: B-Revo Questions



cdis
30-03-2008, 12:18 PM
So, I'm considering converting my revo 3.3 to brushless. I'm probably going to purchase the Tekno RC brushless conversion kit, as I don't have any means to do the required metal work to make a mount myself. The clutch thing that the Tekno kit comes with looks awesome as well, as I'd like to keep the mechanical brakes, as it'll probably be running the CD with rear brakes. I've got a Mamba Max ESC and a Feigao 540 7XL (2382KV) sitting around doing nothing.

Now, my question (apart from whether CD's are allowed @ BDR in the MT class) is with regard to voltage. I currently use A123 batts with my aircraft, so I'd be using those instead of LiPo's to save myself some dosh. That and I'm scared to death of putting 2 big ass lipos in my Revo, especially with my driving style and my proneness to accidents :D

I'd probably run a 5s2p setup, as I already have the 5S packs. This would be 16.5v when charged. I've tried looking at their rules page but I can't find anything about this question.

Also, is there a KV limit on motors or KV x v limit or anything like that? That 7XL motor and the 5S A123 pack will give around 39,000RPM which I'm sure will run quite hot, but it saves me getting a lower KV motor.

I'm assuming that I'll have to go in with the nitro MT's which is fine, but would people have a problem with it?

Thanks

gen18
30-03-2008, 01:25 PM
I wouldn't. In fact, it would be awesome. There have been a few brushless MT's run over time since I started there. I ran an Electric myself, although not brushless. I would be interested to see the Tekno kit also. It would probably be the route I would take to go brushless. It's a little expensive, but it is very easy.

I currently run a revo, and you'll be in with us. You may have a little trouble when they run heat/finals. Mike Mcpherson has a brushless Revo. Ryan Cooke has a Brushless E-sav. Mark Williams has run a Brushless Savage. There are a few others also. You won't be alone at least.

As far as your other thread, I'll answer that here, BDR rules state that MT's have to have a fixed centre Driveline. However, they have no rule about Electric at all. Its my opinion that the rules are a little out of date in some areas. In the past several people have run a centre diff, maybe accompanied by a little elbowing and joking about cheaters. I would like to run a centre diff myself. I dont think there is anything wrong with it, but thats another post entirely and not the view of the club officials.

If all you have is the centre diff when you show up, i doubt you will be turned away. Perhaps you should head over to the RCtech forums or email someone like Tony, the race director.

shakzool
30-03-2008, 05:44 PM
isnt 16v a little to much for a mamba max esc ive heard of people using a bec on 4s lipo thats around 14v.
keep us posted i wouldnt mine making my lst2 bl

NitroBurner
30-03-2008, 09:01 PM
16V is REALY pushing it!! if you want that kind of power you will have to sent it in to a guy in the US (unless there is a local guy) to mod your ESC to withstand huge amounts of voltage, amp and just stupid power!!! IMO, you should only need at MAX a 4S, but that is IMO. and even for that you will probably need another ESC.

Castle Creations are realeasing a new ESC, i cant remember what its called, but its supposed to be used in larger ele. trucks that need huge POWER!! Dont qoute me, but i think its going to be released soon, if it already isnt.

Otherwise, i think Quark has a good ESC...

Mabye this will help...

http://rcrally.org/forums/mt-s-cars-buggies-truggies-etc/95-project-e-revo-56k-warning.html
Have a good read... There is also a thread with a youtube vid... basically he tried to run a 5S (he has put stacks of $$ into his ESCs) and it smoked the ESC...

NitroBurner
30-03-2008, 09:03 PM
Here is the youtube vid...

I suggest you read the comments.
http://www.youtube.com/watch?v=C5-K6PbhOkU

... ohh right. Click on the vid to bring up the page, then read the comments.

Gumbyj
30-03-2008, 09:33 PM
So, I'm considering converting my revo 3.3 to brushless. I'm probably going to purchase the Tekno RC brushless conversion kit, as I don't have any means to do the required metal work to make a mount myself. The clutch thing that the Tekno kit comes with looks awesome as well, as I'd like to keep the mechanical brakes, as it'll probably be running the CD with rear brakes. I've got a Mamba Max ESC and a Feigao 540 7XL (2382KV) sitting around doing nothing.

Now, my question (apart from whether CD's are allowed @ BDR in the MT class) is with regard to voltage. I currently use A123 batts with my aircraft, so I'd be using those instead of LiPo's to save myself some dosh. That and I'm scared to death of putting 2 big ass lipos in my Revo, especially with my driving style and my proneness to accidents :D

I'd probably run a 5s2p setup, as I already have the 5S packs. This would be 16.5v when charged. I've tried looking at their rules page but I can't find anything about this question.

