps.

You need to determine the stall current of the motor you're using, this can often be done easily by simply measuring the DC resistance of the motor coils and using the voltage and resistance to figure out it's maximum draw. You also need to consider how much load you'll place it under. 2.5amps is probably it's no load current rating after starting, and it's stall current will be worst case scenario, if you can approximate the percentage of it's full rated load you'll be using this will be an important number as well.

If the stall current is above 15amps, or your average expected load is going to be at or near 10 amps you'll want to consider a new driver.

No the fuse will not prevent shorts from happening in the controller, first of all the 20A fuse is 5amps over it's rated max current, so even once it gets to the point where the fuse will trip the motor driver will likley already be fried.

So determine the stall current and you can proceed from there.

I see. Well, I made the mistakes initially. 2.5 A is not the stall current for my motor as I run the motor and measured the voltage and current from DC Power Supply. Motor will take about 2.5 A when there is no load. My motor will have to deliver about 13 kg load, so the stall current might about 4 A or 5 A. If it is, then my LiPo will not burn the controller, isn't?

 

[audioguru]

The controller's current is determined by the motor's current, not by the battery's maximum current.
You are just guessing at the maximum motor current when it starts or when it is stalled. Instead use Ohm's Law to calculate it from the resistance of the motor and the voltage of the power supply.

 

[killer_fighting]

The controller's current is determined by the motor's current, not by the battery's maximum current.
You are just guessing at the maximum motor current when it starts or when it is stalled. Instead use Ohm's Law to calculate it from the resistance of the motor and the voltage of the power supply.

All right. Does that's means my battery will only output the amount of current that is required by my motor?

 

[audioguru]

Your motor has a very high resistance when it is not working hard. Then its current is low. The motor is the load for your battery.
Your battery is able to provide 264A. When its load resistance is very high then what is its current?????

 

[killer_fighting]

Your motor has a very high resistance when it is not working hard. Then its current is low. The motor is the load for your battery.
Your battery is able to provide 264A. When its load resistance is very high then what is its current?????

Well... Let assume that my motor requires about 3 A, does my battery will output 3 A instead of 264 A?

 

[Sceadwian]

How are you figuring the stall current? For a 2.5A motor a stall current of 4-5 amps would be ridiculously low. Measure the unpowered DC resistance of the motor coil and report that back.


The 264 amps rating of the battery is it's listed maximum current, it will NOT output current it will simply allow current to be drawn by the circuit, as stated already a battery will not force current through a circuit it does nothing by provide a voltage, the circuit path itself (in this case the motor) determines the current draw.

 

[audioguru]

Well... Let assume that my motor requires about 3 A, does my battery will output 3 A instead of 264 A?

OF COURSE!
Does your battery put out 264A when it sits there with no load?
Please learn something about simple electricity.

 

[killer_fighting]

OF COURSE!
Does your battery put out 264A when it sits there with no load?
Please learn something about simple electricity.

I am sorry for my question. This is the first times that I handled such a huge capacity and rate for battery, some more this is Lithium Polymer battery as I just want to be careful about it so that I will not short my motor and controller.

 

[audioguru]

We think that the starting and stalled current of your motor might be too high for your controller. The controller will burn up.

 

[Sceadwian]

Killer, once again measure the DC resistance of the motor you're using and report that back, stall current can be determined from that.