AXE CP Stock Battery & Tail Performance

[atomicplatypus]

Hello all,

I have two of the stock green batteries for my stock Axe CP. With my old battery I find the tail really likes to wonder and I have to fight with the tail to re-orient the heli. My new green battery performs well and the tail performs much better.

At first I thought the original battery just wasn't supplying the tail with enough power but I'm puzzled since both batteries have the same amount of flying time. I can get about 4-5 minutes from each.

I have replaced the tail motor once already with an identical HeliMax version.

Does anyone have an idea why my older battery would cause poor tail performance? Or is it something else perhaps?

[atomicplatypus]

To anyone interested the problem seems to be an output issue. When strapping a small camera to my AXE CP I've noticed the newer battery is able to supply the power necessary to lift the payload. The older battery -- probably weaker from use -- does not have the power to get off the ground.

So, the tail control issue with the older battery must be related to how much power the tail motor is actually receiving. How about that, answered my own question. ;)

[Ray K.]

I was less than pleased with the performance of the stock NiMH battery pack. I think I ran about 50 cycles on it and started to notice decreased performance. HeliMax really should sell the ACP with a LiPo right out of the box!

[skunkworx]

I've been working on my buddy's Axe CP and have noticed the same problem. I figured out that you have to adjust the screw set at the top of the "gyro" side (the little siver + one with CENT on it). This adjusts your center hold. Otherwise it will drift from one side to the next and it's tough to fly. Once you center it, this heli really flies well, but you do have to concentrate like crazy so it doesn't go winging off into the bushes!

As for the batts, the stock NiMhs don't work worth a hill of beans simply because they don't have very high drain capabilities. The more amperage you supply, the more 'grunt' you get and therefore have a much better head speed (in other words, it just flies better!). The voltages are really only relative to the battery size. While it does play a role in the amount of speed the motor will produce, it's just not as important as the amp output.

Think of it like this;

Voltage = Horsepower (a.k.a.- the more you have, the faster the motor goes)
Amps = Torque (a.k.a.- the more you have, the more you can move/lift)

One other thing I've noticed is that the stock 380 motor doesn't have much power regardless of what batt. you use anyways. I really think they should upgrade the motor to a brushless setup and completely stop using the NiMh battery packs.

Any other ????'s? Good luck Atomic!

[atomicplatypus]

Thanks for the in-depth reply Skunkworx. The Voltage/Amps explanation is helpful for a battery newbie such as myself. Everywhere I go it seems everyone is of the same opinion that the NiMh batteries are poor performers. I think its time for an upgrade to lipo… time to do some research on what is the best fit for my Axe CP.

[skunkworx]

Hobbycity is a good place to look. They have a variety of packs from teeny-tiny 50mA to huge 5000mA and all at really good prices. You shouldn't need to buy super high end packs to begin with, so your best bet is to get an 860mA to 1300mA pack for the ACP. It should be able to heft the extra weight of the 1300 but I'm sure you'd have to sling it under the frame using zip-ties or a make-shift battery tray

Here's a few good examples: [Prices are all below $16ea. + S&H]

https://www.unitedhobbies.com/UNITEDHOBBIES/store/uh_viewItem.asp?idProduct=5470
https://www.unitedhobbies.com/UNITEDHOBBIES/store/uh_viewItem.asp?idProduct=5480
https://www.unitedhobbies.com/UNITEDHOBBIES/store/uh_viewItem.asp?idProduct=5513

The difference between the first and second one is the C rating. If you don't know what this means, put simply, it means one has a higher discharge rate (aka higher torque [once again!])

If it were up to me, I'd probably go with the 1300. I just measured out the batt compartment and it looks like you have about 39.34mm vertical clearance and 24.42mm horizontal clearance and will stick out roughly another 19.70mm compared to the stock NiMh (actual batt specs: 68x34xx24). The 1300 on one side should just make it into the frame and at worst might need a little dremeling here or there, but not enough to completely alter the heli's frame. It might be a little bit of a squeeze, but I'm quite sure it will fit like a glove in the frame. Another thing to think about is that you will probably more than double your flight times because you can get sooooo much more out of a LiPo.

