Charger puts out less on generator than on shore power

Spyderweb

After spending a day out on the water, fridge running off house batteries, I'll go back to dock, hook up shore power, turn on charger (Pronautic 1230P), and in a short time volt meter on electrical panel will show somewhere around 14.2 volts.  

Same scenario but near end of day and still on water, I'll run the generator to exercize it, turn on charger, and voltage will only go up to ~12.6.  

In both cases the AC meter reads 120 volts.  Why the difference? 

Dream_Inn

So, mine does the same.  The reason is you charged the batteries up on your alternator before you plugged back into shore power.  So, when you plug in, the charger takes it quickly up to 14.  On the generator it will go up to 14 in time, just longer cause the batteries are down.

Spyderweb

Wow, just opposite of how I thought it worked.  I would have thought if batteries are low, charger starts out high (14) and as batteries come up, charger gradually backs down.  But sounds like if batteries are low, charger slowly builds up to high, and as battery gets closer to full, charger then backs down again?

Dream_Inn

Yep, the charger will go back down again after it gets full.  Watch it the next time you are on your generator.  I typically let my battery get down to 12.2 and then I will charge it back to at least 13.5.  Takes about 3 hours.  But if I wait long enough it will get closer to 14.

Formulaben

And that's why I bought the 50amp version.  Even then, it seems somewhat slow at times...