Need help connecting 72v battery to my controller.

[Dylan23]

So my battery and my controller have 2 different connectors. Controller is using ring terminals and my battery is using xt60. How do I go about connecting them together? Xt60 male and solder my own ring terminals on the end or? I have no idea how thick the wires are, battery seems like 12awg but the controller seems thicker. The battery is a 72v battery. Messing with electricity is pretty scary without plug and play.

 

[harryS]

I would use XT90's between the battery/controller. It's a major solder job. Nuff said about that,

 

[Dylan23]

I would use XT90's between the battery/controller. It's a major solder job. Nuff said about that,

I bought some XT90s anti spark with pigtails. Soldering isn't that hard. The only thing that scares me is messing with the battery end, what happens if I accidentally touch positive and negative from the battery? Asking since I need to cut off the XT60 end and make XT90 end.

 

[retiredNH]

72 volts and you're not sure what to do? Whatever, please do the following:
- DON'T WORK ALONE. 72v is well into the lethal range, as well as the range that can cause serious burns and tissue damage.
- Have a working decent sized ABC fire extinguisher nearby, and know how to use it against a variety of fires.
Batteries of this voltage (and I presume size) are no laughing matter, pack a lethal wallop.

 

[Dylan23]

72 volts and you're not sure what to do? Whatever, please do the following:
- DON'T WORK ALONE. 72v is well into the lethal range, as well as the range that can cause serious burns and tissue damage.
- Have a working decent sized ABC fire extinguisher nearby, and know how to use it against a variety of fires.
Batteries of this voltage (and I presume size) are no laughing matter, pack a lethal wallop.

I mean it's a 72v battery inside of wrapping inside a bag that was professionaly made. I'm not messing with anything besides trying to replace the connector to the controller.

 

[harryS]

The XT60 size is not large enough to carry the current I associate with 72V, A pair of anti-spark XT90's is better.

It might get unwieldy, but you can crimp the pigtails to the battery leads. Cut only one wire at a time, It's easier than trying to solder together two wires that are thick.

I would rather remove the pigtails and solder the controller wires directly to the XT90, but I bet they used lead free solder, and that's really hard to undo. There's no voltage there, by the way, until you plug in the battery.

 

[Dylan23]

The XT60 size is not large enough to carry the current I associate with 72V, A pair of anti-spark XT90's is better.

It might get unwieldy, but you can crimp the pigtails to the battery leads. Cut only one wire at a time, It's easier than trying to solder together two wires that are thick.

I would rather remove the pigtails and solder the controller wires directly to the XT90, but I bet they used lead free solder, and that's really hard to undo. There's no voltage there, by the way, until you plug in the battery.

Yeah I know working on the controller positive and negative is fine, no voltage. Just a little worried about working on the battery positive and negative. I guess I could cut one wire at a time from the battery

 

[tomjasz]

I guess I could cut one wire at a time from the battery

You best be sure. Why in the world would a n00b poke around with a 72V battery and guess? O course you cut one at a time. After I cut I ALWAYS protect the open wire ends to avoid shorting the pack.

Of course, you cut one at a time. Short those power wires and at the very least you'll fry the BMS.

Who built the battery?


Kentucky fried fingers. With HALF the voltage you're messing with.

 

[tomjasz]

This guy screwed up and POOF!
He goes out of his way to defend his build but in FACT seems to have used an external controller on a BBSHD to pull maximum power and speed. No excuse for his mistakes. Even though I've seen some crap builds from UPP it's not all on them. Rossman F'ed up.

 

[retiredNH]

Very important pics, tomjasz. Thank you for posting. I hope more folks here view them to appreciate what a punch our ebike batteries pack.

 

[Dylan23]

You best be sure. Why in the world would a n00b poke around with a 72V battery and guess? O course you cut one at a time. After I cut I ALWAYS protect the open wire ends to avoid shorting the pack.

Of course, you cut one at a time. Short those power wires and at the very least you'll fry the BMS.

Who built the battery?


