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Old Nov 08, 2004, 09:36 AM
Castle Tech
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Olathe, KS
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WOT=Wide Open Throttle
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Old Nov 08, 2004, 09:59 AM
Slow Tiger Stick Moth
Willie Levi's Avatar
Austin, Texas
Joined Oct 2003
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Quote:
Originally Posted by DrkSdeOTM
WOT=Wide Open Throttle
Ah! Thank you kind sir
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Old Nov 08, 2004, 11:49 AM
When in doubt whip it out
French Polynesia
Joined May 2004
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Willie check out the 700mah 5a discarge lipolys here $4.95 a cell. if you have any skills you make a couple of pack for way less then built packs.
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Old Nov 08, 2004, 05:06 PM
Slow Tiger Stick Moth
Willie Levi's Avatar
Austin, Texas
Joined Oct 2003
178 Posts
Quote:
Originally Posted by snowjackal
Willie check out the 700mah 5a discarge lipolys here $4.95 a cell. if you have any skills you make a couple of pack for way less then built packs.
I'm interested. I have a soldering iron one or two extra JST connectors..

I imagine there are plenty of "how-tos" online (and in these forums), but would i simply join (solder) the + tabs, join the - tabs of two cells and then solder on the leads? Two of these cells would make a 7.4v pack right? (and is that 7.4 discharged or fully charged? *scratches head*)

I have limited soldering skills, but am confident I could do what's required here.. I use aluminum solder for this, correct?

Am I spelling solder right?
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Old Nov 08, 2004, 06:16 PM
Elfi Flyer
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Rock Hill, SC
Joined Oct 2002
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Willie:

Here is additional info concerning a LiPo battery selection for the Tiger Moth or similar plane using the IPS motor and JST connectors:

I use a Thunder Pack 1320 2 Cell (2S) pack, with JST connector. The pack weighs 55 grams. A 6 cell NiCad pack (1/2A) weighs 76 grams, the 7 cell version weighs 88 grams. My Moth has been flown on all three battery configurations. The 7 cell gave very good performance, due to higher initial voltage. However, without question, the LiPoly 2S pack has given outstanding duration and good performance. On a freshly charged 1320 LiPo pack, amperage draw is 2.3 at WOT, static test, volts 7.5 for around 17 watts to the prop. More than sufficient for decent Moth flying. Whereas 10-12 minutes was it for the 7 Cell NiCad pack (with heavier weight), the LiPo gave me almost 38 minutes this last time out. Recharging the LiPo showed I only used about 60% of the pack.

So, check the various sizes (dimensions) for the LiPo's you might be interested in, and consider the highest capacity (800, 1320, etc.) for the smallest size and weight pack. Two cell construction (7.4V) should be sufficient. Remember, however, that voltage will drop quicker in a lesser capacity pack then the larger pack. Translation: your rpm's will stay up longer with a 1320 pack versus a 450 or even 800 mAh pack.

Good luck

RD
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Old Nov 08, 2004, 10:08 PM
Slow Tiger Stick Moth
Willie Levi's Avatar
Austin, Texas
Joined Oct 2003
178 Posts
Quote:
Originally Posted by Doug Sipprell
Willie:

Here is additional info concerning a LiPo battery selection for the Tiger Moth or similar plane using the IPS motor and JST connectors:

I use a Thunder Pack 1320 2 Cell (2S) pack, with JST connector. The pack weighs 55 grams. A 6 cell NiCad pack (1/2A) weighs 76 grams, the 7 cell version weighs 88 grams. My Moth has been flown on all three battery configurations. The 7 cell gave very good performance, due to higher initial voltage. However, without question, the LiPoly 2S pack has given outstanding duration and good performance. On a freshly charged 1320 LiPo pack, amperage draw is 2.3 at WOT, static test, volts 7.5 for around 17 watts to the prop. More than sufficient for decent Moth flying. Whereas 10-12 minutes was it for the 7 Cell NiCad pack (with heavier weight), the LiPo gave me almost 38 minutes this last time out. Recharging the LiPo showed I only used about 60% of the pack.

