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micro batteries....performance?

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Old 11-19-2010, 10:37 PM
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kzart
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Default micro batteries....performance?

I have seven e-flight 3.7v 120-180 (various)mah 12cbatteries, and one thunderpower 160 25c. All of the e-flight batteries seem to have gone bad at the same time, or something is going on. The thunderpower is the only one that gives any performance. I don't think it has anything to do with the plane because I've sistimaticly charged all batteries and tried in sukahoi, charged and then p-51. I no longer use batteries a source for charging because the sukahoi came with a charger than plugs into 110 (wall). However, it seems thatI started to loose performace about the same time that I got this charger (but the old style doesnt work with new batteries either). Both was will act like they are charging the batteries. some of the batteries have hundreds of flights on them other have only about two mnths worth(maybee 50 cycles worth, and none of them show any signs of swelling) Anyone have any ideas on what is going on here, if it wasnt for that one thunderpower battery i would asume that the moters were loosing performance. What are issues with shelf life (sitting charged) or anything I'm missing
ps Im not over discharging either.....you can hear it before it cuts you off.....only ocassionally been cut off by esc
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Old 11-20-2010, 08:33 PM
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Default RE: micro batteries....performance?

You need to meter your cells. Will tell you if the wall charger is actually charging them fully.
Also using a meter in line will tell you if the cells are able to sustain the draw on them when you run up the motor.

As for why the TP cell is doing better is more then likely in the C rating, it's double the E-flites, so even if it's not being fully charged too it still has twice the capability.

As the motors wear out they tend to draw higher amps. It could be also that the Eflites just don't have the juice anymore to handle the increased draw.
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Old 11-20-2010, 09:27 PM
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Default RE: micro batteries....performance?

Good information from GG. At the very least, you need a meter so you can measure the voltage of your batteries. A fully charged single-cell lipo should measure 4.2V. If it's less than that after charging, either the battery is defective (or worn out) or there is a problem with the charger.

If some batteries, such as your TP, come off the charger measuring 4.2V, then the charger is probably OK.

Even a $5 meter will do the job of measuring battery voltage. However, you can learn even more with a proper wattmeter that you place inline with the battery while running the motor. The wattmeter will show you both voltage and current, so you will be able to tell if battery voltage is dropping too much under load and if your motor is drawing more current than it should.

Generally speaking, a brushless motor doesn't wear out and draw more current as it ages, unless the motor has overheated. Overheating can damage the magnets, at which point the motor will usually start drawing more current. Brushed motors, on the other hand, definitely wear out and often draw more current as they get older.

In summary, get at least a cheap meter so you can begin to determine what is happening.

- Jeff
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