crankpin

My Feedback: (15)

Here is where I am at. I usually mount the smaller packs over the tank, wrapped in foam, and cased in a baggie. The baggie for possible fuel leaks, etc. Never had that happen. Now I am into this bigger plane, powerful JRdigital servo's onthe control surfaces, need some advice.
This is a 2200 mah pack 6V. The inside bottom of this fuselage is styro-foam, factory installed. Since it is tight under the tank mounting cross pieces, I also have additional cross pieces fore and aft, for the pack to slide under. These cell's are huge, compared to what I am used to. I have not wrapped the pack in foam because it has to slide under the two cross piece's. I do have the bottom of the battery pack setting on 1/4" foam, the kind we usually use on receiver's, etc., secured with velcro. My question, long time coming here: Am I OK with only foam on one side of this pack ? The top of the pack is touching the wood cross piece's. I am using a Hyde mount on this new YS110. Am I being too cautious, and just go for it ?My concern has always been vibration. I can move the pack fore and aft, for CG purpose's, which was my original goal. Thanks for any comment's.
Crank

NM2K

My Feedback: (14)

You cannot be too careful when it comes to vibration isolation.

There is some 1/8" to 1/4" single sided with adhesive foam tape available that would work well if applied to the wood surfaces of the braces that are facing the battery. That would probably be sufficient isolation to protect the battery from vibration. Should. If you had to, you could relieve the battery facing side of the wooden braces a bit to use thicker single adhesive sided foam tape, which would add a bit more protection to your battery pack.

In the old days, when all battery charging was done at the C10 rate (1/10th of the battery's rated output capacity in mah), we could totally wrap our batteries in foam without worry. Those days have long since gone. Leaving one side of your battery exposed to the air, except for where the foam on the bracing touches the battery, is an excellent idea. The first time that I used a fast recharger in a Kaos with a fully wrapped battery pack, I discovered thermal runaway (the battery overheated) which failed to trip the M.E.N. Charger into low rate and which cooked my battery pack. Luckily, the house didn't catch fire. The batteries in this pack were of the Nicad variety. Just imagine what would have happened with some of the latest choices in battery types.

There is more to this battery thing than most folks would think. I'm glad you thought of it and posted your query here on RCU.


Ed Cregger

crankpin

My Feedback: (15)

Thanks for the reply Ed. I forgot to say, this pack is Ni-Cad. I have a 2400 NI-Mih 6V pack here, just use it for bench testing. I am still old school on batteries for on board, stick with NI-Cad's. Received this pack from SR, put it on charge, using an Accu-Cycle Elite, the pack warmed up a little at end of charge. It was up to 7.14V, settled in at 6.75V after alittle use, and I am sure it will get to where it need's to be.
I am not an expert on this, or the battery charger, I just follow the manual charge instruction's. I am thinking, with the foam rubber on the bottom of the pack, and sitting on the styro-foam, I may be OK. If I have to, I can take the cross members out that I put in, do a total foam rubber wrap, slide it under the tank, secure so no movement, unless for CG change. Maybe I am answering my own question, but need input from you guy's.

Crank

TedMo

First of all it seems to me that many folks are going overboard on battery size,why? Of course if you use digital servos you do use more current. How long do you wish to fly? If desire more flights why not bring another packAlso with pack that far foreward, over tank; it seems plane would be nose heavy with that large pack. largest pack I have ever used is 1700ma and can fly forever with that pack. Seems same thing is happening with Tx batteries must be over 1500 ma,why? I'm from the really old school also and we had only 600- 800 ma packs but worked fine then. By the way I fly a very active flight but usually only 3 -4 flights in a day. At 83 I tire fast haa.

crankpin

My Feedback: (15)

Hey TedMo, thanks for the advice. 83 ? That's great, you should get to100, easy. I have the pack mounted so it can slide fore and aft. I will do the maiden with it a little nose heavy. Start there, then adjust as needed. Overboard on battery size ?Yes, probably. Rather have too much then too little.

