RunRyder RC
WATCH
 1 page 696 views POST REPLY
HomeAircraftHelicopterMain Discussion › Charging LiPo question
02-18-2018 12:20 AM  5 months agoPost 1
youngbuck

rrApprentice

Maine

My Posts: All  Forum  Topic

Hey guys I'm sure this question has arisen many times for us newbies getting into big electrics. It's a pretty easy question though. I have an icharger 106b and when charging my 6s 3300's it has an option called "capacity cut off" it defaults to 5000 but considering I have like 6 3300mah I'm going to want to set that cut off to 3300 correct?
And the "end voltage" defaults to 25.20v - is that correct or should I adjust that.
I'm just trying to be safe and I've started to do some research about charging lipos but it feels like the words are in Chinese, like I have a hard time obtaining the information. Any help would be greatly appreciated, thanks.

PM  EMAIL  GALLERY  Attn:RR  Quote
02-18-2018 01:41 AM  5 months agoPost 2
wjvail

rrKey Veteran

Meridian, Mississippi

My Posts: All  Forum  Topic

youngbuck
I have an icharger 106b and when charging my 6s 3300's it has an option called "capacity cut off" it defaults to 5000 but considering I have like 6 3300mah I'm going to want to set that cut off to 3300 correct?
Hmmm... Maybe not. I set this to "ignore". Setting a capacity cutoff is something of a last chance opportunity to catch charging errors - and it is a very poor one at that.

LiPo batteries charge using what is called the constant current to constant voltage method. What that means is, your charger will charge at the programmed current until any cell reaches 4.2 volts at which point it will begin reducing the charge current to maintain that voltage. (You do always use the balance lead don't you?)

So for example, you might set your charger to charge at 6.6 amps and you should expect it to charge at that current until the highest voltage cell reaches 4.2 volt. At that point the charge current will be slowly reduced to near zero while maintaining a cell voltage of 4.2 volts. At that point the charge cycle will terminate.

What you are saying when you set a capacity cut off is, if I program my charger incorrectly, and if my battery was completely dead when the charge started, stop at what I believe is the batteries rated capacity.

A few notes:
- Properly set, a LiPo charger will tell you when it done. Capacity of the pack doesn't matter. Yes if you put 5,000 mAh in a 3,300 mAh pack something is badly wrong and possibly setting a max "capacity cut off" would help in this situation. For instance: If you have set your charger for a NiMh charge instead of the LiPo you intended, and if your LiPo battery was nearly dead at the start of the charge, yes, your charger would possibly terminate the charge before a fire started. (Side note: don't do this. You will burn your house down.)
- But consider - If you take a pack that is 1/2 charged at the start of the charge, as it might be if you take a pack out of storage, you would be trying to put an additional 3,300 mAh in a pack that already has 1,650 mAh in it. In effect you would be trying to put 4,950mAh in a 3,300 mAh battery. Seems like a poor plan to me.
- If you fail to reprogram capacity cutoff for the next pack, nothing is gained by having set it in the first place. If your next battery is 2,000 or 5,000 mAh, nothing has been gained by setting a capacity cut off. In the case of the 2,000 mAh battery you are still over charging it. In the case of the 5,000 mAh battery the charger will cut off at 3,300 mAh. At that point you will likely (hopefully) realize your mistake and start the charge over - with a 1/2 charged battery. Again, nothing has been gained.

Short answer... I disable this "feature". Nice for NiCad or NiMh batteries but useless for LiPos.

Just my thoughts.

Bill

"Well, Nothing bad can happen now."

PM  EMAIL  GALLERY  Attn:RR  Quote
02-18-2018 06:45 AM  5 months agoPost 3
david426

rrNovice

Albuquerque, NM

My Posts: All  Forum  Topic

What Bill said about capacity cut off. The voltage of 25.2 is correct. A regular lipo full charge is 4.2 per cell times 6 cells, that's your 25.2 volts. A different cell chemistry or cell count would have a different voltage.

PM  EMAIL  Attn:RR  Quote
02-18-2018 02:35 PM  5 months agoPost 4
pctomlin

rrVeteran

Texas

My Posts: All  Forum  Topic

I set capacity cutoff to ignore, LiPo cell voltage max at 4.2V and max charge time to 60 minutes.

PM  EMAIL  GALLERY  Attn:RR  Quote
02-18-2018 04:10 PM  5 months agoPost 5
Pistol Pete

rrProfessor

Seffner, FL

My Posts: All  Forum  Topic

...Im just trying to be safe...
youngbuck
I have like 6 3300mah I'm going to want to set that cut off to 3300 correct?
Yes, I do use it (different charger but they all practically have identical "basic" programming) and in your scenario I would most likely set as low as 3100 for starters.

Why? The 80% "recommended maximum discharge" of your 6S-3300mA is only 2640mA.

This [Capacity Cut Off] safety feature ALARM only kicks on IF the set number is reached. Since its an "alarm", it will also sound off and display error. Either a bad battery or operator input error(wrong settings) will trigger this alarm. A fully discharged batt will also trigger it based on the low setting of 3100.

The main downside is that this "Parameter" is a universal setting that applies to any batt plugged into charger. The burdensome of having to change it for different capacity batts is most likely why many bypass it. It would be great if each batt memory slot had its own setting for such.

IF the 3300 are the largest you're charging, then definitely consider it as it's already paid for.

*This "safety" alarm is useless when disabled.

The Balance Charge setting should terminate a charge when each cell reaches 4.2V (6S-25.2V)
youngbuck
I'm just trying to be safe and I've started to do some research about charging lipos but it feels like the words are in Chinese,
http://www.amaflightschool.org/gets...-battery-basics

~~Enjoying the hobby one flight at a time~~

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
02-22-2018 12:03 PM  4 months agoPost 6
youngbuck

rrApprentice

Maine

My Posts: All  Forum  Topic

Awesome post guys. This is great info and thank you for the links, I'm going to read them after work.and yes I always do use the balance ports.

PM  EMAIL  GALLERY  Attn:RR  Quote
02-22-2018 02:55 PM  4 months agoPost 7
Richardmid1

rrProfessor

Leeds, England

My Posts: All  Forum  Topic

Li-po's are charged by voltage. I've never used or need to use capacity cut-off. Either disable it or set it higher than the capacity of your packs. Most modern chargers have a storage charge mode so you don't even need capacity cut-off for that, I'm just not sure what you would use capacity cut-off for?!

60% of the time, it works every time!

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
02-22-2018 04:58 PM  4 months agoPost 8
spaceman spiff

rrKey Veteran

Tucson

My Posts: All  Forum  Topic

I only recently started using storage charge. They get boosted back to storage level within hours of flying. Wish i had been doing that all along.

PM  EMAIL  GALLERY  Attn:RR  Quote
02-22-2018 07:29 PM  4 months agoPost 9
Flyin for Jesus

rrVeteran

Troy, IL. 62294

My Posts: All  Forum  Topic

Capacity cutoff set to disable for me. Sometimes I charge a single pack and other times I parallel charge 6 packs at once.
If your charger is going to screw up and over charge your LiPo, unless you read the state of charge of each pack to accurately set the remaining capacity to charge to 100%, then the capacity limit will do you no good.

PM  EMAIL  GALLERY  Attn:RR  Quote
WATCH
 1 page 696 views POST REPLY
HomeAircraftHelicopterMain Discussion › Charging LiPo question
 Print TOPIC  Make Suggestion 

 6  Topic Subscribe

Friday, July 20 - 12:00 pm - Copyright © 2000-2018 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online