Oh no, not another brushless Revo - what batteries?

[tumad]

Ok, so I've tested my clutch driven Lehner 4200 with Schultze 18.61k controller and of corse there are absolutley no cogging issues, because of the clutch... However, on 12 cells, that's about 1 kilo extra weight, it is just not practical.
Nice thing with this clutch system is that the motor spools up, reducing the amp draw from standstill. And it's much smoother.

Question.

What lipo's should I be running here,
How many volts
Shoudl I run 2 x 7,4 v 2100 to total 14,8 volts,
http://www2.towerhobbies.com/cgi-bin...?&I=LXMDN2&P=7

Or should I run 1 x 2500, 11,1 v battery?
http://www2.towerhobbies.com/cgi-bin...?&I=LXMAH2&P=7

I know the motor can draw up to 45 amps, and both these cells can deliver over 40 amps.

Not looking for alternative motor solutions, just which battery to use.
http://www.mike-duncan.org/lehner.jpg


Thanks folks

[tcolesen]

The Lehner 4200 is not an ideal motor for monster trucks... In that situation the motor really is too small to deliver the required power without heating up to much. Besides that, it will see spikes of over 100amps, depending on if the batteries can handle that.

If a new motor is not a choice for you (you should definitely consider it), then you'll want a battery that can handle about 45amps continuously. 4s Lipo causes that motor to spin past 60,000 RPM, which makes it run inefficiently, yet 3s Lipo may not provide a good amount of power to get the vehicle moving. If you must run this motor, then 3s would be a better choice.

[JakeE]

I'm certainly no expert but it seems to me that for the application you'll be using these batteries in you would want a pack capable of handling a higher continuous / burst discharge rate.

[SpEEdyBL]

You need a least a 60 amp continuous rated pack in a monster truck. What's the weight of your truck rtr? If it's over 8lb, you really need to consider another motor. Otherwise were looking at top speeds of only 30 mph if that.

[TimisTim]

Umm....I have heat issues with my 4200 in my Losi ST. Even when its undergeared. I also had heat issues with other 540 "s" size motors in my roughly 5lb MT2. It is alot lighter than a Revo and I have to use an L can and batts with at least 70amps continuous to get long runtimes out of it. I actually run a 8800mah 3S. When used unparalleled my 4400mah packs would heat up alot more than I like.

You need to use a different motor for this truck. If you really want to use a lehner then go with an xl3600 on 3s. The 4200 is ALOT shorter than most other 540's and is for lighter buggies and ST's. Brushless motors are different in that they will pull as many amps as it takes to get an object moving as long as the batteries can supply the juice. So even though you say the motor is rated at 40amps it will actually pull alot more than that in a given application.

[TimisTim]

Oh one more thing. Don't buy batteries from tower hobbies! Their lipo's are way overpriced. If anything go to www.maxamps.com and buy two $80 6000mah 2S and hook them together for a 4s pack that can handle 70amps continuous and 100 amp spikes! That would really move your truck!

[tumad]

Gee, so many replies...Thanks folks.
Ok, so you reckon the 4200 is NOT the motor of choice here.
Still confused about the battery issue assuming I would want to use the motor.
This motor is rated at 12 cells @ 700 Watts, which I thought would be ample.
Nevertheless,
Lets assume I use 2 x 6000mah 2S battery packs, which motor do you recomend I install? I am looking for power and peformance to match that of the currently installed Sirio .23 which is in my opinionis 'Insane'

I need at least 10 -15 minutes run time and I will install it with the clutch system as pictured above.
Will I still be able to use my Schultze 18.61k controller? I really don't want to have to buy another controller also.

Thanks so much guys...

[starluckrc]

To use the 18.61k, you will need to maximize your voltage to keep current down with a low kv motor. The controller should be able to take 5S. You would want a motor around 2000 rpm/v. Even then you will probably be pushing that controller. You may be better selling the setup and reinvesting in something else.

[TimisTim]

Well the option to sell the system and buy something else would be ideal if you could get a good price for it. Im not sure on how much the schulze would sell for but they do retain value quite well.

