Li Ion Battery Low Voltage Discharge

darlinggj

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Even after I fully charged the removable 48V Li ion battery from my Daymak Recumbent FT ebike (seems the same as the FTR-100 from mobility4less.com) until the light on its 54.6V charger turned from red to green, the battery's discharge port only puts out 3.0V, while the charging port shows 48.6V, while its rear and power indicator lights don't work at all. Can anyone tell me if this is typical for a battery at the end of its lifespan, or if it might be from a loose wire or short circuit that in principle could be repaired, and/or a BMS condition that could be reset (such as from a brief charge through the discharge port, like I've seen mentioned in this forum)?

This is when the battery has been turned On with a key. Turned Off, the discharge port voltage is (of course) 0 V, while the charging port voltage is 49.0V. An identical battery that I also own shows, fully charged, 54.4V across both discharge and charging ports with key On, and 54.4V across charging socket only with key Off.

I knew there was a problem when my motor cut out in mid-ride, even though the bike's display showed plenty of capacity left before it blanked out, and I hadn't noticed any loss of range or speed before then. And I knew the problem was in the battery when I switched in my good battery (I often carry a "spare") and it worked again.

All suggestions welcome. Seeing as the thing costs over C$1000, I'm ready to tinker a bit if it's not hopeless (or fatal). See also:

 
Could be a BMS issue, try the reset, could be faulty BMS, could be a faulty connection internal to the battery. What you are describing, if accurate, is NOT typical of a dying battery.

There is usually a WHOLE BUNCH of information left out about "right before it failed", how fast, how far, how hot, how bumpy, how much weight, yadda, yadda. Error msgs, slamming into trees, fire shooting out, this stuff usually is not mentioned. If I get angry about it the mods just delete my post, so mostly I don't really care anymore and just assume you are lying.

Worth tinkering, below 60V usually not fatal, KFF a real possibility. That's Kentucky Fried Fingers.
 
Thanks, that helped.

As far as I remember, this was a normal ride on a Spring day with the bike's display showing mid-capacity, then just blanking out with no error message as the motor cuts off (a sudden drop to 3V might do that, I think). No collisions, no fire that I noticed (nor singes inside that I can see, now that I've opened it). I'll try the BMS reset (do you have a preferred procedure?), then if that doesn't work, dissect more thoroughly and look for loose or crossed wires etc.

I have no reason to lie, but am perhaps not experienced enough to tell what's important. If you can think of anything else specific that would help that I couId could try to remember or investigate, I'd be pleased to add that, as best I can, to my report.
 
Many e-bike batteries have two separate internal fuses. One for the charging side and one for the load side. They are usually right under the discharge contact plate. You might have a popped fuse on the discharge side. Usually a 40amp fuse.
 
After the mid ride trip, If the battery is recharged, does it work again? How many miles do you get before the mid ride trip. Sounds like the bms is picking up a false voltage and tripping out the battery to protect it. Can you try recharging on a trickle charge at a very low rate, say one amp?
 
Thanks everyone for your comments so far.

I opened both ends of the battery case and didn't see anything that looked like a fuse, including under the discharge port. The cell pack in between is wrapped in several layers of plastic and other materials, which I left alone--I wouldn't expect to need to cut or unwrap that to change a fuse, if there was one.

Since the original failure, the bike doesn't run at all on the bad battery, even after attempting to recharge it with the bike's own charger (I don't have a charger with controllable voltage and amperage--would it help to get one?). The bike runs fine on my spare, good battery.
 
Thanks everyone for your comments so far.

I opened both ends of the battery case and didn't see anything that looked like a fuse, including under the discharge port. The cell pack in between is wrapped in several layers of plastic and other materials, which I left alone--I wouldn't expect to need to cut or unwrap that to change a fuse, if there was one.

Since the original failure, the bike doesn't run at all on the bad battery, even after attempting to recharge it with the bike's own charger (I don't have a charger with controllable voltage and amperage--would it help to get one?). The bike runs fine on my spare, good battery.
Darlinggj, did you get this figured out? I have an Aventon Pace 500 and I am having issues like you described. My bike will be two years old in October and I have just over 1000 miles on it. I've never crashed or fell on my bike. The battery started acting strange last month, and my bike kept quitting (battery totally off with no power to the bike) even though it looked like I had about half or more of the battery left according to the display.) In my case, that first time it acted up, it would keep quitting, but I could restart the battery and continue on my way. I had the feeling it did not charge properly because it should take several hours to charge but seemed done in less than an hour. But I'd turn on the battery and the four lights came on which is supposed to indicate it is fully charged, and the charger light turned green. I left the battery charger on overnight for just under 12 hours for the next 3 rides (to balance the battery according to Aventon). Then it worked fine for the last several rides.

Yesterday, after going 20 miles on PAS 3, this bike should have needed several hours to charge but only charged with the red light showing, about 15 minutes, then turned green. I know it was not fully charged but nothing I could do would make this start charging (with the red charging indicator). I rode 10 miles today and it quit a few times on me while riding and the battery showed low but not really near empty. I am now trying to charge it up again and it is acting strange. The charger light is red for a little while then turns green, and after awhile it will go red again and apparently charge some more (not blinking red and green, but staying red for several minutes, then turning green as if fully charged but it is not, and then turning red again for awhile). I don't see anything wrong with contacts, etc. but I am thinking maybe something wrong with where the charger plugs into the battery, maybe too loose or something...Do you or anyone else have any insights or suggestions?
 
Darlinggj, did you get this figured out? I have an Aventon Pace 500 and I am having issues like you described. My bike will be two years old in October and I have just over 1000 miles on it. I've never crashed or fell on my bike. The battery started acting strange last month, and my bike kept quitting (battery totally off with no power to the bike) even though it looked like I had about half or more of the battery left according to the display.) In my case, that first time it acted up, it would keep quitting, but I could restart the battery and continue on my way. I had the feeling it did not charge properly because it should take several hours to charge but seemed done in less than an hour. But I'd turn on the battery and the four lights came on which is supposed to indicate it is fully charged, and the charger light turned green. I left the battery charger on overnight for just under 12 hours for the next 3 rides (to balance the battery according to Aventon). Then it worked fine for the last several rides.

Yesterday, after going 20 miles on PAS 3, this bike should have needed several hours to charge but only charged with the red light showing, about 15 minutes, then turned green. I know it was not fully charged but nothing I could do would make this start charging (with the red charging indicator). I rode 10 miles today and it quit a few times on me while riding and the battery showed low but not really near empty. I am now trying to charge it up again and it is acting strange. The charger light is red for a little while then turns green, and after awhile it will go red again and apparently charge some more (not blinking red and green, but staying red for several minutes, then turning green as if fully charged but it is not, and then turning red again for awhile). I don't see anything wrong with contacts, etc. but I am thinking maybe something wrong with where the charger plugs into the battery, maybe too loose or something...Do you or anyone else have any insights or suggestions?
Doesn't the Aventon pace 500 have a 2 year warranty. I would email Aventon & see if they will stand behind their product.
 
I emailed them, but mine does not have a 2 year warranty that I know of. I'm waiting for an answer.
I really hope a person could get more life out of a battery. Maybe the 2year warranty is something new they are starting. I think it was worth your time to email them. Keep us posted.
 
its just funny it went down to 3V usually not all the battery goes bad at the same time...and 3v only 1 cell kinda survived.
probably the BMS,,,when you opened the pack is there a way you can measure a cell's voltzage. not an expert just find it funny at 3V
 
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