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LiPo vs NiMH- Different perspective

LiPo vs NiMH- Different perspective

Old 03-18-2007, 08:56 PM
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Originally Posted by adamge
What impossible hurdle prevents 7.4v from being usable in 12th scale?
You probably would need to run a 14-16 turn motor instead of a 10-12 turn motor, but you're right, I don't necessarily see the voltage as an issue. I wonder if you could regulate the voltage in some way like you can with A123 cells and limit it to 6V or so for 12th scale. Of course, policing the regulator could be a pain for a sanctioning body...

The other interesting limitation to Lipos is their weight.... I can't imagine how a 12th scale car would handle with nearly 4oz of weight taken off of it...could be scarry There also isn't a lot of room in a 12th scale to add the weight back...could be interesting...

In my offroad cars, the weight issue is much more pronouced. My B4, T4 and XXX-CR all push like crazy since I started using them because of the loss of 6oz over the nose and middle of the cars. Even when adding weight back (if you can accomplish this..it's hard to get 6oz to fit!) handling can be an issue. I may get an X-6 conversion as a result, or get a Tamiya 501X or Yokomo 4WD that has the motor in the middle and a saddle pack at the rear (I would get the Maxamps saddle lipo for that application...although I wouldn't like the softer shell of these packs.. I wish Orion wouldn't wait for ROAR or other sanctioning bodies to legalize Lipos before they develop these different forms of packs, since other manufactures are making money filling in the configruation gaps and since they introduced their current lipo packs without ROAR approval in the first place... ). You can always get the rear to hook up, but elimiating push is a different matter.

From what I've seen, the on road touring cars don't seem to have as many issues regarding the weight of the lipo packs.. I may have to add some back on my new Evo V, but I haven't heard of any issues. Also Losi and Schumacher have made cars that have been specifically designed to accomidate lipos as well as nimhs and I assume they have been tested for the proper handling characteristics with each type /weight of battery.

I think nimhs when at their optimum performace can outperform a lipo powered car because a lot of cars are designed around the nihms shape and weight, and lipo racers may have trouble finding spots to add weight in the optimal positions. I think the voltage adavantage nimhs possess at the start of a race may not make much difference if you like to run a few warmup laps...that adavantage may get burned up some before the race even begins.
Still, now that a few manufactures are making cars specifically around lipos, the gap could narrow or even favor the lipo car depending on weight allowances in classes..... but I'm not sure if one form fo battery is purely better than the other at the moment...

Personally, I'm a club racer and like the Orion 4800s I have a bunch...I got so tired of replacing bad nimh cells ever 2 months and having to buy 3 packs every 3 or 4 months... I also like the fact that I don't need to worry about getting the battery peaked at just the right time right before the next heat and discharging it /matching it, etc... I just top them off after each race and
do other things...takes a lot of stress out of the racing experience

I have a 12th scale car, but It's going to be on the shelf for a while because I really don't want to go back to nimhs again. If they made nimhs that were more durable and less expensive, I wouldn't mind going back... but they're just a hassle right now as is... I just got a Darkside 10th scale pan car that I'll race instead...using a 4800 lipo down the center of the car..should be fun
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Old 03-19-2007, 09:02 AM
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Originally Posted by adamge
What impossible hurdle prevents 7.4v from being usable in 12th scale?
Because in most instances 1/12 runs on 4 cells, or 4.8 volts.
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Old 03-19-2007, 09:10 AM
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We're considering completely changing the battery as we know it to make racing a better thing to do. The objective here isn't to duplicate what we have, it's to come up with something better.

That generally involves change. There's a difference between a change that can't work and one that can. Going from 4.8v nominal to 7.4v nominal is a change that can work.
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Old 03-19-2007, 10:01 AM
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Originally Posted by Justinian
I wish Orion wouldn't wait for ROAR or other sanctioning bodies to legalize Lipos before they develop these different forms of packs, since other manufactures are making money filling in the configruation gaps and since they introduced their current lipo packs without ROAR approval in the first place... ).
if your willing to use a soft non cased LiPo then we actuaslly already make a battery that can be used as a pair in our avionics line it is 1500mAh and when paired and used in parralel will make a 3000mAh battery that is true 20C this will allow it to be used in a 4 wheeler or 1/12 scale.

http://www.teamorion-avionics.com/Ba...Li-Po/1500mAh+

We have actually have some of drivers useing these in testing.
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Old 03-19-2007, 10:37 AM
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Adamage, I am not sure how long you have been racing, but 1/12th scale was switched to 4.8 volts for a reason. The cars were simply WAY to fast and with the amount of power they had, they were getting impossible to drive. A 7.4 volt lightweight battery would be even worse now, especially with the motors we have now a days.

The class was revived when they switched to 4 cell.....and it has a steady following ever since. 1/10th scale pan never made the switch and suffered a horrible death....

Not to mention, it will make pretty much every single chassis out there worthless.....

Later EddieO
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Old 03-19-2007, 11:01 AM
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Good to know. To make lipo work for 12th scale they would also have to change the motor rules. Maybe a ~35t motor for 12th stock, or even drop motor size.

That's a pretty huge change to the equipment (motor, battery, and chassis).

I'm guessing there won't be much support for it.

-Adam
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Old 03-19-2007, 02:21 PM
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Going to 7.4 volts in 12th won't work because it would be too much power for the average racer. If you figure that we average 30 amps in stock (more or less) you get an average power used of 222 watts at 7.4 volts and 144 watts at 4.8 volts. That's 35% more power at the same weight or less.

More voltage would kill the mod class off almost immediately. We're running 50mph plus on the straights now in mod and that much more power would put things over the top even more.

Running a receiver pack and a one cell voltage of 3.7 would make more sense for 12th than 7.4 volts. With the speeds that we have now, it makes more sense to take about 20% away than add over 30%. I haven't tried running on reduced voltage but it would be worth a try.
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Old 03-19-2007, 03:45 PM
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The 4 cell classes would indeed be a challenge, and shouldn't be overlooked. I suppose they could stay NiMH for a while, but if R/C moves toward LiPo, the supply of quality matched cells could dry up since those are rather small segments in comparison.

Is 3.7V with faster motors out of the question? I'm guessing you'd -have- to run a receiver pack, but would there be any other drawbacks?
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Old 03-19-2007, 03:46 PM
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We would just need Novak to make a regulator that can handle more amps than their servo regulator. Seen here http://www2.towerhobbies.com/cgi-bin...?&I=LXJJF6&P=7 and make it 5V instead of 6.
I am sure the weight of a regulator will help more than hender at that point.
Than you could use a 7.4V lipo in 12th scale with only 5V being let out at any one given time.

I have been using their Servo Regulator in my truggy with a lipo receiver pack for 8 months with nothing but good things to say.
1) I get insane amount of runtime on one charge, full race day without re-peaking.
2) Its lighter than NiMh.

-Shookie <><
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Old 09-05-2007, 12:17 PM
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