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View Full Version : NM vs. lipo battery question



pimpsmurf
10-24-2005, 11:32 PM
I've pretty much decided to go with NMHD 8 cell (Extreme pack from Unitedrc.com), to go with a dynamiterc.com vision peak charger (cheap at LHS). I've also pretty much decided to run a AON 4900, (sell my brand-new Mamba Comp), and a Novak XXL Reciever HS-85MG servo. I will be running with 1:10 sedan wheels/tires on-road (at the house, 13 tooth pinion) and stocker, or perhaps 1:10 HPI "Nubz" wheels at the local 1:10 track.

I don't really want lipo because I'm aiming for a 10-15 minute runtime (is that even possible with NM cells in my config?), and want to have very little time waiting for the next pack to finish after the first pack is out of juice.

Everyone preaches 16 ga wire, but the unitedrc.com packs only come with 18ga (except the lipos). Is this going to cause hesitation on the brushless motor? Any input at all would be helpful!

Thanks for the forum!!
-JNY

plain_simple
10-25-2005, 03:56 PM
The 16g vs 18g wire issue is easy to answer... the more g the wire has the less resistance it will have on power stream... I use 18g wire because i also use it on other scales. On the other hand the shorter the wires the better because that also brings more resistance.
Hope it helps you

P.S.: you must a huge room to be able to run a H8 with that setup inside a house! :D

pimpsmurf
10-25-2005, 04:22 PM
P.S.: you must a huge room to be able to run a H8 with that setup inside a house! :D

I understand simple electronics, and I said at the house (on the asphalt), not in the house! lol. I live on a golf coarse also, so sand traps should be hella fun.

That would be a really big freaking room! hahaha

I do have access to a private basketball court inside that I used to use with my xmod. It was insanely fast, and with the floor swept, and soft treaded tires were fast!

-JNY

plain_simple
10-30-2005, 11:12 AM
If thats the case then you will be changing to lipos pretty fast.. you just need to try them once... trust me on that ;)

pimpsmurf
10-30-2005, 01:11 PM
A guy from unitedrc.com emailed me back and said that 18ga is more than enough for gp1100 cells. He said they could make a special pack with 16ga for me, but I don't think thats really needed. I'm just going to get a couple Xtreme 8 cell packs, and get a 3cel lipo pack later. I know the lipo will be insane, but I will still use mostly NMHs packs. Lipo when it's time to get crazy with the cheesewiz.

-JNY

plain_simple
10-30-2005, 09:00 PM
yeah.. take it slow... you can fit a lipo pack on your baby when you feel you and her are ready for it ;) :D

pimpsmurf
10-30-2005, 09:25 PM
it will be ready this week! :D

I'll sadly never be ready ;)

I'm actually kind of excited about the new sealed diffs. I'm probably going to have to get a couple of those and see how it is. I dig on BB diffs, but rebuilding BB diffs is a pain sometimes (My XXX-NT for instance.)

I would guess a tight center BB diff would last a good while before being rebuilt if the front and rear are operating properly.

-JNY

theturd
10-31-2005, 04:31 AM
Simple Concept: Your power system (battery pack + motor + ESC + wires + connectors + tabs) is as powerful as your weakest link.

As drivers move into the more powerful brushless systems, the need to move higher amount of WATTS is required. In most cases, the voltage stays around 7.2V to 9.6V, that would mean that a minimum of 17-23Amps will need to flow through this power system loop.

So here is the question, will all points (act like gateways) be able to handle the current? If not, then cogging the first clue.

Peace,
Steven Chao,
AON Electric

plain_simple
10-31-2005, 05:46 PM
Yep, Steve is the man on that! ;)
Regarding Pimsmurf's "I'll sadly never be ready" statement... i dont think so!!!! There's a line from Bogart on the movie Casablanca that summs it up:
"No one is ready till "the one" shows up! ;) :D

pimpsmurf
10-31-2005, 10:15 PM
*shrug* I went ahead and had them put 16ga on the NMHd packs. Totally unneeded, but more fun that way.

-JNY

mat3833
10-31-2005, 11:50 PM
you could have done like i did w/ my mini t motor wires. go to 12 ga. same w/ batt. make them as short as possible. i used deans wet noodle.

Matt