7-cell vs. 2s lipoly
 

Lol, pls don't hunt me down for running nimh. I wana upgrade my power for my B-day, and my dad told me to consider what i could get with the money i would spend on lipo. So far, i run:

Stampede with:
novak SS ESC
LRP 8.5t X11 motor
6-cell 4200mah pack made of IB cells by proboat


I was thinking of going with a protek lipo ($40 for a 4000mah 2s on amain)
and a Turnigy accucel-6 with 14v 16a power supply
That lipo setup would cost about $175 (I'll also be getting some misc. supplies like heat shrink, wires, connectors, etc.)

I currently have a Dynamite Vision Peak 2 charger that does my current pack pretty good. It only false-peaks occasionally.

Now my really questions: What kind of performance will i see over nimh with that aformentioned lipo or other similar lipo? What are some good 7-cell packs for the stampede?

Thanks in advance!!

The power difference is INSANE. I went from a gp3300 7 cell, to a 2 cell lipo and I was amazed. It was definatly the best thing I have ever done, but im warning you once you go lipo you never go back.

lol, kinda like going purple with Peanut? anyways, what would you guys suggest? I'm looking at zippy packs on hobbycity, but the protek looks good too. any good quality fairly low priced AC or AC/DC chargers out there? thnx

I aggree with this 100%. :yes:

SOOOOOOOOO much more punch from a battery that weighs alot less mah for mah.

This is because even the BEST Nimh battery is VERY limited on maximum discharge. About the best you can hope for is maybe 45 amps. At this rate, the Nimh cells get really hot. Cheaper Nimh cells get so hot, they melt things. LOL

Even a cheap 2S Lipo will outperform the best Nimh packs money can buy.

It's an entirely different chemistry with alot of advantages.

Lipo packs have came down alot in price over the past few years too.

Go Lipo, you'll never go back. But first, research the proper care and charging of them. Always be safe.

:lol: :lol: Jeff Dunham rules!

...and LiPo does too!!! :yes:

Which Protek packs are you looking at?

Which Zippy packs are you looking at?

Haha ill second that. i ran those same batteries and went to 2s 4900mah rhino's with my emaxx and theres such a huge difference. ill never own a nimh again.

I agree too. But don't ask this question over at the Trx forums. I got into an argument with someone saying that NiMHs can be just as good. His "proof" was a clearly biased (and obviously incorrect) graph showing NiMHs doing better than some FP (IIRC) cells of equal capacity. Whatever :sarcastic:. He rambled on how he backs up his statement with "facts", but I guess we can all disregard the numerous graphs out there showing otherwise, in favor of his one questionable graph. :lol:

You need to make sure, that your lipos will be "big" enough to power your motor.
If you get 4000mah 20C lipos, you will get 80A continous out, and if your motor pulls more than that countinous, your lipos will likely heat and lipos dont like heating.

Well I hate to say it but I'm going the other way here.But with good reason.The esc.The Novak ss ESC can not withstand the amps that the lipos can provide to see a big improvement from .Between my SPC 6c 4600 nihm and SMC 5200 lipos there is very little difference in speed using this controller.You can tell a slight difference in punch though.Throw the same batterys behind the vxl esc with the same Novak motor and the speed difference is much greater..Brian I know the graph of which you speak http://pic20.picturetrail.com/VOL133.../351215442.jpg I do believe it to be accurate.However they are the best nihm cells that I have ever seen ran.But I also wonder about how they would perform on a higher discharge with momentary delays to let the voltage recover,if that would net better performance from the lipos.I have a pair of the matched sport packs from there ,and there performance is very close to my Hecell 4000mah 25c lipos.Running both in my Emaxx with an 8xl and MM The nihms pull 39,the lipos pull 40,gps verified.The lipos feel a little punchier,but that could be from weight.Now my SMC's pull 43 with the same setup,and feel way better everywhere.My point is ,there is no doubt that lipos perform better,generally.But the cheaper lipos,compared to quality nihms,they are much closer then I ever would have believed,before I ran the 4600 cells.Also if your other equipment is limited to 30 amps,well then you have other problems besides needing quality lipos.

thats exactly the graph, LOL as if

wow, lost of replies here... I'll get links for the lipos I'm looking at soon... The ESC I'm running is actually a half-breed between the older SS and the newer Havoc systems. I verified with novak, and they say the ESC will do 100 amps cont. no problem.

