Battery switch leave on?

[Wayners]

My 36v battery has an on off switch. If I leave it on unit shuts down after about 10mins.
I do switch it on and off on every ride but I often think I might as well just leave on? Maybe just turn off at night when I charge.
Oh. Charger is on a switched timer for safety at night..

 

[lenny]

Never leave it charging unattended or charge it while you are asleep.

e-scooters and e-bikes

Are electric bikes and electric scooters safe?

www.london-fire.gov.uk

 

[saneagle]

My 36v battery has an on off switch. If I leave it on unit shuts down after about 10mins.
I do switch it on and off on every ride but I often think I might as well just leave on? Maybe just turn off at night when I charge.
Oh. Charger is on a switched timer for safety at night..

You should switch off the battery before re-attaching it if ever you remove it, otherwise you burn the contacts.

 

[Bikes4two]

Never leave it charging unattended or charge it while you are asleep.

e-scooters and e-bikes

Are electric bikes and electric scooters safe?

www.london-fire.gov.uk

A typical battery takes around 5+ hours to fully charge - to suggest one stays in attendance for that amount of time really isn't practical for most folks and for a well made battery and charging system (as in standard of build, cells used and a reputable charge) isn't needed IMHO.
On the other hand if you've got cheap undranded stuff, have a chat with those who use fire boxes etc.

 

[Wayners]

Bike is in the garage and I put on for 2 hours on a timer. Takes about 3 hours to charge fully as starting around 60%.
Good enough.
Sometimes I put on charge in the evening and watch until its full.

Yeah, I switch off to remove battery but I leave on all the time. Guess I should switch off to charge thinking about it

 

[RollingChunder]

Guess I should switch off to charge thinking about it

BMS should be on to charge. Although I have tried off and it didn't make a difference. I still switch on to charge to help prevent overcharging/balancing as per manufacturer.

 

[Nealh]

The switch is usually a bms switch , if one leaves it on then when not in use then one risks the battery draining . It is quite simple during charging switch the bms on once connected for charging and once it has finsished the charge cycle switch off.

 

[saneagle]

BMS should be on to charge. Although I have tried off and it didn't make a difference. I still switch on to charge to help prevent overcharging/balancing as per manufacturer.

If the battery charges, it makes no difference whether it's switched on or not. Balancing happens whenever the battery is fully charged, however you do it. Normally, a battery wouldn't charge if the BMS is switched off. Are you getting confused by the switch that powers the bike?

 

[RollingChunder]

If the battery charges, it makes no difference whether it's switched on or not. Balancing happens whenever the battery is fully charged, however you do it. Normally, a battery wouldn't charge if the BMS is switched off. Are you getting confused by the switch that powers the bike?

The switch on the side of the Hailong case. It might be that my battery has a cheap BMS with no charging functions. I have not tried fully charging with switch off tbf.

 

[saneagle]

The switch on the side of the Hailong case. It might be that my battery has a cheap BMS with no charging functions. I have not tried fully charging with switch off tbf.

As long as the charger light goes from green to red when you plug it in, it'll be fine. Always switch off that switch before connecting the battery if you take the battery off the bike to charge.

 

[Bikes4two]

BMS should be on to charge. Although I have tried off and it didn't make a difference. I still switch on to charge to help prevent overcharging/balancing as per manufacturer.

I think maybe you are misunderstanding the role of the switch in that the BMS is hard wired into the battery - the switch merely activates the electronic switching components (aka FET's) in the BMS to 'connect' the battery voltage to the output terminals of the battery pack (which is why the switch needs to be in the 'off' position when removing/installing the battery pack into its holder - this prevents sparking between the battery pack terminals and the battery pack casing terminals).

The switch position, on or off, has no effect on the charging of the battery nor in the balancing function - as has already been said, if the charger light goes from green to red, be confident that the battery is being charged.

So the BMS is always taking some power from the battery but it is really small with the switch off and a bit more so with the switch on, but still small.


Do a google search on something like '10s BMS schematic' to get a better understanding of these things.

 

[RollingChunder]

I think maybe you are misunderstanding the role of the switch in that the BMS is hard wired into the battery - the switch merely activates the electronic switching components (aka FET's) in the BMS to 'connect' the battery voltage to the output terminals of the battery pack (which is why the switch needs to be in the 'off' position when removing/installing the battery pack into its holder - this prevents sparking between the battery pack terminals and the battery pack casing terminals).

The switch position, on or off, has no effect on the charging of the battery nor in the balancing function - as has already been said, if the charger light goes from green to red, be confident that the battery is being charged.

So the BMS is always taking some power from the battery but it is really small with the switch off and a bit more so with the switch on, but still small.


Do a google search on something like '10s BMS schematic' to get a better understanding of these things.

Okay thanks. Here is the battery in question if you have any further advice. Annoyingly, it's reduced in price since I bought it and it was already cheap for what it supposedly is.

S039-5 52V 19.2AH BMS40A LG4800mAh cells li-ion Ebike battery with 3A charger for 0-1500W motor/UK stock/Fast delivery/3-5working days arrive (uppbattery.com)

I chose it mainly because of the price which you may disapprove of, but also I have seen videos of UPP battery disassembly and they found genuine cells.

 

[guerney]

I chose it mainly because of the price which you may disapprove of, but also I have seen videos of UPP battery disassembly and they found genuine cells.

"21700 LG 4800mAh"

Do you know which 21700 LG cells specifically? Seems LG M50L, M50U, and LG M48T are all 5000mAh.

 

[RollingChunder]

Do you know which 21700 LG cells specifically? Seems LG M50L, M50U, and LG M48T are all 5,000 mAh.

I don't know for this battery. I watched disassembly videos a while ago when I was researching and it wouldn't have been that exact battery.

My hunch is "LG4800mAh" is LG M48T? They might think this is easier to understand for consumers? I am not familiar with specific cell models my research didn't stretch that far.

 

[guerney]

I don't know for this battery. I watched disassembly videos a while ago when I was researching and it wouldn't have been that exact battery.

My hunch is "LG4800mAh" is LG M48T? They might think this is easier to understand for consumers? I am not familiar with different cell models my research didn't stretch that far.

I didn't know anything about ebike batteries when I bought my conversion kit, but I paid extra for a battery containing cells made by a brand I recognised, namely LG, instead of no-name Chinese cells, and it's still working great 4,090km and three years later. After haunting these forums for years reading numerous battery related posts, I'd never buy a ebike battery without being absolutely certain about which specific cells it comprises of.