36v scooter

[scooterebike]

can anybody help, i have a onemile scooter and it wont turn on at all so i went and check the battery and it shows all cells fully charge and 42v total battery is a 36v then when i check with a multimeter the output is only 21v

 

[Chalo]

Check each cell group for voltage. There's probably some reason the BMS won't turn on the juice. If any single cell group is way too high or low on voltage, the battery will be cut off to protect you from yourself.

 

[E-HP]

can anybody help, i have a onemile scooter and it wont turn on at all so i went and check the battery and it shows all cells fully charge and 42v total battery is a 36v then when i check with a multimeter the output is only 21v

How are you performing this measurement?

 

[scooterebike]

Check each cell group for voltage. There's probably some reason the BMS won't turn on the juice. If any single cell group is way too high or low on voltage, the battery will be cut off to protect you from yourself.

thanks

How are you performing this measurement?

How are you performing this measurement?

so i have 4.1v on all of the cells exept one is 4.07 could that be the reazon for the bms not to out put the full 36v? and how can i fix it?

 

[scooterebike]

How are you performing this measurement?

with a multimeter

 

[amberwolf]

can anybody help, i have a onemile scooter and it wont turn on at all so i went and check the battery and it shows all cells fully charge and 42v total battery is a 36v then when i check with a multimeter the output is only 21v

so i have 4.1v on all of the cells exept one is 4.07 could that be the reazon for the bms not to out put the full 36v? and how can i fix it?

The BMS will turn off the output (and/or the input) anytime any limit it has is exceeded. Since you probably have no way to know what the specific limits it has are, you can assume that if any cell exceeds 4.2v (possibly 4.25v) it would turn the input off, and if any cell is below 2.8v it would turn the output off. It may also turn either or both off if the difference in voltage between any two cells exceeds some amount, perhaps 0.1v. If any balance/sense wire is disconnected from the cells or the BMS, it *should* turn off both input and output, but not all of them do. If current limit (amps, A) is exceeded, it would turn off the port with that overcurrent.


Just need to clarify a few things from the above. More detail in your answers is better; the less you tell us the less info we have to help you with, since you are there and we are not, and we cannot know anything you do not tell us.

Your picture shows the output is 3.6v, not 21v.

Where *exactly* do you measure 21v? (if you can mark a copy of your picture with where you connect the meter leads, it may help us see where you're measuring)

Full charge on a 42v 10s (36v battery) is 4.2v per cell. If each cell group shows 4.1v, except for one at 4.07v, that doesn't add up to 42v.

Where *exactly* do you measure 42v? (if you can mark a copy of your picture with where you connect the meter leads, it may help us see where you're measuring)

The BMS would only output 36v when the battery is about half empty. Since you're saying it's full, it would not output 36v.

What happened to the scooter between the time the scooter worked, and the time it did not?

 

[Chalo]

With regard to the 21V measurement, does it gradually drop the longer you measure it? Because if so, that's just the leaked charge from the BMS cutoff transistors getting depleted by measuring its voltage.

 

[scooterebike]

The BMS will turn off the output (and/or the input) anytime any limit it has is exceeded. Since you probably have no way to know what the specific limits it has are, you can assume that if any cell exceeds 4.2v (possibly 4.25v) it would turn the input off, and if any cell is below 2.8v it would turn the output off. It may also turn either or both off if the difference in voltage between any two cells exceeds some amount, perhaps 0.1v. If any balance/sense wire is disconnected from the cells or the BMS, it *should* turn off both input and output, but not all of them do. If current limit (amps, A) is exceeded, it would turn off the port with that overcurrent.


Just need to clarify a few things from the above. More detail in your answers is better; the less you tell us the less info we have to help you with, since you are there and we are not, and we cannot know anything you do not tell us.

Your picture shows the output is 3.6v, not 21v.

