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Charging and discharging a new 300AH lithium battery questions

August 10, 2024, 03:37:49 pm

My new battery arrived in good shape yesterday  I was amazed at the professional packing they used.
Out of the box, the battery registered 13.15 volts. My understanding is it should be fully charged before it's initial use. The manual says it should be fully charged in 4.5 hours "with recommended solar panels" but they don't say what those are.
I have 500 watts of panels connected to this battery and the MPPT controller is currently putting out 10 amps at what I believe is 14.6 volts. After about 4 hours the controller says the battery is at 13.5 volts but my volt meter says the battery is at 13.32 volts. 
Should I give it the rest of the day and be done with it, or charge it for another day?
THEN, the manual doesn't say anything about totally draining the battery but but Google's AI says "When you first use the battery, it's recommended to fully charge and discharge it 3–5 times to help extend its life."
Any thoughts?
 

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Re: Charging and discharging a new 300AH lithium battery questions

Reply #1 – August 10, 2024, 04:31:54 pm

If you are using Victron BMV712, the only reason to fully charge the battery is to set the state of charge at 100%  13.15v is just fine to start using the battery and your solar will pump up to full charge and the battery BMS cuts off current at around 13.67v.  Then reset your victron to 100 SOC.  The final arbiter of charging any big lithium is the BMS built into the battery.  This can vary slightly depending on manufacturer,  Read the literature that came with your battery to fully understand the battery.  Google AI is just crazy and you will use up several of your 5000+ cycles of the battery.  Almost certainly past your lifetime and probably beyond the next owners also.

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Re: Charging and discharging a new 300AH lithium battery questions

Reply #2 – August 10, 2024, 04:50:35 pm

Agree with DaBus. My 2 200ah lithiums were charged up through the panels (900w+) and my meter (I have a Trimetric TM2030) has a chance to find 100%. My Victron MPPT is set to the lithium settings from the manufacturer. I don't recommend taking your battery down all the way.

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Re: Charging and discharging a new 300AH lithium battery questions

Reply #3 – August 10, 2024, 06:49:55 pm

Thanks Jerre and Chucl. Google's AI is all over the place on many questions.
My solar controller is an older Renogy MTTP with settings for lead acid, GEL and AGM. I have it set for AGM and will likely change it over. Now that I have a good house battery again I may make a trip to Quartzsite when it cools off. It's 110 in the shade here today with no relief in sight.

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