Battery

Ash123

Finding my (electric) wheels
Jun 16, 2024
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5
Does anyone have an answer to why my BMS is flashing, battery stopped charging and has a very low output, there is no on and off button on this battery, it's off a longbow e bike, I'll attach a video if I can, was thinking woukd a battery balance charger boost it up, just thought worth a try cos I've left the bike in the shed for a while and it's very cold in there,
 

saneagle

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Oct 10, 2010
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Does anyone have an answer to why my BMS is flashing, battery stopped charging and has a very low output, there is no on and off button on this battery, it's off a longbow e bike, I'll attach a video if I can, was thinking woukd a battery balance charger boost it up, just thought worth a try cos I've left the bike in the shed for a while and it's very cold in there,
The only way to be sure is to open it and measure the voltages on the multi-pin connector on the BMS.
 
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matthewslack

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Nov 26, 2021
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Does anyone have an answer to why my BMS is flashing, battery stopped charging and has a very low output, there is no on and off button on this battery, it's off a longbow e bike, I'll attach a video if I can, was thinking woukd a battery balance charger boost it up, just thought worth a try cos I've left the bike in the shed for a while and it's very cold in there,
My battery charger will not charge the battery if temperature is too low. It is fine when it warms up. Maybe yours is doing something similar.

Don't leave it charging overnight obviously, but you could bring the battery indoors overnight and see if it charges OK in the morning.
 
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Ash123

Finding my (electric) wheels
Jun 16, 2024
18
5
My battery charger will not charge the battery if temperature is too low. It is fine when it warms up. Maybe yours is doing something similar.

Don't leave it charging overnight obviously, but you could bring the battery indoors overnight and see if it charges OK in the morning.
Thanks that's worth a try
 

Ash123

Finding my (electric) wheels
Jun 16, 2024
18
5
Evening guys,
I'm gonna try and upload of my BMS flashing, if not I'll attach a picture, now on my digital multimeter it says just over 40 volts but that's without the charger, does that sound right, put the charger on then the lights flash slower but after about 30 seconds charger goes from orange light to green and the lights flash quicker again, I'm not that technically minded so excuse my lack of know 20250109_215948.jpghow
 

soundwave

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May 23, 2015
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Evening guys,
I'm gonna try and upload of my BMS flashing, if not I'll attach a picture, now on my digital multimeter it says just over 40 volts but that's without the charger, does that sound right, put the charger on then the lights flash slower but after about 30 seconds charger goes from orange light to green and the lights flash quicker again, I'm not that technically minded so excuse my lack of know View attachment 61723how

;) batt cell voltage connector is melting :eek:
 

saneagle

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Oct 10, 2010
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How many LEDs are there - lit and unlit?
What is the actual voltage of the battery immediately after taking it off the charger when the charger shows fully charged?
Is this something that didn't happen before, or did you get it like that?
 

Ash123

Finding my (electric) wheels
Jun 16, 2024
18
5
How many LEDs are there - lit and unlit?
What is the actual voltage of the battery immediately after taking it off the charger when the charger shows fully charged?
Is this something that didn't happen before, or did you get it like that?
Hi, it's a 36volt battery 10amp, I've just tested it again and the battery is saying 40.5 volts with a multimeter, that's unplugged from the charger, the lights just flash on and off and never stay solid, the bike was left in a cold place and left for about a year without any charging, so I just put my charger on and took roughly 30 seconds to go from the orange charge light to green, just seems odd if the battery is ok it should light up the handlebar control unit,or maybe its the unit and not the battery, but my way of thinking is if the bike hasn't been charged for nearly a year surly the charger should stay orange, but as I said its showing 40.5 volts with my meter
 

Ash123

Finding my (electric) wheels
Jun 16, 2024
18
5
Hi, it's a 36volt battery 10amp, I've just tested it again and the battery is saying 40.5 volts with a multimeter, that's unplugged from the charger, the lights just flash on and off and never stay solid, the bike was left in a cold place and left for about a year without any charging, so I just put my charger on and took roughly 30 seconds to go from the orange charge light to green, just seems odd if the battery is ok it should light up the handlebar control unit,or maybe its the unit and not the battery, but my way of thinking is if the bike hasn't been charged for nearly a year surly the charger should stay orange, but as I said its showing 40.5 volts with my meter
Forgot to say there is no on off button on the battery, and those lights you see are on the bms board,until you strip the battery down you can't see them lights from the outside.
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
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Hi, it's a 36volt battery 10amp, I've just tested it again and the battery is saying 40.5 volts with a multimeter, that's unplugged from the charger, the lights just flash on and off and never stay solid, the bike was left in a cold place and left for about a year without any charging, so I just put my charger on and took roughly 30 seconds to go from the orange charge light to green, just seems odd if the battery is ok it should light up the handlebar control unit,or maybe its the unit and not the battery, but my way of thinking is if the bike hasn't been charged for nearly a year surly the charger should stay orange, but as I said its showing 40.5 volts with my meter
Maybe I didn't make it clear. I asked how many LEDs are there. You slow things down when you don't answer questions.
 
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saneagle

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Oct 10, 2010
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There are 10 lights flashing
OK. It's a long time since I've seen that on a BMS. It's a pretty neat idea. Each LED is attached to one of the ten channels (cell groups). On the ones I've seen before, the LED for that channel comes on when the bleed transistor opens. It would open at around 4.2 v in order to balance the battery. When you charge the battery, you get a visual indication of how well balanced the battery is, and you can wait until all the LEDs are lit before removing the charger to get a perfectly balanced battery. When the LEDs take too long to light after others have lit, it's an indication that something might be wrong with that cell group.

The ones I've had never flashed. My guess is that the flashing is indicating that something is out of range, like one cell-group too low or too high.

When I look at your photo, it seems to show 8 lit LEDs. That's why I asked the question, so I ask again one more time but in a different way. How many are flashing? Do they stop flashing? is there any situation where some are lit but not others. If any are unlit, which ones?
 

Ash123

Finding my (electric) wheels
Jun 16, 2024
18
5
OK. It's a long time since I've seen that on a BMS. It's a pretty neat idea. Each LED is attached to one of the ten channels (cell groups). On the ones I've seen before, the LED for that channel comes on when the bleed transistor opens. It would open at around 4.2 v in order to balance the battery. When you charge the battery, you get a visual indication of how well balanced the battery is, and you can wait until all the LEDs are lit before removing the charger to get a perfectly balanced battery. When the LEDs take too long to light after others have lit, it's an indication that something might be wrong with that cell group.

The ones I've had never flashed. My guess is that the flashing is indicating that something is out of range, like one cell-group too low or too high.

When I look at your photo, it seems to show 8 lit LEDs. That's why I asked the question, so I ask again one more time but in a different way. How many are flashing? Do they stop flashing? is there any situation where some are lit but not others. If any are unlit, which ones?
Ok let's try again, there are ten lights but 1 dosent flash, plus the charger quickly goes to green when plugged in, so taking a guess maybe the one that not flashing is the problem, appreciate your help but like I said I'm not very technically minded when it comes to batteries,
 

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