Also, is there a KV limit on motors or KV x v limit or anything like that? That 7XL motor and the 5S A123 pack will give around 39,000RPM which I'm sure will run quite hot, but it saves me getting a lower KV motor.

I'm assuming that I'll have to go in with the nitro MT's which is fine, but would people have a problem with it?

Thanks

Nothing more satisfying that making it yourself!! yeah right. Take a look here https://www.ausrc.com/forum/showthread.php?t=8186 for my attempt. Took a few ideas from Teckno.

Higher voltage systems are more efficient and powerful, however I don't believe that the mamba max takes more the 3S lipo, only 12c NiMh so thats 14.4v. could try pushing it to 16.5v, it's your money. How much does a 5s2p A123 battery weigh? and whats the capacity?

If you keep the 2 speed you'll need to keep the mechanical brakes, My HV 4.5 on 3S lipo spins at 53280RPM, theoretically.

The rules at BDR are more "Guidelines", we're monster truckers damit and we like to push the boundaries.

GumbyJ

cdis
31-03-2008, 12:59 AM
Ooooer, I see. I thought they were only limited by Amps and max rpm, not voltage. No matter, I can easily make 4S packs. I'm already using 4S packs in my GF's Evader with a MM 4600kv combo and it flys.

The 5S2P batt would be pretty phat, but I haven't weighed it yet. There are 2 kinds of A123's, 1100mah and 2300mah. The 5S2P pack was going to be the 2300 variety, which are 70g/cell without any solder or wires. So with wires, heat shrink, solder and a balance tap, I think they'd be around 400g or slightly less each. I'd have to use 2 to make it 2P obviously :D.

I'm using 4S 1100mah packs in the evader at the moment, which are around 170g, so FAR lighter than say a 4200mah Sub C cell pack, but the battery life is pretty pathetic. I only get about a 5-7 minute run time, but I've usually broken the evader by then :D

I've been reading up on the rc-monster forum, and quite a few people are running 5S A123 packs with their MM ESC's safely. A few are even running 5S LiPos but thats a bit of overkill IMO. Apparantly you just have to chose a motor and gearing that doesn't overload it. Keep in mind, a 5S A123 pack is 16.5v whereas a 5S LiPo pack is 18.5v.
The 3S limit on the Mamba Max box is more for the motor than the speedy, from my understanding. Basically, the 7700kv MM is limited to 2S, or 8.4v because at 8.4v its doing 64,680RPM. If you went to 3S on the 7700kv, you'd be pulling 85,470RPM.... thats INSANE. I think motor's break apart at like 67000rpm or something like that. Thats why with the 5700kv and the 4600kv you can get away with 3S, I think.

Anyway, with that Feigao 540 7XL, its only a 2300kv motor, so with a 5S A123 pack, it'd only be pulling 37,950RPM, which should be right, provided I gear it correctly. Less RPM's than yours Gumbyj, maybe I'll have to get a different motor hehe :D

Also, I think with regard to frying electronics, thats more from people not using an external BEC with their ESC. From what I've researched, anything over 3S LiPo should be using a BEC, and if so, then the only thing to make sure of is to not go over the 100A which the MM ESC is limited to.

I shall do some more research on the 5S with the MM thing tho, I don't wanna pop my nice new ESC :(

Gumby, what ESC are you running in yours?

Gumbyj
31-03-2008, 08:14 AM
I run the Novak HV maxx and the HV 4.5 motor. when I initially converted to brushless I was running the HV maxx motor (HV 6.5) on 12 NimH cells, I have recently changed to the HV 4.5 motor and dropped back to 3S lipo to save approx 500g in weight.

Running a lower kV motor on higher voltage should be more efficient though as you have less I2R losses.

GumbyJ

commando
31-03-2008, 12:31 PM
Im on the MM ESC and an 8XL on 2 x 8000mah 7.4 Lipos! (2s2p, peak 120A draw each)

Works fine for me. 22/58 gearing too.

poorbie:(
02-04-2008, 02:06 PM
i think i may pipe in here. (ryan, mentioned before)

my setup is 12xnimh and an ammo 2600kv setup. u got those cells from united hobbies didnt you!! (i wouldnt mind some actually if you got any for sale)

in an e savage, which now ive found out, isnt the best choice, but limited in money, was the only option i could actaully afford. temps in my heavy (4.8kg) truck are fine, motor is not too hot to touch ever, and the esc has never cut out and gets quite warm.

lots and lots of people are running the same setup but on 14 cells to give 16.8v, more than the 5S liFe. only thing is, castle has modified the design last year and all new escs (from about august?) are designed to not work on 14 cells. mine does, but some wont even turn on! os its luck of the draw in regards to that.

looking seriously at the a123 as my setup is clearly too heavy and cannot provide the power the motor is looking for. (60A cont. i think)

the feigao 7xl would be more eficcient and it would probably work. i guess there is 1 way to find out!


hope this helped you a little bit,


ryan

MTBikerTim
02-04-2008, 02:41 PM
cdis I think you are on the right track. The MM should work on the 5s A123 from what people say on rc-monster but you are more likely to smoke the esc as it doesn't leave a lot of overhead. The other option is get the MMM which I am sure you know about if you are visiting rc-monster. The 5s2p pack is going to be a heavy pack though, racing you might only need 4s2p.

