Battery to mid drive connection

[Mercadr]

Hello!
So I just finished installing a bafang mid drive. The battery plate and motor both have bullet connectors. After putting these together should they be crimped or just secured with electrical tape?

 

[Gionnirocket]

Hello!
So I just finished installing a bafang mid drive. The battery plate and motor both have bullet connectors. After putting these together should they be crimped or just secured with electrical tape?

I would use weather proof heat shrink
Or replace the bullets with a butt crimp

 

[Mercadr]

Thank you for the reply. I’ll use the he suggested shrink wrap. Any suggestions to make the connections tighter? One seems a little loose.

 

[indianajo]

The .157" bullet connectors from dorman sold at auto supplies like o'reillys don't have quality problems. They fit. They do not pop loose. I do not have shrink wrap over them. My phase connectors are 4 years old. The garbage from ***** not only may have tolerance problems, they may be thinner and melt at 30 amps.

 

[Gionnirocket]

Thank you for the reply. I’ll use the he suggested shrink wrap. Any suggestions to make the connections tighter? One seems a little loose.

Yes the quality of the bullet connector supplied with the bafang kit, especially those of the battery were of poor quality. I replaced them with the butt splice.

 

[teskow]

If you really want a 100 percent electrical connection cut the connector off and solder and then shrink wrap.

 

[Gionnirocket]

If you really want a 100 percent electrical connection cut the connector off and solder and then shrink wrap.

I agree... But these are typically 14 - 12 gauge wire and require a lot of heat and a bit of experience to not melt the insulation and make a neat connection. The waterproof butt splice are more than adequate. ymmv

 

[m@Robertson]

I just finished a 2-parter on reliable, safe crimp connections. I've had zero failures in 7 years of daily riding. Also if you do some digging you will see that the solder vs. crimp debate is a heated one, with the crimping side belonging mostly to the automotive world where vibration and shock reportedly will lead soldered connections to fail. The solder crowd replies "oh yeah well your mother wears combat boots" and the mud slings from there. Its like yelling "Ford!" at a monster truck rally. The Chevy guys all start foaming at the mouth and the other side is no better.

Private Site

short version:
1. Invest in the right tools
2. Only use marine adhesive wire connectors.
3. Only use marine adhesive shrinkwrap.
4. Only use professionally manufactured pigtails for the final connections.

#4 assumes you don't already know your way around a soldering iron. But even if you do pigtails make the job fast, easy and brainless.

 

[m@Robertson]

oh and also, having done many BBSHD connections, the way to do it is

1. Snip off the 30a Anderson connectors at the end of the power wire coming from the motor. Andersons are the darling of the old school electronics crowd but they have been replaced by: An XT90S anti spark connector. You will use the male end on the motor.
2. Use the female end (the anti-spark side with the green markers on it) leading to the battery. You always want female on the side that is hot.

Thats your connection. Size it down (cable length) to fit. Ideally, if you are making a connection to the battery (hot side) do not snip the cables at the same spot. Cut off one end shorter than the other so if anything bad ever does happen to your connection - or more likely you screw up while making it - the positive and negative live leads cannot touch one another. I also like to fully connect one wire at a time and snip only one at a time for this reason.

The XT90S is to all intents and purposes waterproof. However I like to do a single layer wrap of silicone X-Treme (plumbers) tape around it. Even if you have to disconnect, slitting the tape with a razor still leaves it over the connection as a quasi-seal after the fact. I get the heebie jeebies with bullet connectors since they only have a hard physical connection to the wire over about 20 degrees of the circle of the bullet. Its a weak spot that has admittedly never failed me, but I like to have a lot of unbroken metal running across a connection that is supporting 30 continuous amps on a 14S/52v battery. You can see what I'm talking about in the pic below. This bullet is one of the better marine adhesive variety. But look at how little physical connection there is across the male bullet itself. Its true you stuff wire in up there if you are doing it right, but thats not a structural aid. Like I said I have never had one fail but I would rather not use something with a known weakness in the first place and regardless, an XT90 is best-practice, inexpensive and a day away via Amazon.

Click for link to these. Genuine Amass so top quality.

 

[Mercadr]

Thanks for all the advice. I thought no I’ll go with the marine butt splice heat shrink connection with an electrical tape wrap. This seems the easiest way since my motor is mounted and I have crumpets and a heat gun.

 

[Mercadr]

Thanks for all the advice. I think I’ll go with the marine butt splice heat shrink connection with an electrical tape wrap. This seems the easiest way since my motor is already mounted and I have crimpers and a heat gun.

 

[m@Robertson]

Thanks for all the advice. I thought no I’ll go with the marine butt splice heat shrink connection with an electrical tape wrap. This seems the easiest way since my motor is mounted and I have crumpets and a heat gun.

