Pixie-14 ESC compatible with Li-Poly?

| Not sure if this was addressed in my previous post. | | I'm using a speed-400 (4:1), 10x6-7, 2 servos. Was planning on using some | 7x600AEs lying around but am beginning to think these may be a bit short on | flight duration. Since I'm building a slow-flier and know of a great deal on | Cellpro Kokam [1500mAh 3s 11.1v ($25)] I'd like to get a couple if the | Pixie-14 is Li-Poly compatible. | | Pixie-14 > |

For three cells, you still have the 6-7 volt cutoff, but once your LiPo pack starts going unde 10 volts, the loss in power is usually quite pronounced. If you make it a point to land when you notice that loss of power, you'll never have a problem. If you keep on flying, you'll have a problem.

I guess if you had a plane where a loss of power isn't immediately obvious -- like in an electric glider way up there, for example -- then you'll probably want the right ESC. But for most planes where you'd use a 2 or 3 cell LiPo pack, any ESC will work, as long as you pay attention (for the three cell pack.)

(As for the Pixie 14, I don't have any, so I can't address that specific ESC.)

Thanks for the great explanation! Looks like I'll make the purchase (along with the appropriate charger) and just be sure to keep alert when used with this combo. Expect they'll be perect for my next project...hopefully soon. ;-)

Best Regards, Terry

In article , Terry wrote: | | Thanks for the great explanation! Looks like I'll make the purchase (along | with the appropriate charger) and just be sure to keep alert when used with | this combo. Expect they'll be perect for my next project...hopefully soon. | ;-)

I could have added a little more to my explanation ...

What `Lipo-compatible' usually means is that you can adjust your cutoff voltage. Looking at the documentation of the Pixie-14, it looks like the cutoff is set at 4.7 volts and cannot be adjusted. So I'd say it's not `lipo-compatible'.

If you already had the Pixie-14, I'd say go ahead and use it. Since you don't already have it, I'd suggest spending a few dollars extra (unless this is some sort of really good deal) and getting one with an adjustable cutoff. (And really, 4.7 volts is too low for anything with more than 5 NiCd/NiMH cells. What were they thinking?)

Since I'm building a slow-flier and know of a great deal on

Care to share the source with the rest of us?

Steve

Yes, you can use it. 10x7 is ideal for that combo BTW ob 3s LIPO. Draws around 7-8A.

BUT there are two gotchas.

2/. The BEC is quite small and going to 3s LIPO adds a lot of stress to it. Limit yourself to two servos only. And small ones at that. You MAY get away with three..but beware. BEC shutdown will shove all the sticks into a corner and you WILL crash.

The only thing you can do is arrange plenty of airflow for the ESC and test the whole thing on a pack, indoors. Basically don't use the throttle at all on the test, and remove the prop to avoid accidents - simply stir the sticks for 15 minutes. If the radio goes dead, you have a BEC overheating problem. If not its safe to fly, as in general you will have a lower air temp and better cooling whilst flying.

I agree with this. You CAN fly without LVC..I mean slimer pilots always time their flights so as not to dead stick, so its no big deal. The point of LVC was originally only to retain enough control to dead stick the model if you DID run out of battery.

With a speed 400 correctly set up and stooging around, I get at least 30 minutes on a 1200 pack. Way more than I need for a single flight...

So although I wouldn't use a pixie 14 as a new purchase, I would be happy to use one if it came my way cheap enough. I have NEVER EVER used LVC on any model since I 'went LIPO'

"What were they thinking?"...Probably now the same as you, and likely the reason they no longer sell this model ESC. ;-)

Unfortunately this is the only one I have laying around and I'm hoping to hold off on purchasing another untill the next build. I'm not quite sure what it will be (probably in the 20a-25a range) but I'd rather not have to buy now AND later.

Again I thank you for the follow-up. Will definitely consider your caution!

Best Regards, Terry

Hey! You again! ;-)

Both you and Doug have provided fine examples of required caution. This I will heed!

Considering I'd be almost exclusively 1/4-1/2 throttle (or less) on just two mini servos has me thinking that a small bit of bench-testing should allow me some comfort-factor with this combination. Also, this build is mostly for my dad's enjoyment and he would be hard pressed to keep his head crained toward the sky for more than 15 minutes at a time anyhow.

No matter how much internet research I do I always find the newsgroups to be quite informative. Much appreciate all your input!

Best Regards, Terry

;-) I sheepishly apologize. Not knowing how deep their stock is I was trying to keep it a secret until I made my purchase. Listed as a "February Special" so not sure how long it will be extended.

Actually low throttle=high pack voltage=worst case heating on BEC.

I had a 12A one shutdown on me on 4xHS55 after 5 minutes of 1/2 throttle stooging. Trouble is 2x aileron servos is what you use all the time to keep the plane turning. Ailerons went full left, elevator went full up, and rudder went full something. Motor stopped. Classic death spiral. Ive got a 22A in there now - it has a bigger heatsink, but the same chip, and airflow over it..not happened since.

That isn't a great deal, since Fred Marks Kokam cells are utter overpriced crap, and I can get a better pack than that for the same money, but hey, they should be able to handle 8A or so from a speed 400..

Sheesh...isn't anything as it seems any more

That IS an eye-opener and more good info to catalog. I should probably modify my bench test to include partial throttle with whatever packs I choose, even if I end up using the Nicads.

Also, you surprise me with your opinion of FMA's products (at least the batteries). I haven't made a purchase from them since the late 90's and at the time I was feeling their lines were of decent quality. In truth I haven't made the LiPo buy yet because I am still assessing what I think will be my charger needs currently and into the future. I have a dedicated Nicad charger and am reviewing dedicated LiPo options. Would you like to share an opinion of on quality "sport" grade LiPo packs? Would be most appreciated. ;-) I did note that the Kokam's were only rated at 8C so that should have been to me an indicator of the packs servicability.

Thanks again for everything! Terry

AS long as you totally disregard any claim Fred Marks makes about them, and derate them to about 60% of what he claims they can do, then you will get perfectly reasonable life. However, when you realise that they are only 60% of (claimed) current carrying capacity, and compare the price with some of the better cheaper imports from China etc, you realise why Fd Marks spends all his money on himself, amd marketingf shoddy batteries as really state of the art stuff rather than acrually buting in state of the art cells.. Which they ain't.

I haven't made a purchase from them since the late 90's and at

I've bought all OVER the place. Have a look at

Better still hang out in the E-zone and soak up the scuttlebutt.

Ouch! Re. FMA. As I've not come across anything (i.e. reviews, board banter, etc.) to refute that view I will take heed.

Yeah, I have been driving myself crazy for the past week and a half scouring the i-net for e-flight related info. Spending mucho time on E-zone and RC Groups following one thread after another.

BIG thanks for the battery links and all your support! ;-) Just got my dad's Miss Stik in today so guess it's time to get building while I order a few packs. Btw, eyeing the scratch-build "Skeeter" by Quicker for myself...gotta have some fun too!

Best Regards, Terry

When I was a kid we used to have fun flying toy planes. Then when I came back to the hobby it was 'flying club this, glo plug that, safety nazi the other'

Now, with electrics, its charge, walk out to the neighbours field,fly, have fun, come in, have coffee, and feel good.

Electrics are more fun.