9xl, 5s, Quark 125b + Lipo battery holders?
 

So I am planning on converting my savage to brushless. I have to ask just to make sure though. I have read a lot of the threads on this forum and have come to the conclusion this would be a reasonable combo 9xl, 5s, Quark 125b. Would this setup stay at a reasonable temp with the right pinion in a savage? Mine will have the 3 speed in it as I don't really have the kit to make a slipperential. Also for battery mounting I was looking a getting a 3s and a 2s 8000mah lipo in series and mounting one on each side of the truck. I was looking at serums revo conversion and wondering if anyone knows where to get cf U section or if it even exists. CF U section would make really cool battery holders I would think.

The 9XL is a good all-around motor. But since it is not as efficient as the higher-end motors, it WILL heat up after a while no matter what. If you run for ~20-30 minutes, let rest for ~20 minutes, and then run again, it should be fine. But if you are looking for a non-stop running motor, I would look at a Neu 1512 or 1515 series, or Lehner 1940 or 1950 series.

I am not familiar with the Savage, but most auto-shifting trannies I've seen cannot use the motor for braking or reverse because of a OWB. Besides, these motors have enough torque for ~35mph that you don't really need multple gears unless you are trying for some VERY high speeds.

CF battery holders are quite strong and can be made from L shaped pieces to form a U shape. Graphiteelegance.com used to be a good place to go, or try McMastercarr.com. Be aware that CF is electrically conductive so if you have any chafe points in the wrong place, it could short out the battery. The same is true with Al too, but most people don't think CF is conductive.

If you are runnning the 3 speed tranny, just use a 20-22T pinion with the 47T plastic spur gear and get a heatsink and fans for both the Quark and Feigao motors and you should be good to go.

The U section of CF would probably need to be be custom. The guy at www.graphiteelegance.com could make it if he ever comes back form vacation. Other than that there should be other places that can make, but it would probably cost more. Just do a web search.

Google has failed me on the cf stuff. It brings up complete rubbish. Maybe I don't know what to search for. It is a shame graphite elegance seems to have given up. I'll check McMastercarr.com out.

On the motors I would love to get a Neu 1515 but I don't think the funds are going to stretch that far. I was going to heat sink the motor as I knew it would run a bit hot. The quark seems to have a reputation for running hot. what other esc are similarly spec'ed. I won't be too upset if I burn a motor but to have an esc die at $250 each I'll do more then cry.

Also any one recommend a fan? I know people use pc fans but the ones I can get would be far too big.

Edit: I worked out why google is failing me. bloody Americans and their crazy spelling. What's 'fiber'.

lol, thats funny. =)

As for another ESC, the MGM Compro 160 has been running very cool for people with it, and it can actually run 6s successfully if you ever want to unlike the Quark. There is also computer programming for it, so that makes it even easier. same price as the quark as well.

Keep us updated with pictures of the Savage. BTW - who is making your motor mount or where are you getting it from?

Does the MGM Compro 160 support 4 pole motors (a neu 1515 may come one day)? Did I read it right. Does this not need a separate bec even when running 6s?

As far as motor mount goes I was going to get the Kershaw Designs one but I wanted one that mounts the engine lower for a better cg and to keep the motor out of harms way. I discovered that one of the guys at work has access to a workshop and can make me the mount. I just need to draw one up. Does anyone have a low mounting engine plate design in cad that I could possible use? I know it's a big ask as I would be copying someone else's hard work but I though I would ask.

And as far as keeping you guys posted I definitely will. As soon as I get all the bits I have ordered so I can at least put the savage back together I will post pics and weigh it so I can use the calculators that are setup on this site. This forum has been a massive help so far. I was really struggling to find any info on converting savages and the different options until I found this forum.

Edit: and as far as the CF battery mounts go I will probably go aluminium U channel. The CF is too expensive.

Etid2: To answer an earlier point to, I don't feel like destroying my savage tranny too much. I may eventually get an LST2 and move the BL setup to that and make the savage a nitro again. I think the LST2 is a better platform for a brushless setup just because the battery mounting is so much simpler. Plus it would be nice to have to monster trucks in case one breaks.

Yes

That is correct.

