Soldering 25D Motors

[Henry Nourse]

Hi all.

I've been getting around to soldering up my beetle recently and am having some issues soldering the wires to the small, copper connectors on the motors. Does anyone have any advice on how to go about doing this?

I'm using 12AWG wiring which may be a little over sized so if I'm better with something smaller do let me know. I previously used #22 AWG and that was for too small! The ESC's are ready to go with XT60 connectors on them, but actually soldering wires to the motors in order for them to have connectors on is proving a major issue.

Thanks,
Henry

[cosmin]

22 AWG should work just fine for beetle drive, what problems did you have? I use 24 AWG in The O'Neill.

You haven't described what issues you had soldering the new wires, so I can only guess the large thermal mass of those chunky 12 AWG wires is sinking too much heat.

[Henry Nourse]

Thanks Cosmin. The issue we had before was that the 22AWG wires got so hot they melted their insulation before the fuse tripped! The battery has a very high discharge rate, 50-90c at 850MaH, but it could've just been poor quality wire. The main problem is really just attaching such thick wires to such small connectors, but I'll try using some high quality 20AWG we have laying around if you think that's strong enough. Plus as you say the heat in to get proper solder flow has been a right pain so hopefully thinner wire will work out

[cosmin]

Hmm, that's strange. The maximum current in the wires to the motor is given by the stall current of the motors, and for 25mm motors that's usually in the 1-4A range on 3S. 22 AWG wires should be fine carrying that continuously. Could it have been the motors themselves or the ESC getting hot and melting the insulation on the connected wires?

By the way, I recommend using RC silicone-insulated wires in bots. The insulation is rated for 200 degrees C and it's also tougher than PVC. The wires are made of very fine strands, which makes them soft and easy to route inside the bot. Hobbyking's UK warehouse seems to be the cheapest UK seller.

[Henry Nourse]

I should just quickly correct myself, it's 14AWG not 12, I'd gotten mixed up!

[Henry Nourse]

Thanks again Cosmin! Absolutely sure it's the wires, the lid was off and they were glowing! Probably just dodgy wires. As for the silicone suggestion, we're going to move over to Turnigy Silicone insulated wire instead. The Pololu 25D motors we are using have a current draw at stall of 5.2-5.4 I believe so I'm really not sure what could of happened short of terrible wire quality!

Thanks for the advice though, I'll give it a shot with some #22 AWG wire from Turnigy and hopefully be back in this thread with the results by Sunday. I had no idea about silicone insulation so thanks for that bit of advice!

[daveimi]

To make life easier you need a really hot high wattage soldering iron. Warm the motor tabs with the iron and introduce the solder slowly. It will form a big lump on the tab. Then strip and tin your wire. Then with them both not far apart, warm the tab to melting point, blob the wire in and hold it whilst the solder cools down. Works every time.14 awg wire is big for 5Amp

[cosmin]

Absolutely sure it's the wires, the lid was off and they were glowing! Probably just dodgy wires

I think you must have had a short somewhere then. They would have been hotter than 500 degrees C to glow.

[Henry Nourse]

Well originally I'd thought the same though only one set of the #22AWG wires actually overheated, the other set from a different place didn't. So I'm guessing that once the wires melted their insulation they hit each other causing the short and thus them to glow, but I can't be sure