Why are 24 volts LiFePO4 batteries a lot more expensive than buying two units of 12 volts version of the same battery brand for same AmpHour capacity?

[Cuteajax]

Why are 24 volts LiFePO4 batteries a lot more expensive than buying two units of 12 volts version of the same battery brand for same AmpHour capacity? For example, on most e-commerce websites that sells LiFePO4 batteries, a 24 volts 200Ah is about $1,800 but the 12volts 200Ah of the same branch would be about $600. The implication of this is that buying two units of the 12volts 200Ah version and connecting in series should give the resultant output of 24 volts 200Ah but would only cost $1,200. I had expected the 24 volts version to be less expensive than the cost of two units of 12volts 200Ah version. I'm curious? Why is this not the case? Should I just buy two units of the 12volts 200Ah then? What would be the trade off or what would I be missing?

 

[sunshine_eggo]

Some claim their 12V can't be put in series - charge more for 24V.

 

[Steve_S]

12V requires 4 Cells, 24V requires 8 and 48V takes 16 Cells. Each get's a different BMS and BMS cost is relative to # of cells managed, features, functions and Amperage Handling Capacity.

ALSO and most importantly, you will see MANY prebuilt batteries on the market. Of course BattleBorn, SimpliPhi, Relion and such are Top Grade Commercial batteries and they are all guaranteed, warrantied & reputable too. Then you have lower level Good Batteries like AmperTime, SOK etc... and THEN you get the "others" that are offshore generics. They could be B Grade or Used Cells, and may have whatever kind of BMS they can get for as little as possible and of course "those will have a great sale price" and then people realize what they got.

As for linking batteries in Series, that is really NOT the proper method for Lithium Based Systems... This is a remnant / left-over method used with Lead. Whatever Battery Packs you get should be for the Target Voltage of teh system, so 24V Battery Packs for 2V System and so on.

Yes some (not all) BMS' will allow for a limited number of identical batteries to be put in series, they can all be installed in Parallel.

 

[rmaddy]

Depends on what brand you are looking at. SOK and Battle Born are both cheaper building a 24V system using their 24V batteries than their 12V batteries. But both of those brands are more expensive than the prices you quoted.

 

[John Frum]

Depends on what brand you are looking at. SOK and Battle Born are both cheaper building a 24V system using their 24V batteries than their 12V batteries. But both of those brands are more expensive than the prices you quoted.

I just checked

100Ah 12V LiFePO4 Deep Cycle Battery

The 100Ah 12V LiFePO4 Deep Cycle battery is the pinnacle of battery technology and the lightweight drop-in replacement for lead acid batteries.

battlebornbatteries.com

50 Ah 24V LiFePO4 Deep Cycle Battery

The 50Ah 24V LiFePO4 Deep Cycle battery weighs a fraction of lead acid, is backed by a ten year warranty, and designed and assembled in the USA!

battlebornbatteries.com

Same price per watt hour.

 

[rmaddy]

Same price per watt hour.

OK, BB is the same. SOK is cheaper at 24V. But at least both are examples where the 24V are not 50% more than the 12V.

 

[A.Justice]

I would think that 24 volt batteries would be less expensive than 12 volt ones. It's one case, one set of terminals, one BMS, one set of insulation, one set of wiring & fusing, etc, etc...

Also, generally speaking, a higher voltage battery would need a smaller BMS for the same performance as a a lower voltage one. 100 amps @ 12 volts = 1200 watts, but at 24 volts, you could use a 60 or 80 amp BMS and get more power than the 12v system (60a @ 24v = 1440w). That also means a 24 volt battery could get by with smaller wiring, BMS, and cost (of course this depends on the application and the battery, I'm just speaking generally).

I wonder if the price has something to do with the market demand for 24 volt systems. I know that some large trucks and construction equipment use 24v, and the prices of that stuff can be artificially inflated.

A DIY battery is almost always cheaper to build with higher voltages.