Rules are made to be broken. I know our club for the local races will just stick you in the class you are closest too.

NitroBurner
02-04-2008, 05:14 PM
Did somone say a NEU motor??

Man, those things are SICK!!

poorbie:(
02-04-2008, 08:31 PM
NB, yes they are sick. but not many can afford or need to afford such a motor.... the MMM promises to be awesome, but come on, 3 years in the making... im guessing itl be delayed at least till june
imo... 4s would be suitable for racing and well within the limits of the MM though :)

ryan

NitroBurner
02-04-2008, 09:10 PM
But that thing would be awsome fun in a Revo!!

Caleb
02-04-2008, 09:11 PM
I'd probably run a 5s2p setup, as I already have the 5S packs. This would be 16.5v when charged. I've tried looking at their rules page but I can't find anything about this question.


From the "BDR general Rules and Conditions 2008.pdf" available here....
http://www.users.bigpond.net.au/bigfix/rules.html

------------------------------
5.2.6 Monster Truck
LiPo/electric “conversions” are permitted with a maximum nominal voltage of
16.8 volts.
------------------------------

The rules also state that no centre diff's are allowed either, but people have been running them for awhile now and no-one has complained. I'll be talking to the MT crowd at the next race meet with a view to getting that rule removed at the next committee meeting.

I think Gumbyj said it best...


The rules at BDR are more "Guidelines", we're monster truckers damit and we like to push the boundaries.

MTBikerTim
02-04-2008, 09:41 PM
NB, yes they are sick. but not many can afford or need to afford such a motor.... the MMM promises to be awesome, but come on, 3 years in the making... im guessing itl be delayed at least till june
imo... 4s would be suitable for racing and well within the limits of the MM though :)

ryan

Since castle has the cases and all the other components ready for maufacture of the MMM I think they are well and truely on their way. Supposedly they will be done and in the post before the end of this month. This time I beleive them too. The neu motor might be a little behind the controller though.

cdis
03-04-2008, 08:50 AM
Thanks for all the advice guys. I think I'm going to wait and see what will happen with the MMM.

As for motors, hmm, $70 for a 7XL, or like $260 for a NEU :D I'll stick to the nice cheapish motors that I can smoke and not feel too bad about afterwards hehe :D

gen18
03-04-2008, 05:04 PM
I'll be talking to the MT crowd at the next race meet with a view to getting that rule removed at the next committee meeting.


Nice. It will be good to have standard rules all round for MT. I was planning to have two transmissions to swap in and out depending where i race, but would definitely prefer for that to be entirely my decision to make.

Caleb
03-04-2008, 05:25 PM
Nice. It will be good to have standard rules all round for MT. I was planning to have two transmissions to swap in and out depending where i race, but would definitely prefer for that to be entirely my decision to make.


Oh, i for got to mention. I'll also be looking for a consensus on banning those obnoxiously loud trinity pipes too :D

gen18
03-04-2008, 05:31 PM
Nooooooo! How else will everyone for miles know I'm carving up the track!

poorbie:(
03-04-2008, 05:57 PM
hmm. didnt know about the voltage rule, but you learn something everyday. that pipe wasnt as loud as your flat mates bloody hyper 8.5!! THAT WAS LOUD!

gen18
03-04-2008, 06:33 PM
Truthfully its not as bad as I thought it was going to be. Its noisy sure, but the vantage pipe Vaughn ran was loud too.

cdis
12-05-2008, 09:17 AM
Righto, time for a bit of an update!

I took my newly converted B-Revo out to BDR yesterday, and I was suitably impressed.

I ended up getting the Tekno Conversion, a Mamba Max ESC + CCBEC and an 8XL to start with. I'm running 5s A123 2300mAh packs. I have 2, so I could go parallel but that makes for a phat ass battery lol.
I have enough cells to make 2 x 6s packs, but I remember someone mentioning a 16.8v voltage limitation. A 5s A123 pack is 16.5v, a 6s is 19.8v lol.

Anyway, I also kept the 2 speed transmission and mechanical braking as the Revo has the CD and rear brakes. Had a few runs yesterday and chucked the DPRII-150 in to get some amp draw and voltage readings.

