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Old Jan 20, 2013, 09:39 AM
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United States, NJ, Phillipsburg
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Lipo charge time

I'm totally new to electric. I have the Great planes Carl Goldberg EP. I had everything hooked up and ran the motor holding the plane in my hand (won't do that again). It ran for 6 minutes but it took 75 minutes to recharge the 3S1350mAh 11.1v lipo. I also noticed one cell was way out of balance when starting the charger. Is this normal?
I'm thinking if it takes this long to charge a spent pack I need a cpl more packs.

Tom
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Old Jan 20, 2013, 09:50 AM
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Quote:
Originally Posted by iflircaircraft View Post
I'm totally new to electric. I have the Great planes Carl Goldberg EP. I had everything hooked up and ran the motor holding the plane in my hand (won't do that again). It ran for 6 minutes but it took 75 minutes to recharge the 3S1350mAh 11.1v lipo. I also noticed one cell was way out of balance when starting the charger. Is this normal?
I'm thinking if it takes this long to charge a spent pack I need a cpl more packs.

Tom
You want to treat new Lipo packs in the following way.
Charge them at about .8 of their normal charging rate. In the case of your 1350 pack, charge it around 1 to 1.1 amps.

Discharging, or using new Lipo packs... you want to "harden" them by only discharging them to about 50% of their capacity. If you have a watt-meter showing amps, you can monitor the consumption rate.
If you don't have a watt-meter yet, pay close attention to how much the charger puts back into your Lipo. In this case, you want to put back around 700 mah to reach full charge.

A watt-meter will also indicate voltage during the trial runs. Try to end the run when the voltage is around 3.5 volts/cell, or 10.5 volts for the pack. Once you get the pack ready for regular use, use a timer to indicate when to end the run.

Odds are you don't have a watt-meter yet. So, you're going to have to "sneak up" on the numbers.

You'll also find that the "low voltage cutoff" built into the ESC isn't such a safe concept. It can easily allow the Lipo pack to drop below a safe voltage.

Drawing any Lipo down too low on a run is detrimental to it, especially a brand new one.

After about 10 charge and discharge cycles, you can begin to increase the amount you draw from the pack. Once the pack is "hardened", your goal becomes to never suck more than 80% of its capacity out of it (1080 mAh in the case of your 1350 Lipo).
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Old Jan 20, 2013, 09:59 AM
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My charger can discharge my Lipo pack. should I cycle them as I did with my Nicads?
The battery has a tag which instructs to charge at 1C. Good thing there are forums such as this.
Tom
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Old Jan 20, 2013, 10:00 AM
DJO
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Yes, when charging batteries at 1C, which is what I do, it'll take about an hour.

If you're not going to use them for over a week, just put them into "storage voltage", which is 11.4v for a 3S pack.

If its out if balance you'll need to balance it too, most chargers have a specific balance function.



Dan
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Old Jan 20, 2013, 10:17 AM
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I don't know about "hardening" a pack, but I usually take it easy the first few flights til I get a feeling of how long I can run the plane til the pack is down to about 20% of the capacity. If you don't have a smart charger then you need to get one. You will want more than one battery because it's not advisable to charge most LiPo's at much more than 1C charge rate. Did you charge the battery before using it the fist time? Usually they only come with about half of a charge because they're close to the storage voltage, you will probably see longer run times once you break in the battery and start from a fresh charge. You don't need to cycle these batteries, but you do want to discharge them to their storage voltage if you're not going to fly for a week or more as DJO said... that's about 3.75-3.8v per cell.
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Old Jan 20, 2013, 10:34 AM
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Yes I charged the pack before running the motor. I'm sure it would have flown longer then it ran when holding it in my hand.
Looks like I should get it down to "storage voltage' since it will be a week or more until I get to fly. Thanks for the help.

Tom
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Old Jan 20, 2013, 12:01 PM
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By definition most chargers will charge a lipo in about 1 hour, from fully discharged. That's what "1C" charging means. Some of the newer/better batteries can be charged at 2x or even 5x that rate, but you must be absolutely sure your battery is rated for that kind of accelerated charging. And the charger will almost certainly default to 1C charging, so you'll have to specifically tell the charger to use that higher rate.
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Old Jan 20, 2013, 12:17 PM
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Quote:
Originally Posted by iflircaircraft View Post
I'm totally new to electric. I have the Great planes Carl Goldberg EP. I had everything hooked up and ran the motor holding the plane in my hand (won't do that again). It ran for 6 minutes but it took 75 minutes to recharge the 3S1350mAh 11.1v lipo. I also noticed one cell was way out of balance when starting the charger. Is this normal?
I'm thinking if it takes this long to charge a spent pack I need a cpl more packs.

