Two good sites to read through:
Link:
https://marinehowto.com/lifepo4-batteries-on-boats/
and
Link:
Marine lithium batteries in operation | Nordkyn Design
I think the
charge to 13.8V comes from marinehowto. His data shows it works for him. It's a
very specific charge and use routine though. From the site:
Quote:
Before you get too excited these cells have:
--Never been floated, they get charged, then discharged
--Only absorbed to a net 8A - 10A at 13.8V -14.0V
--Not charged above 14.0V unless for testing purposes (I now have a few other banks for that)
--Max charge rate at approx .3C
--Stored at 50% SOC when not being used or cycled
--Stored in 45-60F temps when not being used or cycled
--Only very rarely exceeded 80F
--Highest voltage they have ever seen was 3.8VPC while top balancing initially.
|
Note: 13.8 to
14.0V, never floated, stored at 50% SOC etc., charged then discharged - so no partial charges, no partial discharges. The battery is cycled from full charge then discharged and then it's charged again. Very little mention of solar in that article.
That usage isn't doesn't match up well with how Class B's are typically used. Overnights might result in a low state of charge, then you get some solar in morning & might drive the van a bit then return to a campsite & the cycle starts all over again.
Lots of partial charging and discharging.
nordkyndesign site has more technical information. I refer to the site often. How the conclusions are reached is well documented with references.
It gives the definition of 100% charged. It is 3.65V per cell and tail current at C/30. IMO,
you have to know what 100% is to be able to determine all other state of charge points.
It's just a definition & you don't have to charge to 100%.
Whereas marinehowto says to charge to 13.8-
14.0V, nordkyndesign indicates
14.0V should be the minimum target. From the site:
Quote:
|
My experience so far has been that any termination voltage below at least 3.5V/cell should be considered as inadequate if the installation experiences incomplete charge cycles.
|
3.5*4 =
14V
My takeaway: Both sites see to charging to
14V as acceptable. Both sites recommend charge termination and not continuously charging. Both sites indicate charging to 14.6V is the upper safe limit
if charging is terminated at that point and individual cell voltages aren't allowed to exceed 3.65V.
Power goes out with Batteries at 12.5
Linear Mode