Vince

anuthabubba

My Feedback: (102)

crank,

Do you trust that styrofoam belly to hold that big ol' battery in at 6Gs? Just a thought. As long as the battery is sufficiently isolated from the airframe there won't be a vibration problem.

I still use NiCads and charge at the overnight rate so covering them completely is not a concern. TedMo's suggestion of a lighter battery and a spare sounds reasonable to me. As long as access isn't too difficult. A 1200mah vs a 2600mah ould save quite a bit of weight. You check the battery after flights, right?

Those Focuses are good looking planes.

Terry in LP

NM2K

My Feedback: (14)

Hi, TedMo.

Most R/C transmitters use microprocessors today, which is one reason why the TX batteries are growing larger from demand.

Some of the 2.4 GHz receivers are sensitive to low voltage, which triggers a reset of the CPU and a temporary loss of control for sufficient seconds to crash the model. Two or three (or four or five...) digital servos under a bit of a load can drag the Rx battery pack voltage down below the reset point for the receiver. It's good insurance to simply use a larger battery capacity, especially when new technologies permit you to get twice the capacity of an equivalent weight/size Nicad battery.

Ed Cregger

doxilia

My Feedback: (3)

Mmm....

that sounds scary. To my mind NiCd and 2.4 just don't go together. NiMHis not much better.

Because of what Ed comments, my personal choice is to go with regulated ~7V packs. Some prefer Lipo's, I prefer A123's - 2 cells and you're set; either 1100's or 2300's depending on servo count and size. For your FS Crank I'd go with a 2s2300 wired with a Rx switch lead and a high current Deans lead. Glue the Deans female plug somewhere inconspicous on the outside of the model and you can flash charge the pack even at 10C in between flights. 5-10 min is all it takes. Safe, won't swell, and you don't have to worry about a fire in your model.

The only thing to watch out for is to not let the pack get down below the 30% capacity mark. You get too low and the A123's will just run for the cliff dropoff and there goes your FS. But all things in good care and you're golden!

Here's one of my 2s A123 1100 mAh packs. They are also dual purpose (I can use two of them in series for a 4s pack on electric models) and can take considerably more cycles than a Lipo.

Oh... one more thing:don't ever, ever short the leads on these puppies - they will blow your finger right off!! (once, as Iwas soldering a Deans on to the leads, Iaccidentally... and a lightning bolt flashed - good thing I was wearing glasses).

David.

crankpin

My Feedback: (15)

Terry - The styrofoam bottom is about 3/8" thick, secured to the balsa bottom. I am only assumingthis thickness, I have notpulledit up anywhere. This is a Piedmont ARF. Theoutside of the fuselage, whole plane, covered in Ultra-Cote. My choice would have been MonoKote, not impressed with this covering material. Do it over, I would have ordered an ARC.

Vince

Lazer

My Feedback: (27)

I used the Ultra coat on a small model recently and I'll tell you now that I will never go back to Monokote again. The UltraCote has the color going through the complete material and when you need to reheat and lift you don't have to worry about the adhisive sticking to the model when you lift it and reset the covering. The tear resistance of the materials seems to be much higher than Monokote. I've notice that Monokote (I heard that Hobbico bought them) is getting complaints about the consistancy of the color of one run to another are not very close. Try the UltraCote I think you'll really like it.
Terry in Georgetown, TX

PS- I don't work for UltraCote

crankpin

My Feedback: (15)

MonoKote vs. Ultra-Cote - My only MonoKote usage has been over a year ago. Thing's change, and at that time, I had excellent results, still looking good. Thanks for the update.

Crank

NM2K

My Feedback: (14)

I like both coverings and use both, plus others. No one covering is "the best" to me. It depends upon the job at hand. I tend to favor Monokote because of their strong colors. I'm not much into pastels.


Ed Cregger