200a/hr LFP Load test results…

[3_tons]

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

[3_tons]

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]

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

[Lwiddis]

Interesting report and opinions based on real world testing.

[jaycocreek]

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..

[time2roll]

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%.

[StirCrazy]

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.)