I'm very sad :(

Was only pulling 48A max. Even with 5s2p, was only maxing out like 51A. The ESC was barely warm, and the motor was at around 65-70 degrees, after 2 back to back packs. Not bad at all :D I didn't even bother with an ESC fan.

So I have a few questions:

1. How can I draw more amps? Ok, I know that sounds a little strange but hear me out lol. I went ahead and pre-ordered up a Monster Mamba Max thinking that there was no way the Mamba Max would handle 5s and a 7XL lol. Seeing how easily the MM is handling the 5S and 8XL makes me think it would have had no trouble with the 7XL either.
So basically, I want to give the Monster some actual work to do, otherwise it was a wasted purchase (for the moment) and I can just keep using the MM.
I've tried using the biggest spur gear (40T), but all that did was make the revo have terrible bottom end and no jumping ability at all, so I went back to the 38T quick smart. I'm too scared to try the 36T after seeing how the 38T handles :D I might give it a go and see if I get any longer run times.

2. Run time. As you BDR peeps know, we run 6min races. I run a Hyper ST pro in the truggy class, and I can normally get 7 laps in (if the marshals are on the ball lol), and 8 laps if I've had a particularly good run. Yesterday, the best runs with the packs ended with 1 dying at 6.5 laps, and another dying just short of the finish line to complete 7 laps.

What can I do to increase run time (apart from going 5s2p)? I can always make 6S packs, but I wanted to keep lower than that 16.8v voltage limitation.

I'll take some pics later :D

Thanks

MTBikerTim
12-05-2008, 04:05 PM
I'd almost say try 4s2p. Does your logger show voltage drop? It would be interesting see how the 1p A123s are holding up voltage wise. I have read that the A123's are only good for about 50a before the voltage drops really badly. I have read threw a bit of you thread on rc-monster too. I read that you have tried going 2p but didn't notice much of a difference which is really strange. 4s2p should also get you a bit more run time.

What's the actual performance of the car like? Also what KV is written on the actual motor? Is it possible the KV on the motor is lower then what it should be.

cdis
12-05-2008, 06:02 PM
Yea, there is a bit of voltage drop under load, but I thought that it was just normal sag. Hang on, I'll post the screenys of the DPR readout.

MTBikerTim
12-05-2008, 06:21 PM
Post up the readouts. I'll probably post up mine tomorrow if the MMM arrives.

cdis
12-05-2008, 06:28 PM
Keep in mind, the 1p run (top pic was for almost 4 min), whereas the bottom one was for only 2, which is why the second one looks less cluttered.

The kv rating sticker on the motor says 2084kv.

I must have written it wrong on RC Monster. I mean to say that with 2p the amperage draw doesn't really change, as compared to 1p. I do get WAYY longer run times with 2p, but I'm trying to avoid having the extra weight in the car. That and it's much more convenient obviously to have 2 packs rotating instead of having to charge both between races.

The performance with the 1p pack is awesome! Slightly slower at top speed than when I had the nitro engine in, but its MUCH more agile and far lighter on landings because of the weight loss. Also, the bottom end is way punchier. Might have something to do with me removing the clutch spring and mounting the shoes backwards tho ;) When accelerating from a standing start, you can hear the slipper clutch squealing in protest lol.

Overall, I'm very happy with the performance, I'm just trying to tweak the setup to get a few more minutes of runtime so I can just run 5s1p.

I don't really want to go down to 4s2p (apart from the effort of remaking my packs), thats still 8 cells in the car, and will be as heavy if not heavier than when it was nitro.



5s1p with 38T spur - 4min run
http://i157.photobucket.com/albums/t63/cdisah/Misc/5s1p38Tspur.jpg


5s2p with 38T spur - 2 min run
http://i157.photobucket.com/albums/t63/cdisah/Misc/5s2p38Tspur.jpg

cdis
12-05-2008, 06:30 PM
This is a zoomed in pic of the first 2 min of the 5s1p run from above.

Just to make it easier to compare with the 5s2p run, as its around the same length of time.


http://i157.photobucket.com/albums/t63/cdisah/Misc/5s1p38Tspur2.jpg

Gumbyj
12-05-2008, 08:56 PM
cdis, I can't understand why the bottom end would be worse running the 40T? I'd have said give the 36T a try, with the auto 2 speed you don't really have to compromise so much on the gear ratio.

I'm running the HV Maxx 4.5 on 3S 5000mah lipo, you may have seen me running it last meet. The bottom end on it is awesome and I was blasting past the nitro's down the straight, just ask gen18:) so the top speed isn't shabby.

I've only got a Watts up meter so no fancy graphing but in the testing that I did I was getting 90 amp peaks. During the 6min races, closer to 7 minutes once you finish the last lap I was using 2400mah so that equates to an average amp draw of 20ish amps. At the end of the 6min race my temps are motor 45, batt 45, ESC 46.

