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Old Aug 03, 2004, 11:12 PM
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Surplus 1400 Mah Li-on cells - Can I do a 3-cell pack?

I picked up some surplus Panasonic #CGR18650 Lithium Ion Cells. I was thinking of making up a 3-cell 11.2 Volt pack & using two of these packs in Parallel (3S2P) configuration. Is it possible to make these into a 3-cell pack? If I use JST connectors, what will happen?

P.S. - These will be going into an Electric GWS300C powered Airboat.

-Mike-
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Old Aug 04, 2004, 01:40 PM
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You'll burn out the speed 300 motor if you don't choose the right prop.
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Old Aug 04, 2004, 07:37 PM
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hall:
I know that the higher voltage will probably burn out the motor but I figure I will use throttle management, the main thing is to NOT run full throttle all the time. I was more like fishing to see if the Panasonic #CGR18650 would hang in there or flame out on me, Anybody tries a 3S pack of these?

-Thanks-

Mike
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Old Aug 05, 2004, 12:43 PM
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mrebman

Where did you purchase your batteries????
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Old Aug 05, 2004, 12:49 PM
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Quote:
Originally Posted by mrebman
hall:
I know that the higher voltage will probably burn out the motor but I figure I will use throttle management, the main thing is to NOT run full throttle all the time. I was more like fishing to see if the Panasonic #CGR18650 would hang in there or flame out on me, Anybody tries a 3S pack of these?

-Thanks-

Mike
Yes I made a 3s1p and it works fine, but I haven't tried 3s2p but you should try to stay below 5 amps with a 2p configuration.

Wolf
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Old Aug 05, 2004, 01:38 PM
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I can verify that 3S1P Sony US18650GR 1500mAh Li-ions can reliably deliver ~4A continuous, as I get consistent 20-minute flights at full throttle before power drops off. I cannot verify if the Panasonic CGR18650 1400s can match the performance of the US18650GR 1500s. Note that a 3S2P pack will weigh ~10 oz., so it's quite a load. I got my Sonys out of a used laptop computer battery pack.
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Old Aug 05, 2004, 06:00 PM
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Dave:
Thanks, I actually have BOTH the Panasonic & Sony Cells but I have more of the Sony "Blue color" cells than the Panasonic "Pink" cells. OK! I just finished my first 3S1P pack of the "Pink" Panasonic Lion Cells & my digital Voltmeter is saying I did it right. I plan on using this pack in an Airboat or in my Slowstik so weight is not a problem. However, I'm using a GWS 300 "C" Motor & 10x4.7SF GWS Prop, will that be too much amp draw for a 3S1P Lion Pack?N

NoMr'crash:
Check out Electronics Goldmine or some other electronics suplus outfits. Goldmine has a website & you can order online.

-Thanks-

Mike
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Old Aug 05, 2004, 09:39 PM
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Mike, according to the GWS motor tables, an EPS-300 with C gearing (5.33:1) with 10x4.7 prop will draw 7.8A at 8.4V. So, with a 3S1P Li-ion pack, you're going to have 11.1V, which would result in a lot more than 7.8A, which is way more than a 3S1P CGR18650 pack will handle.

How did you arrive at the idea of running this motor/gear/prop combo on a 3S1P Li-ion pack?

http://www.gws.com.tw/english/produc...em/eps300c.htm
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Old Aug 05, 2004, 10:44 PM
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Dave:
I have been running the Panasonic Li-on Cells in a 2S2P Configuration in the airboat for some time now with no problems & runs for like 45 Minutes (With throttle management). I thought I might make a 3S1P pack to speed the boat up a little but do worry about Over-amping these cells. What's the worst that can happen?

P.S. - I run the smaller Qualcomm 830 Cells in a 2S2P configuration in my Slowstik with fine results & cells are barely warm. I think these cells are more capable of amp draw than people give them credit for. I am about to buy an Amp meter, I may do some static testing & see what the numbers say, I don't always trust charts.

-Mike-
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Old Aug 05, 2004, 11:13 PM
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Quote:
Originally Posted by mrebman
Dave:
I have been running the Panasonic Li-on Cells in a 2S2P Configuration in the airboat for some time now with no problems & runs for like 45 Minutes (With throttle management). -Mike-
==================
Mrebman,

I also used the same Panasonic CGR18650 /2S2P configuration on my slow stick, but I don't have the oomp power I expect. What size of prop you are using? 2S2P of this size of the battery weight about the same as 7- AA 1300 mah NimH pack battery. With the 7 pack AA NimH I have more oomp but less duration.

Thanks,
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Old Aug 06, 2004, 08:26 AM
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Turn:
I'm using the standard 11x8 GWS Slowstik prop & it is kinda boring using the 2S2P pack of Qualcomm 830's & 1400's but it will fly for like an hour! My favorite pack for the Slowstick is my 8-Cell CBP-650 Nimh pack, LOTS of power, light but lower duration.

P.S. - The airboat is a hoot, with a fresh set of 2S2P Panasonic 1400 MaH Lion cells, I can actually go up on step & almost zoom across the lake, with a 3s2p setup it would be awesome, might even take off.;-)

(I'm using a Dumas Little swamp Buggy & GWS 300C "C" gearing)

-Mike-
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Old Aug 06, 2004, 09:03 AM
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Mike, I don't fully trust the charts, either. I just use them as a starting point for basic setups, and then do my own measurements. The worst that can happen is that you will burn out the motor by feeding it too many watts, or you will damage the cells by trying to pull too much current out of them. Increasing voltage by 50% will result in a major stress increase on your whole system. There are many threads in the Power Systems forum discussing going from 2S to 3S Li setups, and how you can manage current overload by downsizing to a smaller prop.
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Old Aug 06, 2004, 08:34 PM
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Dave:
Thanks, Fortunately I have a wide selection of props so I think I may do some static testing with a Watt Meter. Fortunately also, I have lots of GWS Motors & as I slowly convert all my planes to Brushless, I use the gearbox & chuck the motor into a bin so plenty of motors available to burn up. I see no reason that you cannot use 3S on the GWS motor as long as two things are used (1) Throttle Management (2) Proping down to reduce amp draw.

P.S. - If this works, I have a total of (16) Li-on Cells to experiment with & all at what $1-$2 each? Sure beats the cost of Lipo!

-Mike-
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Old Aug 07, 2004, 10:08 AM
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Quote:
Originally Posted by mrebman
I see no reason that you cannot use 3S on the GWS motor as long as two things are used (1) Throttle Management (2) Proping down to reduce amp draw.
Absolutely correct. The other consideration with high voltage is to avoid exceeding the mechanical rpm limits of the motor. In reality, this has rarely been a problem for those who have experimented with 3S Li and common e-flight motors.
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Old Aug 09, 2004, 11:09 AM
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Try www.wirelesscellutions.com Lots of surplus Li-Ions, try the Nokia 1500s
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