HV-Maxx motor thermal shutdown problem
 

Hi guys, this is my first post - sorry it's long! :D

After many months of waiting, I finally got my hands on a HV-Maxx brushless system (it's only recently been released here in the UK). Here's a few pics of if installed in my truck - I do plan to shorten the motor power wires, removing the excess length. Oh, and I also bought a nice matched pair of GP3700 1.19v 7-cell packs to go with it!


http://img183.exs.cx/img183/1928/086xo.th.jpg http://img183.exs.cx/img183/2827/116nj.th.jpg http://img183.exs.cx/img183/2307/144vn.th.jpg


I am running the transmission the opposite way around to stock, because I am using a Torpedo chassis, and the motor power/sensor wires won't reach the ESC at the back of the truck if the transmission is in the stock orientation.


Now, Novak's recommended gearing for the HV-Maxx in the E-Maxx is 14-16/70, which equals 13-15/66 if using a stock 66T spur. So I started at the lower end of the gearing, 13/66, which I increased to 15/66 to compensate for the lower internal gearing of the UE Spyder diffs I have.


First impressions are very good, it has great torque, and plenty of speed (I will strap my Garmin Foretrex 101 GPS into it soon and get some speed figures). But then, after nearly 7 minutes of fairly hard running, the motor lost all drive. I still had steering though, so I brought the truck back over to me and removed the body. The blue & amber lights on the ESC were blinking, indicating 'motor thermal shut-down', according to the set-up guide. So I got out my IR temp gun and took some readings. The air temperature was 60*F. The cells were at around 100*F, the ESC heatsink was 120*F (the fan was running), but the motor heatsink was at 175*F!


I let everything cool down and recharged the packs. For the 2nd run, I dropped the gearing to 14/66 (12/66 stock equivalent), but that is the smallest 32DP pinion I have. I got 9 1/2 minutes running before the motor thermal shut-down kicked in again. The ambient temperature was a bit lower (50*F), the cells and ESC were at about the temps. as the on 1st run, and the motor heatsink was 165*F. It was a mixture of 1st & 2nd gear running, on mainly concrete and gravel.


There is no binding in the drivetrain that I am aware of. The truck does weigh 12 lb 9 ozs. RTR though, so maybe it's too much truck for the HV-Maxx? I know running it on 14 cells is at the ESC's limit, but I use the 7-cell packs in my brushless T4 as well, so want to continue using them if possible. Any advice from the brushless guru's? Continue lowering the gearing until I can go a full run without thermalling? Drop down to 12 cells? Try it without the motor heatsink? Install a motor fan?


Whilst waiting for the HV to be released, I did seriously think about getting a Feigao 9L/10L motor with a BK 9918 controller. That setup would undoubtedly have much more power, but I wanted to start with a lower-powered setup, that has a few advantages over the Feigao/BK setup in my opinion (sensored system, useable BEC, better warranty, motor heatsink & ESC fan as standard). Maybe I should have taken that route instead. If the HV motor gets this hot in mild Spring temperatures, it's surely going to be even more of a problem in the Summer... :M:

i think you should go to the 9L/9918 setup. i dont think the novak can really be run on 14 cells

if you wanted something slow and reliable, which runs smooth, you should of gotten a 9l-9918. Even though it can go very fast, you don't have to go very fast. You can always get 13-72 and get similar top speeds as the HV, be cooler than the hv (both temperature and cool factor), very long life, and plenty of torque.

Re: HV-Maxx motor thermal shutdown problem
 

Well, I don't know about the better warranty statement. BK has been great so far in my dealings with them. The warrior and Feigao combos have been very reliable and would outperform your Novak without question. The Novak gets the edge in low speed operation, but I would rank the BK/Feigao systems higher in reliability and overall capability. Also, the BEC on the warrior controller is quite stout and can be used for up to 16 cells in most applications.
Your truck is on the heavy side, which is certainly part of the struggle with the Novak system and the thermalling. I would continue to gear down until it stops thermalling. A fan on the motor will help a bit as well.

Welcome to the forums, too!

ya BK really needs to empahsize their warranty. They have a good one yet no one knows about it. Thats why people are thinking the HV has the best in Customer Service

Thaks for the replies guys.

I think that ESC warranty problems with other brushless manufacturers such a Schulze have created a bad impression amongst the E-Maxx user base. If BK have good warranty support, then that definately needs to be more widely known. It's certainly making me consider an alterntive setup to the HV.

Another thing that swung me in the HV's direction was its availability in the UK. I bought it direct from my LHS, and can take it back there if there are any problems. I am not aware of anywhere in the UK that sells Feigao/BK/Schulze/Pletty etc. products. I know thats it's easy to order from overseas, but that creates problems if a return becomes necessary. Plus the fact that there is a very high customs/tax levy on items originating from the USA, coming into Europe. I may be able to buy an ESC + motor + shipping for $300, but the package can have anything up to 50% of that total added on in tax & customs duties! I can get a 9918 direct from BK in Germany for $253 though, and as it's in the EU, no additional charges would apply.