Thats much less likely then the graph.I don't believe my hv esc will do that.Have you tried them?

What a silly graph. Can we have another that shows a micro t lipo vs a car lead acid battery at 100 amp cont draw. We can then prove that lead acid is better than lipo...

WTF does a cont 30amp load prove? That X battery is better than Y battery at handling a 30amp cont load... When do we have a 30amp cont load in a rc vehicle? This may be better suited to test batts for helis and small planes, but not cars. I want to see a 20c load on all of the metioned cells. Lets see those nimhs pump ot 80+ amps. No temp info on the graph either. All BS IMO.

think it may be time to repost my graph

http://i278.photobucket.com/albums/k...lishplug-1.jpg

You'll are acting like it's showing the nihm hold 8 volts for 10 minutes.In reality it shows it holding a little better voltage for only a few minutes of the test,better then really the only descent lipo on there,the SMC.Which beats it for the first 3 minutes and the last 4.If they were bursts rates of higher rates ,like we run,I'm sure the lipos would be recovering to a higher voltage quicker.Also while it's rated 4600,the 5000 gets much longer runtime.IMO if your gonna try to doctor a graph why show these shortcomings? Pedeboi,sorry to get your thread off track.Lipos are definately the superior technology,and sooner or later the switch is inevitable.

Now that's a graph... That's making some serious power there!:lol:

You should also add an LVC to your list unless that Novak already has one.

Alright, so can anyone tell me if my LiPos can be made to be "waterproof" enough for me? I plan on getting a Summit when they some out, and lets face it, my Summit is going to get wet, probably submerged, and I want to do what I can to make sure my LiPos make it.

I plan on getting some large 3" heat shrink and some electrical tape to protect the cells themselves. I also plan on using RTV silicone to seal around where the connections attach to the cells. I know that I will have to protect the balance taps during run times, but no one has ever answered me as to whether or not LiPos can "take the plunge".

Here's to hoping to getting some straight answers.

I still think the sun could take the green girl. I got 20 to 1 odds on it...

I have been submerging lipos for a while and they are fine. I use plasti-dip (plier handle coating). I find using some thin packing tape to wrap the cells helps if you want the plasti dip off. Silicone around the wires where the plasti dip meets, as movement will cause the wires to come off the dip. Some dielectric grease in the balance tap will keep the water off the contacts, same with the deans plugs.

Thanks. I will be running a Dewalt 14.4v motor w/EVX-2 in the Summit as I plan on it staying as waterproof as much as possible and I really got used to having 8k 15c lipos in my E-Revo and getting 30+ minutes of runtime. It was really nice.

I plan on getting some SPC 5k 2s2p LiPos for 50 each, which is surprisingly less than a majority of the NiMh packs I have been looking at. Next up, some 8ks for the Summit and then I am good to go.

Welcome to the forums! I can't wait for the summit. I want to get stuck in mud, and then lock her up and crawl my way out.

Ditto. I live by a bunch of woods that have rocky slopes down to small creeks, less than a foot or so of water. It calls my name every time I drive by them. All I see is rough terrain, rocks going down to said creek, and rocks coming back up to said rough terrain.

It just says "Summit, come get some. You know the Revo couldn't do it. You know the E-Maxx couldn't do. Do you really think the Summit can conquer this!! Hunh! Do ya!!" OK not really, but it is calling for me to come and play on it.

^^^thread jacker. lol, jk, welcome to the threads. Anyways, what kind of LVC should i get and how much will this be costing me to grab a lipo with a discharge of at least 100a cont. and a burst between 100a-120a? thnx

it this works you should see my wish list a hobbycity. I'm looking at the lipos (products) with a quantity order of 12 http://www.hobbycity.com/hobbycity/s...idProduct=7028

I have some of those Lipos coming to run/test in my E Revo and in my E maxx.

