Testing shore power system on bench top?

[Jdege]

I bought a boat that had been in the middle of a refit.

It had pretty much no installed electrics, other than the alterbator and the starter battery.

It did, though, have an isolation transformer and a battery charger, sitting in a locker, uninstalled.

I don't know that either works. They might, they might not.

I'm thinking about grabbing a 12v battery and trying them out, sitting on my workbench, plugged into the house mains.

Any we suggestions on how to do this?

Any test equipment I need?

Can I do this safely?

[smac999]

chop the end off an extension cord and connect to isotransformer input. connect another wire from iso output to charger. plug cord into 15a outlet to test both.

you don't really need breakers for the transformer or charger if you are testing from a normal 15a wall outlet. could use a gfi outlet if really concerned.

[goboatingnow]

What type/make is the transformer

[EngineerRetired]

What you are describing is a pretty simple and straight forward task so by asking these question I surmise you are not familiar or comfortable working with electrical systems.


That's not an insult or negative statement, every electrician alive started where you are at. The best suggestion (advice) I can give is to have someone that knows know a bit to work with you doing this and explaining how and why as it goes along. Learning your boats electrical system is a GOOD thing.

[Jdege]

I'm familiar with low voltage DC circuits. And that doesn't carry over into AC power circuits much.

It's anyone aware of a good online resource for learning power systems?

[rwidman]

You can connect the battery charger to 120 volts AC and a partially discharged 12 volt battery to test it.

As for the isolation transformer, there's really nothing to go wrong with one, it's just two coils of wire wound around a core and you would be able to smell if one was burned out.

Basically, connect the input terminals to 120 volts AC and connect a 120 volt lamp to the output terminals. If the lamp lights, the transformer is OK.

As for an online source for learning power systems, electricians spend four years going to school at night while working as apprentices in the daytime to learn their trade. I don't think you are going to learn this online.

There are some books that touch on boat wiring. Maybe you can learn enough to satisfy your curiosity.

I would suggest not taking on the task of completely wiring a boat without a really good understanding of marine electrical wiring.

[Jdege]

As for an online source for learning power systems, electricians spend four years going to school at night while working as apprentices in the daytime to learn their trade. I don't think you are going to learn this online.

There's always this:

ABYC Online Store: Certification Study Guides

[EngineerRetired]

Here is one of the better books I have seen, it specifically deals with the very things you are working on. https://www.amazon.com/Sailboat-Elec...a-418370145297




With that said I want to throw up a bit of a caution flag. 12 volt "low voltage" is in some ways more dangerous than 120 volt ac. I say that because with 12 volts you are dealing with much higher amperage and the average starting battery can easily put out over 1000 amps in a dead short. Enough to melt just about any wire or conductor. I don't have any numbers to back me up but I would be willing to bet boat fires are far more likely from the 12 volt side of things than the 120 volt ac.

[Jdege]

OTOH, I'm thinking it's time I sat down and read that book by Nigel Calder I bought a few years ago.

[Flatswing]

You might want to check out Jim Healy on the MTOA & AGLCA sites also . He has a very hood section on properly testing your shore power set up

[Nicholson58]

Pretty good advice already posted. They are correct about the isolation assuming 115 to 115 isolation. Ours is 230 single phase input to two separate 115 single phase outputs. Get the wiring diagram for your transformer.

Our isolation transformer eliminates issues with stray currents at the marina so nasty corrosion problems caused by wonky shore power or other boats is mostly eliminated.

Your charger may need to be connected to a battery to avoid damage. Read the data sheets.

Find a friend who is a bit comfortable with this stuff. Usually a dockmate can help or point you towards help. Do read the books you have. Make sure you use ABYC marine grade wires. (Fine strand, high flex, pre-tinned).

[Lake-Effect]

Originally Posted by Jdege

There's always this:

ABYC Online Store: Certification Study Guides

These guides are intended to help already knowledgeable pros brush up on the current ABYC Code, and review some common troubleshooting issues, in preparation for the tests. They are not "Boat Electrical 101". And they're like US$175 for a 100 page book.

There are many many resources (books and online) for learning the basics of electricity and electronics, and for marine specifics, the boat owner will get more for their money with one or a few of the good books out there. I especially like the Calder book.

[celle2000]

Some informative youtube videos by Jeff Cote of Pacific Yacht Systems

[rwidman]

Originally Posted by EngineerRetired

With that said I want to throw up a bit of a caution flag. 12 volt "low voltage" is in some ways more dangerous than 120 volt ac. I say that because with 12 volts you are dealing with much higher amperage and the average starting battery can easily put out over 1000 amps in a dead short. Enough to melt just about any wire or conductor. I don't have any numbers to back me up but I would be willing to bet boat fires are far more likely from the 12 volt side of things than the 120 volt ac.

It may be more likely that boat fires are from 12 volt DC wiring, but electrocutions are more likely from 120 volt AC wiring.

Water and electricity can be a lethal combination and it's a bad idea to mess with electricity, especially on a boat, if you don't know what you are doing.

[celle2000]

and I concur with suggestion of looking at books from Nigel Calder - for example "Boatowner's Mechanical and Electrical Manual: How to Maintain, Repair, and Improve Your Boat's Essential Systems"
Calder, Nigel