Alternator upgrade and using Internal Regulator

[Stu Jackson]

Hi Mainesail,
Does the LN internal regulator have a "soft start" feature?  I noticed on start up in the morning after being on the hook all night with the fridge and anchor light burning all night, that the volt meter in the engine panel showed about 12.5 volts after starting the engine. The voltage then slowly increased to 14 volts after about 15 min. Is to be expected?

Paul

Of course it is.  This is part of basic battery charging.  The battery bank is at, say, 12.1V after a night on the hook.  The charging starts with the charging source's maximum setpoint at 14.4 or so.  Until the SYSTEM voltage rises due to the charging, it will always exhibit what you describe.

Ramp up usually is found in only external regulators, which do not start right away, but have a built in delay from the engine start to starting the regulator.  Ramp up is not usually defined as the rise of voltage in a system, 'cuz that's part of any charging system.

[waterdog]

Paul, aside from the alternator issues (and you will be fine internal, external with a portable generator), have a great cruise!   

[mainesail]

Hi Mainesail,
Does the LN internal regulator have a "soft start" feature?

No.. It is a simple CC/CV regulator or bulk/absorption..

I noticed on start up in the morning after being on the hook all night with the fridge and anchor light burning all night, that the volt meter in the engine panel showed about 12.5 volts after starting the engine. The voltage then slowly increased to 14 volts after about 15 min.  Is to be expected?

Yes, you start in bulk or constant current, meaning the alternator is producing all it can while bank voltage slowly increases.

-- The less charge current the longer it takes to raise bank voltage to the absorption limit point and the higher in the SOC curve the bulk to absorption transition occurs..

-- The more charge current the less time it takes to raise battery voltage to the absorption limit point and the lower in the SOC curve the bulk to absorption transition occurs..

When bank voltage gets to the voltage limit, perhaps 14.4V, (ideally higher for flooded batteries) the alternator then switches to CV or voltage limiting and holds voltage steady where current will begin to decline.

This thread and links should hep you better understand the bulk & absorption charging process. Ignore that it is discussing AGM batteries, all lead acid batteries charge similarly.

How Fast Can an AGM Battery be Charged? (LINK)