Lipo Charging
12-06-2009, 10:47 AM
#16
Sounds like you're talking about NiMh? I'm asking about lipo. I'd like to see data not just anecodotes too.
Early on when lipo started to make a dent in surface RC, there were graphs thet showed cycle life vs charge rate and these 1st gen lipos showed a big decreas in life when charged at over 1C. There has been at least 2 diff generations since then and they've gotten way better in may ways, not jusy cycle life.
The comapnies like Hyperion that are making what they advertise as 5C capcble lipos are testing them and making a value judgement on what they see in the way of a reduced cycle life. I'd like to see some of that data, I don't think its as bad as people believe it is. This is leftover from the early days.
Reduced C rate charging another ques entirely. I've never seen that addressed. If you do charge at 0.5C do you see an increase in cycle life or not? It certainly takes more time, but is that time well spent?
One of the things I like about my a123s is my chargers can have them charged in 18-20mins and I'm limited to 10amps. I can run them almost 3 times before a set of 1C lipos have fully charged.
Early on when lipo started to make a dent in surface RC, there were graphs thet showed cycle life vs charge rate and these 1st gen lipos showed a big decreas in life when charged at over 1C. There has been at least 2 diff generations since then and they've gotten way better in may ways, not jusy cycle life.
The comapnies like Hyperion that are making what they advertise as 5C capcble lipos are testing them and making a value judgement on what they see in the way of a reduced cycle life. I'd like to see some of that data, I don't think its as bad as people believe it is. This is leftover from the early days.
Reduced C rate charging another ques entirely. I've never seen that addressed. If you do charge at 0.5C do you see an increase in cycle life or not? It certainly takes more time, but is that time well spent?
One of the things I like about my a123s is my chargers can have them charged in 18-20mins and I'm limited to 10amps. I can run them almost 3 times before a set of 1C lipos have fully charged.
12-06-2009, 08:42 PM
#18
Thats not quite the ques - is there any benefit to all that extra time as in increasing lipo cycle life?? If not, then whats the point?
I used keep all the numbers in a notebook or on one of my laptops, but it got to the point that I found myself not running cause of all the business with charging. I stopped worrying about it and just charge them and run.
I used keep all the numbers in a notebook or on one of my laptops, but it got to the point that I found myself not running cause of all the business with charging. I stopped worrying about it and just charge them and run.
I've always stuck to 1C and have never had an issue
12-07-2009, 02:03 PM
#19
Actually no, it's going to be about 47 minutes.
Charging at 2C only quickens the "ramp up" to 8.4V, once it gets to 8.4V the "ramp down" is going to take the same amount of time.
I've charged a pack at up to 4C to see how much faster it was, I saved 3 minutes by charging at 2C, 7 minutes charging at 3C, and 11 minutes charging at 4C also swelling up my pack and ruining my charger.
Your best bet is stick to 1C charging, (5000Mah @ 5A)
Charging at 2C only quickens the "ramp up" to 8.4V, once it gets to 8.4V the "ramp down" is going to take the same amount of time.
I've charged a pack at up to 4C to see how much faster it was, I saved 3 minutes by charging at 2C, 7 minutes charging at 3C, and 11 minutes charging at 4C also swelling up my pack and ruining my charger.
Your best bet is stick to 1C charging, (5000Mah @ 5A)
yea but 80% of thr charge is the ramp up sooooo i dont see how you only save 3 minutes buy charging at 2c....on my hyperion charger after charging for 45 mins at 1c when it hits 8.4 its done in like 5 minutes topps so if i hit 8.4 in 23 minutes and it takes another 5 to ramp down to zero amps the total would be 28 not 50......ive tryied it and its way faster not 2 times because like you said the ramp down is the same but close
12-07-2009, 02:09 PM
#20
yea but 80% of thr charge is the ramp up sooooo i dont see how you only save 3 minutes buy charging at 2c....on my hyperion charger after charging for 45 mins at 1c when it hits 8.4 its done in like 5 minutes topps so if i hit 8.4 in 23 minutes and it takes another 5 to ramp down to zero amps the total would be 28 not 50......ive tryied it and its way faster not 2 times because like you said the ramp down is the same but close
My Ice back in the day was about 35 minutes
My GFX takes about 32 minutes
My Core UDC-30 takes like 40 minutes
My Hyperion takes about 25 minutes and is by far the fastest for the back half of the charge cycle.
