Solved Charging battery

[Factorz]

I am new in this field.
I have few questions
I am using imax b6 charger.
1. How much time it takes to full charge 3s 5200mah lipo?
2. It says 3.7v on battery as wel on imax charger menu, but it goes to 3.84v and sometimes 4v is it safe or normal?
3. At what rate should i charge someone told me not go beyond 0.5A but is so slow and i think it is not charging to full capacity, i used 5.0A then these questions i arose.

 

[Hvon11]

The number of cells in a LiPo pack are counted by the S value. You say it says 3.7v on your battery so that means your battery is a single cell pack also known as a 1S.

Your questions is about how long to charge a 3S battery. So I’m not sure what you really need here.

LiPo batteries can burst into flames if they are charged at an excesive rate beyond the rated specifications. Be careful and charge on a cement floor and always attend the area when charging.

1S= 3.7v, 2S= 7.4v, 3s = 11.1v, 4S= 14.8v.

If you have a 3S battery then you should be charging at 11.1 to 12.6V. The imax B6 will check the battery configiuration (number of cells) and will ask you to confirm before it actually starts the charge. Make sure the iMax detected S value matched the battery you have attached. If you have a balance port on your battery (usually small white connector) then set the imax charge profile to LiPo Charge Balance and connect both the white connector and the main lead connector to the charger. Always balance charge if you can. It may take a bit longer but it is much better for the battery than just charging through the main leads.

The manufacturer of your battery will provide a maximum allowable charge current. Don’t exceed that. 0.5 A = 500mA is a good safe charge for most batteries. The gentler you charge, the longer the battery will last. When I am topping off a slightly used battery, I use 100mA=0.1A.

At 0.5A =500mAh, it will take about 10.5 hours to charge an empty 5,200mAh battery. But it is unlikely the battery is empty. It should never be drained past 20% remaining capacity. If you cahrge at 5.0A = 5,000mA it will take about 1 hour.

See the attached chart of charge voltage vs capacity and look at the note at below 20% capacity, AND RAPID VOLTAGE DUMP OCCURS. Best to keep from discharging below 3.7V/S

 

[Factorz]

The number of cells in a LiPo pack are counted by the S value. You say it says 3.7v on your battery so that means your battery is a single cell pack also known as a 1S.

Your questions is about how long to charge a 3S battery. So I’m not sure what you really need here.

LiPo batteries can burst into flames if they are charged at an excesive rate beyond the rated specifications. Be careful and charge on a cement floor and always attend the area when charging.

1S= 3.7v, 2S= 7.4v, 3s = 11.1v, 4S= 14.8v.

If you have a 3S battery then you should be charging at 11.1 to 12.6V. The imax B6 will check the battery configiuration (number of cells) and will ask you to confirm before it actually starts the charge. Make sure the iMax detected S value matched the battery you have attached. If you have a balance port on your battery (usually small white connector) then set the imax charge profile to LiPo Charge Balance and connect both the white connector and the main lead connector to the charger. Always balance charge if you can. It may take a bit longer but it is much better for the battery than just charging through the main leads.

The manufacturer of your battery will provide a maximum allowable charge current. Don’t exceed that. 0.5 A = 500mA is a good safe charge for most batteries. The gentler you charge, the longer the battery will last. When I am topping off a slightly used battery, I use 100mA=0.1A.

At 0.5A =500mAh, it will take about 10.5 hours to charge an empty 5,200mAh battery. But it is unlikely the battery is empty. It should never be drained past 20% remaining capacity. If you cahrge at 5.0A = 5,000mA it will take about 1 hour.

See the attached chart of charge voltage vs capacity and look at the note at below 20% capacity, AND RAPID VOLTAGE DUMP OCCURS. Best to keep from discharging below 3.7V/S

Thank you
I knew the basics and safety guidelines you mentioned at the start thanks for revision.
My main concern was how long it takes it to fully charge because i feared i might be over charging and damaging my battery, and when a bought the drone at that time a friend of mine told me to charge at 0.5A and don't change it.
This is my very 1st experience with drones.
And by saying 3.7V i meant 3.7V/cell
I have 3S 5200mah and i am charging it at 5.0A and i set cut off safety timer to 1hr.

Thanks again

 

[Hvon11]

Thank you
I knew the basics and safety guidelines you mentioned at the start thanks for revision.
My main concern was how long it takes it to fully charge because i feared i might be over charging and damaging my battery, and when a bought the drone at that time a friend of mine told me to charge at 0.5A and don't change it.
This is my very 1st experience with drones.
And by saying 3.7V i meant 3.7V/cell
I have 3S 5200mah and i am charging it at 5.0A and i set cut off safety timer to 1hr.

Thanks again

Good, so I would check manufacturer’s recommended max charge rate and abide by it. After 1 hr charging, when your timer has expried, check the voltage, if less than 12.6v, charge at .1A = 100mA for another hour. Repeat until charger reads Capacity Full.

