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Experience of using high LiPo charge rates

Old 03-17-2012, 10:58 AM
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mikehannah
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Default Experience of using high LiPo charge rates

Hi
Rather than hijack someones elses thread I thought I would start my own. After contributing to another thread on charger selection, some of the posts that have been made subsequent to my original post have got me wondering if my LiPo management practices of never charging at greater than 1C, may be overly conservative with modern packs.
So I thought I would ask the following questions.

1) What are peoples experiences at charging at greater than 1C, what charge rate are you using
2) What cycle life are you getting out of your packs
3) What make of LiPo are you using?

Thanks in advance for indulging my curiosity.

Mike
Old 03-17-2012, 03:00 PM
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wingster
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Default RE: Experience of using high LiPo charge rates

Over at RC Groups there's at lot of info on high charge rates. 5C is common and some people are even charging in the 10C region in accordance with manufacturer specs.

Parallel charging is also becoming common practice, If you have a high power charger like the Revoelectric PL8 you can charge 5S at up to 40 Amps. I typically charge a half dozen 5000mah batteries inparallel at about 25A. So I'm at a little less than 1C for each battery, but you can charge six batteries in about 45 minutes.
Old 03-17-2012, 05:23 PM
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Anthony-RCU
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Default RE: Experience of using high LiPo charge rates

I have been following this on RCG for the last year and have bee experimenting with some smaller packs. I have two 4s 40c 2650 zippys that have been flown with 50a peaks and charged mostly over 4c. Only 30 flights so far but the packs are running great. Only invested in 2 packs but with 20 minute charges plenty of flying.

Started parallel charging my 6s packs and it is great! Charge 3 of these at 2c in 35 minutes and only use one charger. These are Turnigy 20c 2650 cells that are only rated for 2c charge. These are new only eight flights but much better than three hours of charging.

Planning on charging my pattern packs as fast as I can this year and not owning as many packs.
Old 03-17-2012, 09:34 PM
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Default RE: Experience of using high LiPo charge rates

I have been charging my old&faithful Rhino packs already for a long time at first 1.5C and now 2C. These are the old ones, later makes were 2C charge by the manufacturer, but I don't believe they really changed anything beside the spec. These have run 250 cycles now and are still good.

I have also used 3 sets of Xcell lipos which i charged from the start with 1.5C but I never liked them much. I sold them after app. 80 cycles. They were always showing somewhat high (4-6ohm/cell) Ir.

I now run one TP 4400 25C which I charge with 11amp (the max I get out of my current power supply/charger combo). Combined with the low power usage I see on the Hacker C50 (2500-2700 per flight) my recharge time is about 20 minutes. Effectively i now only use this one battery with the old Rhino as backup. The TP is doing great and i see no adverse effects of the higher charge rates.

Volkert
Old 03-18-2012, 08:12 PM
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Default RE: Experience of using high LiPo charge rates

I've been using Thunderpower G6 packs, and charging them at 5C, which I'm sure reduces the life of the packs, but I only need two sets to fly as long as I want, and if I'm flying with someone else, I only need one set, because I can charge a pack in under 12 minutes.

Also, I don't have to spend any time charging when I go home, because I either charge everything before I leave the field, or I charge when I'm flying my first flight the next time I fly.

Brenner ...
Old 03-19-2012, 01:52 AM
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Default RE: Experience of using high LiPo charge rates

Mike

Like you I started off charging everything at 1C, now I charge everything at 2C on my Cellpro 10S I have not got more than 100 cycles on any of my packs yet but no problems so far.

John
Old 03-19-2012, 08:22 AM
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Default RE: Experience of using high LiPo charge rates

.
I use FMA PL8 chargers and charged my HobbyKing Blue ($40) 5S-5000 LiPo's all last year at 10 amps (2C) at the field and 20 amps (4C) at home.  I would have charged at the higher rate at the field, but my poor generator would "dance" at the higher rate.
.
I'm convinced that it is more important for battery longevity to store / keep your batteries at 50% charge rate (3.8V per cell) as much as possible.  Every time you fully charge your LiPo it is the same as winding up a rubber band to its limit.  The longer you make it hold that potential, the more damage you're doing to the cell.  Also, every time you discharge it past 20%, you're doing the same thing.  That's why they come from the factory at 50% charge. . .
.
I am adamant about finishing the flying day with a storage charge, preferably at the field, but definitely at home.  Then I don't charge them back up until I am either at the field or until I've committed to go to the flying field for the day.  It doesn't take long to bring a battery up to full charge from 50% at 20 amps. . . also my field just got connected to "the grid" . . . (yay!!)
.

