It would work... but not recommended... though it should be ok for RC.

Another way would be to tin the two ends of the wire, then tin a piece of smaller 20ga wire. Butt the ends of the large wires together and put the 20ga wire next to them, and use it to bridge the pieces so you get plenty of solder for a strong joint. Or use a flat piece of copper or piece from a terminal lug.


The real question... why do you need to splice like that? Why not just cut to length and solder the connector directly to the wire?

Thanks! That's a good question and the reason being that I already have an EC5 connector on the battery lead,so not wanting to garbage a "real" E-Flite EC5,not a knock off and have to resolder the bullets,I thought that this splicing would be easier for me,but if it's going to cause problems electrically,I will cut the connector off and shorten my lead as needed.
Are EC5 connectors removeable once they are assembled?
After thinking about it,I guess a $6.00 connector is cheaper than somehow destroying or creating problems with a $130.00 battery!Thanks,Huck50

Probably best... less loses overall.

Hi: This will be my first time soldering EC5 bullets and I was wondering about my 63/37 solder I just bought. I have seen the videos of how to solder these connectors and not to fill the cups with too much solder to avoid spilling over when installing the tinned wires,but is there enough flux inside my solder,or should I add a little bit (if I can find it somewhere!?)
Also would I be better off using a torch,( all I have is a regular torch for soldering copper pipes,but maybe too much heat?) to properly heat the bullets, so as to get get them to the proper temp and not sure if my 40 watt Weller can cut it as far as heat goes?
Do you find that there is sufficient flux inside the rosin core solder? Thanks,Huck

If you can not find flux, you can make do, but try to get some online if local is not possible.

Try the iron first... If it does not work, you can try the torch. Turn it on low, and hold it farther away to lessen the heat and flame. If you go the torch route, its on you to be safe and not damage things.

Thanks! I would like to get one of those Kester flux pens,but not sure which model number I need for use with my 63/37 solder. Mostly doing electrical wires.Too many to choose from! Thanks,Huck50

Most fluxes labeled Rosin medium/mildly activated should be fine.

Kester 186 is a good one to go with.

Thanks! Any tips on soldering EC5 battery connectors?. I only have one,so I need to make it good the first time!. I think the main thing is to not use too much solder when filling the "cup",so that it does not overflow when placing the tinned battery wire in and screwing up the bevel on the bullet? I have seen the vids on installing EC3's,so it should be the same,I guess? Thanks,Huck50

nice tips. Although I had done soldering myself many time but never use flex after soldering.

This is very useful article for a person to do task in better way.

If you get too much solder in the connector, its easy to fix.

Heat the connector and then tap it on the table while the solder is still liquid. It will knock off most of it.

I don't use the fill method. I tin the wire then I stick the wire in the cup and then heat the connector and wire then apply solder.


Use the biggest tip you can fit in your iron, it will help.

Thanks! I think I will not use the fill method.Thanks,Huck50

Marine6680. Thank you for all your posted info. I have been racing rc for 55 yrs and I just learned a few things.. I love information like this that someone with an iq of 10 can understand. LOL Thanks

Glad to help, have fun.

Excellent write up. My apologies if this has been covered. I'm having a lot of trouble soldering half bullet connections to me speed passion ESC. I can't find the angle to keep the solder in the bullet liquid so I can insert the wire. The open part faces away from the ESC, so the options are the bottom wedged by ESC housing, side with 5 posts, top with little surface area and hard insertion angle. Any tips?

I'm using a TK950 at 650*. Believe it's 14 AWG wire.

Get the biggest tip that you can fit into the iron, and try that. You will probably need to order it online.

Use a little solder on the iron tip to help conduct heat into the connector.

Pre-tin the wire and immediately try to solder it in the connector while it is still hot, instead of letting it cool for a few seconds. This will decrease the amount of heat needed to be put into the components to heat them up enough.

Usually a bigger tip is the answer, when not possible, add 50* to your iron temp. Always try a bigger tip first, unless the task somehow prohibits one.

Remember the TK950 is a rebranded Hakko, so get hakko tips.