I like the crumpets version much better. Just sayin'

 

[Gionnirocket]

Thanks for all the advice. I think I’ll go with the marine butt splice heat shrink connection with an electrical tape wrap. This seems the easiest way since my motor is already mounted and I have crimpers and a heat gun.

Yeah... That's why in part I recommended what I did. I got the impression that you didn't want to start over or start soldering in an awkward position with everything mounted.

@m@Robertson... Very well done!
The only thing that I would suggest if wire length allows is to stager the butt splices so the final heat shrink lays thinner.

 

[tomjasz]

XT90S

I went back to Andersons after 4 failed anti spark fried. 45A. Bafang and Grin are still using Andersons. I may have some left. ST60 for sure and even some black XT60 and black XT90. You’re more of a power user than I. Perhaps if I were you I’d go back to XT.

 

[m@Robertson]

@m@Robertson... Very well done!
The only thing that I would suggest if wire length allows is to stager the butt splices so the final heat shrink lays thinner.

thx! I THINK I recommended the staggered splicing in the article somewhere. I remember writing it, just not whether or not it made it into the final draft Reality is thats one of those things I know to do and know I should do but not one I do myself. BTW the reason for the staggering I mentioned was so if you ever have live wires or a break in your connections, you don't have a danger of the wires inadvertently touching and arc'ing.

 

[m@Robertson]

I went back to Andersons after 4 failed anti spark fried. 45A. Bafang and Grin are still using Andersons. I may have some left. ST60 for sure and even some black XT60 and black XT90. You’re more of a power user than I. Perhaps if I were you I’d go back to XT.

I've always used XT90S' and never had one fail. I have always been concerned about Andersons, the need to wrap them to make them waterproof, and the fact they don't handle disconnects and reconnects over time very well (although to be fair, experience has shown that seldom happens). Come to think of it a couple of my bikes have an XT90-Anderson extension on them instead of a snip and an XT90 on the motor side. Because I was lazy. World didn't end.

My current project-in-progress is going to need a VERY short motor-to-pack extension. The final battery will be a Luna Wolf v2 with the inline plug and no wire sticking out (a Wolf v1 is in the pic below), so at least there's that. But I'll be making a short HD-->XT90 cord and plugging straight into the battery.

 

[tomjasz]

We build very different bikes. You’re like a majority of upper-tier builders. I get it. I’m a big fan of ACF50 and Anderson accessories to lock connection and also shield the connectors. My connections are inside a Chrystalyte battery bag.. 30A are more than adequate for my 18A maximum. I’m going to put up a “rummage sale” this spring. I bought black XT90’s to transition to but decided to not move on that project. I appreciate your insight and most builders with soldering skills are smart to follow your lead. Never have liked butt spliced wiring. No good reason, so they are another RS item. BTW I’m waiting for the heat sinks for my last BBSxx build. Thanks for that.

Chrystalyte battery bag with key switch. 2 new Shanghai Aijiu Energy Tech 20Ah batteries. One Reention case and one shrink wrap. 36V and 48V. 48v for speed and handling test on new Day6 Joy. Once completed I will donate the 48V to the fella I gave a complete bike to 2 years ago. I cover all his repairs as well. An old not so healthy friend down on his luck ($600/month SS!!!) with a life-changing eBike. Thankfully it is an inexpensive motor to repair and maintain the first version of TSDZ2. An evaluation sample from TongSheng. several years ago. I only actually donated the KHS Smoothie bike. EM3ev donated a battery. I guess that's what excites me most about eBikes. They can be life changers. For me as well.

Sorry if this is an overshare...

 

[tomjasz]

BTW, best practice IME. TWO primary lock rings!

 

[m@Robertson]

BTW, best practice IME. TWO primary lock rings!

View attachment 118279

Based on some comments I heard from another builder on a FB group, I also added back in the two hose clamps. Check out this picture. the lock ring is not even tightened. the motor is immobile as if it was fully installed just from the two clamps. I have motors going back to 2017 that are still affixed without adjustment like this. I stopped doing the clamps when the lock rings resulted in perfect results... but those bikes are all street riders. This one will get some doubletrack at the least (I still have to put some heat to the heatshrink to tidy that part up).

40T Lekkie ring from Empowered is waiting for me at the post office.

 

[m@Robertson]

Chrystalyte battery bag with key switch. 2 new Shanghai Aijiu Energy Tech 20Ah batteries.
<snip>
I guess that's what excites me most about eBikes. They can be life changers. For me as well.

View attachment 118277

I totally agree. I did not realize how much I missed cycling until I got back on the bike thanks to the 'e' in ebike.

That is totally my favorite battery bag. As far as I can tell its no longer on the market. I tried to get one as a spare at one point (got mine from Grin) and they were gone. I use that bag on the back of 2Fat to hold one of its two parallel'd 16ah packs and my tools in that wonderful expando top section. Only drawback is those velcro straps are not the strongest. I use a small cargo net over top of the bag and its fine. I removed the key switch on mine.