What gear set are you running in the gearbox? I run the wide ratio which can make it a little edgy when it changes gear on the up ramp of the table top:rolleyes:

Look forward to seeing another BRevo out at BDR.

GumbyJ

cdis
12-05-2008, 10:32 PM
Yea man I saw you :D Red revo with yellow or white dish wheels yea?

I have no idea why the bottom end is so bad. I thought that with the brushless it would be a negligible difference on bottom end and would be more speed on top... I might chuck the 40T back on there just to make sure. Maybe the pack wasn't fully charged or something.

Which spur are you running?

Haha, I just looked up the kv of the HV 4.5 Maxx - 5000kv unloaded. Mine is 2084kv :( Me thinks I need a bigger motor under the hood lol.

It's just the standard tranny with std offset gears. I was going to get a wide ratio set until I saw the crazy price at Hobby**** lol.

Even my top end at the moment is not as fast as pre-conversion with the same 38T spur. Its only slightly slower, but I can feel it lol. I even had to change the shift point down a tad.

Those temps are awesome man. I did 2 packs without stopping and checked temps. Battery wasn't even warm, ESC was on 32 and motor was on 70ish.

I only tested it for a few packs tho. I'll get back down there this week and test some more as I want to run both the B-Revo and my Hyper ST (provided the classes are separate) this weekend.

MTBikerTim
12-05-2008, 10:41 PM
Those graphs make no sense. You should be getting higher amp spikes on the 5s2p just from the added weight and you get lower amp spikes. I'll take a bit better look tomorrow and see if I can see anything.

cdis
12-05-2008, 11:20 PM
I agree totally. So unless I mis-labeled the save files (which is entirely possible lol), something fishy is going on lol.

Also, check this out. Just put in all my stats on Brian's top speed calc thing over at rcmonster, http://scriptasylum.com/rc_speed/_top_speed.html, and how's this for weird.
I put in all my stats, even measured my tires ballooning quite accurately etc.
I put in 51A for amp draw.

Put in the 38T spur, and it reckons I should be doing 67kph, or 63kph taking into account drag.
I put the 40T in, and it goes DOWN in speed estimate, ( 63 and 60kph ) which is exactly what I noticed when I did the same thing.
Now check this out, I put the 36T in and BOOM estimate of 70kph, or 67 with drag.

Now all that said, I'm not really sure how accurate his program is, but more than a few people say its pretty close.

So, guess who's trying out the 36T spur ASAP lol? :D Strange that it works that way I suppose, but I'm not going to complain if it makes me go faster. Hopefully it will also give me a bit more run time.

Gumbyj
13-05-2008, 07:56 AM
Yeah that was me:thumb:

The HV4.5 is 4800kV but I was limited by the fact that the HV-Maxx speedo can only handle 16.8V. Knowing what I know now I could have stuck with the HV6.5 (3100kV) motor and gone to a 4S 4000mah pack to get a similar result.

I'm running 15/54 pinion/spur but that is due to the higher kV of the motor, the numbers I run on my setup put my max speed at 67kph, I can & have geared up to 18/54 which puts me up to 81kph but It was way too fast and I was having trouble pullsing it up at the end of the straight:D mind you now that I've dialed the max brake up it might be worth a try again just for some crazy speed.

Going fewer teeth on the spur will put your speed up. What clutch bell are you running? the standard 15T? If I plug in those figure I have your max speed at 57.12kph which is why it's slower. Your gonna need to go up to a 17T clutch bell and/or the wide ratio box.

GumbyJ

MTBikerTim
13-05-2008, 09:39 AM
I agree totally. So unless I mis-labeled the save files (which is entirely possible lol), something fishy is going on lol.

Also, check this out. Just put in all my stats on Brian's top speed calc thing over at rcmonster, http://scriptasylum.com/rc_speed/_top_speed.html, and how's this for weird.
I put in all my stats, even measured my tires ballooning quite accurately etc.
I put in 51A for amp draw.

Put in the 38T spur, and it reckons I should be doing 67kph, or 63kph taking into account drag.
I put the 40T in, and it goes DOWN in speed estimate, ( 63 and 60kph ) which is exactly what I noticed when I did the same thing.
Now check this out, I put the 36T in and BOOM estimate of 70kph, or 67 with drag.

Now all that said, I'm not really sure how accurate his program is, but more than a few people say its pretty close.

So, guess who's trying out the 36T spur ASAP lol? :D Strange that it works that way I suppose, but I'm not going to complain if it makes me go faster. Hopefully it will also give me a bit more run time.

