Just checked and the 2 white wires do go to the on/off switch.Try the low reading voltage reading on that discharge solder joint but this time with the battery switch on.
I have just connected the battery back to the bike and connected the live from the battery base to the controller live input but used the ground from the soldered connector on the right side of BMS, which I think is the ground from all cells to the BMS and all works on the bikeJust checked and the 2 white wires do go to the on/off switch.
The low reading of 51v to the low left solder is with switch on. 0v with switch off. Other 2 reading stay the same at high 53v with switch on or off
I am not going to use it like this , it was just a test to verify all was working inc controller and display.Don't leave it like that for too long because you've bi-passed all the safety controls. As your battery is well-balanced, you should be OK for a few charges as long as you don't over-discharge it.
It seems that you're losing something through the output mosfets, so probably easier to replace the BMS.
My battery is 48v 14.5amp. Does it matter that the one above is 35amp?In principle, you can use any 13s BMS that can supply the current that your present one does or more. They have different connector arrangements. You have to make sure that your B1, B2, B3... wires go to the right positions. In the worst case, you have to cut off the connector from the cel-pack and solder all the wires to the new connector in the correct sequence.
Another problem is that your present one has a switch and BMSs with the switch connection point are not very common, so take a bit of hunting. you can normally find them on Aliexpress or Amazon and Ebay.
This one looks interesting if you don't mind soldering all the sense wires:
This BMS is super thin and the only one of its kind! There are no other so affordable BMS on the market with On/Off function! But if you want to use a switch, you can cut the white wires and connect it there.www.ebay.co.uk
How many amps do you need?
You're getting confused between amps and amp-hours. They're completely different things. The current is regulated by the controller. What's the maximum current written on it?My battery is 48v 14.5amp. Does it matter that the one above is 35amp?
What are the chances of the sense wire connector from my battery fitting this one? If you were to ignore the big blue surround and just fit the sense connector from by battery to it!
I have found this from PSWPower, where I sourced the original battery from. Hopefully a straight swap. Ordered from China so a couple of week wait!You need a BMS that can provide say 20A or more, so the 35A one will be finefrom that point of view.
If you do a bit of searching, you might find one with the right connector.