Which motor for a BK3695
 

Which motor will be the best for an E-maxx with a BK 3695 controller?

We plan to run wit 7 cells packs, maybe 8 .

how many packs you going to run

2 packs with 7 or 8 1,2V cells.

No money for lipos...

For that low of cell counts, you do not need the 3695 (36 cells, 95 amps). You can use the 9920 (99 amps, 20 cells) which is half the price. If you will be running on 14-16 cells total, I'd recommend a 7 or 8XL.

Is for a friend,

he has that controller an the e-maxx.

EDIT: maybe we can fit 4 packs in the e-maxx to get 24-28 volts?

Does the 36 95 your friend have have the rpm limit on it. If it does it is not a good idea to push the motor over 42000 rpm cause bad stuff can happen. 14-16 cells sounds like a good candiate for 8xl or 7xl. Depends on run time and speed looking for.

WHat does happen when it goes over the limit? esc fries?

I will ask for that rev limit and tell you.

Is it possible to fit 4 6 cells packs in an e-maxx?

On a gmaxx chassis yes. I don't know about a stock chassis. I think the motor plate will get in way unless you have a way to drop them down.

Yes, there is a special chasis that allows you to fit 12 cells on each side, on top of each other. Here's a link: http://www.horizonhobby.com/Shop/ByC...ProdID=DYN7635

It's dicontinued now, but you might be able to fiond one on ebay or someplace else.


EDIT: I found one! http://cgi.ebay.com/Traxxas-E-Maxx-A...QQcmdZViewItem It's not the dynamite one, but it holds 24 cells nonetheless!

I cant see the second link.

The new FLM chassis is also able to hold 4 packs. the g-maxx is capable of holding 2X 15 cells

The new FLM chassis lokks great and is not so expensive , $90.

Then, with 28 cells and 33,6 volts is better the Feigao 10XL?

On so many cells(28) a 13XL would be beter then you will hit the 40000rpm max

The 13XL will go 1155 RPM/V so on 33,6v you got 38808rpm
And your limet will be 42000rpm whit the old 3695

I would agree on the rpm. I would go with like a 12 xl or so as well for 28 cells. but you would have an awesom run time.

i would aim a little less high.. lower KV is cool with those HV setups.

Finally we will connect 4 battery packs in serie.

I will wire with 4 Ultra Deans male so:

http://img34.imageshack.us/img34/326...erie2ug.th.jpg

Is it a good idea?

And another female self-conected for a 3 pack setup:

http://img362.imageshack.us/img362/1...lo3p6rn.th.jpg

They are all in serie my friend! parralel is when you put two batteries on eachother, with the + and the - pole

:C:

Thks Serum, you're right.

To achieve the 28.8 volts is in serie.

I will correct it.

RPM limit is 80.000

The RPM limit coolhand was talking about is for the controller (3695)
And you are talking about the motor
But it isn't very smart to go to the max rpm of the motor
it won't last very long

Than you can beter go for a lover kv (RPM/V)
this way you get lower RPM more torque so you can gear higher
Get the same speed and keep the motor cooler and longer life

It took an email or 10-15 before i convinced Mack though..

in the HV setups, you don't want a motor to rev too high.. 30-40K is the maxx. RPM i would use.

[QUOTE]Originally posted by Serum
[B]It took an email or 10-15 before i convinced Mack though..

That's true bud since I now got your wisdom I have to share it
;) ;) may the force be whit you;) ;)

No mack, I am talking about controller RPM limit.

I asked Alexander, from BK electronics in Germany and he said me this model is 80.000 rpm limit.

If i'am not wrong you have only a 3695 wiht 42000rpm limit or no limit at all except for the amps thats 95amp.

And on the site of BK you can see that the wandere XL have a max rpm of 80.000.
So I think that Alexander confused the motor rpm with the controller rpm limiter.

Alexander sold us the 3695 and said it has a 80.000rpm limit.

Here Mike explains that all 20120 and 20150 controllers and some 3695 are 100k limit .

I will ask to BK again.

EDIT: very fast answer ...

100.000 rpm is the limit of controller and 80.000 rpm the limit on motor

[QUOTE]Originally posted by VWT4
[B]Alexander sold us the 3695 and said it has a 80.000rpm limit.

Here Mike explains that all 20120 and 20150 controllers and some 3695 are 100k limit .

Okay if mike says so then it is so mike is way more experienced
than me.

But I now for a fect that the motor has got a rpm limit of 80.000rpm.
Bud what are we talking about because you will never want to drive your motor to this high rpm right?

I will try a 12XL , 55amp and 1390rpm/V :

- 24 cells = 28,8V= 40.000 rpm
- 28 cells 33,6V= 46.700 rpm

"Than you can beter go for a lover kv (RPM/V)
this way you get lower RPM more torque so you can gear higher
Get the same speed and keep the motor cooler and longer life"

Still a little high ideally IMO.It'll need all the help it can get to keep cool hauling all that weight around.i'd get the 13XL.

[QUOTE]Originally posted by VWT4
[B]I will try a 12XL , 55amp and 1390rpm/V :

- 24 cells = 28,8V= 40.000 rpm
- 28 cells 33,6V= 46.700 rpm

Please look at what SERUM told you he knows this

"in the HV setups, you don't want a motor to rev too high.. 30-40K is the maxx. RPM i would use."

So that means you have to go to a lower rpm/v.
So I think that what Gustav says the 13XL would be the (max/beter rpm/v) option at 28 cells

The 3695 could have a 42k rpm limit, or a 100k rpm limit, depending on the frequency of the controller(If you have a programming cable, you can find this out for yourself). I would absolutely agree with Serum, too. Keep the rpms around 35k to 40k and you will experience long term success in power, speed, runtime and system reliability. Gear the system to meet your speed needs withi these rpms and you will be happy in the end!

Mike is 100% right!! You do not need to push these motors that hard to get speed and power. Use a low KV motor and gear for the speed. You will be rewarded with a cool running system and long run times.
Reving the motors that hard is old thinking and should be forgotten. In my stupid days I did the same thing 8s 18 cells,5XL 24 cells,7XL 32 cells. Than I learned about low KV motors and never looked back and went much faster.

Thank you,
Promod

Yep I also thougt that how higher the rpm how faster the car.
But SERUM convinced to go for the lower rpm/v enegine :D

Thanks for all the explanations.

I will try the XL12 with 21 cells (35.000rpm) and 24 cells (40.000rpm).


Which chassis do you think will fit 4 packs better, the new extended E-maxx Chassis by Fast Lane Machine or Gorillamaxx G2 X-Brace Chassis ?

[QUOTE]Originally posted by VWT4
[B]Thanks for all the explanations.

I will try the XL12 with 21 cells (35.000rpm) and 24 cells (40.000rpm).


And yes we have anohter believer:D hallelujah:D

The 12 XL is a great choice and will rock on 24 cells. Have fun!!:D
Thank you,
Promod

The gmaxx will have the cells lower to the ground. It will make your handling better like this. Are you going to stack 6 cells or build a pack with the cells in it?

My idea is working with 6 and 7 cells packs .

In the future I will get lipos.