Running radio on 9.6 volts

[FilthyPierre]

Hey, anybody out there experienced problems running your radio on rechargeable batteries (i.e. 1.2 volt NiCd/NiMh cells as opposed to 1.5 volt alkalines) ?
I have a JR XR3, which is built to take 8 x 1.5 volt cells, or 12 volts in total. I got sick of replacing them every couple of meets, so I bought a bunch of Energiser NiMh cells, which are 1.2V at 1200mAH capacity. 8 x 1.2 volt cells puts out 9.6 volts, which is a fair bit below the rating of 12 volts for the radio. Sure enough after about 3 races, when the car was at the furthest point on the track away from the drivers stand, it wasn't responsive and at one point just kept going straight ahead when I turned right. Actually, once the voltage gets to the low 10's (10.4, 10.2 etc) it seems to lack responsiveness. (The XR3 has a voltmeter display).
The JR manual says the XR3 will run on 9.6 volts, but the low voltage warning is at 9.0 volts, and once it gets there, it turns itself off pretty quickly. Running on 9.6 volts gets it down to the LV warning quickly too.
So the upshot of all this is I'm wondering what others do - do you just have a few sets of rechargeable cells or replace standard alkaline cells often ???? Is there any way I can modify my radio to run properly on 9.6 volts ?
FP

[Strange Desires]

I dont know about the volts and stuff in my radio but all I do is go to a store called The Super Store. They have boxes of, I think it was 40, AA batteries for pretty cheap. Then I just replace the eight in my radio when needed.

[Top End]

Pierre - I had the same problem you are describing, I had the same brand NiMH batteries even. I eventually stopped using them and just went back to alkalines. Just too much glitching from the weaker signal.

[Grizzbob]

That's why I use rechargeable alkalines(the ones from Rayovak). I first tried some in my Discman, & they worked so well, I decided to try them in my transmitters too, & I couldn't be happier. The voltage output is exactly like regular alkalines, & as long as you don't deep discharge them, you'll get many months of strong service out of them before they start to lose some capacity. As a routine, I always put them back in the charger for them right after I get home from a day of racing(they will usually always last a full day's worth of racing with no problems), & then they can sit until it's time to race again(though it doesn't hurt to repeak right before you leave to go to the track). They really do work just as well as advertised, just follow their directions, & you'll be happy..... http://www.rccaraction.com/ubb/smile.gif

[Grant Tokumi]

Grizzbob, thats a good idea with the rechargable alkalines. I never thought about that.

I currently run alkalines in my JR756 and live with just replacing them. You know how the saying goes "if it sounds too good to be true, it probably is". That was my feeling towards those recharging alkalines when I first heard about them, but maybe I'll try it now.

Filthy, if you are willing to do some modifications to your radio, I've heard of people using an external 12 volt battery pack (gel cell, or 10 nicads) in their pocket with a wire to the radio. Another option would be to somehow attach 2 extra AA nicad cells to your radio, with 10 cells you'll have 12 volts.

[FilthyPierre]

Grizzbob, thanks I'll give 'em a try. I too was a bit dubious about rechargeable alkalines.
Grant, I've thought about an external power source, but had that idea thwarted when I found out that external power sources for radios were banned at official meets here in Oz (of course noone can tell me why). And seeing as our club secretary is also secretary of the state governing body, it's a pretty fair assumption that ext power sources won't be allowed at our club meets (she rules with an iron fist...).
I'll try a 10-cell x 1.2V AA pack that shouldn't deform the base of the XR3 too much.
What I was really thinking about was more along the lines of getting the schematics for the XR3 and seeing if I could modify the internal circuitry to run off 9.6 volts instead of 12. But I suppose I've got no chance of getting the XR3 schematics..... unless there's anybody out there with a copy ??? Hmmm ???

[Grant Tokumi]

Thats interesting about not being able to use external batteries in big meets. The only thing I can think of is since these meets are big public events (as far as this hobby goes), the radio manufacturers might not want to see their products "modified" when they see it in the magazines. I know radio manufacturers really discourage people from modifying their radios, so to see a modified one in the magazines might be reason for them to get on the various racings organizations to discourage obvious modifications of their radios. Thats the only thing I can think of.

[rvrrun]

Maybe it has more to do with the FCC...

MS

[Nairb]

Guess what? My Multiplex Profi Car 403 radio is made to work with only 6 Nicd batteries. It comes with a small rechargeable pack of six AAs. This makes it lighter and very easy to deal with. So long expensive alkalines...

[FilthyPierre]

The Profi 403 eh ? I was looking at buying one of those to replace my stick radio. But there's only one person in Oz importing them (back then anyway) and he had just sold the last one, and a new one would take 4 weeks. The other problem was that it was $510 Oz for the radio and a receiver. The JR was $280. So what to do... wait 4 weeks and pay $510, or get it now and pay $280. Hmmmm.....
But, now I'm thinking of buying a Profi 403 anyway. Not to say the Xr3 is no good, I think it's a great radio for what you get.

As for not being allowed to use external battery packs at big meets, I seem to recall now it was on a rule sheet for the state titles.... I should look into it I guess.......

[Raimond Bogerd]

Why not look at the Profi 301? It's cheaper then a 403, has a 3 model memory ,dual rate, exponential steering ,gas- brake separate exponential, a timer. And you can just charge it with 0.6A on your peak charger as it is also is 7.2V

[Railman]

Grizz is right about the Rayovac rechargable alkalines. We have a gazillion of them around for our 3 boys' calculators, cd players, game boys, etc. They perform & hold up very well...once you understand them. They are not however very forgiving. They act just the opposite of nicads in regards to when you charge them. They do not like a deep cycle, & will fail prematurely if you run them down too low. It's still the way to go, you just got to get used to their charactaristics. I still use nicads in my Mars. It doesn't seem to mind the low voltage. The other thing about nicads is that you can blast them in about 3 minutes at 1 3/4 amps with enough juice to run 3 or 4 heats. With NMH batts it's always a trickle charge, & they take forever. Filthy, it almost sounds like the batt ends are not making good contact for some reason. My youngest son has trouble with his Python that way.