 

[Ketchup]

I would like to add a few things here. The 3.7 volts is the nominal voltage of a lipo cell. 4.2 volts is the maximum voltage, so the charger should actually be bringing each cell up to 4.2 volts to get a full charge.
Charging at 5 amps is safe I would say and here's why. With lipos we have something called c rating, which is kinda a way to measure charge/discharge rate based on the capacity of the lipo. For example, 1C is the battery's capacity, or in your case 5.2 amps (5200 mAh = 5.2 amps). If the max discharge rate of the pack is 25C for example, you can safely draw 130 amps from the pack because 5.2 amps x 25C is 130 amps. Now normally you can discharge at much higher than 1C safely, and most times you will be pushing way past that, that isn't an issue and is normal. When it comes to charging though, it is not recommended to go past 1C (5.2 amps in your case). The manufacturer might say that you can do 2C, 5C, or whatever else, but it is generally advised to stay at 1C or below.
If you charge at 1C (5.2 amps for a 5200 mAh pack), it should take about an hour to charge, but some chargers (like mine) take much longer, closer to 90 minutes, because the charger slows down the charge rate near the end of the charge and gets ready to stop charging.

When somebody told you to stay below 0.5A charge rate, it is probably because some people set a maximum charge rate for themselves, regardless of battery capacity. Some won't pass 1 amp, and whoever told you to stay below 0.5 obviously has set their limit to 0.5. I personally just charge at 1C, but my packs usually aren't very big like yours is. I would recommend sticking to 5 amps for charging, and maybe going down a little bit more in charge rate just to be safe (as low as you have the patience for really). You could go to a lower charge rate like 1 amp, but it will take over 5 hours at 1 amp so I'm guessing you don't want to do that. I did say that I stick to 1C, but your pack is larger and usually larger packs are scarier and more dangerous, so you want to be extra careful with them, so the extra level of precautions is a good thing here.

Now a few general charging tips:
1. NEVER leave a charging lipo unattended. Things happen quick with lipo fires, so you don't want to leave it alone while charging (arguably when it has the highest chance of lighting on fire other than when it is damaged).
2. It is hard to put out a lipo fire, I have heard that sometimes fire extinguishers aren't super good at it. A fire extinguisher will most likely work, but the best method that I know of to stop a lipo fire is to cover it with sand. I personally keep a container of sand next to the charging setup while charging so that I am always ready.
3. Things like battery bunkers are great for safe charging. There are even designs that will automatically douse the lipo in sand if there is a fire. You can make one yourself and it shouldn't cost too much. (I will put a video on battery bunkers at the end of the post)
4. If you don't have a battery bunker right now, then at least charge the lipo inside of a lipo bag, it will provide some level of protection.


The battery bunker video:

Any questions will be welcome, and stay safe with your lipos!

 

[Hvon11]

I would like to add a few things here. The 3.7 volts is the nominal voltage of a lipo cell. 4.2 volts is the maximum voltage, so the charger should actually be bringing each cell up to 4.2 volts to get a full charge.
Charging at 5 amps is safe I would say and here's why. With lipos we have something called c rating, which is kinda a way to measure charge/discharge rate based on the capacity of the lipo. For example, 1C is the battery's capacity, or in your case 5.2 amps (5200 mAh = 5.2 amps). If the max discharge rate of the pack is 25C for example, you can safely draw 130 amps from the pack because 5.2 amps x 25C is 130 amps. Now normally you can discharge at much higher than 1C safely, and most times you will be pushing way past that, that isn't an issue and is normal. When it comes to charging though, it is not recommended to go past 1C (5.2 amps in your case). The manufacturer might say that you can do 2C, 5C, or whatever else, but it is generally advised to stay at 1C or below.
If you charge at 1C (5.2 amps for a 5200 mAh pack), it should take about an hour to charge, but some chargers (like mine) take much longer, closer to 90 minutes, because the charger slows down the charge rate near the end of the charge and gets ready to stop charging.

When somebody told you to stay below 0.5A charge rate, it is probably because some people set a maximum charge rate for themselves, regardless of battery capacity. Some won't pass 1 amp, and whoever told you to stay below 0.5 obviously has set their limit to 0.5. I personally just charge at 1C, but my packs usually aren't very big like yours is. I would recommend sticking to 5 amps for charging, and maybe going down a little bit more in charge rate just to be safe (as low as you have the patience for really). You could go to a lower charge rate like 1 amp, but it will take over 5 hours at 1 amp so I'm guessing you don't want to do that. I did say that I stick to 1C, but your pack is larger and usually larger packs are scarier and more dangerous, so you want to be extra careful with them, so the extra level of precautions is a good thing here.

