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Old Jun 25, 2016, 08:39 PM
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Help!
3s Lipo - 1 volt difference between cells!

Hi all,

After another flight on my Eachine 250 Falcon I tested my lipo to check if I could squeeze a few minutes more. But what my lipo tester told me was quite disturbing. It read:
Cell 1: 3.7, Cell 2:2.7 Cell 3: 3.6 Total: 9.9

I think the lipo tester might be out, but I;m scared to try and plug it into the charger.

What would you do?
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Old Jun 25, 2016, 09:04 PM
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Measure the voltage with a multi-meter to verify lipo tester accuracy.
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Old Jun 25, 2016, 09:25 PM
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Quote:
Originally Posted by kamcoman View Post
Measure the voltage with a multi-meter to verify lipo tester accuracy.
I don't actually have a multimetre, but my charger will give me a reading of the battery's total voltage but not each cell.
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Old Jun 25, 2016, 10:13 PM
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Plug it in and out a few times. Sometimes a little bit of contamination on the pins will give strange readings.

BTW, squeezing a little bit more out is a sure way to kill a battery as you now know.
Lipos should not be discharged below 3.7V/cell (resting v). 11.1V(3.7/cell) is a long way from 9.9V.

What charger are you using?
See sticky above about charging "dead" packs.
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Old Jun 25, 2016, 10:40 PM
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Quote:
Originally Posted by hoppy View Post
Plug it in and out a few times. Sometimes a little bit of contamination on the pins will give strange readings.

BTW, squeezing a little bit more out is a sure way to kill a battery as you now know.
Lipos should not be discharged below 3.7V/cell (resting v). 11.1V(3.7/cell) is a long way from 9.9V.

What charger are you using?
See sticky above about charging "dead" packs.
I tested it again and the bad cell reads 3.2 volts, I charging the Lipo up now. Close call, I've learnt my lesson. Thank you for your help.
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Old Jun 26, 2016, 07:12 AM
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There are several tools that every electric flier should have in the tool box.
1. Wattmeter. It's the only way you can tell exactly how much current your system demands. Without a wattmeter you can easily damage motors, ESC's and batteries.
2. Digital Volt meter. This is so that you can verify battery voltages. The cheap cell checkers are OK for a quick check but you need a decent DVM for varification.
3. A full function charger. It must balance charge, storage charge and discharge. It must report pack and cell voltages as well as charging current and mAh returned to the pack during charge. A good one will also measure Internal Resistance (IR).

Glen
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Old Jun 27, 2016, 06:04 PM
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Quote:
Originally Posted by ggcrandall1 View Post
There are several tools that every electric flier should have in the tool box.
1. Wattmeter. It's the only way you can tell exactly how much current your system demands. Without a wattmeter you can easily damage motors, ESC's and batteries.
2. Digital Volt meter. This is so that you can verify battery voltages. The cheap cell checkers are OK for a quick check but you need a decent DVM for varification.
3. A full function charger. It must balance charge, storage charge and discharge. It must report pack and cell voltages as well as charging current and mAh returned to the pack during charge. A good one will also measure Internal Resistance (IR).

Glen
Looks like I need to add few things to my shopping list.
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Old Jun 27, 2016, 07:01 PM
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Quote:
Originally Posted by ggcrandall1 View Post
There are several tools that every electric flier should have in the tool box.
1. Wattmeter. It's the only way you can tell exactly how much current your system demands. Without a wattmeter you can easily damage motors, ESC's and batteries.
2. Digital Volt meter. This is so that you can verify battery voltages. The cheap cell checkers are OK for a quick check but you need a decent DVM for varification.
3. A full function charger. It must balance charge, storage charge and discharge. It must report pack and cell voltages as well as charging current and mAh returned to the pack during charge. A good one will also measure Internal Resistance (IR).

Glen
Quote:
Originally Posted by DroneRequired View Post
Looks like I need to add few things to my shopping list.
And if you haven't already done so, read this:
http://www.tjinguytech.com/charging-how-tos

Glen
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