9-cell?

[belem]

I'm a new flier and not quite ready to switch over to Lipo. I have a couple 8-cell batteries but wondered about putting a 9-cell in. Seems like I could just cut the box a bit and it would fit. But I'm still a bit new to batteries and am confused by something I read in this forum. A couple people posted long ago that they flew 9-cells but that after a while their motor started cutting out. But since people are flying lipos with stock cubs I can't see why that would be. A 9-cell would still be sending fewer volts to the motor than your avg 3s lipo right?

[gagallagher04401]

"motor started cutting out" They were probably hitting the LVC (low voltage cut off limit)
Yeah if you want to mod your cub I see no problem in useing a 9 cell. Eventually you will make the change to lipo's.
I use stock electronics and 3s Lipo's and LOVE IT!

George

[flydiver]

If not LVC then likely crappy Tamiya connectors.
You do NOT pull the lipo jumper for 9-cells. Doing so WOULD produce obnoxious LVC.

Folks have done it. It's in the battery section. I keep telling you it's all there. Just look and read.

Interesting, you are working right hard to avoid lipos. Most folks jump in giddy with anticipation and the lure of power.

[belem]

The battery section is where I read the two posts about trouble with 9-cells. I'm trying to track them down, but with 8 pages of threads it might take a while.

I will eventually move into lipos. I have a charger that will work with them, I'm just determined to take things slow. I've only been flying for about 2 months.

[belem]

Here we go, this was the post that drew my concern. Two different fliers cautioning against the 9-cells. See...I do read. ;D

supercubclub.proboards.com/index.cgi?board=batt&action=display&thread=620

[gagallagher04401]

9-CELL is doable, I my self woudl not spend much to upgrade Nimh, because sooner or later you are goign to want to get into lipo's, once you do (AND UNDERSTAND THEM, AND THE SAFTEY NEEDED USING THEM ETC..) You will never want to fly the Nimh's again.

So.... start reading about lipo's that will be your next step guranteed.

Have fun
George

[flydiver]

May 19, 2009 18:51:48 GMT 1 belem said:

See...I do read. ;D

Excellent-I'll quit harassing you.

It appears they were using Tamiya connectors (stock). Frankly they suck. Replace. Use Deans, Anderson Power Poles, or EC3-all are clearly superior. As voltage goes up all connectors have a limit and the Tamiya is likely exceeded.

9 x 1.2v = 10.8v (nominal)
At TOP/FULL charge it is more like 9x1.4= 12.6v (won't last long at this level before dropping to 1.2v)

So, if you have a warm, freshly charged 9-cell of decent quality for a couple of minutes there will be strain of the stock system.

Read this about the amp pull with different batteries and props. The stock system is not designed to handle 12.6v with THAT motor+prop and THAT ESC. Some folks are getting away with it but usually by NOT using full throttle much. If you have a heavy thumb you risk frying something. You would be advised to prop down also with a 9-cell.

supercubclub.proboards.com/index.cgi?action=display&board=batt&thread=1831&page=1

[belem]

Interesting thanks.

About replacing the connectors....how do you do that safely? Seems like it would be easy to touch the ends together while soldering.

[flydiver]

Part of this sport is learning how to solder. People that are poor at it or hate it have a buddy do it or get Anderson Power poles and a crimper. This doesn't save them from all soldering though.

One wire at a time.
How to solder-follow some links, video available.
www.wattflyer.com/forums/showthread.php?t=31630

And you thought this was about learning to fly a plane, didn't you?
Fooled me too.

[belem]

Thanks, that video helps. I did a pretty piss-poor job this weekend when I soldered a adapter for my charger. My tip was dirty and I didn't realized what the problem was for a good long while. Live and learn.