It's really nicely made actually. Maybe if I have time to get my sewing machine out over the summer I can make a few bucks out of all of
New bottle battery under the rain... is dead :(
- Thread starter cwah
- Start date
Hello,
So I've done the check now:
- The continuity test on the "Ok" big thing (what is it?) is fine.
- Continuity test failed on 1 of the Fets completely on the top of the picture (not the black one)
- Voltage on all cells have a very healthy 3.72v. Which seems good.
So, it does feel I need to change 1 Fet, the issue is that the BMS is attached to a board glued to the plastic cells bracket.
How do I unglue that? I can't use heat gun!
Also, where should I buy my Fet? I have few other blown controller, so I may as well buy few more to replace the blown one from my other controllers.
Thanks
So I've done the check now:
- The continuity test on the "Ok" big thing (what is it?) is fine.
- Continuity test failed on 1 of the Fets completely on the top of the picture (not the black one)
- Voltage on all cells have a very healthy 3.72v. Which seems good.
So, it does feel I need to change 1 Fet, the issue is that the BMS is attached to a board glued to the plastic cells bracket.
How do I unglue that? I can't use heat gun!
Also, where should I buy my Fet? I have few other blown controller, so I may as well buy few more to replace the blown one from my other controllers.
Thanks
D
Deleted member 4366
Guest
There's lots of different FETs for different purposes. You should read the number on it and get the same type, however, your problems could run deeper than one blown FET. The FETs are electronic switches, and you have several in parallel. They're switched on when they get about 12v on their left leg. The middle and right legs are the switch, so you should check continuity between those legs only after checking that you have 12v on the left leg. If there's no 12v, there should be no continuity. Therefore, the fact that you have continuity on a FET would probably mean that it's OK. It's the ones without continuity that are the problem. A BMS is different to a controller. In a BMS, the FETs should be switched on all the time the battery is healthy. In a controller, they give pulses of power to the motor, so they're normally switched off.
To test the 12v (could be anything from 8v to 18v), put your black probe on B- and your red probe on the left leg. To decide which is left, you look at the FET from the front with the legs downwards, like shown in my photo of the complete pcb above.
If you look at the PCB with the FETs at the top of the photo, the right hand one is the charging one that opens to allow charging, and closes when your cells are up to 4.2v. The other four are the discharge ones that all work in parallel.
If one were blown, the others should still switch on and allow discharge. If you haven't got any discharge, the transistor that provides the 12v to them may also be blown. Also, water in the BMS could have damaged anything. Try removing the blown FET and see if the BMS works without it. If that doesn't work, it might be easier to get a new BMS.
While you're waiting for a new BMS, as a temporary measure, you can bypass the output FETs by using a bit of 14g wire to bridge between B- and P-. That would only work if the charging FET is still operational. You can bypass the charging FET too by bridging its middle and right leg, but then you have no protection. The charger will cut off at 42v, so no immediate danger, but it's 50/50 whether the balancing is still working. Again, you'd be OK for a few cycles. If you do bypass the output FETs, don't forget that the battery won't switch off when it gets too low. Hopefully, your controller will switch off instead, but just be careful in case it doesn't. Don't let the voltage go too far down. Your LCD should show that.
To test the 12v (could be anything from 8v to 18v), put your black probe on B- and your red probe on the left leg. To decide which is left, you look at the FET from the front with the legs downwards, like shown in my photo of the complete pcb above.
If you look at the PCB with the FETs at the top of the photo, the right hand one is the charging one that opens to allow charging, and closes when your cells are up to 4.2v. The other four are the discharge ones that all work in parallel.
If one were blown, the others should still switch on and allow discharge. If you haven't got any discharge, the transistor that provides the 12v to them may also be blown. Also, water in the BMS could have damaged anything. Try removing the blown FET and see if the BMS works without it. If that doesn't work, it might be easier to get a new BMS.
While you're waiting for a new BMS, as a temporary measure, you can bypass the output FETs by using a bit of 14g wire to bridge between B- and P-. That would only work if the charging FET is still operational. You can bypass the charging FET too by bridging its middle and right leg, but then you have no protection. The charger will cut off at 42v, so no immediate danger, but it's 50/50 whether the balancing is still working. Again, you'd be OK for a few cycles. If you do bypass the output FETs, don't forget that the battery won't switch off when it gets too low. Hopefully, your controller will switch off instead, but just be careful in case it doesn't. Don't let the voltage go too far down. Your LCD should show that.
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Not of much use now but if I leave my bike out any where, I always take the battery with me and put in my backpack also can't be nicked that way. The bike connector has a placky bag tied around it.
So I used my multimeter and tested voltage between the B- and all the other Fets leg:
- The 4 Fets on the right do not have any voltage on the left or right leg. However, they all have 43V on the middle one. Continuity test is positive.
- The last Fet on the right (the charging one?) doesn't show any voltage anywhere. And continuity test is negative.
So no 12v anywhere but 43V on the middle, what does that mean?
Also, how can I change Fets when the board is glued to the cells brackets? And where shall I buy Fets?
Thank you
So I can do that without needing to unglue the board? A bit of solder sucker and fet should be removed?
Where shall I buy the spare fet?
Where shall I buy the spare fet?
Cwah a solder sucker is a cheap to buy plastic tool a vacuum pump that is used to remove liquid solder.
D
Deleted member 4366
Guest
There's nothing to say that you need to replace any FETs is there? They won't switch on unless they've got voltage on the left legs, which they haven't. It could be that the whole board is knackered. Those capacitors that blew, must have got battery voltage from somewhere when they should only have got maybe 5v. Presumably the water caused that. Battery voltage would destroy just about every component on the board. I think it's time to get a new BMS.
I'd like to avoid bmsbattery, is there any other decent supplier?
Also, what's the best way to remove the bms?
Also, what's the best way to remove the bms?
Try giving Hatti a call and see if Woosh can help as they also sell the 09 battery.
D
Deleted member 4366
Guest
Ironic isn't it - how do you get customers without selling stuff?Damn woosh only provide support to their customer. They don't want to sell bms to me
Surely they should have told that to cwah and let him make his mind up about whether he wanted to risk it instead of just a straight NO!
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