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3_tons's avatar
3_tons
Explorer III
Dec 09, 2021

200a/hr LFP Load test results…

I choose not to charge my 200a/h LFP from the alternator because (say, once fully charged…) I prefer not to have it maintained at say 100% SOC…I suppose a switch would remedy this, but as primarily a ‘desert camper’ I’m mostly able to keep within a decent SOC range (based on usage) with just harvest alone…

So, I recently conducted a hands-on real world amp/hr test to determine just how much ‘head room’ I might be able to rely upon (capacity rumors aside…) from this single 200a/h LFP battery and found out quite to my own utter amazement that (per Victron meter) the microwave could still run at a whopping 138 amps with the battery even at only 1% SOC!!…. Just to be sure about this I repeated this using a Keurig brewer (@124 amps) and got the same result… So to the LFP uninitiated (non-LFP users - I donno??) this claim might indeed sound at least a bit dubious (I concur!), but it is an empirical hands-on fact - How could this be?? FWIW, this 200a/h battery actually bench tested at a net 215a/hrs before the BMS cut-out!!…Details:

At 1% SOC (while still under this uber heavy load) the voltage was still at 11.10v with 201a/h consumed amp/hrs per the Victron BMS display (1% is as low as it’ll read), but the voltage recovered to 12.06 shortly after the M/W had finished it’s last tasking…

Note too that the ProSine 2.0 inverter’s low voltage alarm never once sounded…

So in abstract terms, this arguably might equate to four GC’s with a lower limit of say 50% SOC, but at only 65# (rather than 245# minus cabling…) and with a near insignificant amount of voltage sag…Quite honestly, I’d always gotten decent service from my former two GC’s (based on camping style and harvest) but often with a few ‘white knuckle’ episodes thrown into the mix (Ugg…)…I’d be most interested in hearing other’s testimonies :), and would encourage a ‘bench test’ as well !!

I can’t say how widespread this is, but hope this example might add to the LFP knowledge base..

3 tons
  • pianotuna wrote:
    jaycocreek wrote:


    I find that interesting as I have been running my Iceco JP 42 compressor fridge 24/7 (33*) for quite some time..I'm at 40% SOC AT the end of the 6th day and down 58ah..Gives people an idea on how long these lfp last,compared to the same ah AGM..


    Or you could use an SiO2 with similar total power.


    Relative to the test that the OP is describing, you would get far worse performance from SiO2. Remember when BFL13 performed exactly the same test with his SiO2 battery?

    He was only able to use 39Ah from his 100Ah battery with a 0.65C load.
  • pianotuna wrote:
    jaycocreek wrote:


    I find that interesting as I have been running my Iceco JP 42 compressor fridge 24/7 (33*) for quite some time..I'm at 40% SOC AT the end of the 6th day and down 58ah..Gives people an idea on how long these lfp last,compared to the same ah AGM..


    Or you could use an SiO2 with similar total power.


    I had a hard time deciding between 2-6V/SIO2 and LFP...Weight and fast charging in the boonies won out..The cold really isn't an issue where I have them....Theres nothing wrong with them at all IMHO (SIO2) or 6V...
  • jaycocreek wrote:


    I find that interesting as I have been running my Iceco JP 42 compressor fridge 24/7 (33*) for quite some time..I'm at 40% SOC AT the end of the 6th day and down 58ah..Gives people an idea on how long these lfp last,compared to the same ah AGM..


    Or you could use an SiO2 with similar total power.
  • 3 tons wrote:
    FWIW, Heres a ‘real-time’ followup for those interested - at present our final day of camping off-grid on the Oregon coast, SOC is at only 11% remaining, voltage 12.76, with180 total consumed amp/hrs (starting out with 200a/hr full charge)… started Keurig coffee maker:

    124 to 127amps, voltage dropped to 11.8v.

