run time needed to top of batts

[goodoldboat]

My boats sits on the mooring all season the motor runs about 45 minutes to an hour per week maybe a little more . Mostly going in and out of the channel
under load .

For the last month not much sailing , but i do go down once a week and start
the engine I run for 45 min to an hour in reverse against the mooring . the voltmeter says i am charging at 14.35


My question is , is that enough ..

BTW there is a small solar trickle charger of uncertain age or wattage ..

any thoughts guys

[ndutton]

Sorry but it's an impossible question to answer. Sufficient run time depends on the state of charge of the depleted battery bank when you begin and the alternator's capacity to deliver what the battery bank can accept which is related to RPM.

Examples:

• A slightly discharged bank won't need as much run time as one deeply discharged
• If the bank is discharged enough to accept 50A of charge current, our stock 35A alternator will take longer to charge it up compared to a higher capacity alternator.
• Even so, a high capacity alternator running at low RPM won't deliver to specification either.

So you see, there are too many variables for a simple answer.

[goodoldboat]

run time

Before i make myself crazy with what ifs .. Im going to take them off the boat for a good charge .

The boat does not have access to shore power being on the mooring , they may have been depleted over the course of the season ..

the hour once a week was not enough to keep them topped off .

that's what I'm hoping ..

[ndutton]

The basic formula is you have to produce more than you consume, assuming the batteries are in good condition and able to maintain their charge. The first step is to do an honest power consumption budget. Once that is established you can figure your charging needs. Complicating the time analysis is the charge rate continuously declines as the battery bank state of charge rises.

[sailboatguy]

If you have flooded lead-acid batteries with removable caps you can check the state of charge with a hydrometer.

[goodoldboat]

run time

Good idea ..

[joe_db]

Charge time is hugely variable depending on the battery chemistry and the type and set points of your voltage regulator.
I learned the hard way that a 35 amp stock Motorola set to 13.8 volts will NEVER bring a big wet cell battery to full charge and sulfated a $500 Rolls battery to death