New battery pack causing problems

cdog4w · #1 02-16-2004, 09:33 PM

I just made my first custom battery pack out of 6 1/3AA cells. I hooked everything up and it seemed ok until I tried it out on the floor. The ESC lights (red for forward green for reverse I think) start to flicker if I floor it and the car ends up jittering. Once I've floored it like this it keeps jittering even at lower speeds.

I tried re-setting the ESC and it didn't seem to help. I checked the voltage out on the pack with my multimeter and it gave a rock steady 7.38V. I hooked the battery pack up to a 2WD motor (spinbrush magnets) and the motor drew a constant .4A (consistant with my previous test on 4 cells). So I think the battery pack is OK.

Is it possible that I damaged the ESC when desoldering the springs and soldering on the new connectors? I was pretty careful since new batteries are cheap, but new ESC aren't.

This shouldn't be running too much voltage for the ESC since Xpress sells 6 cell packs and many people have had no problems.

The other thought that occurs to me is interferance due to the new wiring being in a different location (I remember hearing something about having certain wires near each other screwing things up).

I am testing with the basic Futaba Tx that Tiny sells here.

Before any of you ask, I haven't added the new connectors to my existing 5 cell pack so I haven't tested it with it.

I've attached a pic of the car with the pack installed and connected.

cdog4w · #2 02-16-2004, 09:34 PM

pack out of the car

mde · #3 02-16-2004, 10:36 PM

Hi cdogaw,

My friend and I got our Mini x's last week. Great fun. Mine is set up stock with the optional bearing installed and a 5 cell and the original radio gear and controller.

His is set up with his own electronics, no bearings and the factory 7 volt battery pack. He wasn't as careful as he might have been and burnt the motor out.

My contact at the factory warned us about the 7 volt pack burning the motor out quickly if you're not careful especially if you are running on carpet.

Once sorted out your car will go fast but be careful of the motor.

cdog4w · #4 02-16-2004, 11:03 PM

Thanks for the tip. Glad you're enjoying yours and that the community here is still growing :P

Anyone else burn out their motor with a 7.2V pack (factory or otherwise)?

So you have a contact at the factory?! I assume that you mean the HK factory since I also assume that all are made there (except maybe the canadian one?).

mde · #5 02-17-2004, 02:15 AM

Yes my contact is at the factory in HK. The mini Q is a mini x. That retailer changed the name and repackaged the cars to differentiate himself from the others selling mini x.

He is in Ontario and we are in Vancouver. The mini x has little exposure here and what it has had was with the earlier cars that had some problems.

We bought 3 cars, 1 complete with bearing kit installed and controller, a car kit with all the electronics but no controller and 1 basic chassis kit as well as one of each of all the tuner parts.

The mini x was well received at a club meeting this past weekend even though the motor in that car burned out. I guess 11 people driving it non-stop, except to change battery packs wouldn't be considered being careful with the 7 volt battery pack.

We will hit an open track session this Friday night with both cars running for some head to head comparisons with a few mini zs.

cdog4w · #6 02-17-2004, 02:37 AM

Sweet, can't wait to hear the results...

Cian · #7 02-17-2004, 03:56 AM

I haven't burnt out any motor, but I reckon that 7+ volts could have damaged your ESC. I've fried a couple of them before, the early versions os the ESC can't handle as much as the V2.0 elecs..

cdog4w · #8 02-17-2004, 09:57 AM

I've got v2.0 electronics. Those should be able to handle 7.2V right?

avenan · #9 02-17-2004, 10:41 AM

I've been using 1.0 electronics with 7.2v (6 cell) packs for quite some time now. While the ESC is lacking in several key areas (like decent brakes) they don't seem to have any issues with batteries.

I'd try out the original battery pack. Try hooking up a different motor to the ESC. I can't remember -- does the stock mini-x ship with caps on the motor? If not, put some on and see if it helps -- the increased voltage may cause interference.

cdog4w · #10 02-17-2004, 04:54 PM

Will try to test with the stock battery pack tonight (need to solder those connectors on). The stock motor has caps on it.

EDIT: You can see one of the caps in the pics above. I'm pretty sure there are two (tho only one is visible).

cdog4w · #11 02-19-2004, 02:19 AM

Put the connectors on the stock battery pack. I had some trouble when I first connected the pack, but resetting the ESC seems to have fixed it. Still not sure whats up with the 6 cell, but its still not going... even the steering twitches on it.

Anyone have any ideas?

So dissapointed, was eager for 6 cell speed.

3series takumi · #12 02-19-2004, 02:33 AM

did you make sure that you new cells current isnt dropping when you go? i had that same problem b4 with a different esc. usin a punch or esc capacitor cleared it up.
hope that helps

cdog4w · #13 02-19-2004, 02:43 AM

My multimeter is fruiting out on me. Will see if I can get it working and check for current drop.

Where would you suggest I get a cap and how would you recommend I wire it in to my existing wire setup (so that I don't have to redo much)? I dunno how comfortable I'd be popping the ESC open (looks like you'd have to break the plastic case to get at the underside of the top board) to add a connection there. I'm using the existing ESC wires, but I just desoldered the battery springs and added my new connectors to them.

3series takumi · #14 02-19-2004, 03:17 PM

all you have to do is wire it in parallel with your batteries

cdog4w · #15 02-22-2004, 05:00 AM

It seems to be working, I think it just needed a full charge. What I was seeing must have been low voltage under use that wouldn't be shown on a multimeter? My multimeter crapped out too, stupid RS brand... time to find the receipt and pray its under warranty.