So, check the various sizes (dimensions) for the LiPo's you might be interested in, and consider the highest capacity (800, 1320, etc.) for the smallest size and weight pack. Two cell construction (7.4V) should be sufficient. Remember, however, that voltage will drop quicker in a lesser capacity pack then the larger pack. Translation: your rpm's will stay up longer with a 1320 pack versus a 450 or even 800 mAh pack.

Good luck

RD

Thanks for the info! I am totally on the fence about what mAh of a pack to get.

I see various Li-Po batteries with much greater mAh capacity weighing the same or less (as my 6 cell). I definately want to keep it light, lighter than it currently is. You may or may not have seen my TM thread. After extensive repairs to the tail it is probably significantly heavier than before, so, cutting weight is important here. However, a high capacity battery would be fantastic.


So, I thank you for the comments/suggestions. If my mind was made up, I would order immidiately! Money is a slight factor (I could afford any of them, but cheaper the better *but I want good stuff*. So I'm considering "building" whatever it is I decide on.) *Sigh*

I'm gonna grab some pizza, check out some sites for LiPo cells, and hurry to make up my mind!
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Old Nov 08, 2004, 10:17 PM
Elfi Flyer
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Rock Hill, SC
Joined Oct 2002
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Willie:

It is a no-brainer. Go to LiPo, something in the 800 mAh range if size and lightness is a real concern. The 1320 is about as much as you would want to go, but this cell's dimensions and weight are NOT a negative factor. Remember, the TP 1320 2S pack weighs a svelt 55 grams, LESS than the 6 cell 350 mAh NiCads.

One thing I forgot, and it's a biggie: you will need a battery charger that will handle Lithium Polymer packs. There are several out there. The Triton model is good for all batteries. Check the Batteries & Chargers forum for updates and specs on what is available.

Good luck and..........Love your Moth!

RD
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Old Nov 08, 2004, 10:19 PM
Slow Tiger Stick Moth
Willie Levi's Avatar
Austin, Texas
Joined Oct 2003
178 Posts
Quote:
Originally Posted by Doug Sipprell
Willie:

It is a no-brainer. Go to LiPo, something in the 800 mAh range if size and lightness is a real concern. The 1320 is about as much as you would want to go, but this cell's dimensions and weight are NOT a negative factor. Remember, the TP 1320 2S pack weighs a svelt 55 grams, LESS than the 6 cell 350 mAh NiCads.

One thing I forgot, and it's a biggie: you will need a battery charger that will handle Lithium Polymer packs. There are several out there. The Triton model is good for all batteries. Check the Batteries & Chargers forum for updates and specs on what is available.

Good luck and..........Love your Moth!

RD
Ooh, quick response! I got a Triton last year after feeling weary about some Duratrax charger I was sold. (which i was able to return!)
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Last edited by Willie Levi; Nov 08, 2004 at 10:22 PM.
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Old Nov 08, 2004, 10:20 PM
Elfi Flyer
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Rock Hill, SC
Joined Oct 2002
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Oooops

Duh!!

Just realized, we ARE in the Batteries & Chargers forum. I have been hanging around the Parkflyers forum too long!


RD
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Old Nov 08, 2004, 10:23 PM
Elfi Flyer
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Rock Hill, SC
Joined Oct 2002
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The Triton is as great charger. If it were not for already having 4 regular chargers for NiCad and NiMH, I would have probably gone with the Triton. However, I am VERY HAPPY with my Astro 109 LiPo charger.

So, your decision will be easier. How much punch and duration can you pack into your Moth. Hmmmmm........sure sounds like 1300 territory.

RD
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Old Nov 08, 2004, 10:23 PM
Slow Tiger Stick Moth
Willie Levi's Avatar
Austin, Texas
Joined Oct 2003
178 Posts
Quote:
Originally Posted by Doug Sipprell
Duh!!

Just realized, we ARE in the Batteries & Chargers forum. I have been hanging around the Parkflyers forum too long!


RD
Hehe. All the info I need is probably in here.. sometimes (most the time) I need direct contact.. someone telling me what's up and answering my questions!

