Best way to discharge battery

[Deus]

I have recently bought and fitted a mid motor kit and 17.5 aH battery i purchased a charger that charges to 90% as i understand it the charger is supposed to cut off then but it is instead cutting off at 96% i emailed the supplier and was told
''The battery needs to be fully charged and fully discharged for the BMS to calibrate the correct capacity. If you do this you will find that the charged voltage in the Low setting will be about 90%.''
I asked the supplier the best way to discharge the battery but as yet i have had no response i have also read that i should not fully discharge the battery as this will damage the cells.

 

[soundwave]

the bms will cut off the batt b4 it gets to low if it drains the cells to 0v then its broken.

just ride the bike down to 1 bar and recharge

 

[Deus]

the bms will cut off the batt b4 it gets to low if it drains the cells to 0v then its broken.

just ride the bike down to 1 bar and recharge

Thanks for the quick reply so it is not possible to fully discharge the battery safely then like the supplier said to do? does that mean that i paid extra for a charger with a 90% cut off that will not ever work properly ?

 

[wheeliepete]

Where do you get the 96% from? You may need to open the charger and adjust the output voltage to get the 90%. What voltage are you running?

 

[wheeliepete]

Charge the battery to 100% and ride, as SW said, down to 1 bar a couple of times, then try charging to 90%.

 

[Deus]

Where do you get the 96% from? You may need to open the charger and adjust the output voltage to get the 90%. What voltage are you running?

I get the 96% charge capacity from the smart BMS app on my phone the charger in the low position gives 57.5v
the charger has 2 positions L 57.5v H 58.8v

Also i do not have a bar display only voltage so what is the lowest voltage i can discharge to for a 52v pack ?

 

[soundwave]

the bms will cut the voltage when it sees that the pack is low so id not worry about it.

as for the app well id not bother with it as its probable useless anyway.

a 18650 cell flat is about 3v-3.3v and fully charged its 4.2v at 3v and lower the voltage will fall of a cliff and also damage the cell.

 

[flecc]

Lithium rechargeable cells should never be fully discharged, it can destroy them. What's meant by fully discharging is using them until the low voltage cutoff of the bike, which occurs at about 3.15 volts per cell.
.

 

[wheeliepete]

57.5v is 4.1v per parallel string of cells, so that's fine. To keep the pack balanced, charge to 100% every 10 charges or so. Check the LVC on the app., it should be set around 43v.

 

[Deus]

Lithium rechargeable cells should never be fully discharged, it can destroy them. What's meant by fully discharging is using them until the low voltage cutoff of the bike, which occurs at about 3.15 volts per cell.
.

The vendor EM3EV should have said that to me instead of just saying ''fully discharge'' i am new to Ebikes i guess they are used to dealing with more tech savvy users than first time builders like me.

57.5v is 4.1v per parallel string of cells, so that's fine. To keep the pack balanced, charge to 100% every 10 charges or so. Check the LVC on the app., it should be set around 43v.

There is no LVC on the app (it is the EM3EV smart BMS app) i guess EM3EV will tell me the cut off voltage but Joseph from there has been slow to reply so far.

 

[Nealh]

When discharging don't go much lower then 44.1v which is 3.15v per cell, your 52v battery is 14s so 14 cell groups in series.
As already mentioned if not charging to 100% do a full charge every 6 -10 cycles to ensure the battery cells remain balanced.

 

[Deus]

When discharging don't go much lower then 44.1v which is 3.15v per cell, your 52v battery is 14s so 14 cell groups in series.
As already mentioned if not charging to 100% do a full charge every 6 -10 cycles to ensure the battery cells remain balanced.

Em3EV say the BMS will balance the cells at only 90% charge

 

[Throwawat1]

Hey do you guys happen to have the apk for their app