Kentucky fried fingers. With HALF the voltage you're messing with.

https://www.aliexpress.com/item/225...st.0.0.21ef1802sF0smN&gatewayAdapt=4itemAdapt

I bought the 72v 26.1ah

 

[tomjasz]

I bought the 72v 26.1ah

WOW! Old 29E cells. Pretty much gone from mainstream battery packs. My 2014, 2015 packs were 29E. Reliable cells if in fact, they are genuine.

Samsung 29E 18650 Battery, 2850mAh, 2.75A, 3.65V, Grade A Lithium-ion (INR18650-29E)​

 

[Dylan23]

WOW! Old 29E cells. Pretty much gone from mainstream battery packs. My 2014, 2015 packs were 29E. Reliable cells if in fact, they are genuine.

Samsung 29E 18650 Battery, 2850mAh, 2.75A, 3.65V, Grade A Lithium-ion (INR18650-29E)​

So a good thing yeah? Lol

 

[tomjasz]

It wouldn't excite me. With the power, you apparently want to pull I'd be happier with a newer and more powerful cell. That said I have little regard for the move to 72V batteries on home builds. Especially with an unknown make and unknown BMS parameters, and OLD cells not best suited for a 72V nominal pack(84V). Too many risks to mitigate, for me.

 

[Dylan23]

It wouldn't excite me. With the power, you apparently want to pull I'd be happier with a newer and more powerful cell. That said I have little regard for the move to 72V batteries on home builds. Especially with an unknown make and unknown BMS parameters, and OLD cells not best suited for a 72V nominal pack(84V). Too many risks to mitigate, for me.

I plan on drastically reducing the amps the controller supplies to the motor. Probably like 35amps max. I don't need any higher as 35 is more than enough torque

 

[harryS]

And those pics with the blackened fingers. Was that the guy who learned how to "wake up" dead lawnmower batteries on youtube and it exploded on him? So much stuff that is wrong on the net.

 

[Dylan23]

And those pics with the blackened fingers. Was that the guy who learned how to "wake up" dead lawnmower batteries on youtube and it exploded on him? So much stuff that is wrong on the net.

Are you saying this guy is fearmongering basically? Or just pointing out what that guy did was stupid

 

[harryS]

Are you saying this guy is fearmongering basically? Or just pointing out what that guy did was stupid

Those would be two unconnected incidents. The youtube video is some guy who wired two batteries in parallel with a scheme to run them off one charger. If his connection circuits were to fail, it could cause a fire. A fire happened. Who we gonna believe? That a battery failed. or a home made connection scheme failed? Anyway, he let the fire burn out on his front porch, while filming it. He didn't get his hands dirty or burnt.

The blackened fingers ... some other guy owned a lawnscaping business and found the batteries could run his ebike. He found youtube videos explaining how to connect a dead battery and a good one together to "jump start" them. He jump started an explosion and he posted his blackened fingers on another forum. I mean there are plenty of KFF pix, so it could be yet another foolish victim.

 

[Dylan23]

Those would be two unconnected incidents. The youtube video is some guy who wired two batteries in parallel with a scheme to run them off one charger. If his connection circuits were to fail, it could cause a fire. A fire happened. Who we gonna believe? That a battery failed. or a home made connection scheme failed? Anyway, he let the fire burn out on his front porch, while filming it. He didn't get his hands dirty or burnt.

The blackened fingers ... some other guy owned a lawnscaping business and found the batteries could run his ebike. He found youtube videos explaining how to connect a dead battery and a good one together to "jump start" them. He jump started an explosion and he posted his blackened fingers on another forum. I mean there are plenty of KFF pix, so it could be yet another foolish victim.

I found it amusing, but also tragic, that are so many people who believe you can revive dead lithium cells, when the manufacturers tell us it's dangerous. It's not because they want you to buy more cells, it is dangerous.

I see. Yeah I don't want to do anything crazy at all.. I literally just want to connect a battery to a controller without dying or anything catching fire lol, not funny those things could happen but yeah

 

[kevinmccune]

You could make an adapter a XT 60 is supposed to carry 60 amps if it doesn't get hot you are good to go put a fuse inline to make sure it will not overload