2canSAM

iTrader: (248)

Found my answer here http://www.rcuniverse.com/forum/m_90...tm.htm#9060712

Now if Hobbyking would just get them to me so I can play


I have been in an out of RC for years. Started electric with 6 cell, went to nitro then back to electric. For the past 2 years I have run only 7 cell (8.4) nimh batteries and just recently moved to a brushless setup. Since I was going brushless I decided to move to lipo and went with these. I recently tried a 6cell nimh and was really surprised at how much slower it seemed. Seeing as 2S lipo is only 7.4 volt will me speeds be about equal to a 7.2volt 6 cell nimh?

BCbud

iTrader: (37)

Good day!

Brushless motors have less rpm and more tourque, did you chainge your gearing for this?

Duster_360

iTrader: (21)

2S lipo 'nominal' voltage is 7.4v but when fully charged off the charger, it will be 8.4v since lipo chargers charge the cells to 4.2v/cell. Lipo holds voltage much better than all but the very best, precisely maintained NiMhs so you'll have higher voltage longer while running hence the performance diff.

This nominal business is like saying all sub c cells are 1.2v when they are higher when fully charged.

racer1812

iTrader: (31)

+1....2s 7.4v lipo is equal to a 8.4 nimh...give or take a little one way or the other depending on the quality of the nimh. IMO

benben10

your 2s lipo should be similar to your 7-cell nimh but more runtime and much less power dropoff over the course of a run. you might even be able to put a larger pinion on the motor to go faster and the batteries should be able to support the higher current load. by supporting current i mean it will hold voltage. batteries drop in voltage temporarily whenever they have to "push" more current in addition to the gradual dropoff in voltage as the battery drains. lipos are better about both of these things than nimh batteries. they have higher voltage under similar current loads to nimh and they drop voltage less as the battery drains. a 7-cell nimh finishes with voltage near 6volt and probably drops near that under high current loads. a good 2s lipo will stay well above 7 volts most of the run and even during high loads. these batteries will definitly out perform 6-cell nimhs and even keep up with 7-cell and out last them. the only time 7-cell might have an advantage is during the first 30seconds-1minute that you start running them IF the nimh is still warm and fresh from the charger.

plus if treated properly your lipos will last much longer and maintain performance better as they age compared to nimh

1717LST

iTrader: (5)

You definatly notice a difference. The lipo will have a much better punch.

Duster_360

iTrader: (21)

And noticeably longer runtime. Lipo doesn't get hot like NiMh since teh IR is much less for lipop that NiMh. Lipo doesn't waste all that energy as heat like NiMh and that translates to longer run time. Plus lipo weighs less than NiMh.

You do need a lipo capable charger and a low voltage cutoff in your RC so the lipo is protected from overdischarge.