Good luck with the project.

The MGM is looking good. Is the bec in the MGM Compro 160 amp, 18 cell brushless car controller reliable? After reading a few threads people are still saying use a ubec as the mgm bec has blown and taken out a servo with it.

So does anyone have a design for a low cg motor mount I could steal? I don't have a motor yet to design one around and i'm kind of impatient :o. Also if I do mount the motor below the spur does any one know if I am going to have to remove my nitro motor plate and braces?

PM serum. He's got a few designs.

thanks jnev

For 5S Lipo, I might consider a 10XL.

IMO, geared appropriately, 5s on a 9XL (kv=1853) or 6s on a 10XL (kv=1668) would be ideal. Gotta remember those kv values are unloaded.

Hi Brian

Going for the 35000rpm isn't the 9xl perfect for 5s if not a bit low. It comes out at 34280 unloaded. Compared to the 10xl at 30000 rpm unloaded. I must admit though that I don't want this setup to overheat so a 10xl may be an option.

I just had a thought if I am going to run the MGM Compro 160 why not run 6s since it can handle it and stay cool. I like the idea of having 2 identical batteries too. Then I can run a 10XL or so. The compro does run cool still on 6s doesn't it.

I have to admit that I too am guilty of quoting specs and numbers. I've often used 30K rpms as a "sweet spot" to shoot for and adhere to that more closely with the Feigao motors. The fact of the matter is that there are variables that will also play a substantial role in the amount of success that you have with a particular setup.

The two most substantial variables to consider will be the type of terrain that you will be running on that the ambient temperature of the area of the world that you are in.

Although the better Neu motors are more forgiving of these considerations, the Feigaos are not.

I'm in southern Louisiana and it's always hot down here. I think that winter lasted all of two days last year. LOL.

Anyway, the 9XL might perform well for you and the temps might not get too bad if it is relatively cool where you are.

Down here where I am, a 9XL does fairly well on 4S, but will jump up to 200*F on 5S pretty quickly. Although I run Neu motors in almost all of my vehicles, I still run a MM/Feigao combo in my Monster GT conversion. Running the 9XL on 4S makes for plenty of power and loads of fun.

In my experience with the Compro controllers, they run cool no matter what you put them through. If you can run 6S, you could look to an 11XL or 12XL.

If you are new to brushless, you may just not know what to expect. Here's a link to a video of my 8ight T running a 9XL on 4S geared 14/46...http://s154.photobucket.com/albums/s...DSCF0303-1.flv

It is, of course, not stupid powerful, but still much more powerful than a nitro setup.

I gotta pee too...:rofl:

I was wondering what you on about. That 8T is pretty quick. If I got that sort of performance out of my savage and the electrics stayed cool I'd be happy. The 350Z in the background is quick too I bet.

The temp here vary from about 5-15c (41-59f) in middle of winter to around 25-40c (77-104f) in summer. I have used BrianG's speed calculator and I may try an 11xl. It will be mainly off road work that the savage will do. Dirt and grass. It is going to probably be a basher so I still want heaps of torque. Here is what i put in:

Vehicle Weight (approx): 15 (I assume this is in pounds, I have no idea what my truck weighs)
Desired top speed in MPH: 40
Differential Ratio: 3.3076923076923075
Transmission Ratio: 1.6956521739130435
Additional Ratio: 0.967741935483871
Spur Tooth Count: 47
Pinion Tooth Count: 16
Battery Voltage: 22.2
Tire Diameter (inches): 6
Total Ratio: 15.94407 : 1
Tire Circumference: 18.85 inches (478.779 mm)
Required Motor RPM: 35729.102 RPM
Required Motor KV: 1609.419 RPM/V
Good Motor Choices: BK Wanderer 12 XL (kv=1390) BK Wanderer 11 XL (kv=1516) BK Wanderer 10 XL (kv=1668)
Better Motor Choices: No motors of this class fit the parameters you entered.
Best Motor Choices: Neu 1515 2.5d (kv=1700) Neu 1515 1.5y (kv=1500) Neu 1512 3d (kv=1700) Neu 1512 2y (kv=1400) LMT 1940/10 (kv=1588) LMT 1940/9 (kv=1742) LMT 1950/9 (kv=1452) LMT 1950/8 (kv=1634)

I'd love to get a neu motor in the future but for the momment I'm going to stick to feiago's. If I try to get a neu now this truck will never be finished. I have almost enough parts to build the chassis now, so pics should be coming soon. Just waiting on a couple of bits.

