Lithium Battery Charging System
It is time for a new battery in my '04 Lance 921. I am looking at an Interstate battery they sell up the road. But through my research into charging systems/problems, I got to thinking about Lithium...
Forum Discussion
The prior lithium hazard was associated with a ‘hotter’ more power dense chemistry using cobalt… A common ‘drop-in’ type RV battery (straight replacement) is of a friendlier, safer chemistry (LiFePO4, or ‘LFP’ = Lithium, iron, phosphate..) and there’s virtually no record of such mishaps with this chemistry and can be shipped as non-hazardous…Also, the built-in BMS System (Battery maintenance system) works as a redundant secondary catastrophic safeguard that prevents over current, overcharge (etc…), and acts to balance the cells upon a full recharge (although with LFP a ‘full recharge’ that enables cell balancing should be viewed more as a periodic rather than a routine regime)..
Your PD with charge wizard will work fine so long as you kick it into the Absorption or Boost Mode (14.4v), but once fully charged (i.e. post cell-balancing) discontinue charging shortly thereafter since it’s not good to continue charging for extended periods, and for this same reason (unlike wet-cell types) LFP’s should not be equalized (over time can lead to damaging dendrite formation)…
Determining ‘accurate’ LFP State of Charge (SOC) will require a decent LFP compatible meter (or say bluetooth), such as a Victron ‘Smart Shunt’ or BMV-712 (or equiv), this due to LFP’s relatively flat discharge voltage plateau…With either battery type a good shunt based meter (shunt installed in batt neg cable) is truly an invaluable asset!!
Usable wet-cell depth of discharge (DOD) is down to about 50’ish percent, whereas LFP’s can routinely go down much deeper discharge, some even advertised to zero percent, but in the interest of cycle longevity a somewhat lesser DOD would seem more practical…
In summary, LFP’s have a relatively flat, stable voltage plateau, uber deep DOD (Depth of Discharge), a FULL daily charge is not a routine objective (unlike FWC, something best avoided except for occasional re-balancing), single stage charging is ideal (tolerant to a relatively wide breadth of ‘Absorption’ or ‘Boost’ voltages (upper 13’s not to exceed 14.6v), tolerant to extended Float mode (at less than 13.6v,) tolerant towards infrequent charging or ‘less than full’ charging cycles for a near grid-like experience, and efficient harvest receptivity to more rapidly exploit peak harvest hours…
On the downside, LFP’s cannot be charged below 32d/F, but can continue to be discharged to as low as -4d/F…Since they don’t off-gas one option may be to interior mount (or heated basement), while higher-end versions can be had with built-in heaters, or one might insulate battery case with a electric (12 or 120v) battery blanket…Due to LFP’s uber deep DOD ability, charging can often be postponed until the arrival of warmer ambient temps..
3 tons
Your PD with charge wizard will work fine so long as you kick it into the Absorption or Boost Mode (14.4v), but once fully charged (i.e. post cell-balancing) discontinue charging shortly thereafter since it’s not good to continue charging for extended periods, and for this same reason (unlike wet-cell types) LFP’s should not be equalized (over time can lead to damaging dendrite formation)…
Determining ‘accurate’ LFP State of Charge (SOC) will require a decent LFP compatible meter (or say bluetooth), such as a Victron ‘Smart Shunt’ or BMV-712 (or equiv), this due to LFP’s relatively flat discharge voltage plateau…With either battery type a good shunt based meter (shunt installed in batt neg cable) is truly an invaluable asset!!
Usable wet-cell depth of discharge (DOD) is down to about 50’ish percent, whereas LFP’s can routinely go down much deeper discharge, some even advertised to zero percent, but in the interest of cycle longevity a somewhat lesser DOD would seem more practical…
In summary, LFP’s have a relatively flat, stable voltage plateau, uber deep DOD (Depth of Discharge), a FULL daily charge is not a routine objective (unlike FWC, something best avoided except for occasional re-balancing), single stage charging is ideal (tolerant to a relatively wide breadth of ‘Absorption’ or ‘Boost’ voltages (upper 13’s not to exceed 14.6v), tolerant to extended Float mode (at less than 13.6v,) tolerant towards infrequent charging or ‘less than full’ charging cycles for a near grid-like experience, and efficient harvest receptivity to more rapidly exploit peak harvest hours…
On the downside, LFP’s cannot be charged below 32d/F, but can continue to be discharged to as low as -4d/F…Since they don’t off-gas one option may be to interior mount (or heated basement), while higher-end versions can be had with built-in heaters, or one might insulate battery case with a electric (12 or 120v) battery blanket…Due to LFP’s uber deep DOD ability, charging can often be postponed until the arrival of warmer ambient temps..
3 tons
