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I want to build a 32V LiFePO₄ battery for boat - Very new at this

32 volt boater

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I successfully got the FlexMax 80 to charge 32v lead acid and have a FX2532MT inverter charger so I want to stick with 32v.

I just started reading on building LiFePO₄ batteries but I kind of expect the same problem, those battery management systems probably all designed to work with 12 24 36 and 48v ...

The first thing I though of is if I am stuck somehow with multiples of 12 is to build a 36v and just leave 2 cells unused.

12 cells in a so called 36v LifePO₄ , minus 2 cells or a total of 10 looks perfect for a 32v system.

They are fully charged at 3.65 volts and fully discharged at 2.5 volts.

1661056147192.png


That looks perfect. My 32v lead acid rests around 34 volts and all charged up and floating at 36.
 
I don't think you should have a problem finding a BMS. Just search for "10S Lifepo4 BMS". Some BMS'S are compatible with a range of cell numbers, and can be programmed according to the actual number of cells.

My recommendation would be either a JBD or JK BMS, with Bluetooth.
 
Another bms that will work is a Batrium. It is on the expensive side, plus you need a contactor. But it can handle any number of cells.
 
[1. Protection board support 8-24 cells any battery pack (lithium titanate, iron lithium, ternary, lifepo4 etc.) (greater than 18v).]

Now my question is are they all or most BMS like this where you can just leave unwanted series ports out ?


1662872140911.png
 
[1. Protection board support 8-24 cells any battery pack (lithium titanate, iron lithium, ternary, lifepo4 etc.) (greater than 18v).]

Now my question is are they all or most BMS like this where you can just leave unwanted series ports out ?


View attachment 111397
I suppose not all BMSs will allow a specific number of cells.
This one supposedly does support 10S.
I will carefully say that most "smart" BMSs with a cell range (like 8s-20s) should support your use case. Smart BMSs can be programmed via an app, for example the JBD an JK smart ones, and can be configured for cell number.

As for how to wire them, each kind will probably have its own instructions.
 
A contactor is like a high current relay.
Other BMSs usually use MOSFETS.
The problem with contactor based BMSs is that AFAIK, they stop discharge and charge at the same time. MOSFET based BMS can control charging/discharging separately.
But a contactor is more reliable for heavy currents.
 
The contactor I used is an Kilovac EV200AAANA. A small current holds open the contactor (relay). Gigavac is another popular brand (but I don’t know the model numbers).

Other people use a a remote trip circuit breaker. On a signal the breaker trips.

Both have advantages and disadvantages.

You could design it so you have separate charge and discharge contactors - but I didn’t see the need.
 
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