BMS On/Off switch wires?

rg12

100 kW
Joined
Jul 26, 2014
Messages
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Hey Guys,

I got this BMS that has two white thin wires coming out of it and it says that it's the On/Off switch.
Why do I need an On/Off switch? the switch for the battery is in the lock while off it's cutting the red wire from the bottom part of the battery to the battery itself.
Where do I connect those thin wires?
It looks like these two white wires in the middle (not the same BMS though):
ebike-36v-48v-ebike-frame-battery-bms-with-usb-output.jpg
 
this is a 13s bms?
You have 13 sense wires for B+1 up to B+13 and number 14 for B-
One side of the bms you have 2 wires open and this wil be the on/off switch for the bms.
The white in the middel is the temp sensor.

Just put these 2 wires that are open togheter and the bms in always ON(so not the 2 wires to the temp sensor)
 
I soldered the two together (it was a switch for sure, not the temp sensor wires) so the BMS will be on and I thought that I did something wrong since the battery has a random problem that when the switch is turned on the voltage that comes out below the pack either is constant like it should be or goes away after a second.
I first thought it was a switch problem but I wiggled the key in every switch position, pulled on the wires inside to try to make it happen at will and it didn't so it seems that it's something with the BMS.
 
Have you tried pushing a charge into the pack through BMS?

Some of the BMS with on/off switch I’ve used needed a brief charge current to “activate” the circuit.

Dunno why but that’s how the BMS w/switch behaved for me?
 
Ykick said:
Have you tried pushing a charge into the pack through BMS?

Some of the BMS with on/off switch I’ve used needed a brief charge current to “activate” the circuit.

Dunno why but that’s how the BMS w/switch behaved for me?

What do you mean by a brief charge? connecting the switch wire to the + wire or something?
 
rg12 said:
Ykick said:
Have you tried pushing a charge into the pack through BMS?

Some of the BMS with on/off switch I’ve used needed a brief charge current to “activate” the circuit.

Dunno why but that’s how the BMS w/switch behaved for me?

What do you mean by a brief charge? connecting the switch wire to the + wire or something?

No.

On/off wires should be ON (switch closed) and then apply a charge to the charge port or discharge port if they're the same.

Just like you would normally charge the battery pack. In my experience, the BMS w/switch required a brief charge for the BMS to work normally.

I dunno if BMS is the same but simple thing to try?
 
rg12 said:
So before every ride I have to stick the charger in?

No. The BMS I've used with on/off switch worked normally as expected after the initial connections to the battery and a shot from a charger.

But if you ever disconnect the battery from the BMS it will require a shot of charge before it will work again. That happened to me out riding one time and fortunately I also had a range extending pack so I just swapped out packs and continued on until I got home to the charger.

No guarantee it will work for your BMS although the on/off switch versions I've used, that's how they behaved.
 
I have charged it for the first time through the BMS up to about 90% charge and that auto switching off thing happend afterwards...
 
Sorry guys, i know this an old thread,
But i just got my battery pack and it's included with a switch, the seller says that this a bms switches.
Should I always keep it on, or should i turn it off when i'm not use the bike?

And should I turn it on/off while charging?
 
rg12 said:
Hey Guys,

I got this BMS that has two white thin wires coming out of it and it says that it's the On/Off switch.
Why do I need an On/Off switch? the switch for the battery is in the lock while off it's cutting the red wire from the bottom part of the battery to the battery itself.
Where do I connect those thin wires?
It looks like these two white wires in the middle (not the same BMS though):
ebike-36v-48v-ebike-frame-battery-bms-with-usb-output.jpg
That white rectangel connected to the white wire is most likely a THERMAL on/off switch... So that the BMS shuts down if the battery ever overheats... That would be my guess.

Matador
 
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