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Old Oct 01, 2010, 09:36 PM
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United States, FL, Melbourne
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Help!
Need help understanding Discharge rate/ Charge rates, C ratings

I want to make sure I'm charing my Lipo's correctley.
Lipos I'm charging are Turnnigy Nano-tech 3000mah 4S 25-50C rating, abe to charge @ 5C

I bought the Cell Pro Power Lab 8 from progressive rc

When I turn it on, I goto : " Lipo- faster Charge "

Then I enter NO to parrell packs, because I'm charging one at a time, but from what I read, I can charge all three of the same Lipos, given 5 min of flight time on each, together, and balance them all as well, given they have the same state of dis-charge

Next it says: Set charge rate : A2.0C ? It goes upto A3.0C, then goes into amps, and I can charge upto 30 Amps.
I set this at A3.0C

Next it says: Set Dis-Charge rate? So I set it at 2.00A ( I have no idea what this means )

Questions:

If the pack is 3000mah, I can charge at 3.0 amps, ( right ) ? But what do they mean by 5C?

Next: What does 25-50C Dis-charge mean? Can I dis-charge the same as charge rate?

It takes me 24 min to charge a pack, and balance.

Last question: When I connect the Charger to the power supply, it still says type of power supply ( DC power ) It doesn't say A/C , how come?

I have other Lipos I'm charing as well, and I always thought you match the
amps to the pack, meaning if it's 3000mah, you charge at 3.0 amps

If thats the case, is that @ 1C charge rate?

Also, when I connect just the battery ( lipo ) to the balance board, I can't see each cell pack voltage like the video shows. Do I need a Watt Meter to do this?

Lastley : I set my times for 5:00 min on my TX to come down, how can I caculate the flight time for these packs?

Thanks for your help, as i dont want to burn my house down

( I'm hoping Charles @ everydayflyer who has given some great advise helps me here also )
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Last edited by fltekdiver; Oct 02, 2010 at 04:01 AM.
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Old Oct 01, 2010, 10:34 PM
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Chattanooga, Tennessee, United States
Joined May 2003
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Questions:

If the pack is 3000mah, I can charge at 3.0 amps, ( right ) ? But what do they mean by 5C? 5C = 5x capacity = 15A (3A would be the 1C charge rate). But your charger is limited to 10A anyway

Next: What does 25-50C Dis-charge mean? Can I dis-charge the same as charge rate? 25C-50C discharge means you could prop for 25x3 = 75A - 50x3 = 150A. Charge rate is limited to 5C = 15A [but even if you wanted to, you can't charge at more than 10A due to your charger's limitations]


I have other Lipos I'm charing as well, and I always thought you match the
amps to the pack, meaning if it's 3000mah, you charge at 3.0 amps

If thats the case, is that @ 1C charge rate? Yes.

Lastley : I set my times for 5:00 min on my TX to come down, how can I caculate the flight time for these packs? Depends on your discharge rate... if you are drawing 30A then theoretically you should get 6 minutes flight time... if you are drawing 60A you'll get 3 minutes [in practice less than that since you never want to use more than about 80% of capacity]
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Old Oct 02, 2010, 03:33 AM
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United States, FL, Melbourne
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Thanks, what if I charged three packs at the same time , at say 3C = 9.0 amps for one pack, would they be all charging at 9.0 amps a pc, or since the charger is limited to 10.0 amps, would I need 27 amps to charge three of the same lipos?

Also just to make sure, the dis-charge rate is equal to the charge rate, so I could dis-charge at 3C @ 9.0 amps and charge at 3C @ 9 amps since the charger is limited to 10.0 amps
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Old Oct 02, 2010, 04:03 AM
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United States, FL, Melbourne
Joined Jan 2010
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I made a mistake, the charger can charge upto 30 Amps

I remember when I bought it, I wanted a charger that can charge the Lipo's I have at their 5C rating.

So to make sure, The Lipo's say 5C , so I can saftley charge them at 15.0 Amps then ?

Or should I be safer and charge them at 9.0 amps, ( 3C ) ?
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Old Oct 02, 2010, 07:59 AM
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USA, GA, Marietta
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Quote:
Originally Posted by fltekdiver View Post
I want to make sure I'm charing my Lipo's correctley.
Lipos I'm charging are Turnnigy Nano-tech 3000mah 4S 25-50C rating, abe to charge @ 5C

I bought the Cell Pro Power Lab 8 from progressive rc

When I turn it on, I goto : " Lipo- faster Charge "

Then I enter NO to parrell packs, because I'm charging one at a time, but from what I read, I can charge all three of the same Lipos, given 5 min of flight time on each, together, and balance them all as well, given they have the same state of dis-charge

Yes. You should use the parallel charge adapters for this purpose.

Next it says: Set charge rate : A2.0C ? It goes upto A3.0C, then goes into amps, and I can charge upto 30 Amps.
I set this at A3.0C

You could also set the charge rate to 15 amps. The charge will go a bit faster because the charger does not have to spend time figuring out the capacity of your packs.

Next it says: Set Dis-Charge rate? So I set it at 2.00A ( I have no idea what this means )

The preset you are using can also be used to discharge batteries. Remember when you started the charge the charger asked if you wanted to Charge, Discharge, Monitor, or Cycle your battery. If you had specified Discharge the battery would have been discharged at a two amp rate.

Questions:

If the pack is 3000mah, I can charge at 3.0 amps, ( right ) ? But what do they mean by 5C?

