This can't be right? Right? 177A @ 8S? - RC-Monster Forums

Finnster · **This can't be right? Right? 177A @ 8S? -** 08.18.2009, 11:54 PM

Finally converted my Sav XL to BL as planned. Went w/ my MGM 9032 and a 80mm Medusa 1100kv on 8S. Very nice power. I'll post pics in a thread when its totally done.

Anyway, went for the initial test run today. Just some not too heavy grass driving, and mostly parking lot runs. Plugged the MGM tonite to adj settings, and this is what the data recorder said. 177A!
That's almost 5 freaking HP on 8S.

Seemed like it had quite a bit of power, but I still have the stock big balloon tires on, and I could barely get any spd out of it before it wanted to wobble out of control. I only geared it for 40mph.

I have an ET, but I cannot locate the data cable, so I can't confirm with something else. Altho it was 95F today, both the motor and the esc were @ 130F+. When I had my Revo on 8S, everything was dead cold. Not nearly the level of power I have now tho. Wondering if the esc can read burst currents better than the ET can, or is this just way out of line? OTOH, I can't figure out what some of the other stuff is, such as the max revs output. WTF.

08.19.2009, 12:06 AM

6.6hp! damn that is nice, with my 2650kv in 4s , i am getting about 5-6hp.

BrianG · 08.19.2009, 12:49 AM

Don't forget, those peak numbers are just that; peaks. Normal running will be far lower. A gradual trigger finger will help reduce those currents.

As far as the ET is concerned, it samples every 1/10 sec, so if a burst happens in between samples, you won't catch it, or will catch the rising or falling slope of the spike.

bdebde · 01:35 AM

Are you running the MGM "black box"? If not, those figures are way off, Mgm say to use for comparison only as it is not accurate. Heck, I get 400 - 500 amps with my 2.5D on 6s.

Edit: Saw the model number of controller in the original post, so no that is not accurate.

Finnster · 08.19.2009, 01:39 AM

Quote:

Originally Posted by BrianG

Don't forget, those peak numbers are just that; peaks. Normal running will be far lower. A gradual trigger finger will help reduce those currents.

As far as the ET is concerned, it samples every 1/10 sec, so if a burst happens in between samples, you won't catch it, or will catch the rising or falling slope of the spike.

Yeah, I am well aware of that. I've just never seen a burst that high. I do know that the castle guys were talking about having equipment that could catch data at even a finer resolution, and they could see extremely high currents.

This just makes we wonder how sensitive the data capture on the esc is (rather than some artifact.) I really need to get the ET up and running and do some comparisons.

All I do know for sure is that I had a decently tuned LRP .28 in there before, and this setup kicks the hell out of it. My little trist w/ nitro was fun while it lasted, but I can't imagine going back... now what to do w/ the left over fuel....?

Finnster · 08.19.2009, 01:43 AM

Quote:

Originally Posted by bdebde

Are you running the MGM "black box"? If not, those figures are way off, Mgm say to use for comparison only as it is not accurate. Heck, I get 400 - 500 amps with my 2.5D on 6s.

Edit: Saw the model number of controller in the original post, so no that is not accurate.

hmmm... disappointing and comforting at the same time.

The figures are impressive, but seems way high. I was aiming for ~2000W on the bursts, but I could see hitting 2500W or so. 5K is just way crazy for a truck doing 40 odd mph (it is a hvy bitch tho.)

MetalMan · 08.19.2009, 01:51 AM

Which batteries are you running? My FLM extended Savage has that same setup for power (36-80-1100 on 8s) and is using Zippy Rhino 3700mah 20C cells, and a LT-10s ESC. Mine has a center diff and is geared for ~45mph top speed. As of the last time it ran the motor temp was about 150 deg. F or so after a run.

aqwut · 08.19.2009, 12:25 PM

LOL.. and I have 306 Deg Celcius on mine.. LOL, so it's definately not accurate...

Finnster · 08.19.2009, 01:57 PM

Quote:

Originally Posted by MetalMan

Which batteries are you running? My FLM extended Savage has that same setup for power (36-80-1100 on 8s) and is using Zippy Rhino 3700mah 20C cells, and a LT-10s ESC. Mine has a center diff and is geared for ~45mph top speed. As of the last time it ran the motor temp was about 150 deg. F or so after a run.

My 1yo 4000mah Zippy-H's 25/35C IIRC. I also have a number of older trueRC lipos I plan to run as well. I was hoping to keep the amps below 100 so its not too hard on things. Ran it some more today with w/ new 40 series mashers, and I think the top speed is closer to 45 or so. Its a bit fast for it.

