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Old Oct 05, 2014, 07:41 PM
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New Boston, Texas, United States
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Question
How low should you discharge lipo transmitter battery 3s?

I have just put a 3s Lipo battery in my Spectrum transmitter. Love not having to charge all the time. Have been able to get several after work flights.

But how low should I allow them to go before recharging? When fully charged it was at 12.6 volts. Is down to 12.0 now. Is it ok to wait to 11.1 volts?

Thanks
Jim
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Old Oct 06, 2014, 04:06 AM
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Staffs, UK
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11.1V probably won't do any harm but I'd personally err on the side of caution and go for a little more, say 11.4-11.5V. That should still give you ages.

Steve
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Old Oct 06, 2014, 07:47 AM
bth
Bjørn Terje Hansebråten
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Oslo , NORWAY
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Quote:
Originally Posted by JIMA View Post
Love not having to charge all the time.
The time will show . ;-)

Li-Po and not Li-Fe?

Has the Li-Po more than 2400 mAh? ;-)
http://www.hobbyking.com/hobbyking/s...y_to_use_.html

- The Li-Po must storage charge down to (3,8 V/cell) if not used for some days. ;-)

- You have to take the Li-Po out of the transmitter on every charging to not risk fire.
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Old Oct 06, 2014, 07:51 AM
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New Boston, Texas, United States
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It is a 2650 mah battery. And yes I do remove it for charging. I put it on my balance charger. What do you mean by storage charge down to 3.8 volts/cell? Is this the point at which I should recharge them? Only reason I went to lipo is so that I would always have a ready transmitter on hand on the occasions when I get to fly.

Jim
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Old Oct 06, 2014, 08:46 AM
bth
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Oslo , NORWAY
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Maybe there is someone here with experience with Li-Po in Transmitter and how the battery is affected if it constantly kept near full?
Here is something about the storage of Li-Po: http://www.rcgroups.com/forums/showthread.php?t=1436092
In my Futaba I use Hyperion G3 LiFe Radio Pack 3s/9,9v 1600 mAh that have a integrated circuit that monitor each cell so I can use the charging jack with any charge program limited to 4,8A, so when the battery is full, it breaks the connector to the charger.
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Old Oct 06, 2014, 02:05 PM
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Newer lipo chargers have a "storage charge" mode that will lower cell voltage to around 3.85 volts per cell. OP should not let 3-cell transmitter lipo voltage drop below 11 volts (around 3.85 volts per cell). The accepted theory is that leaving motor battery type lipos fully charged , at, or around 4.2 volts per cell, for longer than a week or so, will gradually degrade their performance over a period of time . However, I have read that lipo packs intended for transmitter use are low C-rated and not as likely to lose capacity when kept fully or nearly fully charged as with lipo motor batteries.

Many users recommend replacing transmitter batteries with high capacity equivalent-voltage Eneloop NiMh packs instead of low capacity Nimh packs supplied with transmitters. You can use the same wall-wart Nimh charger that came with the transmitter/system but will get much longer use between charges. Unlike a lipo pack, you don't have to open transmitter case, disconnect pack, charge on a lipo balance charger, reconnect and stuff wires in place and slide cover back in place.

Different brands of transmitters operate on different voltages. For example my Hitec Aurora 9 can use a 2-cell lipo battery but it must be charged with a lipo-type charger, outside of the transmitter case, per the manual. The A9 has a setting for 2S lipo that adjusts the low voltage alarm. Using a 3-cell lipo pack in my A9 transmitter would damage it.

Read your transmitter's manual and/or contact company support to get advice on this. I have edited this based on new information and for clarification sake.
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Old Oct 07, 2014, 11:44 AM
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Canada
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Been using a 3s lipo in my Futaba for 3 years now. Works Fine :-)
I tired of the 'never charged' Round cells.
Looked into the Enerloops, read their fine print, no thanks.
Rather buy Duracells IF I wanted round cells.
Lipo charge seems to last forever.
2.4 TX is a very lo drain loading .
When mine gets to close to 11v on the Fut's display, I recharge it.
Also have a spare pack with me when I go flying.. Just in case.
Not needed it yet, though

PS ; Last year I left a Lipo equipped tx "on ' For a month. The dead as a doorknob pack was resurrected using my charger's Nimh setting.. briefly. Restored to darned near new capacity (careful testings) as well.
Weird but it works .. reliably.. still.
Put and end to that particular worry.. nicely.
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Old Oct 07, 2014, 12:52 PM
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FWIW, I have never used the 'storage charge' for any of my LiPo's. I always leave them fully charged, sometimes for several months at a time. Have never had any noticeable degradation.

Like Bare, I have had some LiPo's I have 'brought back from the dead'. I have also killed two that way, but, they were old to start with.

Lastly, has to be said again, always charge in a fireproof container. Doing that saved me from burning down the house when an old LiPo decided to burn up.

charlie
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