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Old 11-08-2022, 09:45 PM   #2
Pat911
Gone Wild
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Join Date: Dec 2020
Location: Melbourne, Australia
Posts: 1,919
Default Re: Lithium batter voltages different in parallel.

Hi Silenttrouble,

Firstly, why are you bottom balancing? the normal balancing strategy is to top balance. You may have a valid reason for bottom balancing, just asking as BMS's are mostly configure for top balance so you won't be able to use the balance function of your BMS if you bottom balance.

Now, to your question. You need to give us much more information to answer your question accurately, but depending on the initial charge of the battery and how quickly you're discharging, it could take a sh!t load of time. You do have 270Ah cells don't forget.

Let's assume your pack was initially at 50% SOC. That's 135Ah in each cell. You then parallel 16 of them up. You now have 2160Ah capacity at 3.2v. I don't know what current your discharger is, but let's assume 10 amps. That's 216 hours (or 9 days!) just to discharge them. You then have to leave them that way for a few days to a week.

If you tell me your initial SOC and discharger current I'll be able to give you a guide to how long it will take. Lastly, how are you connecting the cells in parallel? Are you using cable or bus bars?

Cheers
Pat.
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