Old 03-19-2012, 09:25 AM
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Default RE: Experience of using high LiPo charge rates

ORIGINAL: klhoard

.
I use FMA PL8 chargers and charged my HobbyKing Blue ($40) 5S-5000 LiPo's all last year at 10 amps (2C) at the field and 20 amps (4C) at home. I would have charged at the higher rate at the field, but my poor generator would ''dance'' at the higher rate.
.
I'm convinced that it is more important for battery longevity to store / keep your batteries at 50% charge rate (3.8V per cell) as much as possible. Every time you fully charge your LiPo it is the same as winding up a rubber band to its limit. The longer you make it hold that potential, the more damage you're doing to the cell. Also, every time you discharge it past 20%, you're doing the same thing. That's why they come from the factory at 50% charge. . .
.
I am adamant about finishing the flying day with a storage charge, preferably at the field, but definitely at home. Then I don't charge them back up until I am either at the field or until I've committed to go to the flying field for the day. It doesn't take long to bring a battery up to full charge from 50% at 20 amps. . . also my field just got connected to ''the grid'' . . . (yay!!)
.

Amen to that; charge tour batteries not too long before flying and store them at 50%. Another, even better solution is to go flying everyday! :-) unfortunately i have not been able to get to that point yet!

Volkert
Old 03-19-2012, 11:04 PM
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Default RE: Experience of using high LiPo charge rates


ORIGINAL: wagen017

ORIGINAL: klhoard

.
I use FMA PL8 chargers and charged my HobbyKing Blue ($40) 5S-5000 LiPo's all last year at 10 amps (2C) at the field and 20 amps (4C) at home. I would have charged at the higher rate at the field, but my poor generator would ''dance'' at the higher rate.
.
I'm convinced that it is more important for battery longevity to store / keep your batteries at 50% charge rate (3.8V per cell) as much as possible. Every time you fully charge your LiPo it is the same as winding up a rubber band to its limit. The longer you make it hold that potential, the more damage you're doing to the cell. Also, every time you discharge it past 20%, you're doing the same thing. That's why they come from the factory at 50% charge. . .
.
I am adamant about finishing the flying day with a storage charge, preferably at the field, but definitely at home. Then I don't charge them back up until I am either at the field or until I've committed to go to the flying field for the day. It doesn't take long to bring a battery up to full charge from 50% at 20 amps. . . also my field just got connected to ''the grid'' . . . (yay!!)
.

Amen to that; charge tour batteries not too long before flying and store them at 50%. Another, even better solution is to go flying everyday! :-) unfortunately i have not been able to get to that point yet!

Volkert
I never charge at home. To go from storage charge to full takes minutes. Get to the field, start charging put model together, by the time it is together batteries are charged. Same when i am finished for the day, place batteries back into storage charge, then pack up the model, then put away the charging setup.

I use two ThunderPower 820's with twin 1000watt supplies. Just need a bigger generator as my little Honda 1000 can't cope. 2000 Honda is on the cards.

I have been charging all my big packs at 2c with no ill effects, can't do more as the generator can't cope. My 2200 3s packs i belt them with 12amps, still under their max charge C of 8c. They are full in under 10 minutes. Can't fly fast enough. These packs get over discharged and pushed hard, ans so far are doing pretty good

Chris
Old 03-19-2012, 11:53 PM
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Default RE: Experience of using high LiPo charge rates

Hi Chris,

Been some time since we have spoken - hope you are keeping well.

Can you tell me what you are using for power supplies?

regards,

Peter P
Brisbane
Old 03-20-2012, 03:26 AM
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Default RE: Experience of using high LiPo charge rates

When I fly I have my timer set so that I land with an unloaded voltage in the range of 3.7 to 3.8v per cell. I have checked and the cells are within .001v of each other.

