Over or under voltage

[El Pirata]

Hear me out here:

Standard alkaline batteries advertised as 1.5 volts but out of the box 1.62.

Standard rechargable batteries NiCD and NiMH advertised at 1.2 but fully charged 1.38

Radio receiver designed for 6.0 volts. Some people use 4 alkaline batteries X 1.62 volts = 6.48 volts/8% over volt. Others use 4 rechargable batteries X 1.38 volts = 5.52 volts/8.3% under volt. Still others use 5 rechargable batteries X 1.38 volts = 6.9 volts/15% over volt.

So the question posed is do you think an additional 8 - 15% over volt in a receiver pack runs the risk of frying the system?

Just a thought.

For the record I run 4 NiMH batteries in my receiver that are generally 1.46 volts off the charger.

 

[SkyMaxx]

As long as the current flow is close to what is required, the voltage shouldn't be a problem.

 

[El Pirata]

So you don't think that there's a higher risk of frying the system due to overvoltage?

 

[SkyMaxx]

Not unless you are strapping on a car battery or moving to AC vice DC. Most systems get fried by overdriving the system and that is typically a current issue.

 

[El Pirata]

Yeah but use 20 gauge wire where you are supposed to be using 3 gauge wire and you'll burn the 20g up.

Same theory, I think. Bear in mind I am not an electrician, I just know how to shock myself.

 

[SkyMaxx]

Again, that has more to do with current than voltage.

I should say current and resistance to said current.

 

[El Pirata]

Ok, I'm too tired to try to discuss this rationally. Well talk tomorrow at the track. Hell we might even get a heated debate on tape.

 

[NooP]

It is to my understanding that recievers themselves handle more than 6v. As far as I know electric cars use the same recievers that nitro cars do, and they hook up with 7.4v packs. I also remeber reading somewhere(I just spent 10minutes looking for it, but can't find it) that reciever can even handle 10 volts.

I think what is more important is what the servos can handle. Most servos are designed for 4.8v or 6v. But if you look at some of the futaba servos, they only run on 4.8volts.

--NooP

 

[SkyMaxx]

LMAO...who said there is anything to discuss. You asked a question, and I provided an answer. If you don't like the answer, that is your prerogative.

Noop...good information. Thanks for posting it.

 

[robriguez]

Well the same servos we use in our nitro rides are used in electric ones as well. It could be the ESC or the speed control thats dropping the voltage down to a certain level but I think I'm going to do some tests this weekend and hook up my 3300MAH 6cell stick pack to my savage and see if I fry anything. I can get about 45 min out of these packs in my electric rides. I should be able to run for DAYS on my nitro. I'll let you all know.

 

[Rolex]

It's all within certain limits, and if we couldn't use a 5 cell hump pack vs. a 4 cell battery pack for a receiver, it wouldn't be available for that application.
Here's the lowdown in simple terms...
UP the voltage to a motor, that includes servos, and you UP the speed.
UP the amperage and you UP the muscle or power.

 

[bill61]

El Pirata if I was you I would use a five cell pack. It will increase the speed, and strength of your servos. I have also heard that it increases the distance the receiver works at, thereby reducing run aways. When I take my five cell pack off the charger it is almost 7 volts, and I have never had a problem with Airtronics or Futaba receivers.
I have a special connector that I made to place in line between my receiver and battery. When I put a load on the steering and throttle/brake servos they will pull up to 2 amps through the reciever. Again even though this is alot of current flow the receivers have never had any problems.
The four cell pack is fine for airplanes as they are always in clear view (no interference from hills, or ground obstacles) and there is usually a lighter load on the servos.

 

[El Pirata]

I've been using 4 cells for couple years now and have not had any problems. I was merely thinking about the overvoltage issue and whether some people were going to be in for a big surprise one day. Maybe as a subtle hint that people were usgine more power than they actually needed.

 

[bill61]

Well I've been running like this for over 14 years and have never burned out anything. Even got receivers wet a few times and when dried they worked fine. I don't know if the distance thing is true about higher voltages, but that is what originally prompted me to up the cell count to five. It just made sense to up the voltage since a NiCd is rated at 1.2v and an alkaline is rated at 1.5v.

 

[Rolex]

My airplanes have 4 cell rechargable packs because the control surfaces don't need as much power as a steering servo. With my mt I was using alkaline batteries for extra power, but got pretty tired of throwing away 4 batteries a day. I just went to the 5 cell hump pack, and now I get 3 days of running between charges. It will pay for itself in a month.

 

[jon2]

OK well THe ratings on battery voltage is never what you actually read. You would have to measure each individual cell to get an accurate reading. Just know that the pack is as strong as its weakest cell. As far as power, The voltage that the servos are rated at is 6v and 4v. I think I have even seen someone here experiment with 9.6v and he was running ok. To actually see what type of current he was getting out of it. Now I have seen RX packs rated at 6v with 2100Mah. That is pretty crazy as 2.1 amps is a lot. You only need 1 amp to kill you and there is a little over 2. I have been wanting to try this pack but I will wait till my pasck shrivel up and die. I went to 6v 1800Mah. It is pretty strong for me.

 

[NooP]

I hooked up a 7.2v 1500mah nicad to my buggy one time. Onlything I noticed is that it felt like I had 100 dollar servos in it.

--NooP

 

[StaticSag]

I have a bud ...I havnt tried this myself....but he uses a 9v duracell in his RC10GT and his 3003 futabas turn more like 100 dollar servos and as far as he knows its supposed to have the 9v on it. It was bought used a year ago with the 9v hook up for the reciever. I havnt seen or heard him cry of melting or burning up anything....

Saggy

 

[GilBeQuick]

Originally posted by El Pirata
Yeah but use 20 gauge wire where you are supposed to be using 3 gauge wire and you'll burn the 20g up.

Same theory, I think. Bear in mind I am not an electrician, I just know how to shock myself.

I know you were using that as an example, so I'll just use the same you used.

20ga and 3g wires are so different in size that you can't even compare the 2. That's comparing wires that one is the size of a servo wire and the other is the size of a Marks-A-Lot permanent marker.
I am an electrician and as far as wire size goes, different wire sizes are intened for different amp draws. Even though a 14 gauge wire is intended for a 15amp circuit, you can safely pull a few more amps....it's intended that way for a tiny bit of overprotection.

But, the real question here isn't really wire size, it's the sensitivity of the electronics to the tiny bit of over voltage you're giving them. Most electronics are also ever-so-slightly underrated as to the voltage they can handle. But, just because a servo can "handle" 8 volts of power doesn't mean it's good for it. It can probably handle it in very short intervals, but not for any kind of extended period of time.

If your servo is intended for 6v and you're feeding it 6.6 - 6.8 volts I wouldn't worry about a thing. If you're under a little bit I wouldn't worry about it, that's not going to hurt anything either.

(BTW, a lot of people ask if you "get used to getting shocked". The answer is NO! It's no because you never expect it. It's kinda funny, you don't know how to react to it so you always wind up squealing like a little girl.)