Smaller spur or larger pinion makes you go faster, bigger spur or smaller pinion makes you go slower but better bottom end. You are geared fairly mildly by the looks but gear up a bit and see how it goes. Also put up the graphs of when you do.

cdis
13-05-2008, 10:39 AM
You can get a 54 tooth spur for Revos? :O WHERE! lol

Ok, so I'm clear in my head what does gearing up/down mean? Gearing up = gearing for more top end?

commando
13-05-2008, 10:50 AM
You can get a 54 tooth spur for Revos? :O WHERE! lol

Ok, so I'm clear in my head what does gearing up/down mean? Gearing up = gearing for more top end?

Yep!

Gearing up = More top end speed, lower torque
Gearing down = Lower top end speed, higher torque

Gumbyj
13-05-2008, 02:43 PM
You can get a 54 tooth spur for Revos? :O WHERE! lol


It's actually a T-Maxx/Jato spur, I'm running 32p pinions.

cdis
13-05-2008, 03:01 PM
Haha, I'm going to have to check out your ride @ BDR this weekend if you're racing! :D

Gotta pinch some ideas lol

cdis
14-05-2008, 10:13 AM
Ok, just tested the revo with the 36T spur in there. Top speed seemed to be about the same as the 38T. It might be a bit faster, but without a radar gun I cant really tell :D

Also, the 5s1p pack I used was charged last night, so it was closer to 16.5v than 18v which is what they are straight off the charger, which is why the voltage line in this one starts a little lower.

Getting slightly larger amp draw now, 56A max, and the motor is running cooler that what it was with the bigger spurs. I guess now I'll just have to get some bigger clutch bells. Anyone got some? :D

The voltage drop under power is HUGE in this one for some reason tho. You can see where it shifts to second, the amp draw jumps up again and the voltage bottoms out for a bit. Much larger increments than with the other graphs. That might account for the slower top speed also, as there appears to be less voltage available.

I'll go try a 2p run and post the graph.


5s1p 36T spur, 15t clutch

http://i157.photobucket.com/albums/t63/cdisah/Misc/5s1p36Tspur.jpg

cdis
14-05-2008, 10:28 AM
Ahh, MUCH better.

Revo was accelerating with some decent speed and had loads of top end, definitely faster than 5s1p with the 38T spur.

I have yet to check run times, but I REALLY don't want to use 5s2p on race days, but it looks like I'm going to have to.

Less voltage drop than with 1p, but WAY more amp draw this time, 69.4A max.

5s2p 36T spur, 15t clutch
http://i157.photobucket.com/albums/t63/cdisah/Misc/5s2p36Tspur.jpg

MTBikerTim
14-05-2008, 02:24 PM
Now you are getting somewhere. It does look like you were geared low and the 1p A123's just aren't delivering enough grunt. I ran my Mamba Monster last night and this morning. It died though. I seem to be one of the unlucky ones.

Gumbyj
14-05-2008, 05:30 PM
I don't know much about A123 cells but at 56A your looking at close to 25C. By paralleling the packs you drop that back to 15C for 69A. In comparison to my Maxamps 3S 5000mah, 90A peaks are 18C, It looks like the packs just aren't able to deliver the power that you require.

NitroBurner
14-05-2008, 06:55 PM
IMO, just go with a high quality Li-Po battery!!

cdis
14-05-2008, 08:53 PM
Yea, they're rated to do 70A discharge, and 120A pulse over 10sec.

I went A123's as I already had em for my planes. Can't really justify spending $150-200 for just 1 4s or 5s 5000mah LiPo. That and the missus doesn't allow lipos in the house lol.

Sorry to hear your MMM doesn't work Tim :( I hope mine will be ok lol.

NitroBurner
14-05-2008, 09:07 PM
Well, if you have the moneyz i would suggest getting this!

http://www.maxamps.com/Lipo-5000-148-Pack.htm

Gumbyj
14-05-2008, 09:17 PM
Well, if you have the moneyz i would suggest getting this!

http://www.maxamps.com/Lipo-5000-148-Pack.htm

or for a little less $ this would probably suffice http://www.maxamps.com/Lipo-4000-148-Pack.htm

MTBikerTim
14-05-2008, 10:21 PM
If you are going to spend that sort of money buy a flight power. The A123 cells seem to be almost indestructible and I don't think you need to get lipos. The 70a continuous they may be able to do with out self destructing but the voltage drop is huge. A 2p setup might be the only way to get the performance.

cdis
14-05-2008, 10:44 PM
Yea, I think I've resigned myself to the fact that I'm going to have to use 2p and have a fat battery pack, or 2 packs strapped together rather. We shall see how the revo fares on Sunday! :D

I'll weight them tomorrow, but I think they'll be at or just under 400g each, so thats one fat 800g battery lol.

