Emergency Dead Lithium Help
So it supposed to be warm tomorrow so I went to my garage to check my cart for a round of golf. Cart BMS has now power (ZEVA). "That's Odd" I thought, maybe the bms needs rebooted. Nope, grabbed a meter my pack reads 9.5 volts. "FOOOOK".... I leave it plugged in so I have no idea whats going on. I moved the plug to a different outlet, charger is flashing red, green, red. Batteries are Chevy Bolt Style LG Cells
Do I have any options? Is my one year old lithium pack shot? DANG |
Re: Emergency Dead Lithium Help
Any bulged cells or deformation? What does the charger manual say about that flashing light sequence? I’ve heard of other guys on this forum doing the same thing and the batteries survived just fine. You may just need to find a “dumb” charger to put enough juice into the batteries until your normal charger can take over. Anything is worth trying at this point, fingers crossed for you!
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Re: Emergency Dead Lithium Help
How long did you leave the cart unused?
So your BMS didn't protect the pack from under voltage? Are you sure you're measuring the pack voltage correctly? If your 48v pack voltage really is 9.5v, then it is shot. Any attempt to revive it most likely will end in tears as each cell, assuming 14s configuration, would be down to 0.68v. A dumb charger may be okay for lead acid batteries but it certainly isn't okay for lithium. Best case scenario, you get your pack back with reduced capacity, worst case scenario CATASTROPHIC lithium battery fire. |
Re: Emergency Dead Lithium Help
I have a Zeva if you read the manual it has a sleep mode. In this mode it still draws a slight amount of power. Zeva recommends you use sleep for a week or less. If it is longer than a week it is recommended you unplug the Zeva connector to prevent it from draining the battery.
Don’t know how long you left the GC without checking the batteries? Sent from my iPad using Tapatalk |
Re: Emergency Dead Lithium Help
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Re: Emergency Dead Lithium Help
Hi Mccainc,
The problem here is not that the pack voltage is too low for his charger to start charging but the fact that the pack voltage is in fact low. Once a lithium cell gets below about 2.5v, some of the negative electrode begins to dissolve and migrate. When recharged, the dissolved negative electrode forms dendrites in places it shouldn’t. In a best-case scenario, this decreases the ability of the cell to collect current. The internal resistance of the cell may go up, causing more heat to be generated during charge and discharge. Simply, it’s capacity is decreased. In the worst case, this will form a short in the cell while it is charging, causing it to fail catastrophically. Research lithium battery fire to see what I mean by catastrophic. A lithium battery fire is very difficult to extinguish as the exploding and burning cell produces its own oxygen to feed the fire. There is a very good reason to use a BMS and to ensure it is operating correctly, and that is to prevent any one cell being over charged or over discharged. Once a cell gets below its threshold, it can no longer be considered safe to use. |
Re: Emergency Dead Lithium Help
Sorry to hear about your situation. If it were me, I would just take the loss and move on to a new battery pack. Here is a very informative thread: https://www.buggiesgonewild.com/showthread.php?t=150460
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Re: Emergency Dead Lithium Help
Yes, I understand the low cell voltage problem. This is not my first rodeo. I’m trying to provide him options. If he wants to try reviving the pack, that’s what he’ll need to do. There certainly are risks involved, and it will be up to him to decide what he’s comfortable with.
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Re: Emergency Dead Lithium Help
Hi mccainc,
I’m not questioning your knowledge, but Nobody should be encouraged to revive a lithium pack that has gone below its threshold. The method you state (current limited constant voltage power supply) will certainly revive the pack but it’s safety is severely compromised. There are 14 cells that have gone below their minimum, chances are very high that at least one of them will develop a short and catch fire. Maybe not on the first recharge, but possibly a dozen recharges down the track. Every time that pack is recharged there’s a very real threat it will catch fire catastrophically. The thread that BBBHC linked to describes exactly that. The cart caught fire many recharges down the track. It’s up to Silenttrouble if he wants to attempt to revive his pack, but he needs to be very aware that there is a real risk of a major fire. Cheers Pat. |
Re: Emergency Dead Lithium Help
So I checked the cells today. First 6 are around 1.35-1.5v the last 8 are less than 1v, with the last cell being at 0.07v.... which I think is indicative of vampiric drain until the voltage was too low to feed whatever was draining.
The bigger issue here is I cant get replacements of what I have that will fit my setup. So now I'm trying to figure out what to do. I'm running LG N2.1 from chevy bolt. |
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