my learning curve with LiPos

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my learning curve with LiPos

Postby vancouverron » Tue Mar 18, 2014 2:27 am

Summary: Bought a Hubsan 107D as a "flight simulator" for a Phantom (to be purchased in the future). Also bought 5 extra 1s 380mA 25C batts with a 5-to-1 tentacle. I have an "industrial" power supply (PowerOne) with 5V out at 10A. The Hubsan 1s wants to be connected to a USB power socket - measured the output with my Fluke DVM to be 5.0 volts. The stock batt takes about 30 minutes to get recharged (the led in the USB connector extinguishes once the batt is charged). I set the PowerOne to 5.0 V out and connected all 5 batts. As expected, charge current for the first batt is 1.8 Amps or so, doubling for the second batt etc. Recharge time is a few minutes for all 5 batts. For whatever reason I decided to keep the original batt separate and have it only recharged via USB.

Issue: After a few cycles of charge / discharge, all 5 batts have become slightly obese. They used to fit fairly well into the Hubsan, but now it takes effort to put them into the compartment (and take them out). One battery swelled to the point of not being useable any longer - it was warm to the touch, and seconds later (off the charger at that time) burst into flames. Fortunately I had the batteries on a tray for "just in case" so I was able to chuck the whole lot out the door where the batt completely burned itself out with a nice flame (for such a small batt) until only the cable was left. None of the other 4 batts retain much of a charge. So this raises a few questions:

1) The USB charger has an output of 5.0V, I set the PowerOne to the same voltage. Is there additional circuitry in the USB plug the shuts off the charger once the batt reaches 4.72 V?
2) Should the max charge voltage be set to 4.72V or ? Charge current of a couple of amps or so should not be an issue if the 25C is really true.
3) is this a classic "you get what you pay for" case? The total price for the 5 one-S batteries was USD 13. including shipping from China.

Thanks in advance for your thoughts / comments on how to adapt non-dedicated LiPo chargers.
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Re: my learning curve with LiPos

Postby cynr100 » Thu Mar 20, 2014 4:01 am

In all honesty grab yourself one of these or similar dedicated LiPo charger. ... ories.html

You have already experienced a LiPo fire that appeared to have been caused by misuse, don't let the next one burn your house down.

LiPo nominal cell voltage is 3.7v and generally charge upto 4.2v, your 4.7+ is excessive. This overcharge and running the packs below 3.7v is causing the puffy cases, these packs are now damaged and very little hope of being restored. Fast charging is also not good for battery life, he above charger will also handle charge time.

If you are aiming for a DJI Phantom best start practising good LiPo management now as the Phantom batteries are expensive.
Not enough time in the day for all my crazy ideas, I'm not slow, I'm just pacing myself
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