Now a few general charging tips:
1. NEVER leave a charging lipo unattended. Things happen quick with lipo fires, so you don't want to leave it alone while charging (arguably when it has the highest chance of lighting on fire other than when it is damaged).
2. It is hard to put out a lipo fire, I have heard that sometimes fire extinguishers aren't super good at it. A fire extinguisher will most likely work, but the best method that I know of to stop a lipo fire is to cover it with sand. I personally keep a container of sand next to the charging setup while charging so that I am always ready.
3. Things like battery bunkers are great for safe charging. There are even designs that will automatically douse the lipo in sand if there is a fire. You can make one yourself and it shouldn't cost too much. (I will put a video on battery bunkers at the end of the post)
4. If you don't have a battery bunker right now, then at least charge the lipo inside of a lipo bag, it will provide some level of protection.


The battery bunker video:

Any questions will be welcome, and stay safe with your lipos!

Thanks for discussing C rating. I learned a few things today. 👍 I have been planning to make a bunker out of an old green ammo can. I better get that done. I charge on my garage floor and also keep a bucket of sand at hand. Haven‘t had a fire yet but I did have a 3S that swelled to about 1.5 times its original size. I never charge over 500mA so I figured it was a defective pack. I flew it in my FT Cub for 10 minutes without issue and then discharged it completely and disposed it.

 

[PsyBorg]

Thanks for discussing C rating. I learned a few things today. 👍 I have been planning to make a bunker out of an old green ammo can. I better get that done. I charge on my garage floor and also keep a bucket of sand at hand. Haven‘t had a fire yet but I did have a 3S that swelled to about 1.5 times its original size. I never charge over 500mA so I figured it was a defective pack. I flew it in my FT Cub for 10 minutes without issue and then discharged it completely and disposed it.

Ammo cans are great for charging but several bad things about them come to mind. You MUST vent them otherwise if a fire does occur you now have a pressure bomb. Ammo cans have lids. Lids work like scissors and battery wires and charging wires are not so durable to sharp things.

Batteries can be dangerous. Safe practices are always a good thing. For your particular case I would suggest since you are already charging in an open area on a cement floor that you simple buy a bakers cooling rack and set several food storage bags of play sand on top of them and simply slide your batteries under the rack. IF for some reason a battery does ignite the bag instantly melts and covers ALL your batteries keeping them undamaged other then the one that went bad. In an ammo can EVERYTHING would be lost.

The main thing with charging batteries that cause issues is first and foremost charging a battery with damaged packaging. Check your batteries EVERY time you go to charge them. Second is heat. When used they generate heat which degrades them. Since the cells are packed in the inner cells get and stay hotter longer. This degrades the chemicals over time unevenly between packs. This is where keeping track of internal resistances is a good idea. This way you can know before hand when a pack is reaching end of life safe operating values. Then you can decide to relegate the pack to running low current draw things like cameras or camp / race gate leds or even portable soldering irons for field repairs.

I number every pack I buy and check internal resistance out of the box. After each break in charge and yes breaking in packs is a good idea some packs like the Fureon lipos are great batteries but take several charges and discharges to balance out the cells. I have 2 of my original 5 3s 2200 packs still working fine with safe internal resistances coming up on their 6th season this month actually.

 

[Hvon11]

Ammo cans are great for charging but several bad things about them come to mind. You MUST vent them otherwise if a fire does occur you now have a pressure bomb. Ammo cans have lids. Lids work like scissors and battery wires and charging wires are not so durable to sharp things.

Batteries can be dangerous. Safe practices are always a good thing. For your particular case I would suggest since you are already charging in an open area on a cement floor that you simple buy a bakers cooling rack and set several food storage bags of play sand on top of them and simply slide your batteries under the rack. IF for some reason a battery does ignite the bag instantly melts and covers ALL your batteries keeping them undamaged other then the one that went bad. In an ammo can EVERYTHING would be lost.

The main thing with charging batteries that cause issues is first and foremost charging a battery with damaged packaging. Check your batteries EVERY time you go to charge them. Second is heat. When used they generate heat which degrades them. Since the cells are packed in the inner cells get and stay hotter longer. This degrades the chemicals over time unevenly between packs. This is where keeping track of internal resistances is a good idea. This way you can know before hand when a pack is reaching end of life safe operating values. Then you can decide to relegate the pack to running low current draw things like cameras or camp / race gate leds or even portable soldering irons for field repairs.

I number every pack I buy and check internal resistance out of the box. After each break in charge and yes breaking in packs is a good idea some packs like the Fureon lipos are great batteries but take several charges and discharges to balance out the cells. I have 2 of my original 5 3s 2200 packs still working fine with safe internal resistances coming up on their 6th season this month actually.

Great idea to put sand in a food storage bag on a rack above batteries. I am saying goodbye to the ammo can. It was a pain to unlatch it and yes the lid acts like a guillotine on wires. This forum has provided me with many great tips. Keep ‘em coming.