Battle Born LiFePO4 as real drop-in replacement

[TitanMike]

Originally Posted by Hclarkx

The usual float voltage, 13.6+/-. will charge a lithium fully given enough time. Heck, anything above 13.3V will do the job but may take hundreds of hours.

For an LiFePo4 battery 13.6 volts is technically 100% SOC but there can be as much as 10% cell imbalance according to some. 13.3 volts will only yield about 90% SOC.

As for cell balance, if one is able to fairly regularly charge Battleborn batteries to 14.6 V using either a DC-DC Charger like the Renogy units, a battery charger/maintainer like those from CTEK, NOCO, etc when connected to shore power, or of course Solar Power with the controller set for LiFePo charging, Cell Balance won't be an issue for most.

LiFePo batteries will deliver so much more usable power even if only recharged to 90% SOC as compared to FLA battereis only discharged to 50% DOD.

I think that a lot of people don't understand that they don't really NEED to upgrade their converters if they want to use the LiFePo batteries as drop in's.

For those with questionable converters like the WFCO units, they might want to upgrade them to better units even if they don't upgrade the batteries to LiFePo4.

For those with Progressive Dynamic's Converters with the Charge Wizard, just adding the pendant that allows one to manually force the converter into Bulk Mode, both Progressive Dynamic's AND Battleborn acknowledge that using this "hack" will more than satisfy the cell balance needs in the batteries.

[Hclarkx]

Originally Posted by TitanMike

For an LiFePo4 battery 13.6 volts is technically 100% SOC but there can be as much as 10% cell imbalance according to some. 13.3 volts will only yield about 90% SOC.

Agree. One of the disadvantages of most "12V" drop-in LFP batteries is that one cannot monitor unbalance. When I shopped for a "drop-in" LFP I went with Lifeblue in part because I could monitor individual cell voltages via bluetooth (along with lots of other data). When boondocking in the off-season my solar may not get the LFP up into balance territory for weeks on end. The most unbalance I've ever seen is 1% voltage difference between the highest and lowest voltage cells. Normal difference after a full charge and presumably a balance if one was needed is around a half percent.

As I recall, high current loading is more likely to cause unbalance than light loading. My loading never exceeds 80 amps on a 300 AH battery though it occurs several times per day (espresso machine). My microwave hits the LFP at only 70 amps. This lack of high current loading may explain why I see very little unbalance.

I should add that the above was my experience with one of the first 300 AH units that Lifeblue produced. Because of weak and eventually (after three years) failed bluetooth, Lifeblue replaced that battery with the current 300 AH unit (not the low temperature one). So far, after a half dozen cycles, the new unit unbalance has never exceeded 0.1%. Additionally the new unit started at 318AH capacity and is now up to 322 AH (the BMS updates the AH capacity occasionally or I can force an update).

I don't know how helpful this information is in that it's just one sample and so not a statistically relevant one. Also, Lifeblue uses the new larger prismatic cells rather than many small round cells in parallel. This may affect balancing issues.

[rk06382]

I made this spreadsheet to compare the SOC of Battle Born LiFePO4 vs Lead Acid.

[TitanMike]

Originally Posted by Hclarkx

As I recall, high current loading is more likely to cause unbalance than light loading.

From what I've read cell imbalance is also created by frequent deep cycling without recharging to 100% SOC.

I would suppose that if one isn't using high current loads that take the battery bank to a low SOC but rather using light loading and frequent recharging, even if not to a full 100% SOC, cell balance may not be a huge issue.

This of course wouldn't negate the need for bringing the battery bank up to a full 100% SOC.

In a LiFePo4 battery I don't think cell imbalance is quite the problem as it could be in FLA batteries. It's just a little more complex to deal with than in FLA's that can withstand the "controlled overcharging" that would damage LiFePo4's.