Lastly (might be a bit pricey or too technical for the newb pilots), you should consider a brushless motor setup. You can switch to B/L's on both the main and tail and probably just about triple your flight times or really make that heli go like a bat outta hell! This of course will be a little costly, but is really fun to do and it's a great learning tool for anyone who can put their mind to it! Here's a link to show you how it's done;

http://www.helihobby.com/html/separate_electronics.html

Hopefully this is all helpful and you can really get into the hobby! Good luck!

Oh also forgot to mention a charger, you have to get one that will be compatible w/LiPos and preferably with a blancer (internal on the charger or aftermarket external -I use a Triton Jr with Sorensen DC power supply [or car cigarette lighter hookup on the go] and a TP205 blancer but have heard great things about Astro Blinkys).

Sorry, quite a bit to swollow, but it all was helpful to me!

[atomicplatypus]

Thanks again for the in-depth and very helpful reply!

Is it possible to burn out the electronics if you go too high on the mAh? I’ve been told that 1300mAh is good for the Axe CP but a little low for a T-Rex 450. I hope to upgrade to a T-Rex 450 down the road and it would be nice to have a battery that will transition over when I’m ready. My local hobby shop recommended a 11.1v 2100mAh battery for both heli’s.

http://thunderpowerrc.com/html/battery/prolite_2100.html

[skunkworx]

no, you'll only burn stuff out if it's ready to go anyways or if you've gotten some wires crossed. The mAh refers to the total amount of battery capacity. The bigger the # the more the capacity. The C rating on the battery again refers to the amount of "punch" you get out of your battery meaning that more power is instantaneously at your command (or if your electronics can demand it).

As for the Pro-lite 2100's, I'm sure they will work ok. They are roughly 30 to 40 grams more weight. I'll try using one of my Trex packs on it tomorrow and see how it fares with the weight. I should be able to re-post results sometime tomorrow afternoon.

Another site you should really read up on is;

http://www.batteryuniversity.com/

I found this to be really helpful in explaining all chemistries to include; NiCd, NiMh, Li-ION, LiPo and LiFe. A lot of the info can be really REALLY boring, but it's well worth it to know. Don't try and learn it all at once and don't feel bad if you have to read through it a few times to really get it. Also, remember to visit the site later on once you start to getting into using the LiPo's as it chock full of info on these (*some of the material is a bit dated. Always follow your battery's manufacturer recommendations for charging, use and care)

[ch3no2Phil]

i am very new and wondered if i could even fly my axe but as soon as i went to a 1300mah lipo the thing just flew perfect. i couldnt believe it. i bought a spare stock green nimh the day i bought the bird and it barely got the thing off the ground. The one that came with it did seem to be a bit better but i really coudnt believe the night and day difference in tail hold and collective response with the lipo. give one a whirl

[skunkworx]

I agree. I just dropped a 2100 3S1P (11.1V) battery in the ACP and it gave it gobs of power compared to the NiMh pack, but it would do light years better with the 1300 as there is a LOT less weight. The Pro-lite WILL work, but it is much heavier and major overkill for this heli. It could get damaged easily because the only place you can put it is under the frame and if your skids go, so might your battery! You can get 3 1300's shipped for LESS than the price of 1 Pro-lite ($47.85 + $12.12 s/h = $59.97 -VS- $69.95)! Simple math to me on this one!

If you have the cash to burn, go ahead and get the TP's. They are great packs, I use them and like them, but it's better to save your cash for bigger better things later on! Also, inevitably you'll end up trashing a couple of them learning how to charge them and care for them so you might want to stick with the cheaper batteries. Besides, if you do swing the T-rex eventually, you might want to get higher discharge packs.

Most of everything we do in this hobby ultimately comes down to personal preference. What I like/recommend may not suit you at all, so I only offer what I think would be the best options for your path towards getting a T-rex, because once you get one, you'll almost certainly never want to fly anything else (unless it's a bigger heli of course!)
Good luck once again! Hopefully this helps!

