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milknbutter
01-02-2006, 12:18 AM
MY SETUP: 8 CELL GP1100, AON 4900.

Wanted to make a thread to discuss the mamba ESC setups people are using.

I have 2 questions.

1. What cutoff voltage would be suitable for a 8 cell GP1100 setup? Currently I am using 6.0v.

2. The motor timing option under 'Basic', for the people running my setup, are you using normal, race or extreme? Any longterm problems / glitches discovered using the extreme or race setup?

Any help would be much appreciated.

Thanks,
MnB

BiGRoB21
01-02-2006, 12:43 AM
1.you do not need a cut off for nimh cells.
2. i am useind race. with 30% drag brake

milknbutter
01-02-2006, 01:08 AM
Thanks for the info. I was wondering about the new drag brake option since I updated to the latest software. I have it on disabled. Could you explain what the 'drag brake' option does?

Cheers,
MnB.

Trickpatrick
01-02-2006, 02:07 AM
Well Robs not on so here goes.
A brushless motor has almost no drag or resitance to keep it from spinning.
A brushed motor has quite a bit of resistance which acts like a brake of sorts when you are in nuetral.

Soo.. adding some drag brake makes it act like a brushed motor.

Some people like this drag brake so the car can settle a little before a corner.
By adjusting it you can add just a little brake effect which if done by you on the trigger it is very hard to be consistant.

In fact a lot of real race cars use this before each corner as well.
It in effect shifts the wieght of the car forward onto the front tires for a moment. If you turn in as you take off the brake you have much better frontend traction letting you turn tighter.

The problem with this is simple not all corners are the same and not all straight's before the corner are the same.

So if you are going very fast and then need to turn around a hairpin you need some pretty strong brake.

If on the otherhand you are going slow and need to turn through a couple chicanes let say, you may need just a tap on the brake.

On a oval type track where all the corners are very similar it can be a real advantage for being consistant!!

Very little may serve you well but I have seen when it is taken off a second a lap or more was gained becase it was just slowing you down more that you knew.

Food for thought ;)

pimpsmurf
01-02-2006, 01:08 PM
1.you do not need a cut off for nimh cells.
2. i am useind race. with 30% drag brake

United RC says to cutoff at .9v/cell or 7.2v for a 9.6v pack. It is suppose to maintain the cell matching. *shrug* Castle creations says it doesn't matter, but those guys said a 5400 mamba would make me happy. haha

-JNY

bermbuster
01-02-2006, 02:12 PM
I believe the cut off voltage was designed to protect lipos. If you select a high cut off and use nimh cells....the mamba will shut down before the cells are drained. CC use 4v as a default. This will ensure enough voltage is present for the rx to operate the vehicle. All nimh cells should not be discharged lower than .9v per cell. When your vehicle slows and or the radio starts acting up. Your pack is done. You will find if you measure your voltage you will be above the .9v per cell. The reason I like nimh so much is you do not have to discharge the pack to the .9v before recharging. You can recharge it anywhere in its capacity cycle and not worry about cell memory.

Trickpatrick
01-02-2006, 06:48 PM
Hi all

This .09 thing is for real but its apples and oranges.
Matching is an advantage in racing, in stock for sure, but they are kind of borrowing these catch phrases.

This only really works in a pack where you can discharge each cell individually.
When you do this with any kind of shrink wrapped pack you cant do this.

So it may say your total = .09 per cell but some may be higher some lower.
NMH dont have a memory this is true so does it matter??.

Yes and no.
There is a little advantage to discharging each cell, pro's may even go as far as to dead short the cells ( if it fails they just throw away and get a new one free. Must be nice).

If you race and you are just seconds from winning alot then I know from experience you can make the battery perform a little better.

Heres why.

If you discharge as a pack some cells will have more juice left in them so when you recharge the charger stops when those allready partly charged cells are charged up. the cells that were empty or even dangerously low will never get a chance to recharge to full capacity.

So your battery appears to be charged but its not really topped off so to speak. So when you use it it wont have the punch it should and will affect run time.

I really dont think this matters a whole lot if you just Bashing but it could help you if you are racing and are close to winning all the time.

Otherwise I would not waste money on matched packs that are shrink wrapped or in a configeration that wont allow you to discharge seperatly. They will be better at first but will become unbalanced pretty quick and are then wasted.

Lipo's cure this as they can just be topped off no worries!

Hawk
01-02-2006, 10:26 PM
Tricky,
Thanks for lending clarity to this. Yes, exactly, you are right. In the end it all depends on what you are doing. If you read the magazines and listen to people that heard from people then try to apply those things out of context, with different equipment and a different running environment then you don't really gain anything.

If I were racing in the region or nation level, I would do it the way you mention with seperate cells that I would dead short then charge just before the race with enough time for them to cool. I don't need to do that and most of the people on this board don't either.

I never really liked nicad because you had to be more careful even if you just bashed in the yard. Nimhs are better than that in many regards, I can be more careless and still get good results. LiPo is great because they have big capacity in a small, light, space. I worry once in a while because the things that can go wrong are higher risk in that they could easily cause serious injury or damage.

I try to use 85/15 rule, that is I put 85% effort in and let the 15% go. It is the point of diminishing returns with most battery technologies. I depend on quality vendors with good reputations, a decent charger that works for me and hope that all works. If not, I try something else.

.9v per cell for nimh is what I use as a storage level. Using a digital multimeter, that is usuallly spot on when I get it from vendor and I don't depend on the cutoff of esc's. I don't think most of them are reliable about that. The same with LiPo cutoff. Cutoff in LiPo technology is more important and I won't count on esc cutoff to save me. I have LiPo packs that cost more than most of the mamba or tekin.

Instead I use large mAh rated batteries to get higher discharge rates and never run them until they cut off. I have been looking at cutoffs for LiPos and BECs so that I can run my receiver and servo at 6v and not more. Once again, the esc's mostly supply the BEC function. Most are limited and are subject to variability. If you look at the higher rated ESCs you will see many have the option for isolation of the motor and the electronics. When I see a situation where something costs more and drops a feature, the feature probably was added to get the low end consumer and is really like most ready to run situations, not ready to race.

At this point I don't know if I have gone completely off the track here or am sort of on point. I guess Matt will let me know. :D

bermbuster
01-02-2006, 11:02 PM
You are right on track Hawk. I agree with you 100%. One thing we always have to remember is all batteries store potential energy and if something goes wrong that power has to go someplace......
I have been playing with rc offroad buggies since 1982 and I remember when a 5 minute runtime on a johnson silver can was considered a good time......how far we have come with battery and motor/esc technology.
The mamba25/tekin rage escs are 25 amp technology. Just think in a few years we will see 45 amp technology with battery power to suit..... :cool:
mini sized vehicles will need a new gear technology........ :D

mat3833
01-03-2006, 06:26 PM
I guess Matt will let me know. :D

lol, you are exactly right man. but the only thing i have to add is on the LVC of the mamba. it is actually spot on. it only drops like .2 or.3v below the cuttoff volage. now i have a fan on my car so the LVC is kinda bypassed (LVC only cuts motor not receiver) so i have to pay attention if i use lipos. oh and i use a 5.5 v cutoff with my 8cell.

Matty