New Brushless With Some Issues

[brijar]

Well, I finally got my brushless setup up and running. My first run was pretty good, but I had forgoten to plug in my shifting servo, so I ran in first thinking I just wasted $250 for most of the run:007:. It was amazing after I fixed the servo though. The motor was extremely hot after the run. So hot I couldn't touch it for even a second:eek:. I was running 16/66 with large Ofna Pirate tires and a rollcage, so it was quite heavy. I have changed to a 14t pinion, but I only have one set of batteries, so it takes a while for me to be able to run again. I had so much torque, it looked like I had a seriously low gearing, but it got really hot which ment the motor had a large load and was probably overgeared. I'm rather new to brushless and I don't know their physics and what they like and don't like, so this is probably an ameture mistake. What can I do to increase my run time and keep my motor cooler without gernading my wallet. I was this || close to my parents saying no to brushless, but I convinced them and doomed my piggybank to a fate worse than death. So I can't do new wheels or an expensive heat sink or anything. Help would be greatly appriciated.

Thanx,
Brijar!!!

[HotnCold]

Which motor are you running? How many batteries are you running ? You ran in First gear for most of the run and the motor was pistol hot? That could come from over gearing or under gearing as well. Was the motor that hot when you were running in first gear as well or only after you switched to second and then ran the heck out of her till the batteries dumped? A heat sink would be a good decision - they are in the RC-Monster Store and are very inexpensive. Probably the best thing for the buck you could get... Its probably impossible for you to run shifting between first and second gear and not be under/over geared. Its probably wise to choose one gear - gear for that gear and leave it at that. Hope this helps ya out a little. List all the factors (motor, batts, gear, etc ) and there are a bunch of very knowledgeable people here that will help you get her dialed in in no time.....

[brijar]

Sorry, I had typed that post before and had said that I was running a 9L/9920 and 13 GP3300's, but it logged me out as I went to post it, so I had to type it again and just forgot or was too lazy to type all of it. Oh ya, it is about 30 - 35 degrees out here when I was running, so the motor coulda been a lot hotter.
I just got back from my second run (actually third because I ran my cheapo 7-cells, but they were so weak and short, it doesn't count:025:), which is always about 1/4 as long as the first due to something stupid about my batteries. I had switched to a 14 tooth pinion and the motor wasn't very hot, but still warm. It didn't go as fast as the 16t did (duh!), so I don't know what to do. I didn't check the heat of the motor on my first run untill I was taking it in after the high speed runs in second gear and my hand was awfully warm due to the heat rising off the motor while carrying it. I may try to lighten it by removing the rollcage, but right now, it makes good insurance so I don't hurt my motor or esc in a crash. I do have a spare heat sink lying around, so I'll throw it on there and see if things improve. I didn't put it on there in the first place because I liked the shiny finish of the 9L and I didn't want to put any scratches on it because the heat sink is not very forgiving. I have one steel idler as you guys were out of stock of the pair and I have it in first gear right now.
I would like to gear for speed in second gear. I will probably do most of my running in second. I think I will switch back to the 16t pinion and stick on my heat sink. Thanks for your replies so far!

Happy Maxxin',
Brijar!!!

[Serum]

What your hands think is too hot to hold, is only 50-52 degree celcius, which is not bad for a motor. A more accurate measuring device would be a tempgun.

In other words;

don't be fooled by your hands.

Do you use stock diffs or 1/8th diffs?

[coolhandcountry]

I agree with serum. If it was cool like you say out and the motor is hot to touch your hands may be cold. So the motor would feel hotter than it is.

[maxxdude1234]

Plus the 9L is going to be quite a hot motor anyway. Also, as well as getting a tempgun (an absolute neccessity fort BL), try disconnecting the motor from the driveline and check to see how smoth the truck rolls - you might have some binding in the driveline.

[brijar]

I have checked for binding and it rolls pretty smoothly. I am running stock diffs. I have a Duratrax Flashpoint Infared Temp gauge. It isn't the best at getting a good temp, but I'll try it on my next run. Maybe it needs new batteries. I just installed a 72t spur to help with the heat a bit. I also put on my heat sink after squeezing it a bit cause it was made for something like a Titan with a torque ring and I installed a large computer fan on the top of my rollcage(inside top) over the motor to provide some cooling. I'm hoping this will help and I'll let ya know how it goes later.

Thanx for your help so far,
Brijar!!!

[coolhandcountry]

When you take a heat reading. Try to find a spot on the motor not heat sink.

[maxxdude1234]

Unless the heatsink is fully in contact with the motor, don't put it on. Otherwise it'll just help to keep the heat within the area around the motor can. Heat, like electricity, is transferred better when contact is made.

[Serum]

You could use a thermal compound between the motor and the heatsink.

[brijar]

I crimped the heat sink in a vise since it was a bit loose. Now it fits fairly tightly. It originally had some kind of heat compound on it, but not anymore. I just got back from a run and the temps were about 56 degreesC on the motor according to my FlashPoint. Everything went pretty well, except about halfway through the run, one of my front stock sliders broke at the drive hub leaving me with rear wheel drive. It was pretty fun because I could do donuts in the grass:005:! I was running 16/72 gearing with mostly high speed runs with a little bit of jumping. I had a fan on my rollcage, but it didn't seem to help much. I'm gonna try to get some pics up of my setup sooner or later. It still seems to have pretty bad cogging when going slow IMO. Is there anyway to fix that?

Thanx,
Brijar!!!

[Sylvester]

Nice to hear your having fun, sorry to hear about the slider, but hey, it wasnt gonna last long either way! What radio are you running? A good radio could eliminate the problem.

[brijar]

Just got in from another run, my second of the day. Did all high speed runs and it lasted about 10 minutes. For some reason, my 13 GP3300 non matched batteries dump a lot quicker on the second run than the first. When I say a lot, I meant like 5-7 minutes sooner. Can anyone tell me why my batteries do this? I don't have another set of quality batteries, so I've never seen others perform. Also, I just have the stock TQ3 radio with a shortened receiver wire that I need to fix, but it hasn't given me any problems yet.
Anyways, when I brought it in and took it back to the shop, I was checking the temps. The highest on the motor was 32C due to the shorter run time. I also noticed that the 6 cell pack was way too hot to touch. Then I noticed that the duct tape I had put around the lower bar of my steel rollcage was kind of torn in one spot, letting the battery bar touch the metal. I also noticed that the other end of the battery was touching the metal too:eek:! It was shorting itself out:mad:1! I quickly pulled the rollcage away from the battery and unstrapped it from the chassis. I had to pull it out by the wires because it was too hot to touch. I have it in my cooling stand with a fan on it as I type. I hope it is ok. I will try to put some electrical tape on it now so it won't happen again.
btw, this brushless is AWESOME!!!

Thanx a lot guys
Later,
Brijar!!!

[coolhandcountry]

Well it sounds like you found where your extra 5 minutes of run time went. That may have been why the batteries was so hot to. That motor temp sounds fine.

[maxxdude1234]

Other thing I will mention is, NiMH batts don't like being cycled (charged/discharged) more than once in a day. For whatever reason they need time to 'settle' after a cycle. Don't know if its the same for NiCAD or lipo.