LiFePo4 voltage under load
Hi all, This is the first chart (stage left graph when looking at the image) I've been able to find that shows voltage under load. I may be reading it wrong.
Forum Discussion
The discharge chart ‘kinda hints’ at why actual LFP experience departs from more conventional battery types - notice the voltage at a uber low 90+% DOD (depth of discharge) - yet (presumably…) still no low voltage alarm…When using an inverter, this aspect (accompanied by LFP’s low voltage sag ‘under a load’ - e.g. no struggling during air cond starts) somewhat mimics shore power experience, thus ideal for appliance loads and such…
However when considering this *chart’s plot, it might also be worth noting that a battery’s actual ‘real-world’ capacity (as determined via bench load test) can often be slightly greater than the Mfg’s rated capacity - per my own load test, a 7% greater capacity result than the mfg’s advertised rating…
*(chart’s 90% of what??…)
In view of this ‘potential overage’, using the abstract example of say a 100a/h battery, 90% DOD might not occur until about the 96 consumed a/h mark, or (if put differently…), upon arrival of say a metered ‘100a/h consumed’ mark (per Victron BMV 712, battery bluetooth or equiv.), a possible 7a/h (+ or - ??…) remaining overage, likely having experienced no low voltage alarms…
Disclaimer: I’m not suggesting this sorta capacity overage is the case for all Mfg’s batteries, nor that such deep DOD excursions be done ‘as a matter of the routine’ - User experience only here, just something to ponder…
3 tons
However when considering this *chart’s plot, it might also be worth noting that a battery’s actual ‘real-world’ capacity (as determined via bench load test) can often be slightly greater than the Mfg’s rated capacity - per my own load test, a 7% greater capacity result than the mfg’s advertised rating…
*(chart’s 90% of what??…)
In view of this ‘potential overage’, using the abstract example of say a 100a/h battery, 90% DOD might not occur until about the 96 consumed a/h mark, or (if put differently…), upon arrival of say a metered ‘100a/h consumed’ mark (per Victron BMV 712, battery bluetooth or equiv.), a possible 7a/h (+ or - ??…) remaining overage, likely having experienced no low voltage alarms…
Disclaimer: I’m not suggesting this sorta capacity overage is the case for all Mfg’s batteries, nor that such deep DOD excursions be done ‘as a matter of the routine’ - User experience only here, just something to ponder…
3 tons
