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Old 12-02-2007, 12:55 AM   #226
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Have you guys considered running mini infernos as a second class? These little buggies are more durable then 1/10th 4wds & would offer a second completely differant class. I know people have been looking at 1/10th truggies, but there just aren't any of the market today. The mini infernos need about $75 in 3racing hop ups, but once you get the set they are just as durable as any 1/8th scale & fast. If 1/10th truck is the biggest chasis on the track then the little mini infernos should run fine on the track, however I have seen the little cars handle rough blown out 1/8th scale tracks like a champ too.
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Old 12-02-2007, 01:13 AM   #227
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So is this class going to be at the Nats again? Since it is going to be out here at Hot Rod I may have to give it a try. I am already sold on BL and LIPo anyway.
It was popular this year considering only 1 months notice of adding the class and maybe different depending on ROAR does with the li-po rules. Hoepfully ROAR will annouce something soon so more can attend just for this class.
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Old 12-02-2007, 01:14 AM   #228
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Thanx guys. In our discussions, it was brought up that the larger Mah batteries have a higher average voltage. Meaning the larger batteries will have a small voltage advantage over the course of a race. But I've always thought that is not the situation with lipos. I've understood lipos to have a similar discharge rate based on their voltage, Not the Mah. Am I wrong thinking this way?

Thanx
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Old 12-02-2007, 09:03 AM   #229
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voltage is not an issue in 2wd truck. I use a 6.6 volt a123 pack & have too much power w/ my motor choice.
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Old 12-02-2007, 09:20 AM   #230
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Thanx guys. In our discussions, it was brought up that the larger Mah batteries have a higher average voltage. Meaning the larger batteries will have a small voltage advantage over the course of a race. But I've always thought that is not the situation with lipos. I've understood lipos to have a similar discharge rate based on their voltage, Not the Mah. Am I wrong thinking this way?

Thanx
You are worried about maybe .1 of volt difference between the 2 packs after 5 minutes in off-road racing where it is 80% driver and the remaining 20% I would give 10% to tire/foam choice as the next difference with the remaining 10% divided up between chassis set-up and motor/battery choice!

Off-road races are not won on the straightaway!
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Old 12-02-2007, 10:26 AM   #231
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shonuff- If you have a older losi XXXT, XXXT MF1, XXXT MF2 (and XXX buggy, XXX BK1, XXX BK2) the Thunder Power 8000 will be pretty snug in the battery box of these vehicles. I dremmeled down the insides of my battery box on my XXXT MF1 just a little on each side to get the Thunder Power 8000 to fit in good. The Maxamps will fit in these vehicles just fine with no mods. The XXXT CR has a wider battery box and will fit both of those batteries with no mods. BUT, with the losi you will need to raise the battery hold down bar to accommodate the taller 8000 pack. With the T4 it is a little easier as all you have to do is to change out the screws that hold the battery bar on with longer screws and use the thumb screw nut things. Here is a pic of the battery hold down I made with brass stock, bent to the right shape, drill some holes and that's it.
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Old 12-02-2007, 02:12 PM   #232
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thanks, i do have an mf2.

thats why i was asking about the capacity. i was going to try and get by with 5000's. but if you need the capacity, you need it.
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Old 12-03-2007, 12:09 AM   #233
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Originally Posted by party_wagon View Post
voltage is not an issue in 2wd truck. I use a 6.6 volt a123 pack & have too much power w/ my motor choice.
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You are worried about maybe .1 of volt difference between the 2 packs after 5 minutes in off-road racing where it is 80% driver and the remaining 20% I would give 10% to tire/foam choice as the next difference with the remaining 10% divided up between chassis set-up and motor/battery choice!

Off-road races are not won on the straightaway!
Thanx guys. I'll mention that and see what the response is. I was to understand that the voltage difference would matter the most in the stock class. Doesn't matter to the LHS owner in mod classes. But in stock class is where he's worries someone would have an advantage.

With Nimh there is a difference when charging at different rates but using the same battery. But lip batteries are a different breed and to me, 7.4 is 7.4 with lipo. Yes, they do vary in voltage but most of them act the same when talking about the same voltage. I appreciate the info and I'll mention your replys. The main thing is we're going Lipo here. Yippeeee.
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Old 12-03-2007, 01:38 AM   #234
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Thanx guys. I'll mention that and see what the response is. I was to understand that the voltage difference would matter the most in the stock class. Doesn't matter to the LHS owner in mod classes. But in stock class is where he's worries someone would have an advantage.

