Modified Racing in 2008 - 5 cells or 6?
10-02-2007, 04:23 AM
#46
For 6 cell racing, most of us today have been using a 4.5 Brushless motor (or more recently a 4.0 since LRP released one). In 5 cell racing, to be competitive you will be running a 3.5 (Speed Passion launched a 2.5 specifically for 4/5 cell racing only a month ago too) at the very least. This impacts on your runtime tremendously.
Of course the other factor is that you are able to get onto the power earlier, stay on the power for longer (ie. deeper into the corner). When you combine these elements, runtime does become an issue.
As with many of my friends up in QLD, I trust their judgement on this tremendously, especially as they have had the most experience with this. The theory behind this also makes sense to me so while I have yet to run 5 cell, I do believe that it is something worth pursuing.
In fact, in the most recent copy of Racing Lines, Andreas Myrberg (a top level racer in Europe) is quoted as saying "The lap times are better at all tracks except the really big ones. Even on those, we are only talking about 1-2 tenths of a second." Definately you all should read this article in the magazine next time you are in a hobby store or newsagent as it's extremely relevant to this thread.
10-02-2007, 04:30 AM
#47
You have forgotten something
P = V x I
Power = voltage x current
when you go down to 6V, you are increasing current to try and achieve the same power, which is your capacity! That is why 5 cells will dump quicker than 6 cells. Driving with a more constant flowing speed will reduce this effect in comparison to on / off style driving for sure though.
P = V x I
Power = voltage x current
when you go down to 6V, you are increasing current to try and achieve the same power, which is your capacity! That is why 5 cells will dump quicker than 6 cells. Driving with a more constant flowing speed will reduce this effect in comparison to on / off style driving for sure though.
I have not forgotten anything, but it seems that there are a couple of things that you dont know, your reply is a total contradiction.
Yes P=IV
But P doesn't equal capacity. Power is measured in watts, capacity is measured in milliamp hours. Hardly the same thing.
Secondly your power equation has little relevance to RC cars.
P= V*V/R will help you to understand why 6 cells is the king of power.
as R = Resistance which is constant.
More voltage more power, simple ah.
10-02-2007, 04:39 AM
#48
Hey Eames you'd better read my post again. You have just confirmed what was said.
Put it another way, if Power is the constant and you reduce the voltage, you have to increase current to get the same power. SO by increasing current you are decreasing run time. Is that better?
Of course this equation is relevant. But it is only one factor granted. I think the fact that was pointed out about going less turns / higher ratio is a more important point though.
Put it another way, if Power is the constant and you reduce the voltage, you have to increase current to get the same power. SO by increasing current you are decreasing run time. Is that better?
Of course this equation is relevant. But it is only one factor granted. I think the fact that was pointed out about going less turns / higher ratio is a more important point though.
Hey Champo
I have not forgotten anything, but it seems that there are a couple of things that you dont know, your reply is a total contradiction.
Yes P=IV
But P doesn't equal capacity. Power is measured in watts, capacity is measured in milliamp hours. Hardly the same thing.
Secondly your power equation has little relevance to RC cars.
P= V*V/R will help you to understand why 6 cells is the king of power.
as R = Resistance which is constant.
More voltage more power, simple ah.
I have not forgotten anything, but it seems that there are a couple of things that you dont know, your reply is a total contradiction.
Yes P=IV
But P doesn't equal capacity. Power is measured in watts, capacity is measured in milliamp hours. Hardly the same thing.
Secondly your power equation has little relevance to RC cars.
P= V*V/R will help you to understand why 6 cells is the king of power.
as R = Resistance which is constant.
More voltage more power, simple ah.
Last edited by X5 Addict; 10-02-2007 at 04:55 AM.
10-02-2007, 05:33 AM
#49
Whatever the electrical theory or the cause, the experience of most who run 5-cell is that run time can be marginal.
My view is that 5 cell is probably a good thing, but that for the time being at least there is no reason to remove 6-cell from the equation. If I were in charge (yeah, yeah, good thing I'm not) I would continue to run 5 and 6 cell side by side for the next 12 months at least. That leaves things open for (a) stock/19t drivers to step up to mod while still running 6 cells; and (b) preserves the potential to incorporate li-po without too much drama.
What i would change is the minimum weight for the 5 cell cars. 1375 incl timing equipment is too light. Nobody can get close to it without spending an lot of money on lightweight parts. I think 1425 incl timing equipment is more realistic - still 100 grams lighter than 6 cell limit, and more likely to be achievable (but still hard to get to).
My view is that 5 cell is probably a good thing, but that for the time being at least there is no reason to remove 6-cell from the equation. If I were in charge (yeah, yeah, good thing I'm not) I would continue to run 5 and 6 cell side by side for the next 12 months at least. That leaves things open for (a) stock/19t drivers to step up to mod while still running 6 cells; and (b) preserves the potential to incorporate li-po without too much drama.
What i would change is the minimum weight for the 5 cell cars. 1375 incl timing equipment is too light. Nobody can get close to it without spending an lot of money on lightweight parts. I think 1425 incl timing equipment is more realistic - still 100 grams lighter than 6 cell limit, and more likely to be achievable (but still hard to get to).
