FLA characteristics

[lateral]

Something I have learned about my batteries over time is that on a 14.8V charger, when it turns to absorb it is not exactly constant voltage from there on.
In bulk it increases voltage to 14.4x volts then switches to absorb.
Current then starts decreasing, but voltage continues to increase to
14.8V which pretty much co-incides with 0.01C.
I always thought:
Bulk --increasing voltage, constant current
Absorb-- constant voltage, decreasing current.
Is this normal?

[sailorboy1]

maybe it is your charger/charging source

mine climbs to absorption voltage and stays there with current decreasing just like it is suppose to. Unless something gets in the way, like clouds. But then is just tries to start doing it again.

[lateral]

Charger sits on 14.8V, batteries 14.4---> 14.8V (Pronautic shore charger)
ie volt drop across batteries until taper current is reached or emf batteries equals
charger emf.
Or/ am I may making this up as I go along as my other half is always saying.

[rslifkin]

Is it possible the cables from the charger are too small? If there's significant voltage drop between the charger and the battery at full output, that would explain the behavior. The batteries will hit full charge faster with bigger cables if there a vintage drop issue.

[lateral]

Hmm, worth investigating. I will do a vd test on cable. (16mm^2) max current is 50A.
Even the primary winding on the pronautic should reflect this right?
Battery bank is 4x6v. 2x12v in parallel.

[lateral]

So, what you are saying is that when the current is higher there is a volt drop and when it is lower there is no volt drop?
I will check the digital reading of the pronautic 1250P is at output and not to config setting.

[billnb]

Originally Posted by lateral

Charger sits on 14.8V, batteries 14.4---> 14.8V (Pronautic shore charger)
ie volt drop across batteries until taper current is reached or emf batteries equals
charger emf.
Or/ am I may making this up as I go along as my other half is always saying.

So the charger remote display reads 14.8V when it enters absorb, but the batteries read 14.4 and continue to climb?


What is the total amp hours of the batteries?



How long is the DC cable run from charger to the batteries?

[lateral]

474Ahrs
2m

[lateral]

Originally Posted by billnb

So the charger remote display reads 14.8V when it enters absorb, but the batteries read 14.4 and continue to climb?

Yes, but not sure whether measurement is on charger output or Max configured setting.

[Pete7]

Or is it that you are on board using some of those electrons for other things at the same time?

Pete

[lateral]

Originally Posted by Pete7

Or is it that you are on board using some of those electrons for other things at the same time?

Pete

Nope, zero load.

From Promariner spiel:
"The user-friendly and efficient ProNauticP Series features dual-digital displays that present realtime charging voltage, amperage"
That would be output voltage, Right?

At say 25A in absorbtion, battery voltage would be ~ 14.65.
At say 5A in absorbtion, battery voltage would be ~ 14.83.

[rslifkin]

Originally Posted by lateral

So, what you are saying is that when the current is higher there is a volt drop and when it is lower there is no volt drop?
I will check the digital reading of the pronautic 1250P is at output and not to config setting.

Yes, a given wire run will drop more voltage as you feed more current through it. So as the current drops off, the voltage drop decreases.

[sailorboy1]

Originally Posted by lateral

Nope, zero load.

From Promariner spiel:
"The user-friendly and efficient ProNauticP Series features dual-digital displays that present realtime charging voltage, amperage"
That would be output voltage, Right?

At say 25A in absorbtion, battery voltage would be ~ 14.65.
At say 5A in absorbtion, battery voltage would be ~ 14.83.

unless you measure the voltage at the charger and at the battery at the same time it is hard to really say, but to me it appears to be your charger if it is on a setting for 14.4V

I have a Promariner and it is a pretty stupid "smart" charger

[Bycrick]

16mm2 metric wire is about AWG 6. When I hooked up a ProMariner 60 amp charger ashore, with 4’ wires, the 3% voltage drop tables said #4 wire was big enough. But it wasn’t. At full current, there was several tenths of a volt drop. We quickly changed to using #2 wire.

[lateral]

Actually mine is AWG 4 as well but 4m round trip.
Sounds like this is the explanation.