Comparison between one Battle Born LiFePO4 battery and two 6V GC2 batteries in series

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A common battery configuration in RVs and golf carts involves the use of multiple 6V GC2-style batteries connected in series to form 12V or 24V systems. In this post, we examine the differences in discharge and charging profiles between a single Battle Born 12V 100Ah (BB10012) pack and two GC2 batteries connected in series (see photograph below). The BB10012 weighs 29 lbs and the two GC2s weigh a combined 150 lbs.

 

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Figure 1: Photograph of comparison test setup

 

Two brand new Duracell Ultra high capacity 6V batteries (Part number SLIGC115) were purchased from Batteries And Bulbs in Reno. These batteries have a capacity rating of 230 Ah. The batteries were fully charged by applying a 14.4V charging voltage until the charging current fell below 1 Amp. After settling for 10 minutes, the batteries were discharged at a constant current until the battery voltages fell below 11.8V. The discharge current among the tests varied between 10A and 50A.  The results of the tests for 3 discharge currents are shown below.

 

LiFePO4

Figure 2: Voltage discharge curve comparisons for three discharge currents.

 

What is clear from the curves in Figure 2 is that the relative performance is highly sensitive to the discharge rate of the batteries. At a 50A discharge rate, the BB10012 can sustain above the 11.8V cutoff for almost 2 hours, whereas the GC2 batteries cutout in less than an hour. At the lowest discharge rate, the BB10012 can deliver 10A for around 9.5 hours, whereas the GC2 batteries last for over almost 12 hours.

 

Figure 3, below, shows the cumulative delivered charge and energy over the discharge curves for all 3 discharge current tests. What is immediately clear from the figure is the known Peukert effect in lead acid batteries. The useable capacity drops from 120 Ah at 10A to 40Ah at 50A for the GC2 batteries – despite their capacity rating of 230Ah. By contrast, the BB10012 pack remains within several percent of 100Ah, independent of the discharge rate. The slight drop in capacity with current is entirely due to the ohmic voltage drop during discharge.
LiFePO4

Figure 3: Discharge curves: Voltage vs Capacity

 

Finally, Figure 4 below shows the head-to-head charging profiles. In this test, a charging current of 40A was used with a bulk and absorption voltage of 14.4V. Absorption was allowed to continue until the charging current fell below 3 Amps. What is evident from the figure is that the BB10012 pack charges completely in less than half the time as the GC2s (2.5 hours, compared to 5 hours), even with the identical charging parameters. The reason is that internal resistance of Li-ion batteries is much lower, and so the high-current bulk charging phase can continue for longer. Therefore, less time is needed for absorption.

LiFePO4

Figure 4: Charging profile comparison

6 Comments
  • Paul Stellberg | Nov 23, 2017 at 6:54 pm

    I found the same thing when comparing two 12V Lead Acid EverMax batteries versus 2 BattleBorn to power a diesel fired RV furnace at a constant 4 amp load. The lead acid batteries actually lasted longer than the BattleBorn batteries. The difference came in when recharging them. The BattleBorns could be brought right back to full charge in half the time of the lead acid! Tha BattleBorn batteries are also easier to handle at half the weight.

  • Scott Braxton | May 16, 2018 at 8:22 am

    I have been struggling with the battery replacement decision for my VW Eurovan for over a month. Use the same 12V deep cycle battery I had before (now $335), use 2-6V batteries (with some modification in the battery space), or take the dive and go lithium.
    The advantages of lithium are legendary: no outgassing (but you get that with AGM batteries), lighter (but it is in a van…), but best of all, the lithium can be discharged most of the way and survive. This is a huge plus for an RV, with an operator who had discharged a battery to exhaustion before (could that be the reason I have to replace my deep cycle battery after 3 years?).
    But the biggest obstacle was the perception that I would get ‘so much more power’ from a set of 2-6V batteries. The promise of 225Ah is very seductive. Plus the cost (at Costco) is much less.
    This study, showing that the 100Ah BattleBorn actually delivers as much or more energy, really pushed me over the edge. The day I found this page is the day I placed my order for the BattleBorn. Time will tell how good a decision this is, but I can tell you that I will not be worried about power for my van (adding solar to the roof is a big plus).
    Thank you BattleBorn for making this generation of technology available, with US manufacturing…

  • Stan Vangilder | Apr 5, 2019 at 2:23 am

    Can someone explain Fig 4? The description says the BB’s charge in less than half the time, yet the figure shows the GC2s at full charge at around 2 hours. Seems either the curves or description is wrong. Thanks

    • Dianne F | Apr 10, 2019 at 5:08 pm

      Hi Stan,

      The Two GC2 batteries are not at a full charge after 2.5 hours, they have just hit the set voltage and need another 2.5 hours in order to be full. You will notice that the black line ends after 2.5 hours and this indicates that the battle born battery is at a full SOC. One of the great benefits of our lithium batteries is that the absorption time is only 20-30 minutes per battery, allowing for a much quicker charge than the lead acid.

      Thanks,

  • michael.noakes | May 2, 2019 at 7:25 am

    Dianne,
    What model charger was used to accomplish the 2.5h charge in Fig 4? Is charging the BattleBorn in this manner considered best practice? Also will it cause the battery harm or damage long term? Thank you.

    • Dianne F | May 3, 2019 at 2:45 pm

      Michael,

      This test was done on an industrial grade cycler not a typical or common charger that is available to the public. Charging our batteries at .5c(50 amps for a 100ah battery)or lower is totally acceptable and is considered best practice and you will definitely not cause any long term harm or damaging when charging with this amperage.

      Thanks,

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