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Old May 15, 2006, 09:48 AM
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luis104's Avatar
Caracas/Venezuela
Joined Jun 2005
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How much time your batteries get to charge...???

I have a problem:

I dont understand why my batteries get so long to charge. About 2 hours to charge, and about 45min to balance, this its what Im using:

-Hobbico Quick Field Charger Mk II
http://www2.towerhobbies.com/cgi-bin...p?&I=LXCTZ5&P=

-SJ Lithium Cell Balancer (2S-5S)
http://www.helidirect.com/product_in...roducts_id=859

-E-Power 11.1V 2200mAH/12C 3S
http://www.helidirect.com/product_in...roducts_id=857

Im using the balancer in conection mode to charge the battery, when the Quick Field Charger Mk II stops (with the stop alarm after 2 hours) I let the balancer to work untill it automatically turns off. all of this process takes about 3 HOURS...!!! This its gettingme crazy...!!! 3 hous to fly 10 to 15 minutes

Am I doing something wrong..???
is this normal...???

Without the balancer the battery takes a lot less time to charge, but Im afraid to damage the battery. Maybe will be less time if I balance the battery before recharge, but this way Im afraid to damage the battery too.

any ideas, suggestions...???



By the way: Im using the Quick Field Charger Mk II with 0.8ams to charge (the instructions say lipos can be charged in 1.00amps, but I choose the safe way and go a little less)
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Old May 15, 2006, 10:09 AM
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rotarypower3's Avatar
Melbourne (east burbs), AUSTRALIA
Joined Mar 2005
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You're charging a 2200maH pack at 0.8amps..... it's going to take well over 2 hours to charge. You know you can charge at 1C (2.2amps for your pack)...

If you're balancing while charging, it shouldn't continue balancing for more than 5-10mins. Otherwise you've either got a bad cell or there are just badly matched cells in the pack.
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Old May 15, 2006, 10:13 AM
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luis104's Avatar
Caracas/Venezuela
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thankyou........!!!!!!
I didnt knew I can charge at 1C youve made me a happy pilot
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Old May 15, 2006, 10:35 AM
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United States, WA, Olympia
Joined Mar 2005
408 Posts
With that charger you will only be able to charge at 1 amp which is about .8C. Also note that charger is rated for Li-Ion which will ony charge a Li-Poly to about 90-95% because Li-Ion are lower volts per cell. No biggie because you won't notice the little bit just FYI.
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Old May 15, 2006, 10:37 AM
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Ottawa, Ontario
Joined Oct 2005
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Unfortunately for you, the Hobbico MkII only charges at a maximum of 1 Amp in lithium ion mode, so you won't be able to charge at 1C which would be 2.2 Amps for the battery you mention.

Also, that charger is for Lithium Ion chemistry and has a constant voltage phase of around 4.08V per cell. Your Lipos are designed to take closer to 4.2V per cell, so you are not quite getting the full capacity out of your cells.
On the good side of things - its probably pretty nice to your cells, and safer

You might also be taking the cells down too low during discharge and possibly damaging them, because I would expect you shold be pretty close to charging those batteries in 2 hours (I have the same charger).
I'm quite nice to my packs, and try to leave my three cell packs resting no lower than 11.1V resting voltage.
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Old May 15, 2006, 02:23 PM
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Wynn1427's Avatar
United States, CA
Joined Jul 2005
743 Posts
A pack also become out of balance the more they are discharged below 11.1, hence the longer balance times.

Wynn
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Old May 15, 2006, 02:35 PM
adicted to FFF...!!!
luis104's Avatar
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Quote:
Originally Posted by lawd
You might also be taking the cells down too low during discharge and possibly damaging them, because I would expect you shold be pretty close to charging those batteries in 2 hours (I have the same charger).
I'm quite nice to my packs, and try to leave my three cell packs resting no lower than 11.1V resting voltage.
NO. I finish flight with the battery in 11.1V to 11.3V (about 12 min in flight)

the recharge takes about 2 hours and the post recharge balance takes about 45minutes
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Old May 15, 2006, 03:13 PM
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Ottawa, Ontario
Joined Oct 2005
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Quote:
Originally Posted by luis104
NO. I finish flight with the battery in 11.1V to 11.3V (about 12 min in flight)

the recharge takes about 2 hours and the post recharge balance takes about 45minutes
Ah, that makes more sense as far as the charging time goes ... it is about what I would expect with that charger.