Too much throttle and the back end just gets squirrelly and wants to hook. I think I need to go down on the rear diff fluid, but the rear toe links are really sloppy. I fixed one, but they are pretty small ball ends, really soft, and have stretched out alot. I am planning on replacing them, w/ 5mm tie rods w/ large ballend off the hellfire or the Savage adj arm kit (got tons of these.) did the Str rack with these already and it came out nice.

First tho I wanted to complete the the setup for the rear servo saver, as I am planning to make it AWS. I will need to remove some material from the rear end of the TVPs, so I'm still comtemplating how I want to go about it. Ideally I would get new TVPs w/ cutouts for the str rack (like the front,) but that is an $$ PITA. I may just trim down the chassis as needed and add some braces in around it. A bit ghetto that way, but easier, faster and cheaper.

As it sits now, the Savage is a fookin tank. Huge 40 series tires, XL spec driveline, Cen diffs, all metal tranny gears, big custom batt trays (came out really nice) holding all those batts, FLM towers and other bits, LST shocks, 80mm medusa. Finish w/ the AWS and its a true monster truck. Its twice the size of my Revo, and prolly half again in weight. Damn thing is scarry at speed. I love it. :)

Finnster · 08.19.2009, 06:35 PM

OK...here's early pix, still got some work to do.
Sucker weighs over 14 lbs

Finnster · 01:08 PM

So I found my ET data cable and ran it a bit. The batts were not fully charged, but it was far closer to what I was planning.
Overall a ~90A/2500W system. If I go upto 10S, it puts me over 3000W.

To be fair I should read the esc again and see what it says.

EDIT: I DL'd from the ESC, and I'm not so sure its so far off. The max current is high, but the current at WOT is only 102A. That's not that far off from the ET data @ 90A (who knows how accurate that really is), plus the ET is only set for 8Hz. It could cert miss a micro burst or top of a peak. Notice how close the voltages are, and I know the voltage on the ET is right as I spent quite a bit of time calibrating it. The temp readings are also close to what I saw.
Hmmmm....

lincpimp · 08.20.2009, 01:35 PM

The savage looks good. Makes me want to finish my stretched chassis savvy, and get some work done on the 5t super stretch...

The big one will be 10s with a 1527, but I will stick to the flux motor on 5s in the smaller one. Pretty sure it is only slightly longer than the XL chassis you have. Not sure what kind of draw to expect, as the smaller will have losi bolt ons on 40 series dish wheels, and the 5t-s (what I plan to call it for simplicity sake) will have narrowed beadlocks with some sort of narrowed 40 series tire (or possibly sectioned moab xl tires on regular MT wheels for a large sidewall look and about 6" height) in order to get the tire to body proportions right (using a 5t body).

Sounds like the 80mm medusa is doing well, glad to hear that.

Finnster · 02:33 PM

Thanks James, I'm pretty happy w/ it so far, but I need to finish up a few little things still (ie mount switch, etc.). The Medusa can rock some socks, but I'm a bit worried it may not be enough. I had the motor up over 140 already, and the run wasn't that hard yet. I do need to drop a tooth tho on the pinion, so maybe that will help. Its already too fast to control as is w/ the sloppy rear toelinks.

I don't like the motor up so high, OTOH it clears space for a rear str servo. That will be a project to work out.

If that doesn't work I may look at getting a 1524 or 1527 or so. That will wait, but I want to have a totally reliable system.

The moabXLs on maxx rims you talk about sound like the terrapins I had on there. Huge sidewall. Good for in the bushes, but was really unstable at speed on the road. Good to keep in mind. Perhaps the Moabs would do much better.

Unsullied_Spy · 08.20.2009, 02:33 PM

From what I've seen, the 80s like to run hot. As long as it's warmer than 60 out mine always gets up 140-160 before the end of the run and I have to stop to let it cool. They are powerhouses though, my Muggy pulls standing backflips with 30k in the CD and 40 series wheels/tires. You may want to look into a heatsink clamp for it though, my rear endbell popped off yesterday, there's not much of anything holding them in.

Finnster · 02:42 PM

Quote:

Originally Posted by Unsullied_Spy

From what I've seen, the 80s like to run hot. As long as it's warmer than 60 out mine always gets up 140-160 before the end of the run and I have to stop to let it cool. They are powerhouses though, my Muggy pulls standing backflips with 30k in the CD and 40 series wheels/tires. You may want to look into a heatsink clamp for it though, my rear endbell popped off yesterday, there's not much of anything holding them in.

Yeah, I'm waiting for them to be in stock. Ideally Mike will get the Medusa version made so I can avoid having to get a front plate as well. I'm taking it easy for now. Thanks for letting me know on the heat. I was driving in 95F heat, so it was horrible. As long as it stays under 160F for all but the worst abuse I will be happy.

I want to get another roll bar to go over the back end as well. I don't want a bad landing on the roof w/ all those unprotected $$$ electronics.