Why not use an automotive AC charger on the boat?

[CSY Man]

My neigbor is using a car type AC charger on his boat and he says there is nothing wrong with that set-up.
I have alsways heard it is a big no-no and can cause problems with grounding issues and stray currents, etc.

So what is the real reason for paying 10 times as much for a Marine AC charger?

[ssullivan]

My humble opinion is that it would be just fine. In fact, you can use automotive compressors to run refrigeration, and plans for this are detailed in Richard Kollmann's "Do it yourself refrigeration" book.

If something works for refrigeration, it's certainly going to work for air conditioning.

[ronbo1]

Is the question A/C or A.C. ??

If you're referring to an A.C. automotive battery charger please don't dock next to me. Zincs are getting expensive to replace.

[CSY Man]

Is the question A/C or A.C. ??

If you're referring to an A.C. automotive battery charger please don't dock next to me. Zincs are getting expensive to replace.

AC as in battery charger for land "vehicles"

The question my neigbor does not understand is why it is not good to use an automotive battery charger on a boat?

My zinks are going fast for sure.

[S/V Antares]

I have not seen an automotive unit that is more than a 12v buzz box and fixed outputs. and crappy output conditioning. Few if any will do a proper job on Gel or AGM batteries.

I use one all the time.... on the boat in my driveway on the trailer. If you have a good sized battery bank it is a cheap investment to have a charging system that can bulk charge then float and measure the battery temp. Real batteries are not cheap!

[knottybuoyz]

I'd hate to think what an insurance investigator would report if he found one on a burned out boat!

[ssullivan]

Originally Posted by ssullivan

My humble opinion is that it would be just fine. In fact, you can use automotive compressors to run refrigeration, and plans for this are detailed in Richard Kollmann's "Do it yourself refrigeration" book.

If something works for refrigeration, it's certainly going to work for air conditioning.

I'm an idiot. ha ha ha

Sorry. Mis-read that.

[CSY Man]

I'm an idiot. ha ha ha

Nah, ya was thinking AC Compressor..

[camaraderie]

I had a hunter in the slip next to me burn to the water line when the auto store charger he had plugged in to the dock electricity shorted out some years ago.Got so hot that MY windows melted. I'll stick with marine units and pay the price.

[Fishspearit]

As far as I know the only real difference is, as Antares stated, the car charger is designed to maintain a float charge with a low amperage output. They're just not designed for deep cycle applications and long term use. As long as you don't splash saltwater on them I don't see why they would be any less safe than any marine charger though. Nor should they have any different effect on your zincs, they'll be wired with a hot, a neutral, and a safety ground just like any other charger.

[Alan Wheeler]

Leaving the regulation aside for the mo, The major difference is in the internal design in relation to how it is earthed. Many automotive chargers are not isolated in the earthing system. So the result is that the boat achieves two earthing points which creates stray voltages and thus the Zincs are often eatin away very quickly. A good charger will have a compleatly isolated output. Finding a transformer based car charger that has an isolated output is very difficult. Unfortunalty this case has resulted in a misnomer that all transformer based chargers are bad and you have to have a switch mode charger.
Back to the regulation side of the discussion, the main difference with "trickle charging" is that long term, the battery will actually go flat, even though a trickle or "float" charge is being applied. A battery connected to a charger for long durations (as found in most boat situations) requires the battery to be cycled. So a "smart multi stage" charger is required. If the boat is used regularly, then that is not as essential. Darryl from seafox used to have a cheap charger and a cheap battery and I was onto him about getting a good charger. His reply was, well I have got 10yrs out of the cheap battery. Am I going to get anybetter from having an expensive charger fitted. Well that blew my argument. He did get a smart charger in the end however, but I certainly had no argument in him spending mega dollars on a flash expensive one.
Which brings me to my final point. There are cheap smart chargers available. Any car charger with trickle charge ability will not be much cheaper. So why not get a charger you can leave on and know it is doing the correct job.

[jscott]

There are certainly lower cost smart automotive battery chargers available around here.

Fully grounded, and isolated, complete with high amp, high temp shutdowns, ramped charging, and selector switchs for lead acid, sealed, AGM.

I havn't seen a lower cost one that has a amp input limit based on an entered amphour. The just have a selector switch that limits the maxs amps.

[Just a Tinch]

About 2 years ago...we had an interesting day.... A fellow that owned a sailboat left an automotive battery charger hooked up on his boat........and apparently forgot that batteries need more than a little "juice"....like distilled water. Well, to make a long story short...his boat caught on fire, scared a lot of people...made quite a ruckus....and did a lot of damage to his boat. Before the fire it was a nice boat....but no more. I think they threw him out of the marina....not much boat left anyway.

I like bona-fide marine quality automatic chargers