The best all around system some of the people on here and myself run is the Mtroniks truck ($185) and Feigao "L" cans ($75). If you were to run somehting like said above you would need a Feigao 10L and gear it up a little.

[scoob]

buy two $80 6000mah 2S and hook them together for a 4s pack that can handle 70amps continuous and 100 amp spikes! That would really move your truck!

I thought it was 60 amps cont. and 72 burst. Anyway I have got one of these packs now and it performs great. For the price you can't beat it. Only complaint, the pack is very big and heavy for a 6000. It's bigger and just as heavy as my TP8000s. Don't buy it for a 1/10 buggy unless you don't mind running it with no foams. I run all my li-pos with at least one foam pad in front and rear. Maybe you could make it work for a buggy but the pack is quite large. For the Revo, I'm sure you would have plenty of room. I run it in a T3 stadium truck.

Overall it's the best value on the market.

As for the motor, I agree that the basic 4200 is too small for a Monster. It would push it along fine but you would have to gear it very low to keep it from burnign itself up.

[TimisTim]

Woops, correction scoob's right on the amp ratings. They are a little heavy but still less than a sub-c pack.

[tumad]

Ok, so from what I gather, I need a lower rpm/v motor. I still have a Jeti Phasor 15/4 rated at 1600 rpm/v will that be any good?

TimisTim, please show me the motor you mean here..
http://caihongz.diytrade.com/sdp/85838/4/cp-102738.html

If all else fails, lets have your motor/controller/battery suggestions. (with links if possible)
Looking for sirio .23 performance and at least 10 minutes run times.

[TimisTim]

Well the motors can be found at a couple of places. If you want a lehner www.rc-monster.com has them in alot of turns, they also have the Feigao 10L as well as www.starluckrc.com.

Lets get back to your original question about batteries. Have you made a choice on those yet? It really should be your main concern as your rig should be built around them. In a Revo I would get something that can take some high amp spikes, like 80 continuous and 100 or more peak. Check out www.rclipos.com for some good batts. I use their polyquest 3S 4400's in parallel for an 8800 pack and get 20 minutes or so runtimes easy. Which is a 12c pack so it can handle 105 amps continuous and 140 amp bursts!

[tumad]

Yes, I will be going with the 6000 mah Lipos form maxxamps (2 x for 15 v)
Then I will couple that to eihter the Quark Monster Pro controller, or the Mtronics Genesis Truck controller, and to that I will either add the 10L or the 7XL motor (similar kv ratings)

Do you guys think that that setup will cook?

Thanks

[tumad]

Also, for a test, would my Jeti Phasor 15/4 rated at 1600 rpm/v be of any use?

[Maxx42]

Yes, I will be going with the 6000 mah Lipos form maxxamps (2 x for 15 v)
Then I will couple that to eihter the Quark Monster Pro controller, or the Mtronics Genesis Truck controller, and to that I will either add the 10L or the 7XL motor (similar kv ratings)

Do you guys think that that setup will cook?

Thanks

I'd be careful using those 6000 mah lipos with the 7XL. That motor is power hungry and may damage your packs when under hard acceleration (I think they are only rated for 60 amps continuous 72 amps peak). I use the 8000 mah lipos from maxamps with a 7XL and a shulze 18.97kw controller. They are very capable of handling that motor and it's quite a beast on just 4s lipo.

[tumad]

I'd be careful using those 6000 mah lipos with the 7XL. That motor is power hungry and may damage your packs when under hard acceleration (I think they are only rated for 60 amps continuous 72 amps peak). I use the 8000 mah lipos from maxamps with a 7XL and a shulze 18.97kw controller. They are very capable of handling that motor and it's quite a beast on just 4s lipo.


If I connect two packs in series (15v) won't that give me 120 amps to draw from?
Then that 7XL should be fine, should I go with it.

Had a word with Chris Fine, he recommends the Nemesis XLT -4 Motor with shulze 18.97kw controller....all very confusing...

