Battery light flashing sequence of red lights but all 14 cells seem good - any way to repair/restore?

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Ok, So I have three EGO 2.0 Ah batteries and three chargers. All have been working fine for about 2 years. Now I have one that flashes red for about 10 seconds (2 short, 1 long, 2 short, and then I loos track...) and it won't charge. If I put in on any of the chargers it gives the same result (red flashes and won't charge) and the charger flashes its LED red. The other batteries charge fine in any of the three chargers so I'm sure my chargers are fine.

I took the battery apart expecting to find some bad cells. I see 14 cells and all of them register between 3.96 - 4.00 Volts. Is this normal?

What else can I do to troubleshoot?

Here is a video and pictures of the error code and each of the 14 cells....

https://photos.app.goo.gl/2kUT5AalCWodixWH2

Thanks in advance!
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Posted 11 months ago

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Blue Angel, Champion

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If it was bought from an Authorized Ego Retailer, registered, and not taken apart ;-) it's covered under Ego's 3 year warranty and you should contact Customer Service to have it replaced.

EDIT: That random red flashing sequence means the BCM is not happy about something.  Could be the temperature probes are out of whack, an internal circuitry problem, not sure.  If the flashing red light is some sort of trouble code there's no known way to decipher it.
(Edited)
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C0reCollector

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I already got a replacement battery under warranty (arrived today). I thought I'd experiment on this one before recycling it.

What is a BCM? Any idea where the temperature probes are located? I could look for them and try and see if they are replaceable. Has anyone done a tear down of this thing to look at the various parts?
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Thanks Blue Angel. That was an interesting read. I caught this nugget from one of Adrien's posts

"I learned that it was an NTC thermistor by measuring one of my good batteries at 11kOhm at room temp, then putting it into the fridge and for about 10 minutes and then measuring it at 16kOhm.  And once I realized my thermistor in the 7.5 Ahr pack was bad, I connected a 12K resistor in parallel with the T and - pins of the charger and the battery charged without any problems.  So if I fix the thermistor, I fix the issue with that battery charging."

Do you think that could be my problem from the symptoms I see?
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Blue Angel, Champion

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It's worth a shot as long as you are comfortable with and understand the risks involved in tampering with a battery pack. There's a TON of energy in those cells... if you manage to cause a short you could have a catastrophic event before you know it!

I'd start by checking the resistance across the B- and T terminals on the defective battery and comparing that to the good batteries. If it's off you may have found the issue.
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Thanks for the warnings. I'll measure the resistance and report back.

What does putting a 12k resistor effectively do? Does it simulate a working thermistor - does that mean it could overheat without the charger knowing? What's a good source for a 12k resistor (Amazon?)? thx.
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Would one of these two 12K resistors be what I need?

https://www.amazon.com/E-Projects-25EP51412K0-12k-Resistors-Pack/dp/B0185FFUQ0/ref=sr_1_2?ie=UTF8&am...

https://www.amazon.com/Ohmite-Brown-Wirewound-Resistor-Single/dp/B074Q6F7LD/ref=sr_1_8?ie=UTF8&q...

I tested resistance from T to negative terminal. It jumped around alot but after 5 or 6 seconds it usually settles into a 10.24 K reading. 
(Edited)
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Blue Angel, Champion

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That seems rather normal to me. I measured about 9kOhms on a couple batteries that were sitting in my fairly warm garage last night. It's a 10x20 single garage and my wife's car was in there with the door shut after driving home.

The thermistor may not be your issue. How erratic? Mine read fairly well within a second or so.
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What is the total voltage of that battery?  Will it run any tool, or is now completely dead, e.g. fast red flash if you try and run it in a tool?  Cell voltages about 4.00v each, give a total of right at 56.0v, so seems like the cells are okay, and BMS (battery management system) or BMC is the issue.  Given that it is potted, not likely you'll be able to fix it (but give it a shot).
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After taking one apart I'll proclaim that the BMS is pretty much unserviceable. You risk damaging the surface mount components just getting the potting material scraped away.

If there's anything serviceable it's probably the temperature thermistors. They could be replaced if they were measured and were out of spec... we just don't know what that spec is.
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(a)Typical Engineer, good questions... The total voltage is 54.3v and if I put it in a tool it will run for about 5 seconds and then it shuts down. If I put it in the charger it initiall shows a green light, then a series of amber flashes followed by a red light and the charger LED blinks red. 

Any idea what this could mean? Sounds like if its a Thermister problem I might be able to run a resistor between T and negative to salvage? It would be just such a shame to toss it. :/

I've updated the photo album with two video's to show what happens when I use it to start the blower and place it on the charger.

https://photos.app.goo.gl/2kUT5AalCWodixWH2

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