Getting a 15lb truck to 40mph may be a bit of a chore. I think that 35 would be more realistic and practical.

In any event, you should prepare yourself for some fun.

As a side note and perhaps a piece of advise, if you are venturing into the unknown, it is usually better to err on the side of being conservative than getting things that are too hot. It really sucks when you put something together only to find that you can't run it the way that you want to, because of excessive heat.

Thanks for the advice. 35mph is probably a better target and I would be happy with that. I just kept reading all these posts saying they want their trucks to do 40mph. Being in australia we use kph so 40mph didn't mean much to me.

I would prefer a more conservative setup, one that is easy on the batteries (longer run time) and runs cool then some thing that can do 40mph. But I don't know what would be a more conservative setup. 5s or 11/12xl.

I have to say I really appreciate all the help you guys are giving me.

For 5s, I'd say 9XL or 10XL. Don't forget that those XL kv ratings are unloaded. Once you load the motors, the kv can drop a couple hundred thereby lowering the total speed.

If you enter an estimated current draw into the speed calc, it will show you the approximate loaded kv (and the adjusted top speed).

If I run 6s will this keep the motor cooler if I get a motor with the same top rpm? eg:

5s on 9xl is max unloaded rpm 30839
6s on 11xl is max unloaded rpm 30303
so they are very similar rpm will the 6s setup run cooler under the same conditions then the 5s? I'm thinking that I might as well go 6s if it will be better as the compro esc sounds like it can handle it, no worries.

Yes, the 11XL/6s setup will be better because you are getting around the same power, but using less current. High current is what makes things run inefficiently. The only downside with the higher voltages is the expense of the battery pack, and maybe a charger that will do 6s...

I would have to run two 3s packs on the savage and I would charge them as 2 seperate packs. Even though just looking at the specs of my charger it will do 6s. If I could get a special balancing lead I could do both at once. My charger won't go up to 8amps (for the 8000mah packs) but they will just charge slower.

As far as batteries go I was looking as the true rc custom packs. I am planning on getting two TrueRC 10c 11.1V 3S2P 8000mAh packs and running them in series. I assume 80A continuous is plenty for the savage on 6s on an 11xl. 60A max on the 11xl on the feigao data sheet if that means anything.

80A on 6s is around 1700w. However, you will probably be drawing around 12-15A average with peaks around 80-90A. No one pays much attention to the current ratings on those motors since car current requirements are different than flight current requirements.

As far as a special balancing lead goes, you might want to check the bottom of this page.

BrianG that link points to your E:. I'm definitely interested though. The balancing lead would half my charge time.

lol, yeah, I was doing some development and forgot which browser window I was in. Oops. :whistle:

Link fixed. :oops:

How close does the voltage on lipo packs need to be for parallel?

Exactly the same would be best. If the packs are different, there will be a decent spark when you parallel them. I would charge both up fresh, and then let both sit until the voltages settle down to within 0.05v of each other. Even then, there will be a spark.

That's probably a good reason to charge them at the same time. then they will be balanced across both packs (at least at the end of the charge).

edit: thanks briang for the link. The problem I have over here is getting the right balancing plugs.

Yeah, getting the right plugs can be a PITA. Most places don't have a pic of the part, just the description, and it's easy to get the wrong end. When I made mine, Mike actually had the plugs I needed, he just doesn't have them specifically listed in the store.

I made my Y adaptor kinda long, but this is what it looks like.

That's a good idea. I want to make one like that. That way I can stick the batteries in a battery bunker while charging. What do people use as battery bunkers? I'm naughty and never watch my batteries while they are charging :gasp:.

I use the liposack, which is why I made the wires kinda long. There is a cement bunker I've seen somewhere. Some people use the pottery-style flower pots. Basically anything that won't conduct electricity and could at least control a flame.