With Nimh there is a difference when charging at different rates but using the same battery. But lip batteries are a different breed and to me, 7.4 is 7.4 with lipo. Yes, they do vary in voltage but most of them act the same when talking about the same voltage. I appreciate the info and I'll mention your replys. The main thing is we're going Lipo here. Yippeeee.
In the stock class I really think you are splitting hairs on something that would make very little if any difference in a 5 minute race. A 5000 mah battery in a 2wd stock truck with a 13.5 would run around 50 minutes and 6000 mah would give around 60 minutes, so for a 5 to 10 minute Stock Truck race I don't see it making a difference unless the lighter weight of the 5000 mah battery might have an advantage over the heavier one.
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Old 12-03-2007, 02:15 AM   #235
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Good. I just wanted to know if I was wrong or not. I've thought the voltages would be the same, and now I can say it with absolute confidence. Again I thank you very much.
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Old 12-03-2007, 08:05 PM   #236
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Anybody have experience running a Novak 3.5 in the 20 minute mains? How does it compare to 4.5 or 5.5 ?

I ask because I've driven a 4.5 on a large banked oval (like 100' long) that gets watered with a fire hose. When the track was right, you could absolutely fly and at times I could have used more motor. But with a 4.5 I could only make about 35-40 laps, or about 4.5 minutes, with a good IB4200 pack (got the pack really hot too) despite a lot of feathering on the throttle. I've made just over 50 laps before, but really had to hold back never getting much past 1/2 throttle most of the time just to make run time. Usually about 35 I could see the truck starting to dump. I was wondering if in a case like that, if a maxamps 8000 would get the job done or not with a 3.5 in a 100 lap race without having to go so soft on the acceleration.

I was leaning towards needing a 12,000 but that also brings extra weight and cost. Obviously I have to be able to put the power down, but on that oval at high speeds there is more traction than you'd think. I have also played around with adding weight to the truck and it got better, but I just didn't have enough motor to really push it out of the corners. So I was thinking a 3.5, maybe with extra weight (maybe some from the LIPO) would be even better. The track is basically a lot like a 1:10 scale Bristol.

Also on a small tight big air track I could have used a little more power up some of the jumps in a place or two, especially for the Friday night races when the track was really good with plenty of grip. There were times that with a little more oomph coming out of the turns just before the doubles, that I could have made a quad jump .

Also I have a 13mm sintered rotor. Has anyone tried that ? How does that affect the power band and can you get more power than the 12.3 rotor if properly geared ? I tried my 13mm rotor in a 10.5 for a touring car enduro in my RDX but I really didn't notice a big difference at all. Not sure I'd have noticed anything if I didn't know it was in there.
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Old 12-03-2007, 08:10 PM   #237
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Good. I just wanted to know if I was wrong or not. I've thought the voltages would be the same, and now I can say it with absolute confidence. Again I thank you very much.
The voltages won't be the same. He's saying they won't be different enough to be a big deal for 5,000 vs 6,000 (true esp. if they are not almost completely discharged).

The discharge curve on the smaller mAh battery (all else being equal) will be more steeply sloped... and you'll see a lower average Volts. That's why a 4200 battery with the same initial volts as a 3800 pack will outperform it.

This all assumes you pull the same mAh from both batteries.

But like C. said above, the diff is pretty small so I wouldn't sweat it for these 2 packs. When you're talking 5,000 vs 8,000 or 12,000 that's a little more significant.
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Old 12-03-2007, 10:50 PM   #238
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swopemike--thanx. That's what I was looking for. I used the 5k and the 6k as an example. I should have put up like 3,000 against 8,000 for a comparison.

So the larger lipos will have a higher average voltage? I guess I imagined the lipo batteries would have the same performance. Just a difference in weight and runtime. But this is not the case? Ok. The hobby shop owner was correct when he explained it this way. Well, thanks again.
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Old 12-04-2007, 02:11 AM   #239
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swopemike--thanx. That's what I was looking for. I used the 5k and the 6k as an example. I should have put up like 3,000 against 8,000 for a comparison.

So the larger lipos will have a higher average voltage? I guess I imagined the lipo batteries would have the same performance. Just a difference in weight and runtime. But this is not the case? Ok. The hobby shop owner was correct when he explained it this way. Well, thanks again.
Our new indoor track has a stock truck class with 6 minute quals and 7 minute mains. I am using a 4000 mah li-po even though I have several spare 8000 mah li-pos, for the reason I want the lighter weight advantage over the voltage advantage the 8000 will have at 7 minutes that I feel will not make that much difference power wise. Voltage/more power or superior handling with weight reduction.....I go with the lighter weight on the stock truck. They're is a real example right there.

Good luck!
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Old 12-04-2007, 03:19 AM   #240
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Thanx Craps. Does the truck still meet the minimum weight with the 4K? That will be the topic from me, so I'll get it out now. LOL. I appreciate the info guys.
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