Lipo for Emaxx

[lipomax]

Hello guys, I thought I'd drop a line here since Mike is such an awesome dude when it comes to BL for emaxxes.

I've got a totally stock emaxx (even the tires) and I've gone brushless with it and lipo.

I've taken 4 of the shocks off because they add weight. I added heavier springs though and since it's cold here in Chicago, the shock oil tends to thicken an add extra dampening. I've also moved the shock mounts to the outer holes on the arms and inner holes on the shock mount so I can limit travel.

Just so you know, I used to run 12 cell GP3300's and a variety of motors. At least for me, it seemed to top out at about mid 40's mph no matter what brushless I used. So, I figured that the 3300's were only capable of putting out so much power.

For a moment, I ran 6s lipo (22.2 volts) and used the Kokam 2000 mah 15 c packs. They were getting slightly overdischarged. Peaks were at 85 amps!!!! That's over 40C!!!! The motor was a Basic 2700 and geared 18/66.

Then I went with 6s and polyquest 3100 mah packs. Same motor and gearing and that was about 60 amps in first gear and 80 amps in second gear. Still too much amp draw for the lipo pack.

Next, I dropped the motor to a Basic XL2400 and went 8s 29.6 volts (but actually, it was at 32 volts) and ran it 15/66. Peak amperage dropped to about 60 amps which is nicer for the batts - only about 20C peaks. So, I'm happy with amp draw now... I might try different motors and lipo combos later on.

My emaxx total weight with body and batteries barely tips the scale at 9.0 pounds. If I had lighter tires, I bet it'd be about 8 1/2 pounds.

The polyquest 3100 packs fit into the stock emaxx trays with a little slop so for me, it was ideal. It fit, no mods, and it was protected by the battery trays. The temps are pretty well under control since I don't continuously run it. Not until I know the batteries can handle that kind of load... and the motor don't fry. I'm peaking out at around 1500 watts. That's 2 HP in a 9 pound emaxx. Keep in mind, that's 2HP from 0 to 50 mph!!!! So, I can instantly flip in first AND second gear.

If you guys have questions, ask away...

[Serum]

I may be wrong, but aren't lipo's allergic to cold?

I ran my mini-t on a lipoly pack in the cold (-23 degrees celsius) and when i used the 1650 pack the next day, my 9volt cutoff on my esc found it was good to cut off. I charged them with a balancer, no imbalance or whatever, i was only able to push in a 785 mAh...

Perhaps my charger is too carefull with them, i don't know.. (intelli V3)

But are you using the Eagletree for monitoring? I love that system.. Ideal for such expiriments! got to get one of those things to..

[lipomax]

Lipo's don't like cold so keep them warm before you're about to use them. During use, power will actually INCREASE for a while due to the slightly warmer temps. Yes, I'm using the Eagletree for monitoring. Great system. Plus, I use it so I can make sure I don't overdraw from the sensitive Lipos. It only takes 1 run at 100 amps to kill a 300 dollar pack!

[RC-Monster Mike]

Interesting. I did not know the lipos had that dramatic of a dislike for the cold (although I don't perform well when its that cold, either:) ). I have seen some of the info that data device gives you. It is a nice thing to have for testing setups for sure.
Lipo - thanks for the kind words!

[Serum]

About the 100A puls, won't the individual cell voltage drop under the 3 volts? Has the controller got a cutt-off?

[lipomax]

Individual voltage drops below 3 volts all the time for me - I don't have my controller cut-off setup at all. One time, I had a 3 cell pack down to 5 volts under load! Now, that's UNDER 2 volts per cell!!! That did damage the cells. Going below 3 volts per cell under draw occasionally doesn't really seem to damage the cells - continuous running below 3.0 volts per cell will damage the cells. Keep in mind, peaks rarely exceed 1/2 a second in RC cars so I think keeping the voltage above 3.0 per cell is more geared toward planes, helis, and boats. Not so much cars.

[Serum]

What cut off voltage do you suggest for my lipo 3S pack in my mini-t? I can make a .1 volt accurate cut off

[lipomax]

Honestly, I'm not the person to ask about cut off voltage safety. I rarely use even 50% of a charge so I never worry about over discharge. In addition, anything in my hands don't last very long. :) They either blow up, break, or burn. So, I keep on getting new stuff over and over again. Over my life, I've gone through at least 100 brushed and brushless motors, 30 vehicles, few planes, helicopters, etc. Right now, I'm down to only two. An E-maxx, and a TC4. I'm thinking about getting an XXX-4 - better designed for decent speed on rough pavement than a TC IMO.

[RC-Monster Mike]

Sounds like you have a good idea of what NOT to do! I've burned up a few things myself, but I have tried to play things safe for the last year or so. I can't seem to let go of my R/Cs, either (30+ vehicles and counting!).

[Serum]

My 'i should not have done this' list;

2X mamba 25
1X schulze 18.97..

You went THRU or thru 100 motorsystems? ;)

[gixxer]

i have burned up
2 shulze 18.97
hacker comp
1 lehner 7018

the shulze were do to the power pole connectors. I didn't know they were only rated for 30amps, asked about them when i ordered threw finedesign :mad: and he said they would be alright, but when i went to send back for repair shulze wont cover unless you use deans or the 4mm plug.

[lipomax]

Funny thing is all this - I've yet to burn up a controller! My first brushless controller was a Schulze 12.97 fwe. Worked well all these years. Then I got the Hacker Master Sport - bought one and got on on ebay also. Both worked pretty well. I also bought a micro 1895 from LMT when Rumrunner used to deal with Lehner. Novak, 18.97 kwf, 32.40k, 24.89f, mamba 25, phoenix 40 and 60, U Force 75. I've only busted one motor - just recently... The motors I've had are the c40 6s, 12s, b50 6s, 8s, basic 5300, 4200, 3600, 3100, 2700, basic xl 5000, 3100xl, mamba 8000, 1920 5 turn, 1930 5 turn, 1515 5 turn, 1515 6 turn, 1520 8 turn, twist 42, himax 5400, Himax 3200, umm.. others, but I've forgotten. Geez, I don't wanna know this - I don't wanna know how much I spent already!!!!

It seems like I break a lot of cars, and car parts instead and lipos. The other stuff seems to hold up pretty well. Most of the car parts are due to too much power, not enough control, and inanimate objects.

[Serum]

That's funny...

Schulze has got his own way by telling the customers, to pee of... (with other words though)

Guess why my schulze was broken down..

Bad motorconnection..

Took me about 50 emails to make them clear that i asked them if the plugs are used where okay..

With castlecreations, its a whole different bag.. Called them.. They sent me a new one instantly..

[RC-Monster Mike]

I have considered picking up castle creations as well, but have been waiting for their "big" car controller to be released (initial order always breaks the bank, so I want to wait for the stuff I am interested in selling). They seem to be popular with the minis and the airplane/boat folks as well.

[Serum]

Well, their service is superior.

They also have got a nice policy;

When you ruin the controller by your own misstake, they have got a fixed price for replacement. (for the Mamba, it's 25 dollars.. That's a lot better then the 79 dollars...)