16.8V NiMH vs 14.8 LiPo

[egnix]

Hiho there...
I have a Summit on pre-order and I'm trying to figure out what batteries to get.
I'm not new to R/C, but I am new to these newfangled LiPo batteries. :cool:

I'd like to get the most performance out of the Summit without changing the speed control or motor. So I'm wondering, since the stock speed control supports up to 16.8 volts, which would be better: 16.8V NiMH or 14.8 LiPo.
I really like the idea of the higher capacity LiPos, but will LiPos give me lower performance due to the lower voltage?
It sounds like LiPos can output more amps than NiMH, so would this make LiPos a better choice over the higher voltage NiMH? I know Volts x Amps = Watts, but I don't know what determines the amp draw. :confused:

Also, if LiPos are the way to go, what "C" rating would be appropriate for the Summit? I don't want to pay for a higher "C" rating if the Summit can't take advantage of it.

Thanks!

Oh, BTW, I did get this out of Traxxas Support:

When using batteries with external LiPo cutoff devices:
Maximum Internal Dimensions: 29mm x 156mm x 50mm LiPo battery size
It will fit two 3s 5000 mAh LiPo packs or two 2s 8000 mAh LiPo packs

[powerslider]

I'm going to use 2 2s lipos, a 2s fully charged is 8.4 volts so two in series will be 16.8v. A good 2s pack and a good 7 cell nimh are very close in performance, the nimh will have a slight advantage initially but it's small. Bump the pinion up one tooth if you need a little more speed...

[egnix]

What "C" rating would be appropriate for use in the Summit?

[powerslider]

I like to see 100a continuous rating so 5000ma pack needs a 20c rating, I'm running brushless though. The stock motor may not need that much current but it's better to be on the high side. A 12c 8000ma pack will yield 96a continuous so that will work also if you want longer run times.

[molinajr]

How about 2 lipo 8000hv 2s 7.4volt packs
which means 40+ mph
and 48 minutes run time!

[GMMWICKED]

I ran these in my stock ERevo and run them in my Brushless ERevo. http://www.specpointbatteries.com/index.php?categoryID=13
They work great. You will need a LVC for EVX2. The lipos are great because your power remains fairly constant through out your run. The Nimhs noticeably(sp) lose thier power during your run and have less runtime. You also have to consider the waterproof element. I don't know if anybody has an exact answer on the lipo/water question. I think they would be fine as long as you do not submerse them.
I think a C rating of 15 and above will be fine for the stock Summit.

[egnix]

gmmwicked,
Which ones do you run - the 5000mah or 8000mah ones?
The 8000mah ones on this page have been the ones I've been leaning towards.

What kind of runtimes did you see with your two revos>?

[GMMWICKED]

I run the 5000. I think most guys here use the 8000. Same battery just longer runtime w/8000. Only reason I got the 5000 was to save a little money. If money is not the issue then get the 8000. :wacko:
I just bash around my frontyard for about 20min a pop w/no power loss. My kids, 5 and 2, don't allow me any more freetime than that.:( :D

[GMMWICKED]

BTW, I have read here (forums) that the 7.4v lipos actually peak to over 8v. So for a short period of time you will get over 16v with the lipos.

[akrimmel]

I'm going to use 2 2s lipos, a 2s fully charged is 8.4 volts so two in series will be 16.8v. A good 2s pack and a good 7 cell nimh are very close in performance, the nimh will have a slight advantage initially but it's small. Bump the pinion up one tooth if you need a little more speed...

the nimh will not have a advantage over lipos ever!!

[DiFabio42]

Lipo will always beat Nimh. I have a Single 700-HO in my E-Revo. I ran (Before I went Lipo) Venom 7 Cell 3000mah's. I went to 2s2p SPC 8000mah Lipos. It wheelied, went soo much faster and performed amazing.

[akrimmel]

Lipo will always beat Nimh. I have a Single 700-HO in my E-Revo. I ran (Before I went Lipo) Venom 7 Cell 3000mah's. I went to 2s2p SPC 8000mah Lipos. It wheelied, went soo much faster and performed amazing.

how many motors does the erevo come with stock?

[DiFabio42]

Two Titan 550's.

Mine went bye, So I got the Kershaw Designs Single 700-HO Kit for my E-Revo.

[akrimmel]

i plan on putting two 775's in my summit. i know i have to get the motor mount from KD, thanks.

[Racer83L]

BTW, Maxamps is now advertising that their Lipos are completely waterproof... So that answers that question.

And Id go Lipo over nimh anyday. Its all I run, I dont own any other battery

[akrimmel]

so they weren't before lets say or this is something they just started to say. with the price on their batts they should be.

[Alectric]

They were saying there batteries are water resistant and now there saying they are water proof. I have there water resistant version and never had a problem doing lots of snow bashing this winter.

[akrimmel]

well in true form snow is different from water.

[Alectric]

Well as things start to warm up in the truck what happens?

[akrimmel]

refering to what specific problem?

[SLASHPEDE]

Well as things start to warm up in the truck what happens? things tend to expand when they heat up:D does that help?:p

[akrimmel]

what was alectric refering too?

[Alectric]

refering to the fact that snow melts and turns to water. Its not submersion but its significant enough if the lipos are not water resistant.

[akrimmel]

ok i wasn't sure what he meant.