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Old 07-13-2006, 09:35 AM   #301
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I think some people are confusing runtime and voltage. This idea of reducing the number of cells is geared to reduce the voltage not runtime. However as stated above the runtime will suffer...but thats not the focus.
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Old 07-13-2006, 09:39 AM   #302
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Originally Posted by WhoMe
I think some people are confusing runtime and voltage. This idea of reducing the number of cells is geared to reduce the voltage not runtime. However as stated above the runtime will suffer...but thats not the focus.
They go hand in hand. Reducing the voltage will possibly solve the heat problem, which is the original issue. It would be tragic to go to 4-cells and solve the heat problem and all of a sudden run time becomes the issue, don't you think?

I mentioned earlier in this thread than nobody had even tested 4-cells. It HAS been tired, but until we know what the actual effects of the change are (run time, speed, lap times, motor and brush life), and if they even solve the heat problem, it is premature to make such a drastic change.
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Old 07-13-2006, 09:42 AM   #303
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Just to clarify my thoughts on 4 cell 27,you probably won't need the runtime anyway so to knock off 2 cells surely won't be a big deal.

The main issue is with modified,where the amp draw/discharge? are higher... (think I got that bit right,lol).
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Old 07-13-2006, 09:59 AM   #304
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Just a thought - if we drop from 6 to 4 cells. . .we're already having some issues with BEC voltage with some of the new receiver and servo systems out there. . . won't dropping 1/3 of the voltage possibly exacerbate this?

(I say this knowing that the ESCs DO some voltage regulation to the BEC circuit. . .)
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Old 07-13-2006, 10:08 AM   #305
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Quote:
Originally Posted by Boomer
Just a thought - if we drop from 6 to 4 cells. . .we're already having some issues with BEC voltage with some of the new receiver and servo systems out there. . . won't dropping 1/3 of the voltage possibly exacerbate this?

(I say this knowing that the ESCs DO some voltage regulation to the BEC circuit. . .)
We'd probably have to run a reciever pack.

4 cells will also kill 27 turn as the spec/stock class, the cars will be brutally slow.
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Old 07-13-2006, 10:09 AM   #306
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and once you add a receiver pack, so much for the weight savings of dropping two cells
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Old 07-13-2006, 10:11 AM   #307
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5 cells

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Old 07-13-2006, 10:14 AM   #308
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Quote:
Today 12:09 PM
tallyrc and once you add a receiver pack, so much for the weight savings of dropping two cells
5 cell mini receiver pack is still lighter than one Sub-C.
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Old 07-13-2006, 10:19 AM   #309
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Quote:
Originally Posted by Rick Hohwart
Not exactly. Battery capacity does remain the same, but you have reduced the packs available energy (which is the point in the first place). Less energy could very well result in less run time.
i'd like to see some real testing on this either empirically under race conditions, or by discharge testing.. losing two cells may cut "energy" (mwhr) but some will be recouped by less resistance becasue of the lack of 2 cells.. under certain conditions 4 cells can be more efficient that 6.. run time will be affected, when people try to compensate for the lack of voltage by once again gearing up or increasing timing...

maybe a timing rule is in order???
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Old 07-13-2006, 10:29 AM   #310
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Quote:
Originally Posted by tallyrc
maybe a timing rule is in order???
in mod ?
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Old 07-13-2006, 10:32 AM   #311
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Quote:
Originally Posted by Boomer
Just a thought - if we drop from 6 to 4 cells. . .we're already having some issues with BEC voltage with some of the new receiver and servo systems out there. . . won't dropping 1/3 of the voltage possibly exacerbate this?
Dropping to 4 (or 5) cells WILL result in more problems not least with personal transponders missing laps, luckily at MRT we have developed the i-PT (our own improved personal transponder) which can run without any problems at lower voltages.

With 4 cells the extra weight of a touring car would mean more potential problems due to the volt drop under hard acceleration or from the current draw of high power servos. A receiver pack would be needed to avoid problems, so more weight to add to cars plus rx batteries to buy and charge etc... is this really such a good idea?

We are of course talking about in the future, right now there are no major problems that need fixing, unless batteries are likely to exceed 5000mAh most existing electronics should be fine and not suffer from overheating. Thermal shutdowns are not what the majority of racers experience in Mod TC even in hot countries.

It would be good to know if we are likely to ever see 5000mAh+ cells, there must be an upper limit to the capacity of Sub C NiMH batteries!
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Old 07-13-2006, 10:35 AM   #312
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It wouldn't be the weight I'd be concerned with. . .it would be the complexity of yet another component to worry about, another battery pack to make sure is charged, another connection and plug and wire to make sure don't get snagged or unplugged. . . you know?
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Old 07-13-2006, 10:45 AM   #313
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Josh your right about the 10 to 15 cars on the track. After thinking it more over, I can your point. It was 4 am when I wrote it. seemed like an intreging idea.

I will be looking forward to see the out come at Vegas this Sept. Just curious is there another major coming up that is on asphalt this summer. would like to see the out come of that too. Also to see what the top drivers are doing to keep everything in check.

I guess time will tell. At least were concerned now before it's to late.
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Old 07-13-2006, 10:45 AM   #314
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Quote:
Originally Posted by Boomer
It wouldn't be the weight I'd be concerned with.
Sorry I meant that the weight of a heavier car compared to 1/12 cars would make more problems. Yes I agree, with a receiver pack there's more expense, more to maintain and charge, more complication and more hassle plus more potential problems
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Old 07-13-2006, 10:59 AM   #315
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From alot of the comments i've read braking seems to be one of the main problems with heat buildup in the esc and motor but can anyone tell me if there is any difference in heat build up between a spool and a diff?

I imagine there would be cause you dont need to brake as much with a diff, you can scrub the speed off when entering the turn. Just a thought but if you only allowed people to run diffs (no one ways either) you may reduce heat buildup (if there is a difference?) and you will slow the cars down and also reduce the chance of breakages. Might even reduce the cost of new kits as you wouldnt really need alloy/titanium driveshafts anymore.
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