Power Inverters

[Pulsar]

I have what I think is a highly technical question.

Here's my set up:

12 Volt Car Battery (no charging system) -> 140 Watt inverter -> 2 plug adapter -> Laptop

The 140 watt power inverter is just a mobile power inverter of the sort you'd purchase from, say, best buy. On the end I plugged in a 2 plug adapter. One of these plugs is plugged into my laptop. I'd like to plug the other outlet on the 2 plug adapter into 110V AC.

In this way, the laptop would run off the inverter if no power was present, and the 110V AC if it IS present. My question is, will this blow out the inverter? Will reverse current flow, or is it likely to have diodes that can handle seeing 110VAC at the outlet side?

 

[Crusty]

Save yourself the fire and get a UPS IMO. Although with a laptop having batteries.... this begs the question, why?

 

[Pulsar]

It's a marine application, in a situation where there is not a charger (sailboat).

Therefore, when I'm hooked to shore power, I want the shore power powering the laptop.

When we're out sailing (for days at a time), I want the laptop to function off the boat battery through the inverter.

The laptop is permanently mounted in the boat as part of the navigation station, and I don't want to have to screw with plugging / unplugging the cord etc.

 

[Mark R]

You will blow out the inverter.

If you don't want to keep plugging/unpugging, either use a manual transfer switch, or a suitable change-over relay to connect the laptop to the inverter in the absence of shore power.

 

[Falloutboy]

they make such systems for RVs, I remember my dads coach had a inveter/charger, that when it was parked and hooked to Elec it charged and conditioned the batterys and used external power for the outlets. when on the road it powered the outlets via the inverter. it was not seemless though, and when you changed power sources the power "blinked"

 

[Crusty]

Originally posted by: Pulsar
It's a marine application, in a situation where there is not a charger (sailboat).

Therefore, when I'm hooked to shore power, I want the shore power powering the laptop.

When we're out sailing (for days at a time), I want the laptop to function off the boat battery through the inverter.

The laptop is permanently mounted in the boat as part of the navigation station, and I don't want to have to screw with plugging / unplugging the cord etc.

That's rather important information to leave out in the OP!

 

[Paperdoc]

Originally posted by: Falloutboy
they make such systems for RVs, I remember my dads coach had a inveter/charger, that when it was parked and hooked to Elec it charged and conditioned the batterys and used external power for the outlets. when on the road it powered the outlets via the inverter. it was not seemless though, and when you changed power sources the power "blinked"

This is the route to investigate if you want a well-contolled system. Or, how about not worrying about switching back and forth? Get a good battery charger for the 12v battery and plug it in when at anchor. All power for the boat will still come though the battery etc, whether you're in port or at sea. You'd just have a way of keeping the battery well charged (even re-charging) when in port. It will need to be a good charger, though, so that it can supply heavy current when needed, but still not overcharge the battery when connected for days at a time.

 

[Modelworks]

What voltage is the output of the laptops power supply ?
I would take the laptop plug in adapter out of the equation. Just convert the 12VDC to whatever the laptop needs, it is probably DC anyway.
Then buy a charger for the DC battery so when your at a dock you can plug it in and have to change nothing at the battery or laptop.
If you can reply what the voltage is, I can point you to a suitable converter. I just built a 24VDC > ATX supply for a 600Watt pc, and it is not as hard as people might think.

 

[Pulsar]

Thanks guys!

You've given me quite a bit to think about. I think taking the inverter out of the equation for the laptop is ideal.

Editted:
Just looked up the voltage requirements. The laptops expect 19.5V and 3.4amps. So I went the easy route and purchased the adapter off of ebay ($12). It has built in current and voltage protection to protect the laptop from under or over volting, and can accept and input voltage of 10-15 volts and still supply the required output.