Tom
Not normal for one cell to be way out of balance for a good battery. And your last statement shows that you have it figured out already - you need several more packs, especially if you only have batteries and chargers capable of standard 1c charge rates. As others above have already stated, 1c charge rate = somewhere close to 1 hour to charge an 80% discharged battery. And it probably takes between 5 and 10 minutes on average to run it down in flight. So if you want to fly 10 times in a typical afternoon at the field and have a field charger, it's going to take probably 6 or 7 batteries to do it utilizing 1c charge rates.
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Old Jan 20, 2013, 12:27 PM
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I'm brand new to this site and don't really know how to properly use it. I have never used rc planes before and am considering buying either the 1500mm Bixler 2 or the 95" super sky surfer as my first plane. Can anyone suggest which of the two I should get and why? When I buy either are there some changes (motor, esc, battery, etc that I should make before I attempt to fly. Remember I have NO experience.
Thank you

PS I would probably get the ARF version and buy my own radio... is that a good idea for someone that has no idea what they are doing?
Thanks
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Old Jan 20, 2013, 12:43 PM
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You should definitely not do either unless you first start on a simulator. You can get a cheap one for about $30 and it's like a game that teaches you how to fly planes. The Bixler is a fine plane to start with, but you need to at least know the basic movements/functions of an airplane before trying to fly it.



Dan
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Old Jan 20, 2013, 12:49 PM
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Quote:
Originally Posted by onco11 View Post
I'm brand new to this site and don't really know how to properly use it. I have never used rc planes before and am considering buying either the 1500mm Bixler 2 or the 95" super sky surfer as my first plane. Can anyone suggest which of the two I should get and why? When I buy either are there some changes (motor, esc, battery, etc that I should make before I attempt to fly. Remember I have NO experience.
Thank you

PS I would probably get the ARF version and buy my own radio... is that a good idea for someone that has no idea what they are doing?
Thanks
The Super Sky Surfer is NOT a beginner plane,it has some nasty habits,and right out of box needs better esc, from all the posts on here i gather the Champ is one of the best for a beginner
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Old Jan 20, 2013, 03:33 PM
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Originally Posted by iflircaircraft View Post
I'm thinking if it takes this long to charge a spent pack I need a cpl more packs.

Tom
Tom,

It may be worth investing in better quality batteries that have a higher charge rate when you get some more. Many these days have a 5c max charge rate which means that if you have a half decent charger you could push over 6 Amps in and have the battery charged in 10-15 minutes.

You can also get chargers with multiple outputs and/or parallel charging boards that allow you to charge several together. IMHO it's just not a practical proposition to have to charge charge several batteries one after the other with each taking an hour. Especially when you consider that it's recommended that you shouldn't leave them untended while charging.

Steve
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Old Jan 20, 2013, 05:23 PM
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Originally Posted by JetPlaneFlyer View Post
Tom,

It may be worth investing in better quality batteries that have a higher charge rate when you get some more. Many these days have a 5c max charge rate which means that if you have a half decent charger you could push over 6 Amps in and have the battery charged in 10-15 minutes.
Yikes, I wouldn't recommend that. Yes it will work but that greatly decreases the life of your batteries over time.

But yeah having a charger with multiple outputs (or just multiple chargers in general), is a great way of charging more stuff at once too. However, this isn't as useful if you haven't bought that many batteries yet

Most batteries I've ever had for a single aircraft was 2 or 3. I set up most of my stuff for longer flight times as it is, 35 minute flights weren't unusual when I had my PopWing... and I had 2 packs for that for a solid hour at the field flying both LOS AND FPV...



Dan
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Old Jan 20, 2013, 06:07 PM
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DJO: I haven't tried charging at > 1C, but lots of batteries these days are rated for > 1C charging. I think as long as the batteries stay relatively cool while charging, there's no harm in it. And yeah, a four-port charger is seriously useful if you're planning a heavy day of flying.

That, and lots of batteries. I have at least six each of 3S/2200 and 3S/1300. Probably half the planes in my fleet use one of those two sizes.
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Old Jan 20, 2013, 06:09 PM
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Originally Posted by rafe_b View Post
DJO: I haven't tried charging at > 1C, but lots of batteries these days are rated for > 1C charging. I think as long as the batteries stay relatively cool while charging, there's no harm in it. And yeah, a four-port charger is seriously useful if you're planning a heavy day of flying.

That, and lots of batteries. I have at least six each of 3S/2200 and 3S/1300. Probably half the planes in my fleet use one of those two sizes.
Yup I used to charge my 2S 950 mAH pack, rated for 2C, at 2C... but it has been proven to decrease the life over time of your batteries, they'll loose their punch quicker!

That being said, my ParkZone 1300 mAH 3S 20C pack is still going pretty strong after charging at 1C for nearly 4 months now I believe!



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