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Old Dec 27, 2012, 04:33 AM
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Bo Edström, Sweden
Joined Jan 2009
1,454 Posts
Quote:
Originally Posted by Red_Jeepster View Post
I am just getting into electric after 30+ years in the building and flying of nitro planes. I have 25C batteries. 11.7v 2650mah tell me about proper charge current. I do plan only a balancing charger. HELP!
Hi,
As said, 2 times the capacity number, in your case 2 x 2650 = 5300 mA(5.3 amp), is not going to be any problem with most moderna LiPo (some 1 cell LiPo do not want to be charged with more then 1C).
In the charger You set LiPo as type and how many cells Your LiPo battery has. Each cell in a LiPo battery has a standard voltage of 3.7 volt per cell so a 3 cell LiPo battery has 11.1 standard (nominal) voltage. It is written on the LiPo pack.
Normally You use the balance connector also in the charger and connect it to the LiPo battery so all cells in the battery pack gets charged to full (4.20 volt per cell) in controlled and proper way. As cells ages they takes little longer to get balanced and reach 4.20 volt and that is normal. You could maybe expect, with proper care, hundreds (maybe 200+) cycles on a normal quality LiPo pack. If You follow just some very basic rules of LiPo care they should last long time: balance charge as often as possible (at the field I charge to 95% usually since it goes faster, the last 5% is what takes time to balance upp to full in my experience), storage charge the LiPo pack when not in use (if I do not plan to fly next day or two I storage charge them and that is about 60% capacity, it is not important value but between 50-70% is OK).
And do not empty (at flying or otherwise) the LiPo below 20% capacity since they can get damaged if they are drained below that, at least repeatadly, and absolute miniumum is not below 10% according to some LiPo manufacturer for example Hyperion say that. But 20% capacity left after landing (in Your case 0.20 x 2650 mAh = 530 mAh should be left) is the general rule to follow. You use some trail and fly with a timer to find out how long You can fly without empty the LiPo below 20% of it's capacity. Then when You charge you take notes how many mAh You can get into the LiPo pack to get it full and that way You can figure out proper flying time to set in the radio timer/alarm. It is easy to find out this. Just remember if you at some flights run the motor on higher power (longer times) then You normally would do You should land little earlier to not exceed the 20% capacity left rule by to much.

I do not know if You have figured out the C rating of LiPo but with Your 25C battery it is that it can deliver current up to 25 times the capacity number, 25 x 2650= 66250 mA (66.250 amp). If Your setup will require more current than this You buy higher C rated battery, like 30, 35, 45, 65C (higher C is usually more expensive and usually little heavier). You use a so called Wattmeter or a current clamp meter to know how much current your setup draw.

If You need advice on charger and power supply just read here in this forum, many to choose from and You should be able to find something that fit Your need and wallet,

/Bo
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Last edited by bossee; Dec 27, 2012 at 04:45 AM.
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