Scott_nra

I have altered my homebuilt foamie to use a 10 X 7 prop instead of the 8/6 that I designed around. The 8 X 6 just did not give it enough climbing power to get up to altitude for fun or recover after tricks.

The bird flies great now but my times are a bit shorter. Performance is what I want but the other side efect is heat of the battery pack and wire leads. They get hot enough by the end of the flight that holding the pack is not comfortable at all!

Is this hot condition going to smoke my packs? I know battery packs do not last forever but I would hate to kill them in a few flights.

Any advice on pack heat during discharge would be appreciated.

Gone to a Higher Plane

almost all batters are going to very warm to melting. Whe you start pulling that much amp draw. You did not say what appilcations you were using in.
You can expect lots of good runs and then the will slowly drop.

.If the batttery is charged 5.0 amps, it surely will get very hot , sldo try to charge the pack more once in a day.

Thats about is all the info you gave us.

Scott_nra

Sorry here is the rest:

I have a 350+ power drive unit and am using an 8 cell 350mA 8.4v pack. This is the drive system from a Crazy Sparrow ARF in a similar size plane. (Speed 300 motor) Motor and pack were the recomended set-up from Hobby Lobby for that bird. It became available for use in this scratch built plane very quickly as my flying skills were not yet developed enough to fly the Sparrow. :-)

I charge it with a great planes dc charger that plugs into the lighter plugs of my vehicle @ the 600mA setting. The packs do not get overly hot but do get a little warm on the charge. I let them cool before running after a charge and cool completely before recharging, even hanging them in front of the AC duct in truck to help cool if I'm going to charge and fly again in the same day.

There are more pics of the plane in my profile. Is there any more information that would give a clue?

Steve Lewin

Changing from 8 x 6 to 10 x7 is likely to almost double the current. Without knowing the gear ratio it's difficult to determine the actual currents so it's a bit debatable whether the battery, motor or speed control will die first, but something surely will.

Steve

Scott_nra

Do to the fact that the plane flies so well now, is there any prop swap that can cure my heat problem and still give me the thrust needed for the plane to fly well.

It has a 5:1 gearbox and came with the 8X6 prop. HL now recomends 7 cells of 500 - 600 mA. At the time it was the 8 cell 350 that I'm using now.

Steve Lewin

Basically you're not going to get the power you want out of that poor little battery.

If you have the room and can manage the weight trying the same prop on 7 x larger cells, e.g. 600AEs, might work. I'm guessing that you'll get at least as much power because the cells you're using now will not be delivering anywhere near their rated voltage. But that's still going to be around 10A which is a bit high for a S300 and you'll want to check the specification of the speed control too.

A 9 x 7 may also be worth trying on 7 cells. A bit less power but better duration.

Steve