Nimth battery help
 

Hi there
I recently bought my son a Slow Stick . I geared it up with a spare flight pack I had which
was 81's with a 555 receiver. I picked up a couple battery packs which were GWS 8.4
730 mill nimth packs. I thought they would be great , light, lots of power, turned out not
to be the case. When I put it at full throttle it shuts off, but if it's 3/4 throttle or less it runs
the battery out. So I tried a nicad pack I have and it worked great with much more power.
By the way I am running a 15 amp GWS speed control.If anyone could help me, or give me
the low down on these batteries it would be great.

RE: Nimth battery help
 

Sounds like the battery isn't put together correctly. I had that happen to me and I returned the battery and got another for free. The battery worked great. Try returning it. Good Luck.

RE: Nimth battery help
 

Those 730 AAA batteries are not up to the task of supplying the current your SS motor demands - it wants 8-10A and those are good for 5-6A max. What is happening is that, under load, your voltage is dropping below the level of the LVC (?5v) in the ESC - thus shutting off the power to the motor. When you are at only 3/4 throttle (?4-5A) the batteries CAN cope without dropping voltage - same with the NiCds. What you need to get are some 7-cell KAN 650 packs or the CBP equivalent - they will give you 8-10A without trouble WITHOUT dropping voltage under load to the same extent.

Cheers, Phil

RE: Nimth battery help
 

Thanks for the help. I'm new to electric rc, I've only flown gas till now. The next time
I'm going to buy something for electric rc I think I'll get on this site and ask first.
Would you be able to tell me what size of motor thes packs good for.
Once again thanks.

RE: Nimth battery help
 

I don't believe you mentioned what prop size you are running, but that is one thing that determines the current your motor pulls. One difference between fuel engines and electric motors is that there are three variables with electric: motor size, gear box ratio, and propsize & pitch. Running the same # of cells in the battery pack, one can "regulate", to some practical degree, the current by varying one or more of the three variables.

Specifically you may be able to run full throttle by down-sizing your prop on your plane. The thrust would be down, but the SS might still fly.

The answer to your question about "what motor will these battery packs support" is that it may support several motors, depending on the thrust required for the airframe and what gearing and prop is needed to generate that thrust. You could probably run a 280, or 370, or 380 motor with the appropriate gearing and prop selection and get about the same output results. Perhaps a little far fetched, but the basic concept is true.

Sierra Gold

***** By the way, I don't disagree with the pack recommendation Dr. Kiwi made and I use to run KAN 1050s on my stock SS motor. I was trying to illustrate that with electric there is not always just one correct answer because of the amount of variables possible. :D :D