[JohnM]

Doing research on battery replacement for my Futaba 12 FGA transmitter. The existing battery is a Futaba brand, 7.2 volt, NiMh. I am considering, if possible, switching to a lithium type battery. Specifically, one sold by Thunderbolt Hobbies - a Li-Ion, 7.4 volt, 2600 mAh battery. (it is rated at 4 amp continuous discharge and 8 amp burst discharge) The maximum charge voltage for this battery would be 8.2 volts which I feel my transmitter could easily handle as often my existing NiMh is charged to that level and even slightly higher.
I e-mailed Futaba and asked them about the practicallity of me replacing the NiMh with a Lithium one. Not surprisingly, they stated that doing so would be entirely at my risk as the correct battery was a 7.2 volt NiMh. (they gave no indication of whether it would work or not). . .
Ok - disregarding the fact that the Li-Ion battery may or may not fit in my transmitter, is there a chance that I could ruin my transmitter by using it? I will be removing the battery from the transmitter in order to charge it. I also note that there are lithium batteries on the market specifically for transmitters but I have found nothing for my Futaba 12 FGA. Would appreciate your input. . . Cheers - John Mickle

[xv-townboy]

It was just pointed it out to me that your stock radio came stock with a 7+ battery. Edited my post regarding battery choice.

[Max]

Originally Posted by xv-townboy

I just put one of these in my DX7 and it works great and the fit is nice and snug(better than stock)..Last forever too.
http://rcflightstore.com/product_inf...oducts_id=3689

I checked out your radio and the stock battery looks to be the same size dimensions as the one in the DX7.Just slap on whatever plug you need and your good to go

http://www.rcgroups.com/forums/attac...mentid=1444104

Umm, I dont think that is good advice, considering JohnM'r radio is 7.2V

A DX7 runs on 9.8V nominal power (8 cell Nidcad or Nimh)

The 12FGA runs on a 7.2V nominal power (6 cell Nidcad or Nimh)

Using a 3 cell lipo that you are using in your DX 7 will FRY the 12FGA. I sure as heck would not put any 3 cell into the 12FGA.

Lets approach this more scientifically;

1) a 6 cell 7.2V Nicad/Nimh can come in anywhere from 8.4V to 6.6 (1.4V @ full charge per cell down to 1.1V @ lowest safe discharge per cell)

2) a 2 CELL lipo comes on from 8.4 to 6.6 under normal operating range. (4.2V @ full charge per cell down to 3.3V @ lowest safe discharge per cell)

If it were me, I would have not hesitation using a 2 cell lipo on the 12FGA

[xv-townboy]

Yup sorry about that.Was brought to my attention through a PM.I missed the 7+ Battery part.Post edited

[Max]

Ah... I see you must have corrected it while I was typing... its all good now

[tskca]

Anyone try one of those inexpensive Tx batteries listed on the HK website?? I am in the market too.

Seems like the only problems encountered so far by buyers have been their size and not checking the polarity of the battery leads before plugging it in. Then they do sell genuine A123 cells to make your own battery??

Ken

[bobreib]

I have not found a lipo that would fit in the existing battery clips. You will probably have to modify this. The biggest lipo that I can find that will fit is 2200 mAh .. you can get after market Nimh 2000 mAh batteries.. Is it really worth changing to a lipo ? If you get the 2700 to fit, let me know !

[JohnM]

Thanks for the replies. Ken and Bob: Ken - a friend purchased an inexpensive Tx battery from HK website to put in his Futaba Cap 9. . . it seems to work fine. He flys a lot and has had no problems. Bob: As you state, I can get an after market battery for my 12 FGA transmitter (Batteries America) but at about the same price as a lithium one from Thunderbolt. What I have learned so far is that my biggest problem will be finding one that fits within my transmitter. I am interested in lithium because I will be able to accurately charge it quickly and it will hold its charge much better than a NiMh. Thus, less charging and on a good day, I can get to the field quickly without going thru the slow charge process. Thanks for your input. . . p.s. I am not in desparate need of a new battery, so if I can find what I am looking for, will wait until the Spring to purchase.

[Flypaper]

This one might work if it fits the back. I put one in my DX8, 2 1/2 months ago and it's still going strong. Trans shows 7.4 volts and the cutoff alarm is 6.3. I do a lot of flying till lately when the weather turned to sh##. You'd just need to splice in your old connector. It has a built in device that, If you accidently left your trans on, it shuts off at a certain voltage to protect the batt. I charged it with my Acc 6 charger. Dimensions are shown on the website.

[craigk]

I've been using the HK 3 cell lipo in my 9303 for several months now with no issues at all.

However, I see that HK has an A123 type for less than $10. These are nominally 9.9 volts which gives me a bit of comfort level given the stock battery is 9.8 NiCad