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,
Battery
- Thread starter Ash123
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The only way to be sure is to open it and measure the voltages on the multi-pin connector on the BMS.
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.
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
how
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
how
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batt cell voltage connector is melting 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?
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
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.
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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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,
It's OK, we often get this, where people are very keen to give us all the information, including sometimes their life story, when all we need is some small piece of specific information to know what the problem is. It can be very frustrating, and the frustration gets vented sometines.
Anyway, your diagnosis is probably correct. Now we can home in on the actual cause of your problem and come to a solution. First some background info for you to help understand, then what to do next.
Most BMSs need power to work. They take that power from either one cell group or all of them. If they take it from one, that cell will go down if the battery isn't used for a long time, until it's below the level where the BMS allows charging. That's probably what's happened.
The next test you need to do is to measure the voltage of that group. The normal way is to remove the white multi-pin connector if you can, then place your black probe on the main black coming from the cell-pack if you can get access to it (on the BMS marked B-), or the ground pin on the multi-pin connector if it has one (black wire). put the red probe into each of the slots on the side of the connector to get ten results. The difference between each adjacent pair is the cell-group voltage, so you need 10 calculated results. Sometimes, there are only 9 results because the main ground doesn't go to that connector or the top of the top cell-group is in a separate wire to the BMS, marked B+. we only need to know the voltage of the one cell-group, so if all else fails, you can get that from the two adjacent pins on the connector, but you never know whether they're using other wires on the first or last, so it's better to test everything. Plus, there may be other cells that need a bit of balancing.
Ask if you don't understand anything.
Ok thanks, I'll have a read over what you have said and try and get my head around it,
And believe me yiu wouldn't want my life story, just a bit of banter there,