Theboot200

Any hobby store. Www.dealextreme.com sell them, and free shipping. Search for lithium polymer 11.1 volt. You will need a lipo balancing charger to, can't use any charger. You can get cheap ones there to. Mah = battery size. 2000 mah means you will be able to draw 2 amps of your battery for 1 hour before it goes flat. C = the rated current draw. 20C would mean it's safe to draw 20amps of the battery without it getting to hot. 10 or 15C should be heaps. When fully charged the battery peaks at a bit over 12 volt. As it gets used the voltage drops. Don't let it drop below high tens or it will ruin the battery. A simple dc multimeter can check the charge of it. As a rule charge them outside, they can explode, (check youtube) although it's highly unlikely. I have tried exploding them by shorting them out. Putting 10c ones on a 40amp draw, numerous big rc plane and heli crashes and still no exploding, I think it's more overcharging them, but the chargers do have a voltage cut off, but still be careful. Use them at your own risk on the 9v Lego it receiver. It worked fine with me. Wire it up like this (thanks to the thread linked in here) you will need a spare Lego connector clip. If possible use a on off switch, at the moment I just plug it in to turn it on. 2 wires join for the positive, 2 to the negative. Make sure you get the negative and positive leads right! I did a test with a spare motor before plugging it in to the ir.

So figured it out. I know theres a slight risk of damaging the receiver but oh well. It's got heaps more power, the red switch works every time and the bucket now has enough power to scoop a half bucket of sand. Massive improvement, it's been running for about 1 1/2 hours sometimes under a fair bit of load, am using a 11.1v 2400 mah 20c lipo of my rc heli.

Thanks I might try that down the track. Right now I don't have the time to try something like that. I want to wire the battery up to a Lego terminal block. Know the 2 center wires are the negative an positive because I read it yesterday (on this forum?). A guy explained with pictures on wiring a 7.2v lipo to the terminal block, but I can't find it anywhere. I'm not sure which one should be the positive which one the negative.

Awesome! I googled for ages looking for a thread like that :) I might give it a go. The excavator just seems to under powered for my liking. Now to figure out the best way to wire it up. To the battery box or to use the clip of my one spare motor. I wish Lego would use there xl motors as standard.

Thanks mate I'll give that a go as well. My main concern is whether the extra volts will blow up the ir receiver. The motors shouldn't get to hot if you don't load them for to long at a time

Hi, new here. I have been thinking of trying an 11.1volt lipo (12v when fully charged) with the 9v medium motors and ir receiver. Will this blow the motors or the or reciever? I find the excavator way to under powered, and also the red gear switch rarely switches when using it. Is it to risky?