Lipo vs Nimh Racing and Minimum Weight
 

for those who want to run Lipos- do you think its fair that if you want to run, say an Orion 4800mah pack, and your car weighs in at 1275g (ex:Yok BD w/ 4800 pack weighs around 1275 rtr) with that pack, and its 7.4v, of course....and you're racing against others who prefer the 6 cell nimh packs, and they are running 6 cells at 1.3v each for a total of 7.8v, but their car weighs in at 1550g, due to the extra nimh pack weight...Here's the catch...those running the NIMH matched cells demand that you run your lipo equiped car at their class's minimum weight limit of 1500g...is that fair? If you now have to run at their weight of 1500g, wouldnt that extra 125g of lead you'll need to add to your car to meet weight decrease your cars performance and put you at a power and speed disadvantage when racing a NIMH equiped car using recent pro matched cells? You'll be running your Lipo at 7.4V @1500g, but they'll be running 7.8V with the current pro matched cells and have more punch and power that our Lipos? Is that fair? Maybe those that run Lipo can run at 4-5 cell nimh weight and thus make it more fair to run against the 6 cell powered cars? That would mean 2 weight limits for each battery type. Or maybe limit the power on the 6 cell nimh so its at 7.4V, like the Lipo? We are trying to sort this out at our club races coming up and would like to know what you all think...it gets even trickier for those running 5 cells...then what?

Its a huge pain to add all that weight and keep the car balanced but its fair.

I think they should run whatever they want. Probably get more racers that way and that's the bottomline right? We're here for fun. No big paychecks at stake right?
See what happens. If one setup absolutely OWNS the other setup, that's when you can determine if adjustments are needed. That will be the best measure of the difference. You know the fastest guys will still be the fastest no matter what they run. They prove that every time out.
It's rarely decided in a dragrace to the checkers.

A regular battery is 7.2 volts not 7.8, Yes Lipos some are 7.4...:cool:

Be happy you can run them at all, and play fair with other racers to avoid animosity. Save the weight reform campaign until a majority of people have switched.

Exactally.. I would give a 25grm wt grace at a club event to lipos users, But thats about all.

you cant have it all, first lipo with nominal volatge of 7.4v and a huge weight savings vs heavier 7.2volt nihms.. They are 7.2 not 7.8volts...


It dont mater if you run lipo or nihm 6 or 5 cells when u hit the scales they all need to be the same.

IF you want to run under 1500g legally disconnect either the front or rear drive belt and run 2wd. The rules for a 2wd TC weight are much lower.

we have compared the two set ups...one running his car w/ Orion 4800 pack and weighed in at 1280g ready to run...the other w/ IB 4200 matched cells weight in at 1501g...the Lipo equiped car was faster. When the Lipo car was brought to the 1500g weight, the Nimh car was faster. THis you can easily test at your local tracks and see for your selves...especially w/ timing equipment. Just make sure the nimh cells are good quality pro matched cells- no practice pack stuff...Now if you run 5 cell nimh at 1500g weight limit, vs a 2S Lipo car at 1500 weight limit, then its a bit different. Things are a bit more even here...the Nimh 5 cell car weighs in about 1450g, but needs to add the 50g to get to the 1500g limit, thus making it like a 6 cell weight car, but it only has about 6.9v-7.0 agains the Lipo's 7.4V. Hmmmmm....

With lipo, it's best to make the weight. Those running NiMH will have a voltage advantage particularly in stock as shown in other discussions. By making weight you'll remove most rational objections against running side by side giving the advantage towards the nimh side.

Today's pro matched cells are in the 1.26-1.27 range and higher...that times 6 = 7.56V...that's significant, and will be a weak cell when the newer and better 4500-4600 nimh 1.28v-1.3v packs come out in a years time...so what then...

Just out of curiosity since I quit using them. What peak voltage out of a 7.2V 4200 pack are you getting? Since lipo will peak at 8.4v do you feel nominal voltage is a valid comparison?

I agree however weight needs to be even to reduce controversy in mixed running.

Its happened at our Club...90% runs Orion Lipos...and for 2008, the Florida State On -Road Series will allow Lipo and brushless...others will soon follow...that's why we need to discuss this now.

As kuzo said, NiMH will have a voltage advantage, and likely be faster in stock touring cars with equal weights. That voltage advantage will vary depending on motor and style of racing, which may be why LiPo seems to be gaining popularity in off-road faster than on-road.

It's very telling that people get so excited about a battery that is much lower voltage than the current "hot" NiMH. For many, the other benefits far outweigh the voltage disadvantage, enough so that they're willing to deal with it an hope to make up time in other ways. It appears the battery companies agree, as evidenced by the recent news that SMC is releasing their own "brand" of LiPo.

Perhaps, then, it's time to consider reforming weight rules locally. Keep in mind that not all chassis will perform well though, which could have the unintentional result of giving an advantage to cars more likely to benefit from lighter weights, such as the Type-R. It would be a mistake to obsolete all other chassis with new weight rules.

Maybe a 7.4 2s lipo can have its 1450 weight limit? Those running 5-6 cells have the 1500g weight limit? Its been proven already that 5 cell nimh is faster per lap than 6 cells, but their weight is 1425g for 5 cells (dont know the exact number off hand...it could be different), but its not 1500g...that would make it unfair agaist a 6 cell 7.5v nimh car.(using recent 1.27v cells)...the 6 cell would have abit of an advantage here, I suppose...I guess it'll be a good test...i'm sure its been tried and tested