RX batteries NiMH AA packs?

[Scota4570]

I am flying a Bridi Big Bee with a 56 cc echo conversion. It has pleanty of power for unlimited vertical and non stop aerobatics. Very FUN! Last weekend I flew about 30 min of non stop aerobatics. My RX battery was done. I am using eight NIMH AA cells made in to one 4.8V pack. I now understand from a charging standpoint that is a mistake. That may explain my short battery life. I am running four big Futaba sevos and a standard one on the throttel. 5200 MAH should have done better??

My initial thought is to make up four seperate four cell AA NiMH packs and charge them seperatly. That is awkward. I would prefer a single charging jack and single charging opertion. My first idea is to make up a five position switch to allow for not opening up the airplane to charge it. I would have to charge one pack then the next etc. that is half the goal. Thing is that is more complicated that I first thought after drawing schematics and looking at my rotary switch collection. Does anyone make such a switch for this purpose.

The second idea is to get some very high capacity Nimh cells an make a four cell single pack. Would it help to go to a five cell (6v) pack? Something like these,

http://www.onlybatteries.com/showite...t1=50&uid=1910

What kind of MAH capacity would give me about two hours of flight time?

What is the best way to go here?

[blackbeer]

Forget about the AA size nimh's they are to fragile for this kind of thing. If you want to stick with nimhs then go with the 2/3 size or subC. I would go with a 5 cell 2000 mah low impedence pack. Be sure to form charge them a few cycles before you put them in the plane to be sure you have full capacity.

Tom

[f5air]

invest a little more money and get a A123 pack or Li.ion fromeco packs with a regulator.

[Zeeb]

AA size NiMH for flight packs, particularly high capacity NiMH?????

UGH!!!!!!!

A123's are my choice but Li-Ion or Li-Po with regs will have more mah capability available with probably less weight than multiple A123 packs.

[Pilotpete]

Hi Zeeb,
I read your post some months back, when you switched to A123 cells for you 50cc plane. Very compelling testimonial for A123's!
I have a 2S 2300mAh in a 26cc powered QQ Yak, a bit overkill. If I tried to run out that pack in one days flying, I'd probably black out
After experiencing a close call recently with a failed solder connection in a high quality heavy duty switch harness in my 4 Star 60, I'm considering going with dual 1100mAh receiver packs and switch harnesses in the Yak.
For next season I will be replacing the aging 5 cell 1100mAh nicds in my slimers, sure a few bucks more for the A123's, but my planes are worth it, kinda like the old L'Oreal adds.
The ability to top off A123's at the field and know how much you put back in, well at least with a good balance charger you'll know.
Regards,
Pete

[Scota4570]

Good input all. Thank you. I ended up calling a company refered to me by a famous vendor that I trust. I have a couple of big high mah 5-cell NIMH packs coming. I will run two switches. I am not ready to get into regulators, expensive batteries and a new expensive charger. I am only running four Hi tech HS 755HB and one Futaba 3004.

[Zeeb]

	Quote: Originally Posted by Pilotpete
	Hi Zeeb, I read your post some months back, when you switched to A123 cells for you 50cc plane. Very compelling testimonial for A123's! I have a 2S 2300mAh in a 26cc powered QQ Yak, a bit overkill. If I tried to run out that pack in one days flying, I'd probably black out

Well Dick Hanson tried to convert me for about 6 months and I just wasn't ready to trash some very spendy Duralite battery setups. But that brownout issue with the 50cc model convinced me and the couple of slimers I keep around even have the 1100 mah A123's now.

Still got Li-Po's to power my foamies and little 'lectric heli but all the flight packs are A123's now.