I might have to do something like go down to 3s2p, and get a really high kv motor and gear up a bit :(

Hmm, that also means I pretty much have no need for a Monster Mamba Max lol. Damn impulse buying :D

NitroBurner
14-05-2008, 10:47 PM
Just get a Li-Po... problem permanently solved!!
PLUS you end up with one helluva lighter car!

MTBikerTim
14-05-2008, 11:16 PM
I'm going to say 4s2p give that a try if you can. I'm sure you can find a use for your MMM. They are really nice escs. Mine was really smooth.

cdis
21-05-2008, 11:38 AM
OMG! Monster Max has arrived finally!!!!! Its a BIG phat ESC lol. I didn't realise quite how big it was going to be.

At least it came with a castle link tho. I must admit I'm a bit scared to plug it in. Hopefully MTBikerTim's mojo wont rub off on my ESC and it wont die.

Anyone know if the BEC in the MMM is programmable? Packet says it comes set at 5.5v. I want 6v dammit! :D It'll seem a bit silly to use a CC BEC just to get an extra .5v.

Now, whatever will I do with my 2 Mamba Max combos? :D

MTBikerTim
21-05-2008, 12:39 PM
I'll take one :D. They are a heavy little esc too. That was the thing that surprised me the most. I was thinking they must have used a lead heatsink (joking it's not that heavy). I doubt the 5.5v will be much of a problem. I was impressed that a crappy jr270 servo running on the MMMs 5.5v could stop my heavy savage really fast (endo fast). The power output is probably dead on 5.5v even under load.

cdis
27-05-2008, 11:10 AM
So finally had a chance to give the Monster Mamba Max a run on the weekend. All I can say is WOW!.

As Tim said, the monster is quite phat, size and weight wise. Also, it came with 10guage wires. I went ahead and ordered 3 sets of 6.5mm castle creations bullet connectors, only to find that they send a set with the monster, so now I have 4 sets lol. So if anyone wants some 6.5mm connectors for $10, gimme a yell lol.

Anyway the motor leads on the 8XL are really short so I had to rig up 3 "jumper" cables to connect to the ESC, but apart from that it was nice and easy to install. I've run about 6 packs through it and so far, no problems. The fan is still kicking and there hasn't been any power issues yet, as many other people have reported.

So, on to the good stuff. I had the 36T spur gear on, with the MM ESC when I go to the track, so I did a run just to get an idea of how that setup was on the dirt (I did the other graph runs above on the street outside).
This is a 2 min segment from that run.

36T Spur, 15T clutch, MM ESC with CC BEC @ 6v, 8XL, 5s1p A123.
http://i157.photobucket.com/albums/t63/cdisah/Misc/BDRMM36Tspur5s1p15Tclutch.jpg

ESC was ok, but motor was a bit warm with this setup, but ran ok.

Time to take out the MM and try out the new MMM. I did a run with exactly the same setup as the MM just to see what would happen. The difference is INSANE. Check out this graph:


36T Spur, 15T clutch, MMM ESC, 8XL, 5s1p A123.
http://i157.photobucket.com/albums/t63/cdisah/Misc/BDRMMM36Tspur5s1p15Tclutch.jpg

85A max on the MMM as opposed to 61A on the MM. I have no idea why, but I like it!

I would have done a few more runs on the 36T but it got shredded. I did the last run with the 38T spur in and the MMM.

38T Spur, 15T clutch, MMM ESC, 8XL, 5s1p A123.
http://i157.photobucket.com/albums/t63/cdisah/Misc/BDRMMM38Tspur5s1p15Tclutch.jpg

Unfortunately, with the huge amp draw my batteries are lasting even less time than before lol. The longest I got was just under 4 laps with the 5s1p. I'm definitely going to have to try a 2p config, but its not going to be 5s1p unless absolutely necessary because thats way to heavy.

I have 12 A123 cells, so I'm thinking of doing 3 x 4s packs so I can run 4s2p and always have a spare pack ready to go. Of course thats still 3 cells heavier than a single 5s1p pack.

My 5s1p packs are just under 400g each, 392g and 396g. A 4s2p pack will be about 640g. I suppose thats better than 800g, but its still pretty fat.

I'll have to see how it goes with only 13.2v instead of 16.5v. Means I'm only going to have 27508 RPM to work with instead of 34386 RPM.
With the voltage sag of using a 1p configuration, I'm sure I'm not getting anywhere near 34000rpm anyway, so I'm hoping that the top speed of 4s2p will be around the same as 5s1p while under load.

Might be time for a faster motor! :D What do you guys think?

commando
27-05-2008, 11:26 AM
yep!
time for a new motor

hows about a 1515 1.5D?

cdis
27-05-2008, 12:16 PM
Hahahaha, was thinking more along the lines of a 7XL for $70 :D

cdis
27-05-2008, 12:33 PM
Whats the deal with the neu motor naming convention anyway? Whats the 1.5d for? I figured out that the F or S on the end means the can has fins or is smooth but no idea about the other stuff.