10-02-2007, 09:35 AM
#50
While i do not want to discourage anyone from racing mod i think that for the general punter wanting to give mod a go, 5 cell is not really gunna help them.
Especially with the brushless motors there is still tremendous grunt under the hood with a 4.5 on 5 cells. I found this wasnt quite the case with a brushed motor which doesnt perform the same on 5 cells.
A better option in my opinon would be for people to start with a mild brushed modified like a 10 - 8 turn (of course depending on the track) instead of jumping straight up to a big brushless motor with 5 cells.
PS. Im not against 5 cell it has a lot of advantages, i just dont think it would be a good thing to see the option of six cell in mod taken away.
Especially with the brushless motors there is still tremendous grunt under the hood with a 4.5 on 5 cells. I found this wasnt quite the case with a brushed motor which doesnt perform the same on 5 cells.
A better option in my opinon would be for people to start with a mild brushed modified like a 10 - 8 turn (of course depending on the track) instead of jumping straight up to a big brushless motor with 5 cells.
PS. Im not against 5 cell it has a lot of advantages, i just dont think it would be a good thing to see the option of six cell in mod taken away.
10-07-2007, 10:24 PM
#52
In fact only 4 drivers ran 6 cell while 12 ran 5 cell (including all 10 a finalists). 5 cell was faster than 6. It was also easier on tyres, easier to drive, cars more "nimble" with better cornering speeds.
That's only one track, but it's a reasonably large track with two decent straights and a 20 sec lap time.
10-07-2007, 10:32 PM
#54
Question is ... will Littlehampton's track suit 5 or 6 cell better..
10-08-2007, 12:20 AM
#56
The weight reduction IMO is not that big a differance in the equation. Drew posted the 3 fastest qualifying time and his weight with 5 cells was 1520g. A number of other drivers were over 1500g as well.
Last edited by tomt2; 10-08-2007 at 12:43 AM.
10-09-2007, 12:16 AM
#57
I am playing with 5 cell setup in my chassis at the moment and even with my mess of wires it will weight less than 1450g (maybe 1435g) with no weight reduction parts. Those guys must have been running a LOT of fans.
10-09-2007, 12:37 AM
#58
I have recently made the jump from Stock to Modified.
I started mod runnning six cells and found it awesome fun, but the car was very twitchy and a wrong blip of the throttle at the wrong time would see me off the track and into oblvion, as much fun as that was I decided to give the 5 cell mod a crack, as I race here in QLD and it seems the thing to do. I now have run time issues and cant afford to buy endless supplies of batteries just to ensure I last the race distance. I have 2 lipo packs, and will probably change my packs back to six cell to avoid the anoying issues of run time.
I must admit that 5 cells has been more controllable and seemingly smoother than six cell to muscle around the tracks, but I am sure that with some testing and fine tuning of my radio I can have a six cell car acting much like a 5 cell, with power to burn if needed and no run time issues. I also feel the weight reduction for 5 cells is way too much. Drop a cell and your allowed to drop from 1525 to 1375. way way too much. Should be more like 1450 for 5 cell in my opinion.
But I have only been racing mod for 3 meets so what would I know.
My prediction is lipo will become the norm as it is the new technology and the companies producing them wouldn't be spending the money in development and testing for nothing.
So Swanny I would make a choice of new car based on the fact that it will take LIPO batteries, rather then worrying too much about 5 or 6 cell.
These are just my newbie (to mod racing) thoughts and I of course reserve the right to be wrong. But at least with 6 cells/lipos I'll make the end of the bloody race....
Cheers
Aaron
I started mod runnning six cells and found it awesome fun, but the car was very twitchy and a wrong blip of the throttle at the wrong time would see me off the track and into oblvion, as much fun as that was I decided to give the 5 cell mod a crack, as I race here in QLD and it seems the thing to do. I now have run time issues and cant afford to buy endless supplies of batteries just to ensure I last the race distance. I have 2 lipo packs, and will probably change my packs back to six cell to avoid the anoying issues of run time.
I must admit that 5 cells has been more controllable and seemingly smoother than six cell to muscle around the tracks, but I am sure that with some testing and fine tuning of my radio I can have a six cell car acting much like a 5 cell, with power to burn if needed and no run time issues. I also feel the weight reduction for 5 cells is way too much. Drop a cell and your allowed to drop from 1525 to 1375. way way too much. Should be more like 1450 for 5 cell in my opinion.
But I have only been racing mod for 3 meets so what would I know.
My prediction is lipo will become the norm as it is the new technology and the companies producing them wouldn't be spending the money in development and testing for nothing.
So Swanny I would make a choice of new car based on the fact that it will take LIPO batteries, rather then worrying too much about 5 or 6 cell.
These are just my newbie (to mod racing) thoughts and I of course reserve the right to be wrong. But at least with 6 cells/lipos I'll make the end of the bloody race....
Cheers
Aaron
10-09-2007, 12:37 AM
#59
Im also yet to notice any troublesome wear as well.