Bigbluecat57
New Member
Can I connect 13S & 14S power packs to a common bus bar to my solar controller without damaging either? They would both have their own BMS's. I'm wondering if the 14S pack will drop down to the 13S level.
13S & 14S
- Thread starter Bigbluecat57
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sunshine_eggo
Happy Breffast!
Assuming you're talking about the same 3.7V chemistry, this is a horrifyingly bad idea (bad idea with any chemistry).
Would you connect a 6V battery in parallel with an 8V golf cart battery - only one cell difference there? Yeah, that's a more extreme example, but the concept is identical. Heckin no.
If you start at the same voltage, sure. No problem Only issue is when the 13S is at 100% SoC, the 14S is at 75%. When the 13S is at 20%, the 14S is empty.
So either you hammer the shit out of the 13S at the top AND hammer the shit out of the bottom end of the 14S, and only get 75-80% of the capacity of the batteries with a ~500 cycle life, or you limit both batteries to ~20-80% operation get about 20% of the entire battery capacity but get good cycle life.
Would you connect a 6V battery in parallel with an 8V golf cart battery - only one cell difference there? Yeah, that's a more extreme example, but the concept is identical. Heckin no.
If you start at the same voltage, sure. No problem Only issue is when the 13S is at 100% SoC, the 14S is at 75%. When the 13S is at 20%, the 14S is empty.
So either you hammer the shit out of the 13S at the top AND hammer the shit out of the bottom end of the 14S, and only get 75-80% of the capacity of the batteries with a ~500 cycle life, or you limit both batteries to ~20-80% operation get about 20% of the entire battery capacity but get good cycle life.
Bigbluecat57
New Member
Both packs are made from 18650 batteries. Both packs work on a 48v system. Wouldn't the BMS's manage the slight difference? When one reaches 100% SOC it prevents overcharging and the other BMS would let the one at 75% continue to charge.
sunshine_eggo
Happy Breffast!
So 3.7V. NCA? NCM? LMO?
One can make 12S and 15S batteries work on a 48V system. Would you consider paralleling those as well?
BMSs are on/off switches. They don't regulate anything.
Designing a system that relies on BMS operation to both terminate charging and discharging on every cycle is an extremely poorly designed system. The system should operate within the limits of the BMS relying on the BMS only when something goes wrong.
Your proposed battery has a high cycle life operating range of 49.00-50.96V if you care about cycle life. If you don't care about cycle life, 42-54.6V.
Bigbluecat57
New Member
I appreciate you taking the time to answer my questions.
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