What Li-poly For an Old Motor? - RC Groups
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May 26, 2006, 05:00 AM
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What Li-poly For an Old Motor?

OK, I don't understand the new lipoly batteries yet so I need some advise.
I have 2, old 2 meter electric gliders I haven't flown in at least 10 years. They both have Astro 05 geared motors swinging 12" props.I want leave everything the way I built it and just drop in a Li-poly and a new speed control. So what size battery should I choose?

Second question, I have a Sig LT-25 with the Model Electronics Turbo 10+ in it. I have been told this motor draws a lot of current. So what li-poly should I choose for this motor?
I hope to order a charger and batteries next week.
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May 26, 2006, 05:27 AM
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If you had7 cells in, replace with 2s LIPO...current on the astro will be up around 30A, so a 3000 pack or bigger is indicated.

HOWEVER by dropping down to a 10" prop and going 3s LIPO (3000 or better) the performance will be hugely increased..

No idea on the turbo ten+..suspect its another 30A plus sort of motor, so 3000 mAh or better, and probably 2s or 3s.
May 26, 2006, 05:27 AM
Registered User
David, It would be worth checking with Astro the max voltage allowed on the 05G but my old charts suggest 7 cells which in theory at least is 8.4 volts (more when cells are at full charge). That being the case a 2 cell Lipo pack of 7.4 volts would be the way to go. If Astro say that you can go to 3S then by all means do it but you may need to drop the prop size in order to stay within amp limits. Even with the 2S Lipo you are going to need something that will handle at least 25 amps constant. With the newer generations of 20C Lipos I would be looking at a 2000 mAh pack on the basis that I was working well within it's limits but I admit to conservatism.

As for your second question you have to know what sort of amps your motor is pulling with whatever set up you are now working with. I suggest that you do not just go out and buy the first thing you come across.

Remember that you'll either need brushed motor controllers that are Lipo enabled or purchase an add on such as the Li-Saver from Diversity which should convert your existing ESCs. Don't use non-Lipo ESCs as these will discharge your Lipos down beyond their lower limit.
May 26, 2006, 07:24 AM
Registered User
The Astro 05's were happy on 12 nickle cells. They still are.

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