[strat1960s]

Hey guys,

I've been flying my AXE CP since June. I, too, have had issues with the greenies. When I installed my GY 240 I went ahead and set it up for lipo (added a larger Deans plug). I've been flying the BP 910 packs ever since. The BP910 gets me 10 minutes of comfortable flying time. Some times I forget how long I've been flying and when the pack get low and I have to give it more stick to stay in the air, I just power down and grab another pack. I have three bp 910s. I average 4 to 5 flights a day. I work in a KC135 hangar and come in early and stay late to get some stick time.
I have the Electrifly PolyCharge and Equinox balancer. I modified the charger so I could run it AC/DC. I cut a few wires and put in some automotive plugs. The only draw back to these "pocket" sized chargers is that you can only charge one battery at a time. I've seen a few that could charge as many as 4 lipo packs at one time, but I haven't seen any that have internal balancers.
Anyhow, a while back I put together an Excell sheet with different lipo packs from the BP 910 to the TP 1320. I have several vendors and their prices for most of the different lipo packs. I also have CNC parts info, replacement parts info and my own crash recovery and parts (O CRAP) kit. If anyone is interested send your email address to: strat1960s@aol.com

Not to steal any of HeliFreaks thunder, but RC Universe has a very active heli-max thread. You may want to check it out some day.
http://www.rcuniverse.com/forum/forumid_462/tt.htm

Ted

[skunkworx]

Thanks for the reply! Lots of really good info here. You definately know way more than I do about these 'lil beasties! How well does the GY240 do on this heli? I want to recommend it to a friend, but am not too sure if he'd rather get the 401 instead because he wants a T-rex or Mini Titan. From what I hear, the 240 does just about as good as the 401 and for some, the price is a lot more bearable. I myself use the 401 because I use a digital tail servo on my T-rex, so I can't really comment on which is better.

The good thing is that you can pick up a used 240 for about 1/2 the price of a new one. The used 401's are a bit tougher to come by, but you can really save a few $$'s if you are patient!

[skunkworx]

On another note, Do any of you have glitching problems with your helis? The one I fixed has a really nasty pitch change which will either send it rocketing up or crashing down for no appearant reason. I know that the 3-in-1 has a low voltage deal on it, but it even did it when I strapped a LiPo to it, so I doubt that's what was wrong with it. I think the board might be on it's way out but am not too sure if it's just interference. Anyone else notice the same thing happening?

OBTW, they just came out with a LiPo version of the ACP. I guess it's identical, but they finally decided to include the much needed 11.1V instead of the dreaded 10.8V NiMh. I wonder just how long it will take for them to ante-up a B/L setup!!!??? Till then, here's to upgrades!!!

[strat1960s]

Skunkworks,

Some folks have lubed up the main shaft with moly lube or a good antiseize compound and have had good results. Others have replace the servos with HS55s and never had a problem since. Like I siad in my previous post, RC Universe has tons of post covering topics such as using a brushless motor, the glitches and many more. It might be worth it to take a look.
As for the GY240. It's great and does exactly what Futabab says it does. It keeps the tail in place. I don't know much about the GY401.
Ted

[strat1960s]

SkunkWorx,

The lipo pack that comes with the AXE CP, I believe is an 850 mAH pack. It's not as strong as the BP 910, but it is better than the stock "greenie".
For those of you who have seen my parts listing just a side note on the LiPo tab. If the battery is marked "RED" that means I felt it was too big to fit into the battery compartment without having to modify the canopy. The packs marked in "BLUE" are ones I was considering for my next lipo packs. The BP 910 is a good fit for the AXE CP. Having said that, if you decide to go with a different pack, compare the dimensions to the BP 910. You should not have to modify anything on the heli or canopy if using a lipo pack that is: 66x37x22 / 83 g.

I hope this helps everyone out.
Ted

[skunkworx]

Thanks again Ted,
I looked up all three LoongMax packs, the biggest being 68x34x24mm (including cell spacers for ventilation). Might be a good investment for you as well. If the 910 fits, then the 1300mAh/20C/11.1V should fit no problem and the heli shouldn't have a problem lifting it as it will easily lift the 2100mAh pack I threw on it last week. I'm probably going to get a few of them ordered for flying foamies, so if I get the chance, I'll try stuffing one in the Axe and see how well it works.

[strat1960s]

This is kind of off the topic, but sort of related. One of the guys on RC Universe tried running to BP910 packs together. It sounds like a great idea and I'm not sure how he wired it, but after about 4 minutes of flying, his e-board was smoked.

Too much juice????

Ted:smokin:

[skunkworx]

Yeah, it would be running double the voltage (25.2V on a full charge!) unless he ran it in parallel. Using a higher capacity won't fry your electronics, it will only make it fly longer.

