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

  |   Uncategorized   |   17 Comments

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.

 

LiFePO4

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

17 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,

  • Stan W Vangilder | May 25, 2019 at 3:14 am

    Thanks, Dianne! I had not noticed the end of the black line in Fig 4. Makes sense.

  • RICH WRIGHT | Jun 28, 2019 at 10:34 am

    I want to power a motorhome with the right battery combo. I use a C-PAP machine nightly for 8hrs. using a inverter 1000. will 2 6volt hooked together work?

    • Dianne F | Jul 1, 2019 at 9:27 am

      Hi Rich, give us a call so we can find out exactly what you need for your system and to determine compatibility. Let me know if you have any other questions. 855.292.2831. Thank you!

  • Joshua Mahr | Sep 19, 2019 at 11:38 am

    I am thinking of converting a 48V golf cart to Battle born batteries. However the the speed controller for the golf cart is rated at 500A. I see that the BB batteries are rated at 100A discharge. Will I run into problems using the BB batteries?

    • Dianne F | Sep 20, 2019 at 7:53 am

      Hello Joshua,

      Many customers are successfully using Battle Born Batteries in golf cart applications but as you were smart enough to catch, there are some limitations. You can definitely use our batteries in a 48 volt configuration(4 batteries in series) but you will exceed their discharging capabilities when running over 100 amps for more than 30 seconds. This will cause the batteries to shut down for a few seconds and then re initiate and be ready for use again. You can increase the discharge rate by adding another set of batteries to the system.

      We would recommend checking with the golf cart manufacturer to find the power requirements before purchasing our batteries for this application. Anyone can give us a call if you would like some assistance with this process and we would be happy to help you out!

      Thanks,

  • Jeremy Helms | Sep 25, 2019 at 12:15 pm

    I am considering a single BB lithium as my current setup is exactly as pictured above. Two duracell GC batteries. What attracts me to this is the massive weight savings. And every lb counts in my setup. That and the super fast recovery / recharge time.

    I noticed you mentioned 100A limit in another post. So for a single battery, anything over 100A and I would need a second battery in parallel (12v system). Pretty common for me to exceed 100A for shorter duration per my 1500w true output inverter (worst case I can hit around 110A for several minutes, rarely into 115A) At this point, my two GC batteries sag something ugly voltage wise down into the mid 11V range and current draw goes ^

    Anything you would suggest on this or would I just be stuck needing two batteries if i wanted the full potential of the 1500w inverter available? My higher draw happens for example if the perfect storm happens and my furnice, fridge and microwave all come on together.

    • Dianne F | Oct 29, 2019 at 12:33 pm

      Hello Jeremy,

      Yes, you are correct that our batteries have a continuous output rating of 100 amps and a 30 second surge of up to 200 amps. Unfortunately a 1500 watt inverter is just a bit over this rate and would shut down the battery for about 5 seconds before it would come back on line and be able to use again. The solution is adding another 100 ah battle born in parallel, giving you the ability to run your inverter at its full wattage.

      Thanks,

  • DANIEL JOHN PETERLIN | Oct 22, 2019 at 12:30 pm

    Can I replace my 4 6volt golf cart batteries with drop in Battleborn batteries? I,have a Zantrex link 1000 with a Zantrex Freedom 485 Series Inverter/charger. I have Solar panels with charge controller. I have a 7.5 KW Onan Diesel Generator. If this will work what should my settings be for the link 1000?

    • Dianne F | Oct 29, 2019 at 4:17 pm

      Hi Daniel,

      We have many customers that use our battle born batteries in place of their existing 6 volt golf cart batteries with great success. Your Xantrex Link 1000 and the 458 inverter is compatable with our batteries and the agm mode works well to charge the batteries. Give us a call for help with setting up your Link 1000 and we will review the manual and adjust it acording to your system. Your solar charge controller should be setup for lithium charging for the best efficiency as well. Your onan Generator will easily start from the 4 lithium batteries and you should not have any issues.

      Thanks,

  • PJ Wander | Nov 15, 2019 at 11:34 pm

    Hello, I live off grid in Alaska. My goal is to do limited welding using the power stored in batteries, solar (maybe 5 kw ish in panels, wind in winter….can blow for a week at 20 knots, and two Honda i2000 generators.
    I would like to know if the inverters in you bundles are true sine. To but the welder to full use I would need a 10 kw inverter.

    • Dianne F | Nov 27, 2019 at 11:24 am

      Hello PJ,

      We sell the Victron and Magnum inverters and they are all pure sine wave, 120 volts at 60Hz. For a 10kw inverter you will want to look into the Victron Quattro series.

      Thank you,

Post A Comment