I don't know why your balance cycle would be so long unless the cells are badly out of balance. If you have a voltmeter, you could check the individual cells voltage before and after charge to see if they are badly mismatched and causing the long balance time. 45m seems long though.
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Old May 15, 2006, 03:55 PM
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Williamsville, NY
Joined Sep 2005
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It takes about an hour to charge my 2200mAH 3 cells 11.1v LiPo at 1250mAh. The battery is not up to the voltage cutoff, and I would say after about 8-10mins of flight.

Rudy
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Old May 15, 2006, 04:28 PM
That tree again!!!!
thanhTran's Avatar
Germantown, MD, US
Joined Sep 2004
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I used to use that MKII as well. I charged at 1A for the 2200mah pack. Never have to balance the batt (it seems slow charging does pretty good job at balancing the cells.) It took probably about 2 hours to finish charging.
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Old May 15, 2006, 05:01 PM
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United States, WA, Olympia
Joined Mar 2005
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If they take that long to ballance be afraid. Be very afraid. Why don't you just charge them with the ballancer attached? That way during the charging process, when most lipo fires happen, you will know the cells are staying in ballance to one another.
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Old May 15, 2006, 05:06 PM
adicted to FFF...!!!
luis104's Avatar
Caracas/Venezuela
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Quote:
Originally Posted by thanhTran
I used to use that MKII as well. I charged at 1A for the 2200mah pack. Never have to balance the batt (it seems slow charging does pretty good job at balancing the cells.) It took probably about 2 hours to finish charging.
did you damage a battery this way...??? (without balancer)

Im shure using the balancer in conection mode takes longer to recharge the battery.
Is it safe to balance first, then recharge without the balancer...???

Quote:
I don't know why your balance cycle would be so long unless the cells are badly out of balance. If you have a voltmeter, you could check the individual cells voltage before and after charge to see if they are badly mismatched and causing the long balance time. 45m seems long though.
the balancer has a light comunication languaje; reading that, the batteries never have been badly out of balance. After recharge and balance, the cells are perfectly balanced (using a voltmeter) before balance the cells are out of balance for about 0.1V to 0.2V.
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Old May 16, 2006, 08:57 AM
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luis104's Avatar
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last night I recharged the battery at 2amps (some how the lipo balancer made this possible) the battery was a lot out of balance and you are not going to believe this:

the recharge and balance process was ready in 5 HOURS...!!!

I yust have two theories about this:

1-(the most ovious) LIPO, AND ELECTRIC FLIGHT SUCKS...!!! I LOVE GLOW (Raptor 30 pilot)

2- this brand of battery its the worst ever. (letme say that this batteries are NEW, I have two of them, and they yust have no more than 10 flights each one, I always have used the lipo balancer and without over discharging them after flight)
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Old May 16, 2006, 06:32 PM
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The MKII doesn't go over 1amp in lipo mode....ever, even if you put the charge knob on 2 amps.

If you want to charge 2.2Ah batteries on 1C (which is perfectly safe) you'll have to buy another charger.


Try to measure the difference in cell voltage after you charge the pack...if it's bigger then 0.02 volts between any 2 of the three cells there is a problem (well, problem...the pack is starting to be unbalanced)...if the biggest difference is smaller then 0.02 volts you're okay.

If the latter is the case you don't have to balance anything BUT it might be usefull to try it once and see how long it takes to get the difference of less then 0.02 volts balanced. If it takes long...maybe your balancer is doing something wrong??
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Old May 16, 2006, 06:37 PM
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charging IS a pain...but in the end it should only take a little over 1 hour (with your new charger...not the MKII)

Some manufacturers (like KOKAM and THUNDER POWER) have batteries that can be charged at 3C which translates in about half an hour (in theory 20 minutes but at the end chargers always go slow).

Charging lipo's at higher then 1c does shorten their livespan...i wonder what the census is on that ...if you don't fly that much it might be worth it, i don't know really...i guess that if i had a charger that could do it...i might sometimes.

It must be nice to be able to fly continiously on two or three packs...now you need vife or six maybe more
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