[gbjets]

Hi All

Can anyone tell me how many cells is needed for the ECU with a RAM 500 , I thought it was 7 KR1400 cells, also what type or size is required if I decide to switch to NiMH.

Thanks

Gaston

[Guest]

The pack is a 7.2 Volt (i.e. 6 cells NiCd). You could use Lithium Ion or Polymer as well. (more money)

Capacity depends on how many flights you want to pull out of your pack.
A 1200mAH will be sufficient for 2 flights if you have your cut-off voltage set at 7.5V as recommended.

I am not sure if a 1400mAH will give you three flights, I would think a 1700mAH or 1800mAH would be better to guarantee 3 flights. Keep in mind the weight of the battery pack.

Having said that, I have 2 packs, of 1200mAH which I charge and swap every two flights. I have my voltage cutoff set at 7.5V so the turbine wont start below that voltage.

Hope this helps.

[gbjets]

Peter

Thanks for the info, a little while ago I made a new pack with six 2050 AA NiMH cells, I guess the batteries I used were not high discharge or too small, and I could'nt even start turn the motor more than a split second, even though they were full charge. I just figured I must have made my pack with a cell short ( my brain too) I had thrown the old pack away. Thanks for the info, I might look into lithium.

Thanks again Peter.
Gaston

[Guest]

I am not a big fan of NiMH for applications where motors and high current draws are needed. After experimenting with NiMH, I am actually no longer a fan of this type of battery at all.

To date, NiCd remain the most cost effective source of power for high current situations, weight is the drawback. Memory is an issue that is way over glorified and with recycling, you should have no probs.

Lithium Polymer batteries are excellent as well, but I have just started using them and have no idea how they will behave.

For the ECU, you probably do not need a regulator with Duralites, or LiPo. Duralites are overpriced for what they really are and because TOC pilots use them, the price also goes up.

[Guest]

If you need some batteries, go to:
http://www.onlybatteries.com

They are located in Montreal, they ship via Canada post.
You can make your own ECU battery. Get some zero loss connectors and you should be all set.

[gbjets]

Peter

Thanks again for the info on the batteries, you're right lithiums are not cheap, then there is the charger.

Gaston

[Helijet]

Gaston

Be careful in choosing what type of cells you use. As I recall Bob Price designed the ECU for the RAM 500 and the starting sequence prior to the CO2C version can draw a very high amperage that neither NiMH or Lipoly can handle. I would suggest that if you decide to experiment with different
baateries that you do so on a test stand rather than on an aircraft. The reason being is that you may get a start and ramp but may not have enough to ensure adequate spooling rpm and a subsequent hot start may take place. Personally I would suggest staying with NiCads and go with 1400 mah or higher ( 7.2 volts 6 cells ) if you have the earlier version ECU ( ie prior to the CO2C )

Dean

[Guest]

Dean, great talking with you today.
When I got home a nice box was waiting for me.
The Eurosport wing bags arrived and they are great. Good quality as expected.

Gaston, I agree with Dean on the choice of batteries. When in doubt, stick with NiCds.

Thanks again
Peter

[gbjets]

Gary

Hopefully you'll be at Quinte, I've been there for quite a few years already, I really missed it last year, we'll have a chance to exchange ideas and chat, I hope Andrew can make it too. I'll also have to look at those wing bags.

Gaston

[gbjets]

Dean

Thanks for the information, I'll keep on using the NiCad's for the time being, I usually charge my batteries after every flight anyways. by the way it's nice to hear from you.

Gaston