MTBikerTim
27-05-2008, 01:49 PM
the 1.5d is really just a way to reference the kv for us mortals. It does mean stuff to the rc gods but really the kv is the important one.

Anyway that is really impressive data. you should post that on rc-monster cause that is exactly what some of the guys are looking for over there. It shows that the MMM is far harder on batteries then the MM. I would say the reason is down to less resistance in the controller when being used so far over spec. Also shows why the MMM is smoother then the MM when they use the same controlling software.

cdis
27-05-2008, 02:48 PM
Righto, posted on RC-Monster.

So what kv is the 1.5d? Is there a chart somewhere that I can go and compare stuff to?

MTBikerTim
27-05-2008, 02:58 PM
There are charts on the neumotors.com website and the castle website. I suppose the other thing is the 1515 part of the name. the first 15 relates to the series (model) of the motor and I am not sure if the 15 has some exact meaning though. The second 15 relates to the length of the motor, 1512 is a shorter can but once again not sure if the 15 means anything specific.

I noticed you posted on rc-monster too. :thumb:

commando
27-05-2008, 06:50 PM
Heh, well for 5S speed runs I'd go for the 1.5D..it would be perfect I reckon. Its a 2700kv motor..5S would put it at about 48,000RPM which should be fine for a neu. the D signifies the type of winding.
I run 4s lipos and personallly Id go with either a 1515 1y or the 1.5D.. (probably the 1.5D, as Id likle to hit about 80-90K's :P.)

MMMrevo
24-08-2008, 06:19 PM
hi guys,

glad i came across this thread. new to the site. its good to see some cracking threads on the BL conversion from nitro. at this point i am at the final stage of MMM fitment and now trying to decide on a type of power source. i have looked at both schools, lipo and lifepo4, not even going to entertain nimh as the batteries will die a horrible death. i too am a bit reserved about the lipo flamability but also concerned on the 123 cell weight and lack of mAh. has anyone run them back to back? do i just need to be a careful basher ( if there is such a thing) and just drive it carefully with lipos? how sensitive are these cells really? on the other hand the 123s seem quite safe and more predictable. your thoughts and answers are appreciated.
thanks.

BTW i think the d and y suffix indicates the type of wind the brushless is, eg pattern type.

NitroBurner
24-08-2008, 06:24 PM
If you mount, charge and care for the Li-Po's carefully you will be fine. ALWAYS run it with a body and keep the battery's securely mounted on the chassis so they receive minimal damage.

MMMrevo
24-08-2008, 06:45 PM
thanks mate,

so how bashable are they? i know that you need to set voltage cut off points so the lipos dont go reverse chem on you. i do know theres different types of casings that you can get with them but how durable are they? mine will be strapped down by velcro and always shelled. also is it possible to diode the connectors in case you reverse pole them?
thanks.

cdis
25-08-2008, 12:48 AM
The MMM has a built in LVC which you can set via Castle Link to whatever voltage. Keep in mind that voltage drop when pulling lots of amps will set it off also.

As for A123's I'm pretty happy with them. For $200 I got 3x 4s1p packs and 1x 2s1p pack. I used to run 4s2p in my B-Revo, and am now running the same packs in my brushless truggy. They're a little heavy and bulky, but IMO they're worth it.
I've shorted them, over charged them like crazy, over dischaged them, had them come flying out of the truck when the velcro broke and they've even survived a mid air T-Bone on the battery side. The body cracked but not even a scratch on the cells :D

Plus charging at whatever max amperage my charger can do is also a plus. Also, I haven't balanced them in about 20 charges. I always have the balancer plugged in, but the invividual voltages are fine.

At the moment I get about 12min out of the 4s2p packs at the track which is fine considering we only do 6 min races.

But yea, good batteries IMO, and a cheaper alternative to decent LiPos.

MMMrevo
01-09-2008, 09:00 PM
well i got the setup ready and all my motor wires soldered to the MMM but to my surprise, and not a good one at that, realized my wires that came with the MMM were too short for my tekno converted revo. there is almost not slack between motor and esc. the esc mount ontop of the tranny will now be used for the receiver. i have to now mount it just above the rear shocks. not the end of the world i know but i thought castle would give more wire than that. anyone got a similar setup and any ideas around this apart from what i have planned?

cdis
03-09-2008, 02:01 AM
All I did was make 3 little extension cables, so that they'd reach.

MMMrevo
03-09-2008, 08:22 PM
yeah thought about that but i did this instead in my lunch break. seems to have solve the problem for now. cost me a lunch break.