Woody 51

I am new to electric flying, having been involved in the world of Glow Engine Power for some years.

I recently purchased an Alfa kit, that came with a Speed 300 motor, 5:1 gearbox and 10 amp (approx) ESC, suitable for 7 cell, 8.4v Nimh Battery packs in the 800-1100 Ma/h range.

I want to use Li Pol battery's in this model and am wondering whether I need a specialist type of ESC to get the best out of one of these packs.

Can anyone advise me on this and also suggest a suitable type of ESC that can handle Li Pol packs in the 10 amp range?

It is possible to change the Speed 300 motor on this model to a Brushless type, which I may look at doing later on.

Matt Kirsch

My Feedback: (21)

Nope, you don't need a special ESC to use LiPolys. Electricity is electricity. There's no special grape flavored LiPoly electricity that requires a special ESC to filter out the purplocity and antioxidants before sending it to the motor

Where the issue is, is Volts. You do not want to draw LiPoly packs down below 3.0 Volts per series cell. There are many ways to accomplish this. You can get an ESC with a programmable cutoff that can be set to cut off the motor when the battery reaches a certain voltage. You can also use a timer and a voltmeter to figure out how long you can fly by flying a few minutes, landing, testing the voltage, and repeating until the battery gets down to 3.0 Volts per series cell.

If you feel you need this optional piece of equipment, look for an ESC with a programmable cutoff.

Jason Beach

My Feedback: (4)

Matt's right on the money.

There are several brushless motors that work well in SP300 applications.

Astro 010 (geared)
AXI 2212 series
Himax 2015-4100 (geared)
PJS 300
Nippy Black 0808
Mini AC 1215 series (geared)
MP Jet 25/25-26

Woody 51

Thanks guys,

I see that there are now ESC's on the market with a 3 V cut off, specifically for LiPols and not at too great a price.

I'll get one when I'm ready to make the change.

Woody 51

Can anyone explain to me what this device actually does?

Dr Kiwi

Read all about it here:

https://www.fmadirect.com/support_docs/item_1133.pdf


Basically it limits the terminal charge voltage (to, for example, 8.4v for 2s) so that your packs do not get overcharged - but it seems to me, that if you have a decent "smart-enough" charger (Apache, Astro 109, Triton, Schulze...), it will do that for you, automatically, anyway!

Cheers, Phil

Woody 51

Thanks Phil,
No, I won't need one of these.
I see it can also be used as a Discharge limiter, but only up to 10amps draw, which is sort of what I was looking for, (for LiPol use) but this one isn't quite "it."
Looks like I'll have to get one of those new ESC's that can be programmed to cut off at a predetermined limit. Yes, I know I can test and do time v discharge rate figures, but I just couldn't be bothered frankly.

Dr Kiwi

Visit www.castlecreations.com - their ESC's are the bench-mark for programmable LVC ESC's.

Cheers, Phil

Woody 51

Thanks Phil, will do.

mohr_dave

My Feedback: (6)

The LiPo batteries do need special care in the ESC area. You need to make sure that your pack does not go below the recommended voltage for LiPo batteries. This is a different voltage than for NiCd or NiMH! You need to keep 3V per "cell" for LiPo. The link to the castle creations from a previous post is a great place. I am using the Castle ESCs in two planes, one with a brushed and one in a brushless motor. Also take care with your charger as LiPos need more care in charging and you need a charger for charging these batteries. You do not peak charge LiPos. I am using a Great Planes Triton charger, and if you download the manual, it is fairly clear as to the difference in charging these batteries. The LiPos are great, just treat them with care.

D.