3DX!
02-05-2004, 07:03 AM
#30
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RE: 3DX!
Chris
They are fine, alittle conservative on the charge rate is all. Still charges them to 95% capacity in an hour and under their maximum voltage (4.3 V per cell). Better safe than sorry anyway.
Matt
They are fine, alittle conservative on the charge rate is all. Still charges them to 95% capacity in an hour and under their maximum voltage (4.3 V per cell). Better safe than sorry anyway.
Matt
02-05-2004, 05:46 PM
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RE: 3DX!
There is a new circuit there that lets you pick from 1-3 cells as well as the current to charge at.
[link]http://www.shdesigns.org/pdf/lionchg3.pdf[/link]
You can build this charger for a 3 cell pack but If you are going to use both 2 and 3 cell packs then I would not use this charger. I would spend the extra money and get an automatic one, one tht sense the voltage in the pack and wont let you charge a 2 cell on a 3 cell setting. This is when the fires happen, it just not worth the risk.
Matt
[link]http://www.shdesigns.org/pdf/lionchg3.pdf[/link]
You can build this charger for a 3 cell pack but If you are going to use both 2 and 3 cell packs then I would not use this charger. I would spend the extra money and get an automatic one, one tht sense the voltage in the pack and wont let you charge a 2 cell on a 3 cell setting. This is when the fires happen, it just not worth the risk.
Matt
02-05-2004, 08:37 PM
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RE: 3DX!
Mc17,
Thanks, I found that one and I don't have any intention of using anything but 3 Cell. I have the Kokam Lipo 402 coming, it is just not here yet. I have a lot of electronics components here and I am going through the calculations to see if I have what I need to build a simplified version for 3 cell only without all of the switches 1 through 8 until the 402 shows. I ran the battery down to 3.1 V per cell or 9.3 V and don't want to leave it like that for too long. Its been 24 hours now and I am a bit concerned.
I have read a lot of frightening accounts of miss charging and also a lot of technical data on charging the LiPos. Including the white paper on the FMA site. I don't think there is any magic in the charging or voltage control circuitry as long as you don't charge over 1C and 4.235 V per cell. To simplify I could use a lower C, say the 985 ma that the paralell bridge does with all switches on and keep it at or below 4.2V per cell. I am only going to build it if I either have everything here tonight or the 402 doesn't show tommorrow.
Thanks, I found that one and I don't have any intention of using anything but 3 Cell. I have the Kokam Lipo 402 coming, it is just not here yet. I have a lot of electronics components here and I am going through the calculations to see if I have what I need to build a simplified version for 3 cell only without all of the switches 1 through 8 until the 402 shows. I ran the battery down to 3.1 V per cell or 9.3 V and don't want to leave it like that for too long. Its been 24 hours now and I am a bit concerned.
I have read a lot of frightening accounts of miss charging and also a lot of technical data on charging the LiPos. Including the white paper on the FMA site. I don't think there is any magic in the charging or voltage control circuitry as long as you don't charge over 1C and 4.235 V per cell. To simplify I could use a lower C, say the 985 ma that the paralell bridge does with all switches on and keep it at or below 4.2V per cell. I am only going to build it if I either have everything here tonight or the 402 doesn't show tommorrow.
02-05-2004, 09:13 PM
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RE: RE: 3DX!
It would be fine if you are charging only 3 cell packs. If you were going to use a bunch of different packs then this charger relies too much on the smarts of the user as it only takes one wrong switch and the pack will catch fire.
Matt
Matt
02-05-2004, 09:20 PM
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RE: RE: 3DX!
Well, as it turns out, I donm't have everything here tonight. If the charger doesn't show tommorrow, I will see if the missing LM317TB can be had locally. or the next step up for up to 3 amps as 1.5 would be ideal and not tax that reg. I had every intention of clearly nmarking the homebuilt as "FOR 3 CELL LIPOS ONLY" on all sides of the enclosure.
I wonder if I could use a 12 volt 400 ma wall wart while monitoring voltage temperature and amperage just to get the cells above the 3.1 V per cell to avoid dammage. Conect it for say 10 - 15 min max while monitoring.
I wonder if I could use a 12 volt 400 ma wall wart while monitoring voltage temperature and amperage just to get the cells above the 3.1 V per cell to avoid dammage. Conect it for say 10 - 15 min max while monitoring.
02-05-2004, 10:54 PM
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RE: RE: 3DX!
I wouldn't be too woried about the cells they hold their capacity for a really long time (months) so I wouldn't be too woried about 0.1-0.2V over a day or so. But if you watched the voltage like a hawk it would be OK to use the wall charger.
Matt
Matt
04-06-2004, 10:48 PM
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RE: 3DX!
mc17,
how did you get your plane so light??!!!! i have just flown my 3DX which had exactly the same setup as yours but it still wheighed 11oz and didn't have enough power to hover. can anyone help?!!
how did you get your plane so light??!!!! i have just flown my 3DX which had exactly the same setup as yours but it still wheighed 11oz and didn't have enough power to hover. can anyone help?!!