Since this is pretty much the ideal storage charge, is there any reason to even put them on "storage" charge? I use 2 Cellpro 10XP chargers.
Old 03-20-2012, 03:39 AM
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Default RE: Experience of using high LiPo charge rates


ORIGINAL: PeterP

Hi Chris,

Been some time since we have spoken - hope you are keeping well.

Can you tell me what you are using for power supplies?

regards,

Peter P
Brisbane
Hi Peter,

All is good thanks, it's been a while.
I'm using meanwell power supplies, 24 volt 1000watt tweaked up to 27 volt(theres a trim pot for doing this) Cheapest place on the web i found them was EP Buddy in the States, cheap, fantastic service, respectable postage to Australia. Used 1000 watt ones even though the 820's require 800 watts. Figure a bit of head room was good, don't want them working 100% all the time.

Cheers Chris
Old 03-20-2012, 04:38 AM
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Default RE: Experience of using high LiPo charge rates

.
I can't imagine that your batteries care how they get to 3.8V. The only issue I could think of is that their "resting voltage" may change once they cool down from the flight.
.
Old 03-20-2012, 05:09 AM
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Default RE: Experience of using high LiPo charge rates

Neither can I, but there may be some wrinkle of which I am not aware.

But thus far I have not been putting them on store charge with no immediately apparent ill effects.
Old 03-20-2012, 03:36 PM
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Default RE: Experience of using high LiPo charge rates

Hi Guys,

I'm about to embark on the fast charge route with LiPo's. I don't think there should be concern over fast charging within reason. It's actually been going on for donkey years. In my previous RC car life, we used to charge 1200mAh nicads at 4A with no ill effects.

I'm using a TP820C and have just bought 4 5S TP 25C 5000 mAh packs. I plan to charge at 2C which should allow 20-25 minutes to charge a pack. Like Chris, I'm using a Mean well PSU but have only bought a 600W 27V unit. This should be adequate for my purpose.

Regarding storage of packs, If storing for long periods, I will put them in storage mode. I usually use my packs every week so I just fly them and leave them with 25-30% until I next use them. Last month I had an F3A Unlimited pack puff a cell. The pack had 85 flights on it. Not sure if any of my actions contributed to this failure but the other 7 5S packs are still going strong. Having said that, the balance leads are getting a bit worn and intermittent which sometimes causes the charger to spit the dummy....

Regards,
Jason.
Old 03-31-2012, 08:45 AM
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Default RE: Experience of using high LiPo charge rates

Hey Jason,

If your 4 new packs are TP's 25C G6 packs, I don't think you'll have any problem at all at 2C. I charge the same packs at 5C (25A) and it works fine. Now I'll admit that I'm known for being a little harsh with my packs, but I don't usually make any plans to keep packs beyond a single season, and then I buy new packs in the spring.

I also use TP's 65C G6 packs, and I charge these at 30A without any problem. I'd charge them faster, (They are rated for 12C ..) but two packs at 30A each reaches the limit of my 2000W generator.

Brenner ...
Old 04-01-2012, 04:26 PM
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Default RE: Experience of using high LiPo charge rates


ORIGINAL: Brenner

Hey Jason,

If your 4 new packs are TP's 25C G6 packs, I don't think you'll have any problem at all at 2C. I charge the same packs at 5C (25A) and it works fine. Now I'll admit that I'm known for being a little harsh with my packs, but I don't usually make any plans to keep packs beyond a single season, and then I buy new packs in the spring.

I also use TP's 65C G6 packs, and I charge these at 30A without any problem. I'd charge them faster, (They are rated for 12C ..) but two packs at 30A each reaches the limit of my 2000W generator.

Brenner ...
Hi Brenner,

Yes, the new packs are the G6 version. Interestingly, they don't seem to perform any different to my 100 flight old F3A unlimited packs but are a little lighter. I guess that means the old packs are still ok.. The old ones have only ever been charged at 1C. As you say, 2C for the new TP packs should be quite safe. I can't imagine charging at 25A... As Tim the tool man would say "more power!". lol.

Working on my charging box now. I'm going to use a Pelican 1550 (orange nice!) case and hopefully be able to store the charger, PSU, Batteries and flight tools within the one box. I'm on a mission to make things smaller. Flying electric certainly means less tools and spares are needed! :-)

Cheers,
Jason.

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