mamba max on emaxx with 2 6s lipo packs (( HELP))
 

I have an emaxx with the stock batteries powering the Mamba Monster. I just ordered from hobbyking.com two 6s 5000mah lipo packs. I am nervous about runningt the packs. I do not want to overheat anything or creat too many voltage spikes and ruin the motor. I know that if i run the packs in parallel I will double the voltage which could creat that voltage spike. Should I sun them in series or parallel.Or sould I just run one pack at a time. I do want it to be stupid fast but so fast I will over heat anything. Again i have already ordered the 6s 5000mah packs. What shoud I do????? Sould I be Worried????? Also Just like everyone else who upgraded from brushed to brushless I also recieved a significant improvement in power and run time, and I am sure I will see another increase when i go to lipos. BUT I DO NOT WANT TO RUIN MY MOTOR OR LIPO'S. Should i gear down A little to reduce heat or what????????? ((( HELP ME OUT)))

if you can get the packs to fit in your truck, run them both in parallel. it will double your run-time and REDUCE voltage spikes. the voltage will be the same unloaded and a little higher loaded due to less stress on the packs.

what is the difference in performance between series and parallel? Wont running two 6s packs in parallel double my voltage. Are my packs too strong?

Calm down man! lol

Parallel is your only choice with 6S packs.

Series wiring doubles voltage, and the MMM is rated for 6S, NOT 12S lol. There is no such thing as 'too strong of a pack' as long as you are within the rated voltage. A single 5000 is ok to run but will make your truck heavy on one side, not really a big deal. Running both will double your runtime. Up to you. But you MUST only run parallel adapter.

Run it 2 or 3 minutes and check your temps, another 2 mins, check again. If things are hot then check back in and let us know what is getting hot, motor or MMM.

Also we need to know what you have for a motor?

2200kv


What about gearing?

You cannot run your 6S lipos in series with the MMM. It is rated for 6S max so you will have to plug them in parallel if you run both of them at the same time. Plugging in parallel increases the total milliamps, not the voltage. Your two 6S 5000 mah lipos plugged in parallel will stay 6S (22.2 volts) but will double the mah to 10 000 which will give looooong run time. If you plug them in series, the opposite will happen as the mah will stay at 5000 and the voltage will double to 12S (44.4 volts) frying your MMM.

For gearing, you can use BrianG's website to calculate your top speed. I know you want your truck to be crazy fast but most people gear to go around 40 mph to keep the temps down. Brian works hard to keep this useful website up to date so feel free to donate something to show your appreciation. Here's BrianG's RC calculation website.

http://scriptasylum.com/rc_speed/_top_speed.html

2200 x 25V(6S fully charged) = 55,000 rpm, you will want to gear on the low side with that kind of motor speed. As for exact ratio, we don't know if you have an old or new Maxx, but use the smallest pinion with the largest spur you have, that's the best starting point I can give you.

I took too long to write my post, I repeated most of what redshift said :lol:

A little backup isn't a bad thing :smile:

16.8 v emaxx long chassis. It wasent brushless when i purchased it. I put the mmm on it. The mmm came with an 18tooth pinion gear and i thing the emaxx came with a 62 tooth spur gear.

That's the same as stock gearing with the Titans IIRC, that's gonna be way high. Probably something like 14/66 or 14/68 will be much closer. But then again if you're looking to do 65+mph then make sure you do short runs, like under a minute and keep a very close eye on temps. But do check BrianG's calc for precise speed first.

Lol, guys this thread is from a friend of mine, who has the e-maxx. He has the most recent edition of the e-maxx, when they started coming out with the BL e-maxx straight from the box. I tried talking him into buying the BL to start with, but he went brushed, then bought the motor within a week :D.

Right now the truck has stock brushed gearing, so we need to look at brian G's website to find the recommended gearing for the motor and esc? It has the very same motor and esc as if it had been bought the BL edition. The truck will mostly be used for bashing, really no competitive racing, so keep that in mind when recommending gearing. The main thing is trying to keep temps in check. Where would you guys recommend purchasing a good budget-friendly temp gun?

Also, it is okay to charge the 6s 5000 packs at 5 amps for a one hour charge time, no?

That's the same as stock gearing with the Titans IIRC, that's gonna be way high. Probably something like 14/66 or 14/68 will be much closer. But then again if you're looking to do 65+mph then make sure you do short runs, like under a minute and keep a very close eye on temps. But do check BrianG's calc for precise speed first. It is stickied at the top of the Brushless forum, click back once and you're there...

Login timed out on me grrrr... sorry for the double post :whistle:

wouldnt by putting a bigger spur gear and pinion gear give me more top end speed and less low end torque.

Nope, just the opposite.

