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Kontronik Drives Jazz and Jive ESC's and other Kontronik equipment support |
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01-25-2015, 12:01 PM | #1 (permalink) |
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Join Date: Apr 2007
Location: UK, Kent coast
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best buffer / backup pack at 5.4 volts?
Per the title, my question is about using a small pack as a buffer (and backup in the event of a failure) with my Jives. But here's the problem: At 5.4 volts it's too low for LiPo or LiFe, leaving NiCad and NiMh. For some time now I have been using the Sanyo Eneloop 4 cell packs but I have just discovered their max discharge is much less than I thought. I have several 2000mah packs as buffer / backup packs but just tried an 800mah pack only to find it simply doesn't have the grunt to power three JR 8717s.
Supposedly these Eneloop cells can only output at 1C ! So even my 2000mah packs are really marginal (though they do seem to power the servos just fine on the ground). Soooo, is there a better option or should I just use a bigger Eneloop pack? Two in parallel? The beauty of them is the long life and low self-discharge. I have also tried the Optipower Ultraguard but find the buffer pack more convenient and have also read that Kontronik doesn't recommend these backup devices like the Scorpion BUG and Opti guard.
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HD Cell 750, RJX Vector, TDR, TDSF, Kasama Dune and Faifa, Minicopter Triabolo 700, Beam Avantgarde, JR E8 leggero, Suzi Laos, Shape 9, Shape S8, Rave 450, TRex 500, Raptor E700, Compass Warp, Steam 700, Spirit, Spartan, Jeti. |
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01-25-2015, 12:09 PM | #2 (permalink) |
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Join Date: Jun 2010
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Hi
the Ultraguards were excessively tested with all old and current contronik ESCs and work perfectly together Cheers Linus |
01-25-2015, 06:27 PM | #3 (permalink) |
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Join Date: Feb 2008
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And again R2.
The eternal question of the buffer voltage source respectively of an emergency power supply here... If you want to avoid an undervoltage condition during the backup time (emergency landing) you need cells with sufficient low IR. (A major reason in this day and age are the microcontrollers used everywhere.) That means then: - no Eneloop - high-capacity cells Means also: heavy and bulky. You must also ensure that the cells will be fully charged automatically - but not overcharged. Another problem is the memory effect of NiXX type cells. An option could be LiFePo, especially A123. One has to make again for battery management. And again: relatively heavy and bulky. Problems are always the same: - battery management ... - ... and: How to make battery and BEC voltage matching? - required low internal resistance -> heavy, bulky cells There is no way around Opti UG or V3 Buffer: - battery management: given - low IR: yep. The buffer based on ELDC supercaps has a very low IR. Electronics of the UG (voltage generation) ensures low IR regardless of the charging state of the 2S LiPo. - light-weight, small This is not a surreptitious, these are facts.
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Tom (j-log.eu) |
01-26-2015, 07:35 AM | #4 (permalink) |
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Join Date: Apr 2007
Location: UK, Kent coast
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Just to add---- I have since been doing some reading and feel pretty sure that the Eneloop packs can deliver much more than 1C discharge. I know for sure that other NiMh packs can output quite a lot more and even if the Eneloop performance is less I don't think the difference is that drastic. I will continue to dig into this subject because I like knowing exactly what the 'bottom line' is.
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HD Cell 750, RJX Vector, TDR, TDSF, Kasama Dune and Faifa, Minicopter Triabolo 700, Beam Avantgarde, JR E8 leggero, Suzi Laos, Shape 9, Shape S8, Rave 450, TRex 500, Raptor E700, Compass Warp, Steam 700, Spirit, Spartan, Jeti. |
01-26-2015, 07:41 AM | #5 (permalink) | |
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Join Date: May 2011
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Quote:
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Richard Zappe Team Kontronik USA PeakAircraft |
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01-26-2015, 07:46 AM | #6 (permalink) |
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Join Date: Feb 2008
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Yes... Everyone saying Eneloop have a relatively high IR.
To be honest: For development purposes I often need a "portable" voltage source. What do I use for that? Eneloop, 4x 800mAh. I like the Eneloop because they are very robust compared to NiXX.
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Tom (j-log.eu) |
01-26-2015, 08:19 AM | #7 (permalink) |
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Join Date: May 2011
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yeah they work well. Honestly when you do have a failure that requires using the buffer as your main supply for the radio equipment and servos, you are going to be using minimal amps anyway. you cant compare normal 3D flight loads to the amount of load you would be using during a level out and auto.
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Richard Zappe Team Kontronik USA PeakAircraft |
01-26-2015, 09:45 AM | #8 (permalink) | |
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Join Date: Apr 2007
Location: UK, Kent coast
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Quote:
I think the most likely situation is that you'd know something was wrong imediately and gently get it back on the ground as quickly as possible. And I will take this opportunity to say many thanks to Linus, Tom and Richard for your thoughts on this.
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HD Cell 750, RJX Vector, TDR, TDSF, Kasama Dune and Faifa, Minicopter Triabolo 700, Beam Avantgarde, JR E8 leggero, Suzi Laos, Shape 9, Shape S8, Rave 450, TRex 500, Raptor E700, Compass Warp, Steam 700, Spirit, Spartan, Jeti. |
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