26 minutes ago, Junger said:

What brand smart charger? Some brands like NoCo have a repair mode which you have to manually activate.

I picked up the NoCo Genius 10 mentioned above

8 hours ago, RLinNH said:

TB, I'm cracking the lid open on this battery to have a look see. Other than the obvious non connected wires and what not, what else should I be looking for while doing the exploratory surgery? Also, while it's open, is there anything I can do while the lid is off to take it out of Sleep?

These batteries are pretty simple. They have 4 cells in most cases (assuming it's 12V), a battery management system, wires, and a case. If you've tried charging with a good Lithium battery charger with no results then I would open the case. BE VERY CAREFUL. SHORTING LITHIUM CELL CAN BE DANGEROUS. I'm assuming the problem is the BMS has put the battery to sleep and will not wake up. Once the case is open you can bypass the BMS and charge the cells directly. You want to charge them enough to activate the BMS. Do not do a full charge because there is no BMS to prevent you from over charging. I would use my adjustable DC bench voltage supply instead of a charger because it would give me more control but if you don't have one then use your charger. Leave it on for 30 minutes and see if the voltage is going up. Check the voltage on each cell seperately to make sure you don't have a dead cell. Keep checking the BMS periodically to see if it's awake. KEEP AN EYE ON THE CHARGER. THE BMS IS THERE FOR SAFETY. IF YOU MESS UP IT'S NOT THERE TO KEEP YOU FROM OVERCHARGING. LITHIUM BATTERY FIRES ARE BAD! If you charge the battery up to 14 volts and the BMS is still dead then you have a bad BMS.

DID I MENTION THAT YOU NEED TO BE CAREFUL.

Well, the new NoCo Genius 10 is a heck of nice charger. I ran the dead Lithium battery through rescue mode at least 12 times. No dice. It keeps going into standby mode after the recue mode. I left it on the charger last night all night. Nada. Still though. After all I have learned now what with how to care for lithium batteries, it's a win in my book. I'll be purchasing another battery here in the next few weeks. Probably going to purchase a Miller Tech. I know I'm overpaying for a name. But the fact that they are made in Ohio and also that they have a 10 year warranty is a major selling point in my book. Again, thank you to all for the education here. 👍

@RLinNH The Noco are great chargers and now you have one that will charge any battery for as long as you need it. If they had a 24/12/12V when I build my boat that’s what I would have added. Sorry it didn’t sort this one out.

Not sure if “made in Ohio” is critical, but they are not manufactured there. They are designed there and sold from there, but the manufacturing is China like other lithiums. The service might be better with them and that’s what you’re paying for. They have a track record of lasting in the industry (as a company). If you’re going high end domestic companies then miller and battle born are two to consider. Alternatively, I would suggest considering LiTime at 1/4 the price.