[strat1960s]

Depending on how you wire it, you'd be increaseing the voltage or Amps or if wired in series/parallel, bothe amps and volts could be increased.:YeaBaby:
Either way, he smoked his e-board and now he's looking at running serparates and a brushless motor. That'll buy him some more stick time, I'm sure.
Good news, my RC Tek Sky Shark arrived today. Next week I'll try to pick up the TX.RX, servos, gyro, lipo pack and whatevers else is needed. So, maybe by the end of the month I could be up and flying a new bird. I've already got offers from the guys I work with to buy my AXE CP. I kind of feel dirty and disloyal for switching over to another heli.:thumbdown:

Ted

[Ray K.]

I think that the biggest LiPo that you want to run in an AXE is a 1250 mAh 3s. The voltage isn't anything that any ESC can't handle, and I've been getting 11 and 12 minute flights with that capacity. Anything more than that will simply be too heavy- I've noticed that the AXE is very sensitive to weight. Anything you can do to reduce weight will help it's performance, too. My project AXE weighs in only 20g heavier than stock, and there is definitely less collective performance than there was... I'd say that I need another degree or two of pitch just to hover. I've got plenty of power, but the heli is flying like it's heavy. That, and larger batteries are harder to adequately mount in the fuse. I had to build a sort of a battery tray out of CF to help hold the large battery. It would have been much easier with a smaller battery.

-Ray

[skunkworx]

Even if you ran 10 batteries in parallel it wouldn't hurt anything because your electronics will only pull so much amperage, the voltage is what will get you in trouble (series).

Congrats on the new bird Strat! Does it have a belt tail drive or is it motor driven? I wouldn't skimp on the servos if possible. Head parts are easier to replace than servos, so metal gears are great for durability (8 crashes on my Trex and never a stripped servo!)



Ray K, I definately have to agree with you on that one. I figured the 1000mAh would work best becaue it's kinda middle of the road, but if all you are doing is hovering around and very basic FF, then it wouldn't hurt to use the bigger packs (I personally plan use my packs for several different things, so the 1300 suits me best). I don't actually own an ACP, just got the chance to fix 'n fly one a few times. :)

[strat1960s]

Skunk Works,

It's a belt driven tail. RC Tek really has a nice heli with this one. Everything feels so smooth.
I was really surprised to see that the 450 is very close to the same size as the AXE CP.

Ted

[strat1960s]

One of the guys over in the RC Universe Forum said his main motor gets too hot when running a 1250 mAh/ 3S pack more than 15 minutes. But then again, he said he hasn't cut out the vent holes in his heatsink yet.
I ran my AXE CP this morning without the canopy for 11 minutes and used a laser thermometer on the main motor heat sink. The temp was 126 on the heat sink.

With all the mods and larger LiPo packs, I guess burning up the main motor is all the more reason to look into converting over to a brushless motor.:wink:

Ted

[skunkworx]

Well what he's not taking into consideration is that he's flying for 14 MINUTES!!!!!! :) Technically, you could fly unlimitedly if your batteries would allow, however, with a brushed motor, this could lead to it wearing out. Even the best B/L motors will get hot after 10 minutes. The best thing you can do is to add some thermal compound to the heat-sink so it has proper heat transfer.

If you were to just slap the heat sink on, it will work ok for most applications, but not nearly as good as with the compound.

Heat sink fins are just an extra way to remove excess heat from the motor which in turn will increase your efficiency. If you provide enough cooling, you once again could fly just about unlimitedly, but most motors only get used for 10 minutes or less. Even running at 90% duty cycle, there would be lots of time for the motor to dump the heat off between flights.

[Ray K.]

I'm running 1250 mAh LiPos on my Axe with a Park 370 BL motor, and temperature has never been a huge concern. I salvaged the stock heat sink and modified it for use on the Park 370 (read: squashed it until it fit), and even after 12 minute flights the motor temperature is nothing to be alarmed over.

And Skunk is right- you can overheat anything if you run it long enough. The trick is just to be sure that you're getting adequate run-time cooling (compound WORKS- use it!), and also that you allow plenty of time (5 minutes / 1 cigarette) between runs to allow the motor to cool. When I go flying, I simply alternate between the Axe and the TRex- taking turns allows one to cool while I'm flying the other.

I've had no problems with 1250/BL though, so I'd say go ahead and do it.

-Ray