So I could use the 9918's BEC, even on 14 cells? I have Hi-Tec 645MG & 945MG servos on my truck. If so, add another tick to that setup. :D

So if I wanted to use 14 cells, and have a system that ran fast (say up to 40mph) and also cool, would a 9L or 10L be the better choice? And whilst it isn't really recommended for car use, I would want a motor with a 1/8" shaft rather than 5mm, as I already have 14T-18T 32DP pinions, and 5mm pinions seem to be scarce. I see that the 9L is available with 1/8" shaft, but not the 10L? Is the motor clamp/heatsink in stock yet?

So for all the questions, but as I have possibly already made one mistake by buying the HV, I want to make sure that if I change system, that it's the right one for my truck. Thanks.

I can help you in a few ways. First, you can buy the controller from me and I can have it shipped direct from germany to you, so you will save the customs fees. I have this arrangement with BK already. For 14 cell operation, the 9L is the best performer, and it is available with the 1/8" shaft. I have a couple heatsinks left in stock (2 or 3 until Monday or Tuesday when I will get more in stock). You would be able to use the controllers BEC on 14 cells. For slightly better steering performance, you could also use the UBEC (allows slightly higher voltage to the servos).
Don't ever worry that you are asking too many questions. I put the forums here so these questions could be answered. :)

Thanks for the info. Mike.

I just got in from another run. Actually it was 2 runs, as after a few minutes in I noticed a loss in power, and discovered that the grub screw had come out of the transmissions rear drive cup, so only the front wheels were getting drive. I made sure the replacement grub screw had plenty of Loctite on it. :rolleyes:

The gearing was 14/66 (12/66 stock), and I ran it without the body on. The motor didn't get too hot (<130*F), but then again it wasn't a full run, and the air temp. was only 50*F.

I had my GPS strapped into the truck as well, so got some speed figures. The maximum speed I got during the run was 29.9 mph. Given that I will usually be running with the body on, doing full runs, and in higher air temperatures, the gearing will undoubtedly have to be lowered further still to stop the motor thermalling. Meaning that the top speed I can expect will aways be <30 mph. Not exactly the performance I was looking for. :M:

I may just be selling the HV soon then... :D

Hey Toon, what's the diameter of those tires? If it's about 6 inches, my calculations show that the motor KV is about 2600-2700. A far cry from the "4400" that they claim. And that's very low load too because of the super small pinion gear.

That novak is top notch, when it comes to smoothness, but however; the 9918 in combination with a Feigao (i've only got experience with the 7XL) is a very smooth ride too! (compared with a plettenberg bigmaxx and the schulze (COUGHCOUOVERRATEDCOUGH)

I personally have got the idea that the 9918 is one smooth controller! (and way more powerfull than the Novak, in combination with a 9L) for about the same price. Keep in mind though, that the GP3700's throw out the 100 amps at a lower voltage than the 3300's do..

Are you from Holland bytheway?

@lipomaxx, those are Traxxas Talon tires (REVO ALLERT) 5.9" in diameter.

As Serum said, they are the Traxxas Talon (Revo) tires, and are 5.75" diameter to be exact.

Yeah, but geared 12/66, I highly doubt his peak current draw excceeds 80 amps for more than 1/2 second - and that's in second gear. Most of the amps are pulled while accelerating. Once it hits top speed, not many amps are actually pulled - that's why at top speed, the batteries could almost be giving out 1.2 volts per cell (fresh pack)! Either way, the motor is only spinning around 2750 rpm/volt. Which is pretty slow. I find that the Novak SS5800 spins around the 4000 rpm/volt. The Feigao is a good motor for all around bashing, racing, etc. There's no reason to use other motors unless that 1 or 2 % efficiency matters or if the extra ounces matters... Or maybe people just want German engineering instead of something made in China. But for me, for all practical purposes, I don't think any motor is significantly better than any other brand brushless. It's about getting the right kV for the power supply and getting the optimal size motor for the vehicle.

I had another run with the HV this afternoon. Gearing was the same as before (14/66 = 12/66 stock), no bodyshell on, and I also removed the transmission gear cover to try and get a bit more airflow onto the motor/heatsink/motor plate to aid cooling. I got a little under 6 minutes runtime before the motor thermalled again, and I temped. the heatsink at ~150*F. ESC was 120 and cells were 110. The air temperature was 60*F.

I have sent an email to Charlie at Novak, asking about the suitability of the HV in a heavy truck, and am awaiting a reply. Who knows, maybe my HV system may even be faulty? It does seem strange that it's the motor thermalling, not the ESC, and that it seems to be doing it at a lower temperature each time.

Whatever the cause, I have just placed an order with Mike for a 9L, 9918, motor clamp/heatsink, and a UBEC. So very soon I will be either selling my HV system as it is, or sending it back to Novak for replacement, then selling that one. :rolleyes:

I expect good things from the new setup... :D

P.S. What size gold plugs/connectors should I use to connect the ESC to motor? Will 3.5mm-4mm be OK? I would have ordered some, but couldn't see them on the site. I intended to keep using the PowerPole/Sermos connectors on the battery connections (as seen in the pics in my 1st post). Will these will be OK, or would it be better to switch to Deans?

I am thinking the reasion is the reversal location of your transmission on E-MAXX leading to reversal motor rotation.
You are running your truck forwards with the motor rotating backwards!
check your throttle setup is reversal or not.

powerpoles will be fine, and you should direct solder your motor wires to the esc wires. good luck.