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

[StirCrazy]

3 tons wrote:
I’d be interested to know how the SiO2’s discharge voltage profile compares to LFP…

3 tons

don't forget even the makers of SIO2 recomend only using 50% of the capacity for maximum life, so thats another trade off if you don't need the ability to leave your batteries in a snowbank while your using them.

Steve

[akkeosflomdis]

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]

“Safe is not stubborn”….

Kinda Interesting having this exchange morph into one of ‘safety’ - by learned default, this always draws my attention…

Not to in anyway to pass judgement here (merely an abstract stream of consciousness - lol …), but in my previous career I discovered that the ‘claim of safety’ could be intentionally mis-used (though not all too common) as a shielding tactic to paralyze dissent, and hamstring forward actions…Obviously we’re not in that type of setting, but know that (when the stakes and stressors are high…) it’s takes an especially rare and accountable Man to dare risk challenging claims of SAFETY - This, FWIW, just my uncolored opinion obtained during a previous career…now RET.

3 tons

[pianotuna]

Safe is not stubborn.

[StirCrazy]

pianotuna wrote:
jaycocreek,

I believe LiFePo4 are excellent--so long as it is not too hot, or too cold.

I dont think any of us have to worry about being to Hot. I was camping last ummer in the middle of the heat dome and I can tell you no one would want to camp at 60degrees, I was in 48 and I had to jump in the truck every few hours and go for a drive for AC, I was miserable and stubbron just so I could get a good site for when the wife came out. people who camp in that weather are not buying a ton of batteries, there getting hookups so they can run there AC 24/7

as for to cole, its not the outside temp it is the battery temp and there are tons of people doing things that your just to stubron to do to ensure that the batteries stay in the proper temp range.

Steve

[3_tons]

It’s true that user requirements often do vary…From my own perspective the sole material issue could be with ‘charging below 32f’ (note, discharging is far lower…), yet this one parameter can be easily overcome with either a built into the battery heater option, or adding a retro-heated battery blanket, or via interior cabinet mounting (as I’ve done), or by simply awaiting the next available harvest window…For added clarity, Mfg specs on my battery state:

Charge Temp: from 32f up to 113f
Discharge Temp: from 149f down to -04f
Storage Temp: -04f to 113f

3 tons

[FWC]

pianotuna wrote:
jaycocreek,

I believe LiFePo4 are excellent--so long as it is not too hot, or too cold.

As far as loading SiO2 is outstanding.

Speed of charging is not an issue for me--because I'll have either six or seven as my house bank. At .25 C that means charging at 150 amps is possible--except I have nothing that could provide that much energy.

I am not sure I would consider only being able to use 40% of rated capacity under a moderate load as 'outstanding'.

[pianotuna]

jaycocreek,

I believe LiFePo4 are excellent--so long as it is not too hot, or too cold.

As far as loading SiO2 is outstanding.

Speed of charging is not an issue for me--because I'll have either six or seven as my house bank. At .25 C that means charging at 150 amps is possible--except I have nothing that could provide that much energy.

[3_tons]

Per FWC: “ Remember when BFL13 performed exactly the same test with his SiO2 battery?”

And recall, “all those hoops” mythology one must ‘jump through’ when using LFP (huh?…kinda strange as I’ve yet to adopt a single new piece of equipment - still using my OEM PD 9245 with charge wizard dongle (in boost) and same two solar controllers)…

3 tons

[3_tons]

I’d be interested to know how the SiO2’s discharge voltage profile compares to LFP…

3 tons

[FWC]

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.

[jaycocreek]

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...

[pianotuna]

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.

[jaycocreek]

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..