Not sure where to post this, but I think if I post it under Electronics, not many people will read it.

I do use NiMh AAs in some of my RCs. 4 of them in the stock battery holder. But they do discharge by themselves quite quickly. So in some of my RCs that I don't use as often, I use Duracells.

A problem arises when using alkalines with a Fail-Safe. Basically, the battery voltage can drop too much under heavy current drain (such as the steering servo on hard corners) and the Fail-Safe activates. Here's what I did to make my Fail-Save work with Duracells.

Added a Futaba FSU2 to the throttle servo. Unit works as advertised for returning the throttle in the event of loss of transmitter signal, but there was a problem with the low battery detection circuit. I didn't know these units wern't designed for alkaline receiver batteries, but were designed to operate with nicads at either 6 volts or 4.8 volts. Well......following the instructions set the unit up for 6 volts with my Duracells I had the trouble they describe......voltage drop from teh Duracells triggered the threshold at 5 volts and the throttle servo returned to idle. (Interestingly, it did not come back in 1 second like it says in the manual, but stayed there until I turned the reciever off and then back on).

Too much servo load caused this voltage drop with new batteries. So after a few voltage checks, it appeared that the voltage bottomed about 4.4 volts under full servo load. So, I decided to set the Fail-Safe up for the 4.8 volt setting. This unit automatically detects the voltage when you turn on the receiver while holding the "SET" button on the fail-safe. So, I took out one of the AAs and shorted the void with a jumper wire. This temporarily gave me 4.5 volts and the Fail-Safe responded thinking I had a 4.8 volt nicad pack. Then I put the AA back in and everything is fine. The fail-safe shouldn't shut anything down now until the batteries are truly on their last legs.

Since then I changed to 4 NiMh AAs and left the Fail_safe adjusted as it was, to 4.8 Volts and everything still worked fine.

A final note: many people use a throttle return spring. A good idea, but keep in mind a strong one drains your Rx batteries quicker as the servo continually fights against the spring during normal running.

That is eerily similar to what my failsafe does. It's almost as if you've driven my CEN before.

Why would you ever use 4 1.2v cells?

1/ Because they hold their voltage at a higher current than alkalines, hence more power to the servo under high servo loads.

2/ They fit the stock battery holder.

3/ They are rechargeable (I added a charging jack to my Savage so I wouldn't have to deal the radio box cover....RTR25)

4/ They are cheap, and avialble locally at many stores such as Wal-Mart, Grocery Store,, Canadian Tire etc, and are often on sale too.

5/ If one battery fails, you only have to replace it, not the whole pack

6/ Performance is great. Maybe my steering servo would be stronger with a 6 volt rechargeable pack, but I havn't seen any performance issues so far.