exeter_acres

My Feedback: (2)

Help....

Put together a foamy using the Himaxx 2015-4100 brushless in the Himaxx gearbox (same as GWS D, 6.6:1 ratio) using a Phx 25 ESC

flew yesterday (fighting the wind really) with a Kokam 2000mAh 3s1p, 15C discharge pack and it flew fine....but the battery (for my Zagi) is REALLLLY heavy...

just purchased from my LHS a new Thunder power Gen 2 1320mAh pack...

charged it up...looks good... plug it in and whenever I go over about 1/2 throttle the BEC cuts in.....

How am I over amping the battery... all the numbers are within specs, arent' they??

and this is a popular setup too....

any thoughts? is there something else I need to set in my ESC
cutoff voltage is at 9.0v for a 3 cell lipo pack,,,

any insight would be great!!!

Exeter

Bevo

The 9.0v cut off is where the problem is. I see it all the time. If you were to move your cut off volt to a custom 7.2v cut off it will probably take care of the problem. This would at least allow you to use the battery. Otherwise if your'd like to keep the 9.0 volt cut off then your have to up the size of the battery say a 1500. Good luck.

Bevo

exeter_acres

My Feedback: (2)

Hmmm.... 7.2? seems low

would I still get a cutoff to save the battery or will I need to time my flights??


I thought this 1320mAh battery was a common one for this setup.... is this what everyone who is using this battery with this setup needs to do??

exeter_acres

My Feedback: (2)

Well...I tested that and it does work and allow me to throttle up.....

What are the risks of frying the battery???

I think I am still within specs (amp draw)(at least according to what I can find and what motocalc says)

Should I just do a few shorter flights and then recharge in order to get my usage figures and then set a timer on my radio??

Bevo

7.2 will still cut the battery off in enough time to keep the voltage at the three cell range. I use the Triton to charge my batteries and at 7.2 volts my voltage on my batteries don't get lower then 11.22v. 7.2 is the old cut off voltage that was used six months ago. Like I said before do what you fell comfortable with. If you want to continue to use 9.0v then upgrade to a larger mah battery.


Bevo

Bevo

When I fly I always set my timer in my radio for about 8 to 10 minutes and I have never had any problems. Do you have an amp meter to check and see how many amps you are pulling with you setup? That will tell you if you are pulling more then what the battery can handle. Second thing would be to change the propeller. Come down a size in the length and that will bring your amp draw down. Happy Flying.

Bevo

Trogdor the Burninator

What prop are you using? I use an eflite 370 4100 or whatever, almost exactly the same as your motor with same gearing. I use an 11x7 gws HD (Think I used a 1080 slo fly gws and pulled 11 or 12 amps, thought it was too high so went to HD prop) prop and can hover and fly for almost 18 minutes. Never a problem with the LVC on the battery (I leave it at 9V although I know it can safely go lower) same tp 1320 3s.

Maybe you're using way to big a prop, you should be able to get 15 amps out of that pack before the amps drop the volts too low.

I have had two 1320 3s packs go bad somehow and relly lose power quickly. One was replaced and the other TP is saying was shorted although I know it was not. LHS may take care of it for me but I think I'm done with TP packs.

exeter_acres

My Feedback: (2)

I'm using a 12 x 6

Hmmmm

Trogdor the Burninator

Wow, try a smaller prop. You probably have really excessive thrust like that, I think you'll pull WAY too much. I really like the 1170HD gws, maybe try that one, cheap, stronger than the sloflys and plenty of thrust for foamies 10-12 oz

exeter_acres

My Feedback: (2)

what is the HD prop?

I've seen the DD and SF, but not HD

Right now I have an APC 12 x 6E... I think I'll pick up an 11 x 7 would the SF be better than the E for this application in APC props?

Trogdor the Burninator

Ya, those E props are really for high rpm and are kinda heavy and strong, your shaft will probably bend before they break! I meant the GWS DD props, I think they call them HD props sometimes, kinda hard to tell with their model numbers but ya, just the direct drive heavy duty kind of gws prop.

I think the APC SF would be best but 11x7 might still be a bit much for the short can 20mm motors. I tried larger props also but tested with a whattmeter and just by touch and the heat and they seemed to start getting hot fast with 11 inch and larger slo fly props (any brand). Can't remember for sure now its been awhile but the GWS DD props draw much less current so thats why I used the 11x7 in that case.

exeter_acres

My Feedback: (2)

Thanks for all the input.... I'll be doing some testing this week!

IA-Flyer

"-5f? So what...I'm going flying!

Fingers? I don't need to feel them! "

I bet the problem is, your lipo’s like the cold less than you!
You’re probably just seeing normal cold temperature behavior of your batteries.
Try warming them to 90 or 100 degrees before flying, and keeping them out of the prop blast. But monitor them to make sure they don’t get too hot during the flight.
If you drop your cutoff voltage, make sure you set it back to 9v when the temperature changes.

exeter_acres

My Feedback: (2)

I wish it was the cold.... Nope this was happening inside before I even took them out[:@]

Going to try a few smaller props today...if the wind dies down....

I have read of many people setting the cutoff voltage around 7.2v but that makes me a bit nervous.... but hey...I live for adventure!

exeter_acres

My Feedback: (2)

Follow up......

Problem was the prop...not the size.....but the type.....

I had an APC 12x6E for electric flight..... but it was too heavy ..

Switched over to a 12 x 6 GWS slow flyer (which I thought was too flexible, but turns out to be perfect) it it flies great.....

tested by setting the cutoff back up to 9v and it works perfectly....
seems the 12 x 6E prop was just a bit too heavy...

Just thought I would post this so other n00bs (like me!) to electric stuff can learn from my mistake!!

raabid

There is another option, APC makes slow flyer props as well, that won't overwork your battery. The three most used are 9X3.8, 10X4.7, and 11X4.7 The Gws props are very inefficient, which is why you can't interchange prop sizes btw APC and GWS. I stripped 3 spur gears when I switched from using GWS to APC, I couldn't figure out why until I hooked it up to my wattmeter. You'd probably want the 10" one.

Plus I can't stand orange props.

exeter_acres

My Feedback: (2)

I have an 11 x 4.7 APC SF waiting to test.... but the wind won't cooperate[:'(]


Hmm... When I first started, I had a bad prop adapter, since switched to another and no problems....

but... My APC prop spun off and flew away from the plane off into some brush... I found it.. but it would have been easier if the prop was OrangE!

Still testing and thanks!