"C" is the capacity of the battery. So 1C for your 3000mah battery is 3 amps. 5C would be 15 amps. This is usually the maximum safe charge rate.

Next: What does 25-50C Dis-charge mean? Can I dis-charge the same as charge rate?

This is the maximum safe discharge rate of your battery. The lower number is usually the steady current rate and the higher number is usually the safe burst rate. Burst meaning short periods of higher current flow. Short is seldom defined but I would be conservative and not go above the lower number. So for your 3000mah 25C battery the maximum safe discharge rate would be 75 amps.

It takes me 24 min to charge a pack, and balance.

That sounds about right for a 3C charge rate. It would be a little shorted if you selected 9 amps instead of 3C because at 3C the charger has to figure out the capacity of your battery. If you go to 15 amps the time will be even shorter but not proportionally as the balance time will remain about the same. Go ahead and try a couple of charges and compare the times.

Last question: When I connect the Charger to the power supply, it still says type of power supply ( DC power ) It doesn't say A/C , how come?

Because the charger only operates from DC voltage. You must power it from a DC power supply or a lead acid battery

I have other Lipos I'm charing as well, and I always thought you match the
amps to the pack, meaning if it's 3000mah, you charge at 3.0 amps

If thats the case, is that @ 1C charge rate?

Yes.

Also, when I connect just the battery ( lipo ) to the balance board, I can't see each cell pack voltage like the video shows. Do I need a Watt Meter to do this?

After the charge starts press the INC button to step though the displays. The pack voltage and individual cell voltages will be displayed. Also power supply current and voltage, charge current etc.

Lastley : I set my times for 5:00 min on my TX to come down, how can I caculate the flight time for these packs?

Use your watt meter to determine the current flow at normal flight current. Then you can calculate the number of minutes the battery will last. Set your timer to 80% of that value to prevent over discharging the battery.

Thanks for your help, as i dont want to burn my house down

( I'm hoping Charles @ everydayflyer who has given some great advise helps me here also )
Glen
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Old Oct 02, 2010, 08:06 AM
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Quote:
Originally Posted by fltekdiver View Post
Thanks, what if I charged three packs at the same time , at say 3C = 9.0 amps for one pack, would they be all charging at 9.0 amps a pc, or since the charger is limited to 10.0 amps, would I need 27 amps to charge three of the same lipos?

If you charge packs in parallel they split the available current. If the charge current is 3 amps then each of the three packs would see 1 amp.

Also just to make sure, the dis-charge rate is equal to the charge rate, so I could dis-charge at 3C @ 9.0 amps and charge at 3C @ 9 amps since the charger is limited to 10.0 amps

Not exactly sure what you are asking here. Only the discharge is limited to 10 amps. You could charge at higher amps if the battery is rated for that.
Glen
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Old Oct 02, 2010, 08:10 AM
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Quote:
Originally Posted by fltekdiver View Post
I made a mistake, the charger can charge upto 30 Amps

I remember when I bought it, I wanted a charger that can charge the Lipo's I have at their 5C rating.

So to make sure, The Lipo's say 5C , so I can saftley charge them at 15.0 Amps then ?

Or should I be safer and charge them at 9.0 amps, ( 3C ) ?
As I stated in an earlier reply you could charge at 15 amps (5C). However the time required for a 9 amp (3C) charge will not be a whole lot longer. Try a charge at each rate and time them. The charger will safely charge at the 5C rate. The batteries may last a bit longer if you use the lower rate. That would depend on the quality of the battery.

Glen
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Old Oct 02, 2010, 08:30 AM
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Glen, thanks for all your help, Its been greatley apprecaited to take the time to answere all those questions !

I'm only confused on the dis-charge part.

When I goto charge the Lipo, should I set a value for the dis-charge?

As you said the charger asks if I want to charge, which I do, so I can set the values to 9.0 -15.0 Amps on these battereis, but when It ask to set the dis-charge rate, should I put 0?
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Old Oct 02, 2010, 08:47 AM
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Haralson County GA. USA
Joined Oct 2004
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If you are not going to use the Discharge( this time) it makes no difference what it is set at.

You would set it for a battery that you wanted to discharge or run cycles on.

Example : I only want to charge a 2200 at 3C charge rate so I set charge rate to 6.6 amps . and I leve Discharge rate set to what ever it happens to be as I am not going to use it this time.


Sometime latter I want to cycles this 2200 at 3C charge and 2c discharge so I set charge rate at 6.6A nad discharge at 4.4A and also set the number of cycles I wish it to complete.

Charles
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Old Oct 02, 2010, 09:32 AM
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Quote:
Originally Posted by fltekdiver View Post
Glen, thanks for all your help, Its been greatley apprecaited to take the time to answere all those questions !

I am very happy to answer your questions. However I think many of your questions would be answered by your reading the battery stickies at the top if this forum. Also I think you might benefit from reading the PL8 owners manual (maybe a couple of times).

I'm only confused on the dis-charge part.

When I goto charge the Lipo, should I set a value for the dis-charge?

As you said the charger asks if I want to charge, which I do, so I can set the values to 9.0 -15.0 Amps on these battereis, but when It ask to set the dis-charge rate, should I put 0?

As Charles said, if you are not discharging, the setting is not relevant.
Glen
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Old Oct 02, 2010, 10:29 AM
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10/4, I'm bringing the manual on my boat today, so when I have down time, I can do some reading, thanks again everyone
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