Where *exactly* do you measure 21v? (if you can mark a copy of your picture with where you connect the meter leads, it may help us see where you're measuring)

Full charge on a 42v 10s (36v battery) is 4.2v per cell. If each cell group shows 4.1v, except for one at 4.07v, that doesn't add up to 42v.

Where *exactly* do you measure 42v? (if you can mark a copy of your picture with where you connect the meter leads, it may help us see where you're measuring)

The BMS would only output 36v when the battery is about half empty. Since you're saying it's full, it would not output 36v.

What happened to the scooter between the time the scooter worked, and the time it did not?

thanks for your help, i will make a detail reading of all cell voltage as soon as

With regard to the 21V measurement, does it gradually drop the longer you measure it? Because if so, that's just the leaked charge from the BMS cutoff transistors getting depleted by measuring its voltage.

it is a steady 20.51 now on the out put so on the cells i have 4.1, 4.1, 4.1, 4.1, 4.1, 4.06, 4.1, 4.1, 4.1, 4.1, 4.1

 

[amberwolf]

it is a steady 20.51 now on the out put so on the cells i have 4.1, 4.1, 4.1, 4.1, 4.1, 4.06, 4.1, 4.1, 4.1, 4.1, 4.1

That's 11 cells, 10 of them at 4.1v for 41v subtotal, plus the 4.06v for a grand total of 45.06v.

A 36v pack should only have 10 series cells in it, for a max total of 42v, assuming they are 4.2v full voltage cells (some only go to 4.1 or 4.15, etc, depending on the specific cell brand and model and chemistry).

 

[scooterebike]

thanks for your help, i will make a detail reading of all cell voltage as soon as

it is a steady 20.51 now on the out put so on the cells i have 4.1, 4.1, 4.1, 4.1, 4.1, 4.06, 4.1, 4.1, 4.1, 4.1, 4.1

With regard to the 21V measurement, does it gradually drop the longer you measure it? Because if so, that's just the leaked charge from the BMS cutoff transistors getting depleted by measuring its voltage.

yes it start hight then it drop real quik

 

[scooterebike]

thanks for your help, i will make a detail reading of all cell voltage as soon as

it is a steady 20.51 now on the out put so on the cells i have 4.1, 4.1, 4.1, 4.1, 4.1, 4.06, 4.1, 4.1, 4.1, 4.1, 4.1

With regard to the 21V measurement, does it gradually drop the longer you measure it? Because if so, that's just the leaked charge from the BMS cutoff transistors getting depleted by measuring its voltage.

yes it start hight then it drop real quik

With regard to the 21V measurement, does it gradually drop the longer you measure it? Because if so, that's just the leaked charge from the BMS cutoff transistors getting depleted by measuring its voltage.

With regard to the 21V measurement, does it gradually drop the longer you measure it? Because if so, that's just the leaked charge from the BMS cutoff transistors getting depleted by measuring its voltage.

 

[Chalo]

yes it start hight then it drop real quik

Your BMS has cut off the pack. Maybe it's a bunk BMS, maybe one of the sense wires for it has detached or become damaged, or there's some other undiagnosed fault. If your cell voltages are all between 4.1 and 4.06, then I can't say why the BMS would isolate the pack.

 

[scooterebike]

Your BMS has cut off the pack. Maybe it's a bunk BMS, maybe one of the sense wires for it has detached or become damaged, or there's some other undiagnosed fault. If your cell voltages are all between 4.1 and 4.06, then I can't say why the BMS would isolate the pack.

so i let it charge for a wile now all cells are equal at 4.1 and the power is still cut off at 20.8 and already reset it removing the fuse

 

[Chalo]

so i let it charge for a wile now all cells are equal at 4.1 and the power is still cut off at 20.8 and already reset it removing the fuse

Well, I reckon the remedy might be a new BMS. They cost about $15 on eBay last time I checked.

 

[scooterebike]

yes i think ima have to do that instead of fighting it, thanks to all of you for your time and help