Dead battery
- Thread starter ChristelG
- Start date
harryS
Well-Known Member
Are you talking about the method where they connect a good battery to a dead one? They only get away with it because they used a small vape or drill battery. It's wrong. It's dangerous. Read this.
https://endless-sphere.com/forums/viewtopic.php?f=14&t=99020
https://endless-sphere.com/forums/viewtopic.php?f=14&t=99020
mako
Member
How do you know its dead? Did you put a voltmeter on it? If so what was the reading and what is the battery rating? (i.e. 48v 15ah) Did you check the output of the charger you are using to see if it works? These batteries usually have a BMS that puts the battery to sleep if not in use for a period of time. They wake up when you put a good charger on them.
rich c
Well-Known Member
They won't wake up if you leave the switch on and the voltage drops below the BMS low set point.
It’s not the charger, you have to bypass the BMS to charge it. I know what to do, I don’t have the equipment to do it. That’s why I’m looking for someone to help me
Again, the question is - what is the battery voltage? Has battery been discharged so deeply that nothing happens when you connect the charger?
If voltage is too low and charger is tested and good, this could mean that either BMS, or charger (or both) are doing their job, preventing fireworks when detecting too low voltage in the battery.
Perhaps a smarter charger could help. Grin Satiator can be programmed with a soft start, applying low voltage first, and then increasing it gradually. Or any regulated DC power supply. Just an idea.
Last edited:
harryS
Well-Known Member
All you need is a accurate voltmeter and the knowledge of where to probe the battery and what to look for. You can't work on a battery w/o a meter. That's like poking at a stick of dynamite with a lit flare.
You can only bypass a BMS when the series groups are at safe voltages.
You can only bypass a BMS when the series groups are at safe voltages.
ebikemom
Well-Known Member
@ChristelG , you might find this thread informative:
https://electricbikereview.com/foru...nued-or-the-company-is-out-of-business.22737/
https://electricbikereview.com/foru...nued-or-the-company-is-out-of-business.22737/
Off road all day
Active Member
I really don't know anything about this but logic dictates a pack can't fail, it's made of individual cells, some can fail but not all at once even drained.
BMS issue i would guess, bypass it, that may take tearing the pack apart to get voltage directly to the cells.
BMS issue i would guess, bypass it, that may take tearing the pack apart to get voltage directly to the cells.
rich c
Well-Known Member
It's likely that nothing failed. The battery pack probably had a drain on it and it went below the safety point set on the BMS. Guessing and logic will never replace engineering and science. Your suggestion could cause even further damage to the pack and possibly a fire. Be careful what you offer to the world.
Logic is only good when based on knowledge. Are you sure you have this knowledge?
A pack can fail - yours did. Could be several reasons, as well as combination of those - failed one cell, failed wiring, failed BMS, drained too deep. The end result is the battery that doesn't work and doesn't charge.
The problem needs to be diagnosed first. Then - fixed, if possible. Or the pack should be send for be re-packing, - this is what I would've done if didn't have knowledge and tools to diagnose and fix it myself.
A pack can fail - yours did. Could be several reasons, as well as combination of those - failed one cell, failed wiring, failed BMS, drained too deep. The end result is the battery that doesn't work and doesn't charge.
The problem needs to be diagnosed first. Then - fixed, if possible. Or the pack should be send for be re-packing, - this is what I would've done if didn't have knowledge and tools to diagnose and fix it myself.
I'm a little late to the party, but I had a similar issue/question.
There is a common issue that is simpler than some of the comments above make it out to be. If you leave the battery for several days or weeks, whether plugged into the bike or not, it will go dormant (somewhat analogous to a computer 'sleep' mode). It will wake up if you plug it into the normal charger. I haven't yet tested how long it needs to be plugged into the charger; I left mine for a couple of hours. When I came back the green light was on (indicating fully charged) and the bike worked fine. I do not believe that a low charge or low battery was the issue since this has happened several times when the battery had been fully charged and not used. I'm just adding this comment to keep someone from perhaps running all around buying voltmeters and so on, when a case where most likely a simple wake-up is all that's needed. Someday I'll test just plugging it into the charger for a couple of minutes. I suspect that will suffice.
It's too bad that bike makers don't/can't put a 'wake-up' button on the controller.
There is a common issue that is simpler than some of the comments above make it out to be. If you leave the battery for several days or weeks, whether plugged into the bike or not, it will go dormant (somewhat analogous to a computer 'sleep' mode). It will wake up if you plug it into the normal charger. I haven't yet tested how long it needs to be plugged into the charger; I left mine for a couple of hours. When I came back the green light was on (indicating fully charged) and the bike worked fine. I do not believe that a low charge or low battery was the issue since this has happened several times when the battery had been fully charged and not used. I'm just adding this comment to keep someone from perhaps running all around buying voltmeters and so on, when a case where most likely a simple wake-up is all that's needed. Someday I'll test just plugging it into the charger for a couple of minutes. I suspect that will suffice.
It's too bad that bike makers don't/can't put a 'wake-up' button on the controller.
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