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Old 10-13-2008, 09:42 PM   #31
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I look at these things when considering which is better..

- 6 cell nimh peaks at a higher voltage but drops to a lower voltage by the end of the 5min run than lipos
- nimh dont have the continuous discharge or burst discharge capabilities that a lipo battery pack does
- charging seems easier for lipos, especially with a built-in balancer
- nimhs have a shorter lifespan than lipos, this is important as despite the fact you might be driving better your nimh packs are getting worse over time and this is masking the fact that you're getting better
- cost of lipos vs nimh seems to be on par at the moment, especially if you're using 5 cell nimh vs lipo.. no need to spend serious $$ on the premium lipos when they are just as good as lipos half their price

There are a lot of factors for me, but the first 2 above are the ones which will see me getting better times with a lipo vs nimh.

-Mark
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Old 10-13-2008, 10:08 PM   #32
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Well i think nimh are a bit funny because they run best on their second run and drop a bit on their third. i ran one day nimh and second day lipo. i think the lipo is prob quicker because it has a smoother throttle response. i noticed that the acceleration on the lipo was very linear so it was easier to drive consistently. Another added bonus is that you can put your weight down low on the chassis and can weight balance your car side to side and adjust forward rearward balance.
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Old 10-13-2008, 11:27 PM   #33
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Before Lipo, I was limited (budget constraints) to using loose nimh sub-C cells. They were ok but definitely no match for other racers' matched packs. After switching to lipo, my lap times were definitely faster and more consistent throughout a 5 minute race. It also reduced the performance gap with those running matched nimh packs. Now most racers in our club run lipo and about 90% run the same pack. It has pretty much evened out the battery factor for now.
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Old 10-13-2008, 11:28 PM   #34
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Quote:
Originally Posted by mok View Post
I look at these things when considering which is better..

- 6 cell nimh peaks at a higher voltage but drops to a lower voltage by the end of the 5min run than lipos
- nimh dont have the continuous discharge or burst discharge capabilities that a lipo battery pack does
- charging seems easier for lipos, especially with a built-in balancer
- nimhs have a shorter lifespan than lipos, this is important as despite the fact you might be driving better your nimh packs are getting worse over time and this is masking the fact that you're getting better
- cost of lipos vs nimh seems to be on par at the moment, especially if you're using 5 cell nimh vs lipo.. no need to spend serious $$ on the premium lipos when they are just as good as lipos half their price

There are a lot of factors for me, but the first 2 above are the ones which will see me getting better times with a lipo vs nimh.

-Mark
Well said
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Old 10-14-2008, 01:10 AM   #35
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What I noticed, is that it is especially faster for smooth drivers. I'm talking about buggy racing here. We have a weight limit of 1479gr here, and with Li-Po packs we weigh about 1500gr. At the start of the heat it gives you an enormous punch, so you have to be able to deal with it, but even my cornering speed increased with it.
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Old 10-14-2008, 04:36 AM   #36
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Originally Posted by RCSteve93 View Post
I think I have to go to TC now... or wait for LiPo in 1/12th.
1/12 is one place where I see Nimh sticking around a little while for 2 reasons

1- even though the lipo will be more consistant through the whole 8 minutes, a 3.7v average voltage will be a definite handicap when compared to a 4.8v average voltages, especially in stock class. There fore the only answer would be to split up the 2 and run 2 seperate classes. And learning from touring that is something i dont want to see happen, There is nothing more silly than to have 6 guys running stock TC but to have it split into 2 because 3 are running foam and 3 are running rubber.

2- It will make weighting the car very tricky.There is already a lack of space to mount things in a 1/12 car so adding 3 oz of weight to a 1/12 car could get to be a little bit of a pain trying to add all that weight and still keep the car balanced.
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Old 10-14-2008, 10:31 AM   #37
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I am faster with Lipo. They can provide more power even with high current draw. This equates to fast acceleration. Having consistent power is so much easier to drive.

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1/12 is one place where I see Nimh sticking around a little while for 2 reasons

1- even though the lipo will be more consistant through the whole 8 minutes, a 3.7v average voltage will be a definite handicap when compared to a 4.8v average voltages, especially in stock class. There fore the only answer would be to split up the 2 and run 2 seperate classes. And learning from touring that is something i dont want to see happen, There is nothing more silly than to have 6 guys running stock TC but to have it split into 2 because 3 are running foam and 3 are running rubber.

2- It will make weighting the car very tricky.There is already a lack of space to mount things in a 1/12 car so adding 3 oz of weight to a 1/12 car could get to be a little bit of a pain trying to add all that weight and still keep the car balanced.
I have seen, but I can't remember where, a saddle pack setup where the two sides of the saddle were 7.4 volts each and the saddle connection was a parallel connection. So, half of the saddle would be about the size of 4-cells and it would be 7.4V. It was a lower amp hour rating, but still, that can be dealt with by adjusting the number of turns in the motor.
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Old 10-14-2008, 06:54 PM   #38
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Originally Posted by SWTour View Post
I don't think SPEED is the issue with LIPO, it's NOT having to chase NiMh batteries...

A lot of people think LIPOs are a ton higher on voltage than a NiMh, but they are really not.

The 'average' discharge voltage (depending on how big of a pack you are running) can be .3 - .4 volts higher I believe...maybe just a tick more.

But, LIPOs can run SO consistant RUN after RUN after RUN. That is where I've seen guys improving their times...NOT from actually being faster.
Exactly, I don't think I'm really going any faster because of LiPos, but that's not why I got them. I finally got a LiPo because I only need ONE pack, instead of the 3-5 packs I needed with NiMh's or NiCd's(in fact, with NiCd's, I usually needed more like 6 packs, since they didn't like being used any more than once per day). Right now, I have just one SMC LiPo, & I use it for EVERY run, from the early practice runs to qualifying & the main(as many as 6 or 7 runs in a race day), & what's even better, after that kind of use for over 6 months, I haven't noticed even the SLIGHTEST bit of dropoff in performance, something I've never been able to say about ANY other kind of battery I've ever used. It's not the performance, it's the convenience & consistency that is the LiPo's real advantage(as well as the money savings in the long run).....
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Old 10-14-2008, 07:02 PM   #39
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Quote:
Originally Posted by kufman View Post
I have seen, but I can't remember where, a saddle pack setup where the two sides of the saddle were 7.4 volts each and the saddle connection was a parallel connection. So, half of the saddle would be about the size of 4-cells and it would be 7.4V. It was a lower amp hour rating, but still, that can be dealt with by adjusting the number of turns in the motor.

I think track power makes them.
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