But you have to remember you can have 2 of the same charger and they can take different amounts of time, also it can change with the battery your using.
12-07-2009, 03:45 PM
#22
I have a turnigy Accruel 6 charger. When i charge the Battery it just lets me choose how many amps and what cell battery im using. if i set it at 1.0A does that mean im charging it at 1c?
12-07-2009, 06:38 PM
#23
Not necessarily - the C rate is calculated from capacity, in mah, divided by 1000. So if your battery is 1000mah, your 1C charge rate is 1000/1000 = 1amp, but if your battery is 5000mah, the 1C charge rate is 5000/1000 = 5amps. a 2C charge rate would be 5000/1000 x2 = 10amps and so on.
If you'er charging at 1amp with a 5000mah batt, it will charge, it damages nothing, it just takes a long time to finish.
Are you talking abnout NiMh? NiMh really don't follow the C charging business, I mean thats a safe, conservative rule of thumb, but for years I charged my 3000-4000 packs at 5 or 5.5amps without probs.
If you'er charging at 1amp with a 5000mah batt, it will charge, it damages nothing, it just takes a long time to finish.
Are you talking abnout NiMh? NiMh really don't follow the C charging business, I mean thats a safe, conservative rule of thumb, but for years I charged my 3000-4000 packs at 5 or 5.5amps without probs.
12-08-2009, 07:16 AM
#25
Ahhh I see, cuz my charger only charges @ 5.0A max and im using 5000mAH. So 1c is the recommended rate to charge lipos?
12-08-2009, 07:35 AM
#27
Tech Adept
12-08-2009, 08:14 AM
#28
Tech Adept
If you time the "ramp down" it normally takes between 30-40 minutes (depending on your charger of course)
My Ice back in the day was about 35 minutes
My GFX takes about 32 minutes
My Core UDC-30 takes like 40 minutes
My Hyperion takes about 25 minutes and is by far the fastest for the back half of the charge cycle.
But you have to remember you can have 2 of the same charger and they can take different amounts of time, also it can change with the battery your using.
My Ice back in the day was about 35 minutes
My GFX takes about 32 minutes
My Core UDC-30 takes like 40 minutes
My Hyperion takes about 25 minutes and is by far the fastest for the back half of the charge cycle.
But you have to remember you can have 2 of the same charger and they can take different amounts of time, also it can change with the battery your using.
One factor that everyone seems to be missing is if you charge at 2C you will have to ramp down from 2C. Instead of going from 5.2 to 0.1 amps you will be starting at 10.4 and going to 0.1. That alone will offset some of the time savings that you get on the constant current portion of the charge cycle.
12-08-2009, 08:31 AM
#29
Part of what may be contributing to charge time hasn't been mentioned - impact of balancing. There's a time diff when charging if youre staring with cells that are 100mv out of balance versus cells that are only 5mv out of balance. Some chargers hold difference balance tolerance as well which may contribute to diffs in times.
In another thread guy with hyperion 0720i is taking 70min to charge his 5000mah Turnigy's back from the lvc (didn't mention value). Thats about 30more min than it takes for my 5000mah Neus to charge on my 0610i.
abailey21 ...pm'ed you...
In another thread guy with hyperion 0720i is taking 70min to charge his 5000mah Turnigy's back from the lvc (didn't mention value). Thats about 30more min than it takes for my 5000mah Neus to charge on my 0610i.
abailey21 ...pm'ed you...
12-08-2009, 08:45 AM
#30
Tech Regular
iTrader: (8)
That's right, my Turnigy 5000 2S took over 90 minutes to take about 4000mAh from around 3.3v. (Accucel-6)
I've now switched over to G3 VX and Neu XP lipos, but still waiting on the power supply for my Hyperion charger.
You can see there's only 10% capacity loss in 200 cycles and they're being charged at 3-5C:
http://www.rcgroups.com/forums/attac...7&d=1254441513
http://www.rcgroups.com/forums/showthread.php?t=1051482
I've now switched over to G3 VX and Neu XP lipos, but still waiting on the power supply for my Hyperion charger.
You can see there's only 10% capacity loss in 200 cycles and they're being charged at 3-5C:
http://www.rcgroups.com/forums/attac...7&d=1254441513
http://www.rcgroups.com/forums/showthread.php?t=1051482