Power Source

[wvnutt]

All of my electronics and lights on my Catalina 22 are powered by a single 12V battery which is charged by my 7.5 HP outboard. Without running the outboard, the lights and electronics last no more than 20 minutes, and I plan to add a few small appliances, possibly including a portable A/C unit. Obviously, I need more power. Am I lacking power because the outboard isn't powerful enough to provide a thorough charge, or could I have a bad battery? What is involved with adding an additional batter? Would I use the two at the same time, or would I use one completely and then switch to the other? Should I simply try charging the battery(s) with a batter charger while at the dock? Is it possible that I may need a small generator if I get an A/C unit? Sorry about all the questions; you get the point. I simply need more power. Thanks.

[USCGRET1990]

...and yes, you need more charging capabillites to run all that (and more) stuff. The outboard charging is just a small plus when you are motoring, not a substantial charge.

[camaraderie]

You existing battery is probably toast too due to improper charging and deep cycling.
You need a deep cycle house battery and a means of charging it via a good 3 stage battery charger. Never discharge your battery below 50% or about 12.1V at rest.
Suggest you use the search function on batteries and charging as there is much more on the subject here.

[sailingdog]

WVNutt-

If you are relying on the OB to fully charge your batteries, you're making a huge mistake. You need to have an AC-powered three or four stage intelligent battery charger for use at the dock. Unless you are motoring for very long periods of time, it is very unlikely that the OB is doing much beyond replacing what you've used starting the OB.

Also, Cam is probably right about the current battery being toast for any significant loads. If you're planning on adding more electrical appliances, you really need to size your battery bank and charging systems accordingly.

Be aware that many small generators are not capable of running an A/C unit, due to the significant startup demand caused by the motor—even if the generator is nominally capable of handling the running load of the A/C unit.

[labatt]

As sailingdog stated - small generators are usually not capable of supporting the loads a small a/c unit will place on them. The Cruisair CO-7000, for example, draws 6.9amps at 115v - that's about 800watts. Starting amperage, however, is 21amps - about 2415watts. From a generator perspective, you'd have to buy the 134lb Honda EU3000 generator (as an example) to handle that startup power. If you wanted to use batteries (DC power) you would need a pretty serious inverter with a very large battery bank and a fast way to charge it to support an air conditioner. Most people use generators or just use a/c when on shore power.

[sailingdog]

Of course, trying to cram an A/C unit and a Honda 3000 genset onto a 22' LOA boat is going to be an interesting puzzle. You do have to be very careful where you put the generator, since it does create a fair amount of carbon monoxide and if you're not careful, you could end up poisoning yourself. If you decide to get a generator for your boat, I highly, seriously, recommend getting a CO detector and mounting it on the boat. There are enough ways to get injured or hurt on the water, and no need to add another that is preventable IMHO.