But I thought you were looking for 2S packs?

i may be able to go 3s

thread revival!! lol... anyways, how about 9.9v of A123 power?

Quit bein a wuss- lets see all those packs in series- 24S or 36S...
Lethal voltage- rubber gloves needed to connect your deans :yes:

pedeboi - Lipo is def the way to go but don't stress your budget to much. You may want to take your $175 and first invest in a good lipo capable charger, that will charge your NiMh packs better than your current charger. Then when you get some money saved up again buy a good Lipo. There's no point in buying a cheap charger and Lipo just so you can get it all at once. Your less likely to be happy in the long run. I would highly recomend the hyperion chargers, integrated balancers and very user friendly.

As far as that stupid discharge graph goes I alos beleive it to be a bunch of BS! I think that even with the bad reputation of MaxAmps most can agree that even they outperform NiMh.

Great info
 

WOW this is some great info/discussion on batteries. Nice to see some really good arguements on which way is better. To Lipo or not to Lipo,that is the question. Of course Lipos are better. Myabe the prices will equalize sooner or later. JayJay that graph had me splitting a gut. You always have this subtle way about you when discribing details to people who have a different spin on the subject. It would be very funny to see you and UE Robin get into a discussion of differneces of opinion. You guys are just too much. Some of the cheap Lipos out there are driving the prices down on all the rest, because the majority of people in R/C are kids who just cannot afford the exagerated inflated prices that some are charging like Maxamps. If people stop buying from them maybe they would be forced to lower their prices to. I love the American way of life and the ability to run your business any way you wnat to, but not when they are trying to take advantage of common people.

hmmm, how about a nice LiFe cell charger? I kind like the idea of A123, not gonna blow up on me (Im not a pro like ya'll) and maybe a 6.6v rx pack?

Any charger with A123 profile, or has programmable CC/CV threshold will work fine. Just remember that lipo are 3.7v nominal and 4.2v "peak", whereas A123s are 3.3v nominal and 3.6v "peak".

Speaking of that, a 2s A123 pack will be at 6.6v nominal, but will be 7.2v right off the charger. Despite the fact that it doesn't stay at that high voltage too long, it's still a bit too high for a RX pack IMO.

well, at 98% doesn't the current return to normal? that was just an idea tho, would be cool. I'm thinking more along the lines of hitting my pede with a 9.9v pack. Like all the chicks say, "We'll make it fit baby." Anyways, would hobbycity be a trustable (is that a word?) retailer of A123 cells? 4 (or how ever many come in a developer kit) for $20 seems a touch low...

Not sure what you mean here. A typical lipo charger will charge at the set current until the voltage gets to 4.2v/cell. At that point, the voltage is held constant at 4.2v and the current slowly drops to a preset small value (something like 1/10 of the mAh rating).

Easier to just get a 3s A123 pack if you want 9.9v. Or, just use a normal 3s lipo pack and turn down the power on the ESC (depending on the ESC used).

I believe the word you are looking for is "trustworthy". And I'm not sure about them as I have never purchased from them, but other people seem to like them. IIRC, A123 cells are sold individually for ~$10 each. If you are getting 4 for $20, make sure they aren't the lower 1100mAh cells (or something like that).

good points, I'll snag the link in a sec.

edit: link! http://www.hobbycity.com/hobbycity/s..._tabs_(Dev_Kit) I can't tell what mah they are, maybe that number means something BrainG?

That link is for a single cell, not the 4 cell developer kit. The 26650 is the size: 26mm X 65mm. That size has a capacity of 2300mAh.

^^hmmm, then where can i get the cheapest A123 cells? What kind of batt. charger can i get to charge A123's (cheap!)

Also, my LHS is having a closing sale :( and they say to go straight for a superbrain or venom lipo charger. I can probably get a pretty good deal on the Venom, so is it a good charger?

I don't own any A123 stuff yet, so I don't know of a good place to buy from. I'm sure SOMEBODY on this forum does. :mdr: