Antweight help

[Max]

Right sabertooth has been replaced and all kinda works now, only problem is that the robot occasionally decides to move completely randomly without me moving the sticks on the transmitter or it decides to go full power backwards and I have to move the stick forwards to get it under control. When I then pulse the brushless motor on for a second the drive seems to fix itself. When the brushless is on a red light also lights up on the sabertooth.
Does anyone know what might be causing this?

[plargen]

you might need an external bec i had something similar with my BW, when i used the servo weapon it would start to dive off and the external bec solved that

actually on second thought have you tried a bigger battery and have you disconnected the bec from either the sabertooth or brushless esc

[razerdave]

The drive issue sounds like a trim issue. It's probably worth your while to check the DIP switches are in the place you want (some of the steering and mixing functions can be messed with).

Red light on the sabretooth can be caused by all sorts: rogue signal, voltage drop (which can also explain the drive randomness), or conflicting BEC's (both the sabretooth and the brushless have one, you need to disable one or the other.
The other option is the battery simply can't hack it, needs a bigger one.

Dr Weston, robot diagnostition at your service. .

[Max]

The drive issue sounds like a trim issue. It's probably worth your while to check the DIP switches are in the place you want (some of the steering and mixing functions can be messed with).

Red light on the sabretooth can be caused by all sorts: rogue signal, voltage drop (which can also explain the drive randomness), or conflicting BEC's (both the sabretooth and the brushless have one, you need to disable one or the other.
The other option is the battery simply can't hack it, needs a bigger one.

Dr Weston, robot diagnostition at your service. .

I don't think it's the trim as it drives fine then randomly it starts ging backwards, I've chopped off the red wire from the brushless esc leaving just the sabertooth's (though maybe if I used the brushless esc one instead it may not cut out?) could be the battery although it doesn't seem to explain why it would suddenly go into full reverse. I'll check through everything and see if I can spot a fault, with try with some other parts to see what's causing it.

[razerdave]

Bulletproof and other robots of mine have gone 'off the rails' due to a sudden voltage drop; loses power to the RX and takes a stab at what signal it got given. It could well be worth trying the BEC on the brushless esc rather than the sabretooth, I've seen a few occasions where something drawing so much power (usually a servo, but it has been brushless motors) it causes the BEC on the drive ESC to falter.

[plargen]

i think the sabertooth has a fit/resets itself to the wrong settings if it doesn't get enough power or if something draws to much from it, but if you have a bigger battery you could strap to it to test the you should know pretty quickly

[razerdave]

Oh, and the DIP switches have a lipo cut off, but it cuts off somewhere daft, better to turn it off and just don't be daft with the Lipos treatment (ie: don't run it into the ground!).

[Max]

I think I may have discovered the problem, I think it's the autorecalibrate function so as you say when it loses the signal then finds it again its assumes the transmitter is at zero, I think the brushless motor shakes it around so much that the link quickly comes out or draws to much current so then when it comes back on and I have it on full forwards it thinks that's neutral. I've changes it on the dip switches and will have a play tommorow evening to check it has worked properly.

The shaking from the drum makes it quite hard to control so may have to turn the power down a bit or it may shake itself out the arena! Also going to replace my removable link with seems to be cr@p with a small switch.
I should have some time at the event aswell to fiddle with it as obviously won't be in the non-spinner comp in the morning.

[Max]

Right, slight problem, my charger is saying virtually all my batteries have low voltage so won't charge them, is there any way of getting it to work?

I've got an IMAX B5 btw

[razerdave]

The usual way to bring back vitually dead cells is to seperate them and charge individually, or, if it has a balance lead, balance charge them. If you can't do that before the AWS, I am sure there will be someone with a spare battery you can use.