[JakeE]

Assuming the 2S 6000 mAH 10C packs discussed above (I know the Maxamps packs are actually 2S2P but ignore the internal pack construction for the sake of discussion, pretend they're 2S1P):
Connecting packs in series adds the voltage (4S1P -> 14.8V, 6000 mAH) whereas connecting them in a parallel adds the capacity (2S2P -> 7.4V, 12,000 mAH, 120A discharge capability). You'd have to use a 4S2P pack (two 4S 6000 mAH packs in parallel) to get the 14.8V and 120A discharge capability you describe.

[Maxx42]

If I connect two packs in series (15v) won't that give me 120 amps to draw from?
Then that 7XL should be fine, should I go with it.

Had a word with Chris Fine, he recommends the Nemesis XLT -4 Motor with shulze 18.97kw controller....all very confusing...

JakeE said it well about the lipo combination you would need if you went with those cells. As far as the Nemesis XLT-4 motor, I have no experience with it and couldn't comment. If I were to get another Feigao or Wanderer (very similar to the feigao) motor I'd go with the 8XL instead of the 7XL. I'm going to upgrade to a Lehner 19xx series motor soon though, but I have some other projects that I'd like to finish first. As far as the shulze 18.97kw goes, I have two of them and like them a lot. The only things I don't like about them are the fact that you must use a bec or receiver pack with them and the long delay they have to go in reverse. Other than that they can handle many of the hotter motors out there today including 4 pole armatures. There are other controllers out there that are cheaper than the shulze if you are going to stick with 2 pole armatures.

[starluckrc]

Quark and Mtroniks both do a good job with 4-pole motors as well.

I know two very unsatisfied customers with the Fine Design conversions that I had the pleasure of talking to at the Southeast Electric Flight Festival. Keep in mind that the Nemesis is just a relabled Feigao motor.

[Maxx42]

How do you like the Quark controllers? I've read up a little on them on this forum and was considering a 125B for monster truck applications.

[tumad]

Thanks for all the info guys.
So can I connect the Maxamp packs in series to give me 14,8 v 4000 Mah
Will that still only give me 60 amp draw? (assuming they are 60amps)
Will that not be enough?
Apparantly the Emaxxes, with simmilar setups really cruise, and only wheigh 200 gramms less than my converted Revo would...

I was just about to put my order through, but now I'm not so sure anymore....
This isn't easy, and I don't have the budget to 'experiment', I need to get it right the first time.....

Thanks again to all those involved..

Had a mail from RC-Monster...Mike says the following:
Quote:
"I would recommend a 5s Lipo setup for this particular application. Given
Lipo batteries, I prefer the Quark monster pro controller, as it has a built
in LVC. It is a good idea to use the single speed emaxx tranny with a steel
idler gear as well. On 5s Lipo, you should be able to beat the .23 Revo
everywhere in the power band. 4s Lipos will hang, but 5s will be better in
my opinion(you could run a 3s on the side opposite the motor and a 2s on the
motor side to balance the weight.
There are many motors that will get the job done, and gearing will
ultimately depend on the motor selection. For 5s Lipo, I like the Lehner
1940 motors(8 turn comes to mind). The lower priced wanderer or Feigao xl
motors will get the job done as well, but aren't nearly as efficient and
will run hotter."

I wasn't really planning on rebuilding the whole car with a new chassis......that's going a bit far...

[TimisTim]

Well mike is right on with everything. I would go a little cheap on the motor and buy the feigao. 4s will be alot of power. The battery end is what you really need to worry about, then the controller. You need alot of amps for this application, amps will go up as the amount of cells does. I would suggest 80amps continuous and over 100 burst. They are expensive, but like you said do it right. It looks like a good deal is the maxamps 80002s2p 96 constant and 128 burst for $130 a piece. Hook two of those up for $260 and you will have a very reliable battery. Just make sure you get a balancer and balance the cells then peak each pack before connecting them together, rebalance every once in a while and check their individual voltages just to be safe.

I would love to have a Quark Monster controller. If you can afford it get it.

[tumad]

Thanks guys for all the input, I have enough info now to make a desicion.
I'll let you know how it all turns out once I have the gear installed.

Great forum by the way....

[Elmo6s]

Check these out:

http://www.boomboombatteries.com/product_details.aspx?ProductID=61