I need help =(
 

My Hacker controller has been acting up on my.

I've been trying to run a 7 cell GP3300 pack on it which arrived this morning.

The pack charged to 10.6V which seems reasonable enough, but in the truck, there's just no real punch there - and it's not all that fast.

I've tried everything i can think of - gearing, timing, endpoints...

I was also getting some horrible glitching on the throttle from the speed controller (the steering was fine and i'm using an FM radio)

Out of ideas. :mad:1

Help?

More info: I just did some more fiddling (of course none of which made even a shade of difference lol).

When i run it seems to deliver spikes of insane and crazy power (grass ripping power) - but thats at low speeds and it will suddenly lurch forward for a fraction of a second - it's a glitch i'm quite sure of that, but i have nowhere near that kind of power available when i'm driving normally.

The speed isn't great - FAR below what i would expect from the 5900Kv 6S on 7 cells - any one of my Nitros would completely kill it in a drag race (which is NOT the situation i wanted lol).

I'm starting to suspect the controller (which i need to change anyway due to a recent LiPo venture which still hasnt arrived) - i dont think it's up to the job.

It seems to run quite hot which could explain the lack of power, but even running the controller from cold (the instant i took the truck out), the power still wasn't there.

I'm just all round not happy with it - going to buy me that MGM 120 that i was going to buy then kept putting off lol

Before i blow $200 though, does anyone have any suggestions?

Probably you need to cycle your batts a few times and see if it works.

Well the power it seems to deliver for short spikes seems to be very very strong, but thats never available to me when i'm just driving the truck, however i dont think the current deliverry is the problem?

I'll measure the voltages under a load

What setup are you using?
Is the truck an E-Maxx?

Its certainly not a E-maxx since he said 6S on 7 cells....If im not mistaken its a RS4 MT?

It's an RC10T3 (was an RS4MT but i prerfer it in the T3)

Geared 16/87, Hacker Master Sport controller, Normal radius tyres.

It's not like the motor is overstressed - it can barely break the wheels loose - my 17x2 brushed i had in there had more power

Sounds like it might be your controller.

That would explain a lot of things.

I tried it again today - it was almost too hot to touch...says it all, really

Gonna buy that MGM 120 next week i guess

It sounds to me like some of the FETs are burned up, but the others aren't. That would explain the heat that you experienced.

Well power devices can usually withstand higher temperatures then say, a big chip like a CPU or something (usually a max junction temp of 120ºC+)

I would have expected the controller to thermal before it got to a FET killing point anyway?

But i agree, it would explain the excessive heat and possibly the erratic performance (especially if just one phase of FETs had partially or completely failed)

Still haven't measured any loaded voltages...going to do that in a bit

Is this the first time you tried the hacker/feigao setup or did it just start acting up after you switched to the new battery?

Yeah, but the current spikes from a BL setup are very quick and any internal protection circuitry may not respond fast enough. Besides, I would NEVER want any electronic device I owned to get that hot! 120ºC is 248ºF!! Yikes.

If several FETs are bad, all that current load is being forced through what is left. The FETs have a low resistance, but this is reduced when you have several in parallel. With fewer available, there is more total resistance which creates a voltage drop and power loss, hence the heat.

Well i tried it with my cheap GP3300s, matched GP3300 6 and 7 cell packs, and recently a Maxamps 6000mah pack - all on the Lehner 5300.

It ran pretty nicely, but not with the punch i was expecting. Thinking of selling the 6S as i dont think it's right for my set up (too hungry), and i want to upgrade to a Lehner 19 series in that truck anyway

I know what you're saying, BrianG. I think that must be the case. on the temperature thing though, you'd be surprised - manufacturers will run these devices very hot indeed. Try touching the power regulators on your computer mainboard - sometimes they can be extremely hot.

Thanks to all of you for the suggestions - i really appreciate you taking the time to reply.

Well, that may be true normally, but I am extremely anal about excess heat on any electronic component. IMO, anything that is 20-25 degrees F over ambient (or a max of ~120 degrees F) does not have sufficient cooling. Anything over that gets added heatsinks, active cooling, etc.

If i had a choice i'd run stuff at a max of about 60C, but it costs too much for manufacturers to bother. It's cheaper to deal with a few failures than to put a $1 heatsink on something that will be sold by the thousand or even the million.

To keep say 12 transistors running at about 40F over ambient, if there was a total dissipation of 240W, you would need a heatsink with a thermal resistance of 0.1c/w temperature rise. Passive cooling of that efficiency is amazingly expensive (a sink that big would be enourmous)

They have to have high heat tollerances, because in an application such as a small mobile device that has to handle a lot of current (such as a brushless ESC), yet be compact and lightweight, it's not always possible to keep it small and also running cool. The total thermal resistance of a sink on a brushless controller might be 2c/w if you were lucky, so if you dissipate 40W on it, it will be 80C over ambient!

I agree, and that's why all my power projects are huge and clunky from heavy duty heatsinks and/or fans. After running my Quark 125B for a while it got too hot for my taste, so I thermal epoxied (Arctic Silver) a secondary heatsink. It doesn't look good, but lowers the temps to more reasonable levels (to me).