No more questions until you look at the calc...:angel:

what i have now is 62/18

what is that link

Look here- http://scriptasylum.com/rc_speed/_wiring.html and click on "2 parallel pack wiring" for proper adapter.

I have the emaxx #3903 the speed calculator asks me if i have #3905 what shall i do

Same transmission, just enter 3905.

So how are you going to mount those packs again? you can barely fit a 3s 5000mah with the optional battery hold down and due to their width they dont seat correclty in the battery tray. You arent going to be able to fit 6S on each side without some duct tape and rope.

I know! Im so excited! I cant hardly wait!

DUCT TAPE! (and zip ties)

:yipi:

I manage with 5s2p on my Gmaxx, but thats a very different beast..

What C rating did you get on those batteries? The higher the C rating the bigger the packs are. You are going to need some pretty big zip ties.

Hey Neil, So are you running 2 5S paralleled packs on an MMM on your Gmaxx? or is it a single 5S2p? What capacity? thats gotta be a big pack. I still say 5S is the sweet spot for the MMM, though.

I believe they were 20c.

You should parallel them for sure. People I know, including myself, have had back luck with the 20C zippies and the MMM on 6S. If you parallel you get 6S at 40C so thats better. I dont know for sure but I just dont recommend only 20C on a 6S setup anymore, no matter how low you gear it to keep amps in check. That of course only applies to the cheap batteries, I'm sure if you get some that are truly rated for 20C then you would be ok. I will be curious how your MMM holds up under 6S though and all that weight.

It does not double the C rating- Paralleling the packs doubles the capacity. so you'd get a 6s 10,000mah pack - if 20C that would give you a theoretical 200amps continuous rating.

More than enough - Your car will be heavy though1

Lol, he pretty much wants it as big and heavy as he can get it(it's not my truck, we just keep posting under the same name-he's too lazy to make his own, and I made the mistake of staying signed in on his pc by accident).

If we ever order more packs, would 2 3s 5000 30c be a better choice?

Just one of these packs can't give enough amperage alone, can it? Can someone explain to me how to calculate this, so I can use it in the future? I have a mamba 5700 on a stampede and an hv-maxx, and it'd be nice to be able to calculate the amps of lipos for those, instead of having to ask so many questions to see if a pack is okay.

We don't do any racing. We've hit the track about twice, but it certainly wasn't competitive, so the added weight shouldn't really matter. Until he crashes lol.

Thanks Arct1k, You are right. My head wasnt working right. I was thinking its the equivalent current of 40C at 5000mah. My bad.
The problem is the stock battery trays in the emaxx wont let you go over 46mm and all the hobbycity bateries are 50mm. The 6000mah 25C nanotechs are 25C and 48mm and that might work better, but yeah the 30C 5000mah would work, they just dont fit snugly in the tray. Two in series for 6S is what everyone is running. Personally though I am not a big fan of cheap batteries and 6S on my monster. If you go that route I would recommend 5S and get as high a C rating as you can, or just buy better batteries. They have some nice ones on this site that will fit an emaxx.

Personally I've had great luck with zippy batteries. They'll definitely be run in parallel though, so amperage should be good either way.

Its a pair of 5s packs yeah, one on either side of the chassis. They are big packs, but still lighter than 14/16 nimh cells and a million times more powerful :intello:

its alive--- its alive (68 tooth spur, 16 tooth pinion, Mamba Monster Max motor ,and two 3000/20c/6s lipo's running in parallel) to boot. Its a beast! Its too torquey though. I think I might go up on the pinion gear some to maybe a 20T or 22T. I cant go down on the spur gear any more because motor has too big a diameter and will not adjust down any further. I have the Batteries in with a velcro strap (that works great). They are just as wide as they are deep and about 2 inches shorter than the stock packs. ( Take two stock battery packs, lay them on top of each other, tape them together tightly, and cut two inches off of the length) and that will be the size of each battery. They are actually a few ounces lighter each. Now I gotta order a castle creations heat sink and fan for the motor to keep the heat from being a problem. and thats my story for now. Oh yeah I did add a wheelie bar for a little insurance!

figured out a few things. I was talking about heat just a minute ago. I was just out side for about 30 min bashing the emaxx with the packs run in parallel. I didnt have a problem at all with heat this time. Last time i was running it i had only one pack hooked up. It runs much cooler with twoo packs hooked up instead of one. Though performance was the same. I went back to my orignal gearing(18t pinion)15t was too low. less torquey, but still one hell of a beast. speed calc says it should run 62mph.( without crashing it) ha ha it will do wheelies at any speed apon command. Its awesome. Much fun ahead. I still ordered the cooling fan anyways for more insurance ;-)