Inverters?

[Trm1765]

Does anyone know anything abut inverters? What I am wondering is if they are able to maintain the stated continuous wattage without the engine running. and for how long? I only need 5 minutes or so with the engines off. Also, is it recommended to go with the size of wattage that I need or should I go a certain size bigger than I need? Example, if I need 700 watts continuous, should I have a 700, 800, 1400 or what is recommended. If I go bigger will that simply drain my batteries quicker and not effect the efficiency of what I am trying to run or is bigger always better?

 

[JetPowered]

What load do you need to run?

 

[Trm1765]

It says a minimum of 700 continuous watts.

 

[JetPowered]

No, I mean are you trying to run a microwave or just charge a laptop?

 

[Trm1765]

the pump for an AirDock.

 

[JetPowered]

What are the specs of the pump, i.e. amps or watts, or was that the 700 watts number? I'm thinking it will require more that you will have. Inverters are not very efficient. you should also size it for the surge of the motor load, not the continuous load. So 1400 watts or greater would be advised. Be sure you will have enough battery power to start the boat when you are done.

 

[christopherglenn]

A 700 watt load is ~70 amps off the batteries. I have a 1500? watt inverter onboard to run a shop vac to fill water toys. I leave the engines idleing to run it.

 

[JEvanoff]

A 700 watt load is ~70 amps off the batteries. I have a 1500? watt inverter onboard to run a shop vac to fill water toys. I leave the engines idleing to run it.

So you are saying your 1500 watt inverter pulls 140 amps at full load?

 

[JetPowered]

Or about 147 amps at full rating of 1500 watts . If course, it's not likely you would be running at that draw for very long, usually only for surge. You also need to account for inverter efficiency. So 1500 watts ÷ 12 Volts ÷ 0.85 percent efficient = 147 amps. The lower the voltage goes, the worse the draw becomes.

 

[Bruce]

Can you use a battery on the dock with a solar charger to power the air dock? I would not want to put the strain on my boat batteries. I use a similar setup for the stereo on my kids playground and it works well. The charger is inside the battery box.

I would go for at least a 1000 watt inverter if you need 700 watts continuous. The larger inverter will remain cooler and likely be more efficient.

5 minutes at 70 amps is 3.5 amp hours. Most marine batteries have a capacity of 80 to 100 amp hours.

It would be more efficient if you could get a 12v pump for the air dock.

I do not have an inverter on my boat because I prefer not to mix 120 and water.

 

[Trm1765]

Thanks everyone..Bruce you must have been reading my mind, that is exactly what I was thinking about.

 

[Noko]

Anyone have any ideas of a good plug in invertor? I wanted to run a blender. Or are there decent DC blenders?

 

[tim h]

I've seen a couple awesome GAS powered ones...

 

[Noko]

I've seen a couple awesome GAS powered ones...

I was looking for something you could plug into the cigarette lighter/dc outlet on the boat.

 

[Gym]

Or about 147 amps at full rating of 1500 watts . If course, it's not likely you would be running at that draw for very long, usually only for surge. You also need to account for inverter efficiency. So 1500 watts ÷ 12 Volts ÷ 0.85 percent efficient = 147 amps. The lower the voltage goes, the worse the draw becomes.

Not to be picky but 1500 watts ÷ 12 volts = 125 Amps X 0.85% = 106 amps.

 

[Bruce]

Not to be picky but 1500 watts ÷ 12 volts = 125 Amps X 0.85% = 106 amps.

It is actually divided by 0.85. This is based on the assumption that the inverter is 85% efficient. The efficiency loss is why it increases to 147 amps. Some of the current will be converted to heat in the inverter.

 

[PaulyB]

a small honda generator works really well, but does take up room. The Margaritaville Explorer makes awesome frozen drinks as well...

 

[Bruce]

Although it is large, this is my suggestion for a blender on the boat https://jetboaters.net/threads/margaritaville-cordless-drink-maker-on-our-boat.3686/

 

[Glassman]

I was looking for something you could plug into the cigarette lighter/dc outlet on the boat.

Hmmm, I wouldn't advise that simply because I don't think it would handle the load. I would recommend going straight to the battery with clips. I've read too many stories about the cigarette lighter/accessory port failing...melting, etc. I know first hand that mine trips under heavy load so I use it for nothing bigger than a cell phone now.

And the cordless blender is the schizznit!

 

[Gym]

It is actually divided by 0.85. This is based on the assumption that the inverter is 85% efficient. The efficiency loss is why it increases to 147 amps. Some of the current will be converted to heat in the inverter.

So, if 1500 Watts is divided by the nominal battery voltage of 12 Volts, that equals 125 Amps. If the inverter is only 85% efficient how do you end up with 147 Amps which is more than the 100% value of 125 Amps? 85% of (x) 100 = 85.