Re: Question about Lithium ION cells from Batteries America

The Sony packs contained protection devices to lessen the chance of a hazardous situation occurring with the lithium battery - something about due dilligence. Sony has a huge corporate presence in the US. Product liability suits against Korean or Chinese companies that have no significant presence here are probably a study in futility, a suit against an importer might be another story.

-- Red S. Red's R/C Battery Clinic

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us out for "revolting" information.

A couple of years ago I bought the Lithium ION battery and charger from > Batteries America. I meant to use it in my GWS pico stick but it just > didn't give it enough RPM for the aditional weight. Well at the same time I > also bought two of the 1200 LION cells to make another pack. Well today I > sat down and put the cells together and charged it up. And for some reason > the cells made the motor turn at a much higher RPM than the pack that came > with the charger. I hooked up both packs to my twin EDF-50's to see how'd > they perform. The pack from B.A. would cut out at about 3 amps. The new > pack I made was able to power the fans all the way up to 5.2amps. So I had > to figure out what was different between the two packs. I tore off the > shrink wrap from the pack from B.A and found this circuit board with surface > mount chip, resisters, and such on it. What the heck is that? Is it a > voltage regulator? Is it a cut off circuit? Is a charging circuit? Any > ideas. > > The cells are different as well, the ones from B.A. are sony cells, the > individual cells I bought say LG Chem on them. > > You can see a photo of the pack at >
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Unfortunatlely they don't show > or mention the circuit board. > > -- > Normen Strobel > snipped-for-privacy@zoominternet.nospam.net > > > > > >
Reply to
Red Scholefield
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Do you know how this device lessoned the chance of a hazardous situation? Does it limit the amount of current?

Reply to
Normen Strobel

The circuitry is designed to prevent overcharging since Lithium Ions can explode if overcharged! If you are correct in your observations, it could possibly limit output as well whether international or not.

Earl

Reply to
<edavis20

Well I took the circuit board off and sure enough it no longer cut out at 3 amps. I think the plane I want to use it on will fly at 3amps, but I would like the extra boost for take off and maneuvers, so hopefully it won't harm the cell much.

However I noticed a difference in RPM between the two packs, both registered

8.1v with no load. So I hooked it up to my Whattmeter and a tach. The sony cells seems to put off less voltage at full throttle. Is this because of a higher internal resistance?

Sony 3900RPM 2.5A 6.3V LG Chem 4200RPM 2.8A 7.2V

But now I'm wondering if the charger that came with it will over charge the cells now. I want to discharge them and charge them with my triton charger to see if it will do a better job than the "smart" charger from Batteries America. What settings should I use with the triton?

Reply to
Normen Strobel

A year and a half ago I bought two of those same Li Ion 1200mah packs from Batteries America, to see how they would compare with the stock 7 cell 720mah NiMH pack my plane uses. They would barely fly the plane at all. Totally gutless. Later on I got to looking at the 'voltage headroom' issue peculiar to Li-Ion and Lipoly batteries. For every tenth of a volt under the rated 4.2V per cell, there is a huge loss of capacity. Come to find that the charger was only putting 8.1V into the pack (or 4.05V per cell). So I built a 'finishing charger' based on the LM317T regulator chip, to bring the pack up to the full rated 8.4V (4.2V per cell). Now the pack would at least fly the plane and give half-hour run times. But it still lacked the voltage of the stock NiMH pack and was very sluggish. Supposedly the mfr. of the charger sets the voltage deliberately low out of liability concerns. I just bought a pair of Batt. America's brand new 'Platinum Power' lipoly 1600mah packs. And these babies ROCK!!! Not only are they nearly an ounce lighter than the old packs, but they give 45 minute run times! (compared to 10-12 minutes for the NiMHs). But there was still the caveat of 'headroom' undervoltage with them, so still have to use the 'finishing charger' to get full capacity.

Bill

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Reply to
Bill Sheppard

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