Adding Inverter For Small Applications (1x800w or 2x400w?)

[Alex F]

Choosing Inverter:
I’m trying to pick the best option for adding an inverter for small applications. For now I have only tow immediate goals:
1. Run cockpit TV (assuming I’ll be buying AC only model). The cockpit TV project is still in planning stage, but the idea is to run it for couple of hours to watch a movie at night while on the hook.

2. Run couple of laptops, router and charging cell phones. The need for router and
laptops could be a whole day event.

As you can see the applications are small and mostly I wont need all (#1 and #2 items) run at the same time. So, even though I have a genset, I think it silly to run it for several hours just to provide power for one or two laptops and a router. Granted, at some point I’ll have to run the genny to recharge the batteries, but this is only like 30min-1hr instead of many hours. So, I’m thinking on adding either single inverter about 800w-1000w or two smaller ones like 400w-500w each. It looks like two smaller ones might be better option due to the fact that TV will be in the cockpit while the router in the cabin (about 20' apart).

Any suggestions on types and brands for an inverter?

Installation:
I read on the web that any inverter over 200w-300w should be wired directly to the batteries. I’ve never installed one on a boat before, but have doubts that anyone is actually wires them directly to the batteries, rather to the breakers panel. Am I wrong here?

I was thinking that I’ll have two options. For the one in the cockpit I could run it of the panel in the engine room and have the inverter mounted in the cabinet under the sink or in the storage under the port seat. The cabin inverter I was thinking to wire from the main 12V panel in the cabin.

I would appreciate any suggestions and experience sharing if you’ve done these types of installations.

Thanks,
Alex.

 

[tobnpr]

All depends on the size inverter(s) you need to run the loads you're talking about.
I hard-wired a 1000w inverter on my Chris-Craft. The larger inverters need to be wired directly to the batteries; the runs need to be kept short (usually 5' or less) because of the large conductors required due to the large amp draw. I installed it with an automatic transfer switch which would automatically switch to shore power when available-some inverters have this built-in; either way a switch is required whether automatic or manual just like you have for your current shorepower/gen switch. This makes the whole 120v panel "hot" so you have to be very mindful of load management and so as not to overload the inverter.

Based on your anticipated usage, neither the multiple laptops/router nor the cockpit tv would require a large inverter. Add up the power requirements for each setup, I'd be surprised if either one needed more than a couple of hundred watts or so. If you go with multiple, smaller inverters, I still would wire directly to the battery if possible, the wire size necessary for each inverter is going to depend on the size of the inverter and location relative to the batteries.

If you currently have 110V outlets in the cockpit for the TV, it might make sense to hardwire a single, larger inverter to your panel.

If it were me, the decision would hinge on the ease of installation and wiring. If there were easy access to install the inverter near the battery bank, and not difficult to route the 120v wiring to the panel I'd go that route.

 

[Alex F]

tobnpr,

I was reading this site http://www.ccis.com/home/mnemeth/12volt/12volta.htm and all sounded ok. The loads matrix is also helpfull to get a good idea on how much each appliances is using. However, they're stating the following regarding installation,

"Mount the inverter in a compartment where it will be accessible and safe from moisture and flammable items or gases. Inverters utilize some components that can create a spark, so never install an inverter in the same compartment as the batteries! "

Their info is conflicting with your suggestion. I can only assume that your suggestion is based marine converter installation that doesn't create any sparks. Did I get it right?

When you say "it might make sense to hardwire a single, larger inverter to your panel" Do you mean that the inverter would feed all the 110v outlets or just one/two dedicated ones?

Thx,
Alex.

 

[tobnpr]

I should have clarified that "near the battery bank" didn't mean in the engine room of a gas powered boat. As you noted, they're not ignition protected. I meant that you need to have a mounting location near enough to the battery bank to keep the 12v cable run short, but it needs to be in a dry, ventilated area forward of the ER bulkhead. Assuming you have a charger, that's probably a good location as they fit the same criteria (short wire runs to the battery).

You could wire the inverter to an isolated breaker or breakers on the panel (or a small sub-panel). First, be sure they're isolated and do not feed them from another AC source. Then you'd have the problem of isolating the outlets you want to feed since they're wired in series with other outlets on the boat. Not an easy thing to do...

It's easier to wire the 120V inverter to the panel itself. This should help explain, it shows both types of installations.
http://www.xantrex.com/web/id/1355/docserve.aspx

For me, it was easier to use a separate transfer switch near the panel, in the example shown you have to route the main AC feed through the inverter then to the panel because the transfer switch is built-in to the inverter.

 

[bobnlee2007]

I think the admonition was about using one of the cigarette lighter type adapters for
long term power usage. The plug connector can get sort of hot. These plug/adapters were meant for very short term use for high AMP devices. Remember it was called a cigarette lighter. A very High AMP short time use device.
By all means wire the Power inverter to a DC breaker/fuse panel since it will be a daily use item on the boat. Safer and more convienent.
Reserve the cigarette lighter adapters for things like, lighting cigars,
powering inflators for tubing toys or iPOD adapters.