RX8 fried - help a noob please
 

A little background: This is my first attemp at BL. I've been reading up since Jan, so I have a pretty good base, but it's still my first try. I just finished converting a brand new XXL to BL. The truck has an Aftershock tranny(forward only), single speed hub, taller than stock tranny gears, and no brakes. I'm running a RX8 1350kv setup on 6s 30C Zippy. It's geared for around 46mph now, I may drop that down. In case it matters, it's all wired together with 10awg wire. It's not my first time soldering so I'm pretty confident the connections are all good.

RX8 settings: I'm not 100% sure, but brakes were ~20%, throttle profile was set for least sensitive, set cutoff to 6s, forward/ delay brake/ reverse and thats about it i think.

I got the truck together the other day and tested it out in the basement.(10x10ft room) I drove it around on and off, probably 5 min total. I was on slippery concrete floor and and hit the throttle a little. There was a small pop or two, but I couldn't tell if it was the ESC or something else and then all the ESC lights were dead. :( Checked out the battery and it was dead too, one of the tabs was fried.

Repaired the tab and the battery checks out fine. Hooked up the ESC to an 8.4v NiMh pack and it lit up and appeared to work, but I didn't drive anywhere. So, I hooked up my LiPo again...instant pop, plume of smoke and 4-5" flames. :surprised: NOTE: the ESC was switched off when I plugged it in.

Does it sound like I'm doing something wrong?(ok, so maybe I should have thought twice before hookin up the 6s again) Will the ESC blow up if there isn't enough current? I'm not real sure what I did to make it blow up in the first place.

Are you confident that you have everything wired up correctly? Almost sounds like reverse polarity the second time.

Maybe just a defective RX8? Not sure...

Yeah I wondered that too, it was wired right. I double and tripple checked that. After I fixed the battery I didn't have to rewire anything so nothing changed. I still double checked it all before plugging it in. I even checked after it happened to make sure. Oh, I'm using EC5s for the connectors, so it would be hard to hook it up wrong.

I'm sorry about your RX8. I have two of them and are very happy with them.

Are you sure the battery was fine after you had repaired the tab? I had the same pop experience once with a Zippy and the RX8 and I then reconiced that a solder tab inside the battery was melted down. When I checked the battery over the balancer tab it was fine but when I measured the voltage on the connector there was no power on. When it poped my hart was standing still. Luckily the ESC was still running just fine.

By the way, how did you convert our XXL to electro? Did you use the conversion kit from Losi or what did you do?

After the initial problem my battery read 0v at the connector like yours and the balance was fine. I opened it up and the lead at the negative was fried. I cleaned a little solder up and did a little sanding. They have an extra tab at each lead so I just soldered that one on. And soldered the old tab to the new one. After I was finished the battery was reading about 23.6v at the leads. After it started on fire I checked it over again all the tabs look good and it is still reading 23.6v. As long as I'm not doing anything wrong I'm sure I'll get this working eventually.

I didn't use the kit from Losi. I used a pinion adapter, one speed hub and motor mount from TD Racing. I had New Era make me a custom roll bar that would let a battery tray fit up front. Then Mike was kind enought to make me a standard 150mmx50mm tray, but with a flat bottom. :D I had to mod the tray a little for the roll bar, but it fits about perfect between the tranny and radio box. I have a RCM 26T and 30T pinion to start with. Running the stock 63T spur. In the tranny are the new gears from the Losi BL conversion, 27/17 I think. ESC is mounted in back where the fuel tank was. I did a bunch of other little things, but I think the only other one that might be of interest as far as BL conversion goes is the HD diff cups.

I was going for a clean build that kept the weight up front and would hold up to abuse. As soon as I get this ESC thing iron out I think I'll be set.

The reason it wouldnt run on the NiMH battery is you had it set for a 6s LVC setting so it saw the voltage as to low and wouldnt run.

I suspect that something wasnt right in the battery after the repair. If there was something wrong enough to melt a tab in the pack, whatever was wrong the first time was probably still wrong and it completely melted down the next time.

True about the settings, I didn't try to run it, but you're right, I'm sure it wouldn't have worked.

So, about the battery. I think I need to learn some more because I'm not understanding. Here is what I thought happened:
- ESC mostly died and shorted(but still lit up the lights when I plugged in the NiMh pack)
- Short drew enough current to burn through a tab on the battery
- I repaired the tab, all voltages were normal again
- Plugged it back in and ESC finished frying because there was voltage again

Can these batteries go bad and do something to fry ESCs? Or how would something wrong with the battery cause the ESC to fry? Can the voltage spike or something? This battery worked fine for 15-20 minutes of messing with the steering endpoints and other stuff. Then worked fine for around 5-7 minutes of driving. Before hooking it up the first time I checked the battery and polarity was correct and the voltage was just over 24v. After repair I tested again and it all tested out fine again.

I'm not saying I don't believe you guys, just want to understand more. This thing is a HK battery so I know it's not top notch. I figured for bashing it would be fine, but maybe I was wrong.

Contact Ty Campbell at Tekin (208)634-5559 he will take care of you.

Your first indicator was that the battery tab fried through. THAT is NOT good right out of the gate. This is the sign of a battery that can't even dish out the current it's rated for.

Rarely can they be fixed properly and that alone could have caused the Rx8 to fail.

Cheap batteries are a no no with this amount of current draw.

Take a Dvom to the HK battery are the wire leads correct color for polarity?

This may not be the case but if everything is wired right the polarity in the rx8 could be backwards? which could def short the battery. If the battery is dead or bad it should not fry the esc under this circumstance since it was a test run in the basement. Doesnt sound like any significant amp draw could be possible unless it was on a stand. I dont know much about the rx8 but this is not the first time i've heard of this issue Im not knocking tekin im sure they have a great product but every product has there own bugs or kinks. Just my 2 cents:whistle: