RC Model Reviews

Hi all,
New to the R/C modding world, so hope you'll be patient.

Was wondering if you can use 2X "Protected 3.7V 900mAh 14500 Lithium Battery" in place of 4X AA batteries to power a receiver?
Thinking of getting 2X and soldering together (a-la Turnigy 9X lithium battery pack mod) to replace the 4X AA that now power the receiver.
http://www.dealextreme.com/details.dx/sku.3435

- 14500 size cells are supposed to be same dimensions as AA batteries but at over double the voltage, take up less space/weight
- my application requires me to be able to fit a replacement battery pack into the space of 4X AA, stacked in a square
- since the MAH is lower (900) than what I would get for AA size Ni-MH (2500) would that mean they would run down quicker, and by how much?
- 2X 14500 = 7.4V, that is over the normal 6V from 4X AA, would that fry my receiver?

Like I said, I'm a noob to this so any comments or advice would be greatly appreciated!
Thanks.

Most receivers will not tolerate 7.4vDC, unless the receiver is labeled 'HV' and then you have to use high voltage servos. The nominal voltage stated will be close to mid to low discharge, and you will see a greater voltage present at full charge. I have successfully used the A123 LiFePo4 cells in the 2S1P arrangements with standard receivers and servos. These cells put out 3.3v each as a nominal voltage, and approach 3.6v at full charge. The are capable of 30C and higher for the larger cells. I have used the 1100 mAh batteries from sz_ohmygod@hotmail.com for around $2.00 US.
I just received an email from them. The following is the body of that email.
Thank you for your email.
The dimension of A123 26650 is : (Diameter) 26mm x ( height) 65mm
The dimension of A123 18650 is : ( Diameter 18mm x ( height) 65mm

For the 2S1P and 3S1P packs, do you just need the welding service but no wires connection ? if so, how many do you want? then we will tell you the price accordingly.

If any question,please feel free to tell us.
Best Regards
Ray

I sent a pack that I made up to Bruce for a review, but it is obvious that he is extremely busy these days.
Bryan

I have tested Ray's pack and it's good -- I'll be publishing details soon.

I agree that A123 is the way to go. Li-Ion or Lipo packs are not a good choice for receivers. You can't get better than A123 though and the pack I was sent for review performed well and was well-constructed.

Feel free to post a contact address Ray.

RCModelReviews wrote:I have tested Ray's pack and it's good -- I'll be publishing details soon.

I agree that A123 is the way to go. Li-Ion or Lipo packs are not a good choice for receivers. You can't get better than A123 though and the pack I was sent for review performed well and was well-constructed.

Feel free to post a contact address Ray.

I understand that they are not a good choice for receivers, but what about for transmitters?

I understand that they are not a good choice for receivers, but what about for transmitters?

I have been using these batteries in a 2S1P configuration for my receivers. They work GREAT! I have also looked into using a 3S1P for the transmitters, and it will work for any transmitter that uses a square style pack, as the dimensions of the batteries are larger than a standard AA size NiCd battery. They will not work in any transmitter that uses a flat pack, without case modification, as the cells are to large.

have tested Ray's pack and it's good -- I'll be publishing details soon.

I agree that A123 is the way to go. Li-Ion or Lipo packs are not a good choice for receivers. You can't get better than A123 though and the pack I was sent for review performed well and was well-constructed.

Feel free to post a contact address Ray.

I purchased these batteries from Ray at sz_ohmygod@hotmail.com and they welded tabs onto the cells in my specified configuration. It took a few emails, and a picture to explain two cells, side by side, negative to positive, with tabs on the open ends for soldering my connector. He seemed to be willing to supply the connector, but I didn't go that route as it was difficult enough to explain the tab configuration.

Ray did not send these cells to Bruce, I did.
Bryan

Thanks to everyone that weighed in on the conversation. The information was very valuable!
Guess I'll be looking into the A123 packs.