Thanks again!

edit: Ugh! I'm still not sure what to do. I am leaning towards this ETEC 1200 from BalsaPr ($24). But those $5 ea 700 cells make it tempting to get out the soldering gun. But then I have to consider the comment about better voltage with the higher capacity packs. As well as weight.. I think shaving off ~20g will be enough. So right now I'm set on the ETEC 1200..
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Last edited by Willie Levi; Nov 09, 2004 at 09:39 AM.
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Old Nov 09, 2004, 08:17 PM
Slow Tiger Stick Moth
Willie Levi's Avatar
Austin, Texas
Joined Oct 2003
178 Posts
Quote:
Originally Posted by Doug Sipprell
On a freshly charged 1320 LiPo pack, amperage draw is 2.3 at WOT, static test, volts 7.5 for around 17 watts to the prop.
Hmm, so, could I get a Thunder Power 1320 7.4v and use it with my 10A ESC? Or is there a risk there?

If so, I'll be ordering one tonight.
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Old Nov 09, 2004, 09:16 PM
Elfi Flyer
Doug Sipprell's Avatar
Rock Hill, SC
Joined Oct 2002
5,553 Posts
Quote:
Originally Posted by Willie Levi
Hmm, so, could I get a Thunder Power 1320 7.4v and use it with my 10A ESC? Or is there a risk there?

If so, I'll be ordering one tonight.
Yes. As I stated, I was only pulling 2.3A at WOT, static test. In actual flying conditions, the prop would be unloading to a certain degree, resulting is a lesser amperage demand. An ESC capable of 10 amps is more than sufficient. You could go with an ESC that handles less than 10 amps, but first check the dimensions and weight of the ESC's. If the 10 amp version is close in weight to a lesser capacity unit, go with the 10 amps. Never hurts to have excess ESC capacity capability.

The E-tec 1200 is a good choice also. Be sure to use a 2 cell (2S) pack, NOT a 3 cell or 1 cell.

RD
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Old Nov 09, 2004, 10:23 PM
Slow Tiger Stick Moth
Willie Levi's Avatar
Austin, Texas
Joined Oct 2003
178 Posts
Quote:
Originally Posted by Doug Sipprell
Yes. As I stated, I was only pulling 2.3A at WOT, static test. In actual flying conditions, the prop would be unloading to a certain degree, resulting is a lesser amperage demand. An ESC capable of 10 amps is more than sufficient. You could go with an ESC that handles less than 10 amps, but first check the dimensions and weight of the ESC's. If the 10 amp version is close in weight to a lesser capacity unit, go with the 10 amps. Never hurts to have excess ESC capacity capability.

The E-tec 1200 is a good choice also. Be sure to use a 2 cell (2S) pack, NOT a 3 cell or 1 cell.

RD
Thanks again! I have a hard time extracting answers from posts, even if it's very clear, it helps me to ask again.

I guess I'll go with the Etec 2 cell 1200 pack! Instead of waiting until I get the pack to bump the thread up and ask about charging it. I'll just ask now.

Do I need an initial slow charge (low A)? How about a cycle (I think I read two or three cycles to check it's capacity)? I'll be using the Triton charger. What kind of A will I be charging with for regular use?
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Old Nov 09, 2004, 10:40 PM
Elfi Flyer
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Rock Hill, SC
Joined Oct 2002
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Ref: 1200 mAh LiPo pack

Charge at 1C, which is 1 times its capacity. In this instance, that would be 1.2 amps. I believe the Triton starts out slow charging, something like 100 milliamps, then works up to full power. Not sure if you have to set the cell number, i.e. 2 cell.

No need to cycle the battery either. There are several threads on LiPo's. The biggest concern is over-charging a pack and also pulling too many amps when discharging. If you are going to be using this 1200 pack on a stock IPS motor for the Tiger Moth, you will not be placing excessive demands on the pack. Most packs today can handle a 5C continuous amp discharge, which would relate to 6 amps draw on your 1200 pack. The IPS motor will not place that heavy of a load on the pack. Another reason for getting as much capacity (milliamps) in the pack design to begin with. A 1200 pack will last longer, per charge, than an 800 pack, assuming the same amperage demand. Check the specs on the E-tec battery pack to see if it is a high discharge design or what the average continuous amperage drain figure is.

If your ESC is programmable, such as the CC Phoenix 10, then you might want to set the low voltage cutoff point at 6 volts, the proper value when using a 2 cell LiPo pack. As you have seen posted before, drawing down a LiPo pack below 3 volts per cell is not advised, it can damage the cells.

RD
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