Battery Wiring before I blow myself up!

[FrodoBaggins]

Hey Guys

I did a post a while back about trying to switch a battery into another case.
I thought I would start a new thread as it has been a while and there might be new people who can help.

The original post is here

Original Post

So I need some help before I blow myself up.
I removed the wires and copied the design. Most was just like for like, but I have hit a worrying point.

I have added some pictures, but I am finding that when I turn off the battery there is still a voltage passing through it. This voltage is half of the full capacity 26V
When the battery switch is on then it shows the 52.6V expected.

My guess is that it is something related to the charging part. Or maybe the BMS
I had to replace the little charger input component with a new (identical one) . Is it possible to solder onto the wrong connectors?

Obviously with the power off there should be no voltage so this is not a good situation.
I have tried to put some pictures and video here for advice.
So here is what I can see

2 main power wires wired into the main pins (this should be OK)
2 small red wires coming from the switch into the battery
A medium thickness red and black battery coming from the battery. The black is soldered directly onto one charger point. The red is joined to a small one on the BMS and then soldered onto the other connecter on the charger.
A small red and small black wire coming from the BMS. The black goes into the battery pack. The red connects to the wire as above and subsequently joins the charging port.

Clearly something needs sorting.
Can anyone help

 

[wheeliepete]

Some residual voltage with the battery switched off is quite normal, don't worry. The switch is part of the BMS. If you have swapped wires carefully to the same connections on the new case, then you will be all good. There is no way of checking this without removing the blue shrink wrap and tracing the wires, but from what I can see in the photos, all looks OK.

 

[FrodoBaggins]

Some residual voltage with the battery switched off is quite normal, don't worry. The switch is part of the BMS. If you have swapped wires carefully to the same connections on the new case, then you will be all good. There is no way of checking this without removing the blue shrink wrap and tracing the wires, but from what I can see in the photos, all looks OK.

I really appreciate your help @wheeliepete .
So what is that residual voltage?

I have another battery and there is no voltage flowing through it when switched off. Also weird that it is exactly half.
Does that also mean when switched off if the PINS connect then it will create the circuit despite being turned off?

 

[wheeliepete]

TBH, having read this is the case a few times here from members I trust, I have accepted it as the case, without fully understanding why. Someone with a bit more technical knowledge may come along and be able to explain it to you. Some battery pack switches cut the main positive discharge wire which do cut all voltage/current to the terminals.

 

[Nealh]

It depends on how the switch is wired.
If direct inline on the v+ supply wire then 0v will register, if the switch is a wired BMS one then one will see up to 50% voltage.

 

[harrys]

Does your voltage go to zero, if switched off, and connected to the controller? Some switched BMS will have residual voltage across the outout transistors when turned off, but with a small resistive load, it drains away to zero. That's normal and fine. Given that you only changed the case, your battery probably always did this, and should be OK. It's something most people are never going to check at unless they work on the battery,

One time I changed the BMS, and it would leak 50-100ma into a load when turned off. That was no good. That's like 1-2AH a day if you forgot to turn off the battery.