which is best? 4.8v or 6v ?
02-04-2008, 11:48 AM
#26
RE: which is best? 4.8v or 6v ?
ORIGINAL: dirtybird
Because they didn't know any better.
Gorden Banks, editor of RCR tested this a year or so ago and published the results in RCR. Check it out.
Because they didn't know any better.
Gorden Banks, editor of RCR tested this a year or so ago and published the results in RCR. Check it out.
Mark
02-04-2008, 12:13 PM
#27
My Feedback: (198)
Join Date: Feb 2002
Location: El Reno, OK
Posts: 6,707
Likes: 0
Received 0 Likes
on
0 Posts
RE: which is best? 4.8v or 6v ?
No.
I = E/R. Voltage goes up, CURRENT goes up, assuming "R" (load) remains the same. 4 / 2 is less than 6 / 2.
Ohm's law.
Total "Power" (as in WATTS) goes up, too.... P= I * E....
Any statements contradicting this "law" is simply someone who is not knowledgeable in the most basic Electronics theory.
Sorry, but that's the fact.
Doesn't matter "who" writes it.... if someone is contradicting Ohm's law, they are WRONG.
I = E/R. Voltage goes up, CURRENT goes up, assuming "R" (load) remains the same. 4 / 2 is less than 6 / 2.
Ohm's law.
Total "Power" (as in WATTS) goes up, too.... P= I * E....
Any statements contradicting this "law" is simply someone who is not knowledgeable in the most basic Electronics theory.
Sorry, but that's the fact.
Doesn't matter "who" writes it.... if someone is contradicting Ohm's law, they are WRONG.
02-05-2008, 08:21 AM
#28
My Feedback: (5)
Join Date: Jan 2002
Location: San Tan Valley,
AZ
Posts: 5,768
Likes: 0
Received 0 Likes
on
0 Posts
RE: which is best? 4.8v or 6v ?
ORIGINAL: Bob Pastorello
No.
I = E/R. Voltage goes up, CURRENT goes up, assuming "R" (load) remains the same. 4 / 2 is less than 6 / 2.
Ohm's law.
Total "Power" (as in WATTS) goes up, too.... P= I * E....
Any statements contradicting this "law" is simply someone who is not knowledgeable in the most basic Electronics theory.
Sorry, but that's the fact.
Doesn't matter "who" writes it.... if someone is contradicting Ohm's law, they are WRONG.
No.
I = E/R. Voltage goes up, CURRENT goes up, assuming "R" (load) remains the same. 4 / 2 is less than 6 / 2.
Ohm's law.
Total "Power" (as in WATTS) goes up, too.... P= I * E....
Any statements contradicting this "law" is simply someone who is not knowledgeable in the most basic Electronics theory.
Sorry, but that's the fact.
Doesn't matter "who" writes it.... if someone is contradicting Ohm's law, they are WRONG.
However servomechanisms react differently. If the load stays the same, the servo amplifier will reduce the current supplied to the motor in order to keep the servo arm from moving. The watts will remain the same. It has to. Otherwise the servo will move away from where you want it to be.
I don't think the RCR report is on line. Email Gordon Banks of RCR. I am sure there is a back issue still available.
Some of you diehards might want to get a book on simple DC motors. Reactive loads are different from resistive loads.
02-05-2008, 10:03 AM
#29
RE: which is best? 4.8v or 6v ?
As a died in the wool weekend sports flier I have often wondered if I was missing out on anything by sticking to using 4.8 volts on all my models and not moving up to 6 volts. Thanks to this thread I now pretty much know the answer.
Karol
Karol
02-05-2008, 12:22 PM
#30
My Feedback: (198)
Join Date: Feb 2002
Location: El Reno, OK
Posts: 6,707
Likes: 0
Received 0 Likes
on
0 Posts
RE: which is best? 4.8v or 6v ?
Good points, db.... so to address that, there is STILL "more" current, and more power consumed using a 6v source above a 4.8v source because the reactive load is greater DURING TRANSIT of the servos.... so... dynamic load of the total system (during servo movement) is using more current and consuming more power with a 6v source than with a 4.8v source. It has, and can, be measured.
02-05-2008, 03:49 PM
#31
My Feedback: (5)
Join Date: Jan 2002
Location: San Tan Valley,
AZ
Posts: 5,768
Likes: 0
Received 0 Likes
on
0 Posts
RE: which is best? 4.8v or 6v ?
Right but during dynamic conditions the back EMF generated by the motor tends to limit the current as well. The end result is you will barely be able to tell the difference in the capacity between the two batteries.
Performance comes at a price. You already paid the price when you installed the extra cell.
Performance comes at a price. You already paid the price when you installed the extra cell.
02-05-2008, 04:08 PM
#32
My Feedback: (198)
Join Date: Feb 2002
Location: El Reno, OK
Posts: 6,707
Likes: 0
Received 0 Likes
on
0 Posts
RE: which is best? 4.8v or 6v ?
Great discussion -- but capacity of the battery wasn't my initial concern, rather the consumption of power under heavy(er) flight loads, digital servos, etc. which DOES increase the current demand and power consumption. Those things *do* occur, and are the primary reason that many choose to run larger capacity cells.
This is almost a chicken and egg thing, but great discussion!!
This is almost a chicken and egg thing, but great discussion!!
02-05-2008, 10:20 PM
#33
RE: which is best? 4.8v or 6v ?
Another factor is that normally a servo will spin faster under 6v than 4.8v. that is, it takes less time to reach a position with a 6v battery pack. So the actual energy used (note the time dimension is involved here) to achieve that could be about the same. assume that the servo load is same for both configurations.
A higher voltage circuit (e.g., a servo) could dissipate more heat, thus consumes more power.
A higher voltage circuit (e.g., a servo) could dissipate more heat, thus consumes more power.
