AC converter question

[SLS]

Hi. Starting my first season with shore power (used to be on a mooring) in my 2007 290 Sun Sport. Will the AC converter keep my batteries charged with the batteries in the off position? Or do I need to turn the batteries on?

Thanks. And any other advice for using shore power would be greatly appreciated.

Also, has anyone utilized their refrigerator powered solely by DC power? How long before your batteries drain?

 

[Henry Boyd]

I honestly don’t know the answer to your questions. Although we kept our 280 on a mooring for many years the fridge was off and nothing in it except when we used the boat. Although we did go out for many multi day trips involving anchoring, we never went more than a day without running/driving the boat.

Once we began living in a slip with AC, battery switches were always on as was the converter. But our electric is a fixed flat rate for the season, so there’s no incentive to not run power while we are away.

 

[SLS]

I honestly don’t know the answer to your questions. Although we kept our 280 on a mooring for many years the fridge was off and nothing in it except when we used the boat. Although we did go out for many multi day trips involving anchoring, we never went more than a day without running/driving the boat.

Once we began living in a slip with AC, battery switches were always on as was the converter. But our electric is a fixed flat rate for the season, so there’s no incentive to not run power while we are away.

thank you, Henry. I am definitely paying for usage but I really want to make sure that I'm actually charging the batteries!

 

[Henry Boyd]

If you have the same fridge we did, then it is natively dc meaning when on 110 vac it’s being converted to 12vdc. So if you are going to leave the converter on while you are away leaving the fridge on vdc isn’t going to add to your bill. Bilge pumps are on regardless. I’d suggest leaving battery switches on, running converter 24x7, leave the fridge on (it’s way more convenient), AC in dehumidifier mode (there is an actual setting and off course only matters if heat& humidity is an issue) and shutting everything else off.

If you have shore water you should shut it off when you leave the boat. It’s also the reason you run the converter 24x7; Bilge pumps will run as long as there is battery power. On your mooring if the water tank sprung a leak, you had a mess and forty gallons to pump out of the bilge. If your water system springs a leak on city water things can get dicey if the water volume coming in exceeds what the bilge pumps pump out, or the pumps run the battery down to dead.

 

[SLS]

If you have the same fridge we did, then it is natively dc meaning when on 110 vac it’s being converted to 12vdc. So if you are going to leave the converter on while you are away leaving the fridge on vdc isn’t going to add to your bill. Bilge pumps are on regardless. I’d suggest leaving battery switches on, running converter 24x7, leave the fridge on (it’s way more convenient), AC in dehumidifier mode (there is an actual setting and off course only matters if heat& humidity is an issue) and shutting everything else off.

If you have shore water you should shut it off when you leave the boat. It’s also the reason you run the converter 24x7; Bilge pumps will run as long as there is battery power. On your mooring if the water tank sprung a leak, you had a mess and forty gallons to pump out of the bilge. If your water system springs a leak on city water things can get dicey if the water volume coming in exceeds what the bilge pumps pump out, or the pumps run the battery down to dead.

That makes sense. I have an AC powered fridge in the cabin and a DC powered fridge on the deck. If I understand what you're saying, If I am connected to the shore power I can keep the DC powered fridge running as the batteries will be charging while on.

 

[Henry Boyd]

That makes sense. I have an AC powered fridge in the cabin and a DC powered fridge on the deck. If I understand what you're saying, If I am connected to the shore power I can keep the DC powered fridge running as the batteries will be charging while on.

Right on the vdc only fridge. The other fridge should be dual vdc/vac. If it is, then it is really a vdc fridge with a vac to vdc transformer. (Vac->vdc is more efficient With a transformer than vdc->vac with an inverter. ) So you can run that on dc as well

 

[SLS]

Right on the vdc only fridge. The other fridge should be dual vdc/vac. If it is, then it is really a vdc fridge with a vac to vdc transformer. (Vac->vdc is more efficient With a transformer than vdc->vac with an inverter. ) So you can run that on dc as well

Thanks for the advice! Will go experiment today.

 

[Creekwood]

I don't see that anyo

Hi. Starting my first season with shore power (used to be on a mooring) in my 2007 290 Sun Sport. Will the AC converter keep my batteries charged with the batteries in the off position? Or do I need to turn the batteries on?

I don't see that your first question was answered. Yes, the Converter/Charger is wired to the battery side of the battery switches, meaning it is always connected to the batteries, regardless of whether the switches are on or off.

On my boat my fridge is autoswitching AC/DC. There are two breakers on my panel for the fridge. One is on the AC side of the panel, and the other is on the DC side.

The fridge will run on AC as priority if both switches are turned on. If only DC is on, it runs from the batteries/converter. If only AC is on, it runs on AC.

When I am at my slip on shore power, I always have my converter "on" so that the batteries stay charged up fully.

I leave BOTH the AC and the DC breaker switches "on" for the fridge if I have any food that will spoil inside. If it is just beer and water, I just use the AC switch and turn the DC side off.

If it is on both power sources, if the power goes out for some reason, the fridge will still run on DC until it comes on again keeping things cool. The downside to this is that it will run down the batteries if the power is out for a long time. That "might" mean the bilge pumps would not have power after the fridge ran them down if the power stayed off. Low risk since my bilge is dry, but if I am not going to the boat for a while, the switch goes to AC only.

I hope that helps

 

[Henry Boyd]

I don't see that anyo

I don't see that your first question was answered. Yes, the Converter/Charger is wired to the battery side of the battery switches, meaning it is always connected to the batteries, regardless of whether the switches are on or off.

On my boat my fridge is autoswitching AC/DC. There are two breakers on my panel for the fridge. One is on the AC side of the panel, and the other is on the DC side.

The fridge will run on AC as priority if both switches are turned on. If only DC is on, it runs from the batteries/converter. If only AC is on, it runs on AC.

When I am at my slip on shore power, I always have my converter "on" so that the batteries stay charged up fully.



I leave BOTH the AC and the DC breaker switches "on" for the fridge if I have any food that will spoil inside. If it is just beer and water, I just use the AC switch and turn the DC side off.

If it is on both power sources, if the power goes out for some reason, the fridge will still run on DC until it comes on again keeping things cool. The downside to this is that it will run down the batteries if the power is out for a long time. That "might" mean the bilge pumps would not have power after the fridge ran them down if the power stayed off. Low risk since my bilge is dry, but if I am not going to the boat for a while, the switch goes to AC only.

I hope that helps

Right, but if the converter is always on as a starting point, won’t the batteries always have a charge, and 12vdc always be available (barring a power failure of shore power)?

 

[Creekwood]

Right, but if the converter is always on as a starting point, won’t the batteries always have a charge, and 12vdc always be available (barring a power failure of shore power)?

That is true. Maybe it make no difference, but my theory is that you want to minimize charge/discharge cycles on batteries. So if there is 110v, I want the fridge to draw that power and not from the batteries.

I think even if the batteries are full, the converter/charger will not kick in until the voltage drops a bit and then will kick in and charge. So I think leaving 12v appliances on drawing power will create continuous minor discharge/recharge cycles that must have some (maybe minor) impact on battery life that can be avoided if you just leave 110v as the power source at the slip. If your fridge is a 12vDC only, I guess that is unavoidable.

 

[Henry Boyd]

After some reflection I think we are both over analyzing the situation.