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Charge rate equation? Beginners question

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Old 09-04-2007, 04:38 AM
  #1
ccondrup
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Default Charge rate equation? Beginners question

Hi there!

I have recently received both packs and a charger I bought from you. I have read the manual for the charger, which states "to determine proper charge current in Ampere, consult the manual for the battery, or your dealer", and since I have found no manual for any batteries, the latter is what I'm doing in this post.

I got this charger: http://www.maxamps.com/Eos5i-AC-DC.htm
this balancer: http://www.maxamps.com/LBA10.htm

This pack: http://maxamps.com/proddetail.php?pr...rt-Pack&cat=13
and this pack: http://www.maxamps.com/Lipo-6000-74-Pack.htm

Questions:
Now, I dont fully understand what settings to use on the charger, or rather how to find out. I need some sort of equation.

- Does this charger detect when the battery is full, or do I have to calculate charge time and disconnect? Does this vary with battery type?
- What are the optimal charge and discharge settings for regular Nimh/nicd's?
- What would be the upper limit of (dis)charge current (C-number) for the packs mentioned above (for speedy operation).

Thanks in advance!
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Old 09-04-2007, 09:51 AM
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Default RE: Charge rate equation? Beginners question

Quote:
ORIGINAL: ccondrup

Hi there!

I have recently received both packs and a charger I bought from you. I have read the manual for the charger, which states "to determine proper charge current in Ampere, consult the manual for the battery, or your dealer", and since I have found no manual for any batteries, the latter is what I'm doing in this post.

I got this charger: http://www.maxamps.com/Eos5i-AC-DC.htm
this balancer: http://www.maxamps.com/LBA10.htm

This pack: http://maxamps.com/proddetail.php?pr...rt-Pack&cat=13
and this pack: http://www.maxamps.com/Lipo-6000-74-Pack.htm

Questions:
Now, I dont fully understand what settings to use on the charger, or rather how to find out. I need some sort of equation.

- Does this charger detect when the battery is full, or do I have to calculate charge time and disconnect? Does this vary with battery type?
- What are the optimal charge and discharge settings for regular Nimh/nicd's?
- What would be the upper limit of (dis)charge current (C-number) for the packs mentioned above (for speedy operation).

Thanks in advance!
You don't need any equations..........

Simply turn on the charger go to the Nimh setting and set the capacity to 4400 mAh. And charge rate of 4.4 amps this is a 1C charge rate make sure the charger is set to 100% charge and let it go. It will finish on it's own.

As for your Li-Po pack Slect Li-Po on the charger set capacity at 6000mAh's and seeing that the EOS5 only charges at 5 amps max you have to charge the 6000 at 5 amps instead of 6 amp which would be A 1C charge rate.

Always charge at 1C ............ 4400Mah pack at 4.4 amps ............... 6000 mAh pack at 6 amps.

If you need further help E-mail me your Phone number and Full Name with a time I can call you. I will walk you through the steps.

Jason
MaxAmps Marketing Manager
jason@maxamps.com
www.maxamps.com
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Old 09-04-2007, 11:04 AM
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ccondrup
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Default RE: Charge rate equation? Beginners question

Thanks for the prompt and thourough reply, it made me realize how simple it really is - great!
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Old 09-04-2007, 11:23 AM
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Default RE: Charge rate equation? Beginners question

Your Very Welcome...... enjoy your new charger and packs.

Jason
MaxAmps Marketing Manager
jason@maxamps.com
www.maxamps.com
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Old 11-19-2007, 10:14 PM
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Default RE: Charge rate equation? Beginners question

Dear MaxAmps,

Thanks for your continued support. I just received two 3S 2100 packs from you today and the construction is tight and beautiful. I also ordered them with pre-wiring for both charger taps that fit my setup and pre-soldered Dean's connectors, what a great convenience. I can't wait to fly my P-47 Brushless on these tomorrow morning. I have some questions for you... I know you and the instructions say to charge these batteries at 1.0C but what if I have a FMA CellPro 4S charger that not only monitors each cell individually but also charges each one individually? Here is the charger:

[link=http://www.fmadirect.com/Detail.htm?item=2218&section=45]http://www.fmadirect.com/Detail.htm?item=2218&section=45[/link]

The FMA charger manual and product description says that I can charge safely at up to 3.0C without affecting the battery's life-time effectiveness provided it is a high-discharge Lipo, as in, over 12C. Your batteries meet this criteria no problem. I've been using the 3.0C charge mode (it also detects the voltage of each cell and turns down the charge rate from 4.0A down to a trickle between 0-0.50A near full) on my other Nexxus 3S 2100's and they are performing super so far, after almost 60 cycles per battery. My questions are:

1) Is it safe to use a 3.0C charge rate with MaxAmps batteries and a charger like the FMA Cellpro that has auto-balancing and charge-rate adjusting abilities?

2) Will it affect the battery's life expectancy?

3) If you have time, can you explain why typically charging a LiPo battery is safe at 1.0C but riskier at 3.0C? I'm curious as to how exactly this impacts the chemistry and what risks are there.

Thank you very much! Looking forward to using all MaxAmps in my aircraft in the future.

- K
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Old 11-20-2007, 08:18 AM
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Default RE: Charge rate equation? Beginners question

Do not ever use one manufacturers recommendations for anothers products. Our Packs can safely be charged at 2C when using a charger and balancer in conjunction with each other. We do not in any way support the charging of our packs at 3C.
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