    End of brewing results:

    SOC 9%, voltage restored to 12.75v (after about 3 min), total consumed amp/hrs 182.5 - will need to do some charging today!!

    3 tons


    I find that interesting as I have been running my Iceco JP 42 compressor fridge 24/7 (33*) for quite some time..I'm at 40% SOC AT the end of the 6th day and down 58ah..Gives people an idea on how long these lfp last,compared to the same ah AGM..
  • 3_tons's avatar
    3_tons
    Explorer III
    FWIW, Heres a ‘real-time’ followup for those interested - at present our final day of camping off-grid on the Oregon coast, SOC is at only 11% remaining, voltage 12.76, with180 total consumed amp/hrs (starting out with 200a/hr full charge)… started Keurig coffee maker:

    124 to 127amps, voltage dropped to 11.8v.

    End of brewing results:

    SOC 9%, voltage restored to 12.75v (after about 3 min), total consumed amp/hrs 182.5 - will need to do some charging today!!

    3 tons
  • 3_tons's avatar
    3_tons
    Explorer III
    Note that I only provided here the short version, this only after first validating that the Victron BMV-12 was near spot on in two separate test by using a steady, continuous 24.5 amp squirrel cage blower (inductive load) and another by using a 500w halogen shop lamp (resistive load) and data logging both per each hour to arrive at total ‘consumed’ amps…In the end, the BMV-12 was off by only a minuscule amount of no empirical concern - really, not at all what I was expecting - so I found it’s accuracy to be quite exceptional…

    There’s even a longer story here that I won’t go into, however that first led me to question the meter - which turned out not to be the case!…This test result then led me down a different road (battery replaced under warranty - subsequently verified it’s replacement!)…But as I stated the meter proved to be highly accurate, especially considering the nuances related to tracking SOC (voltage, coulomb-counting and embedded look-up table - total consumed amps seems like the easiest) Some truly outstanding engineering in my view - Meter programming was strictly per Victron's own user manual….The 200a/hr replacement battery tested out at 215 amps…

    3 tons
  • Interesting report and opinions based on real world testing.
  • 3 tons wrote:
    I’d be most interested in hearing other’s testimonies, and would encourage a ‘bench test’ as well !!


    Per Victron, I am finding interesting based on what settings?I found suggested setting from Amsolar for the LifeBlue/Victron and Battleborn battery which differ from the settings I have been going off of from Will Prowse..This makes a pretty good difference in % on the Victron but seems more spot on,to me anyway.LOL..(Tail current 2% and Peukert at 1.00)

    My last bench/capacity test a few days ago netted 104ah and it was falling fast,my Wagan inverter low voltage alarm went off so I lowered the power only to end the test not wanting the BMS to shut it down..So my capacity is 104.??ah..Close enough for me..

    While I find my Victron shunt to be quite helpful,finding the correct settings for my battery difficult, due to the many internet DIY settings..The Amsolar seems to fit better..
  • Keep in mind the LFP will do the same at the top end. No extended absorption top charging the last 10% of capacity. No loss of solar potential until the battery to tip top 100% charged and then it does not matter.
    If using a generator LFP can cut 4+ hours off the final charge to 100%.
  • 3 tons wrote:

    So in abstract terms, this arguably might equate to four GC’s with a lower limit of say 50% SOC, but at only 65# (rather than 245# minus cabling…) and with a near insignificant amount of voltage sag…Quite honestly, I’d always gotten decent service from my former two GC’s (based on camping style and harvest) but often with a few ‘white knuckle’ episodes thrown into the mix (Ugg…)…I’d be most interested in hearing other’s testimonies :), and would encourage a ‘bench test’ as well !!

    I can’t say how widespread this is, but hope this example might add to the LFP knowledge base..

    3 tons


    ya thats about right. if I was under 55% I couldnt use the microwave with four high quality 235AH GC batteries, as they got older that number climbed to about 90% (but they were very old, 14 years, and should have been replaced a couple years previous.)

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