battery balancing for OLA deep-cycle banks

Thread Starter

djnapoli

Joined Sep 8, 2020
1
Hello fine electronics peoples-
I have several applications for battery balancing "equalizing etc" involving open lead acid batteries (for the moment. That will expand to Li-Polymer or Li-Ion.

At this point, I am just focusing on the following:

2 banks of quantity 8 * 6V open lead acid deep cycle batteries. So I have two large banks of 48VDC lead acid batteries.

I am guessing I'll want to balance not just between the 2 * 48V banks, but also between the 6V individual cells within each bank. Can anyone suggest a circuit design, a pre-made product or any other approach to prevent early retirement of the cells? Thank you!
 

jpanhalt

Joined Jan 18, 2008
11,088
Welcome to AAC.

Why do you think the parallel connected banks need to be balanced? Won't that happen automatically as the voltage will be identical?

As for balancing series connected LA batteries, that is not usually done either. Each of your 6 V batteries is really 3 LA batteries (cells) in series. Will you balance each cell?
 

Irving

Joined Jan 30, 2016
1,539
Its not necessary to balance series LA cells as the chemistry is not (as) voltage critical unlike LiPo or other Li-ion cells. LA cells like to be kept 100% charged. DoD is what generally kills LA cells or lack of adsorption time (float time) so they never get fully charged (most LA chargers turn off too soon).

Li-ion, LiPo or other similar are a very different chemistry and may not be suitable for your application.

What are these battery banks going to be used for?
 

nsaspook

Joined Aug 27, 2009
8,386
You do balance (minimize SOC differences between cells by measuring Specific gravity) series flooded LA cells when you equalize them in a string. It's a function that normally integrated into the charge controller of 48 volt systems designed to handle strings of flooded LA cells.
http://www.xantrex.com/documents/Accessories/C Series/c-series-manual-975-0004-01-02-rev-d_eng.pdf
Manual or Auto Equalization Charge
The C-Series controller can be used to manually or automatically provide the battery bank with an equalize charge. Factory default setting is for MANUAL Equalization charging. Be sure to be familiar with all the cautions and warnings concerning equalization charging batteries or damage to batteries can occur.
The C-Series offers either manual or automatic triggering of the equalization charging process. Equalization charging is the deliberate process of charging a battery (or battery bank) at a high voltage for a set period of time to remix the electrolyte and destratify the internal plates. Equalize charging helps to remove sulfate buildup on the battery plates and balances the charge of individual cells
https://batteryuniversity.com/learn/article/equalizing_charge
http://support.rollsbattery.com/support/solutions/articles/430-corrective-equalization-instructions
 
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