On Board Battery Charger Wiring

[njfishing]

Would like to install a 2 bank batttery charger on my 25 Carolina Classic. I have no shore power as of now so I will need to wire everything up...It's a Volvo Penta Jackshaft with a Duo-Prop so I'm really concerned about wiring it to minimize any galvanic corrosion issues.

Right now I have 2 batteries, a 2 block isolator which keeps the 2 batteries isolated and 1 Guest on off switch.

I've read enough to know that besides the charger I need to install a shore power receptical along with an galvanic isolator. My question is how is the charger, shore power receptical and the galvanic Isolator to be wired ?

Thanks in advance for any help....

[Thom]

In truth if the only thing you will feed with the shore power you don't need an isolator. What is there to isolate?

Make your battery charger lead connections at the battery switch, one lead to each of the lugs where each cable from each individual battery connects. It is better to connect it there (and mount the charger near there) for a couple of reasons. The first is to avoid corrosion, which will be more prevelent near the batterys than away from them. The second is that it often allows you to use much shorter leads from the charger. The third is that while it is not at all uncommon to disconnect and possibly remove batterys its a lot less common to mess with the wires behind the switch, so there is less chance of accidently crossing them - and if you haven't done that with a pair of Group 29's or larger you're in for a real suprise one of these days. Terminals literally vaporize.

As for the wireing of the AC side you can get a whole lot of opnions but to save you some time Marinco has a nice little brochure that will tell you all you need to know. It used to be free and available from their website, probably still is.

Thom

[Birdman]

He needs to isolate the grounds, that is the 12v ground from the 120v ground.* And both from galvonic problems.*

[mwitkowski]

I just installed a duel pro two bank battery charger. I also do not have shore power. I just plug the charger into an extension cord. I thought marine battery chargers isolate the grounds? Should I install a galvanic isolator between the battery charger plug and extension cord?

I have read past posts and there is no mention of a isolator used. I am very confused.

thanks

M.

[Sue D.]

As Thom mentioned, unless you have an AC panel, you do not need a galvanic isolator.

As for a charger, Guest has several models for applications such as yours. I would be happy to recommend a charger for you if you would provide me with the size of your batteries and the approximate 12 volt draw at shore power.

Have a great day!

Sue D.

[Eyeball]

The galvanic isolator has absolutely nothing to do with an AC panel and everything to do with stopping stray DC current less than 1.3v from making its way from the water, thru your boat, and out the grounding (aka safety-ground, aka the green wire) back to shore. Anytime that stray current has that path available, it will take it…and it will take with it any metal parts in its path if the metal is in contact with the water...with or without an AC panel on your boat.

I agree, the simplest way to do what you are looking to do is to get a bat charger with a three-prong ac cord attached and a GFCI enabled extension cord. If you mount the charger on a non-conductive surface you can overlook the GI. If you are not absolutely sure the charger’s case is ALWAYS isolated, you should go the whole route of installing a GI…that entails installing shore power on your boat, that entails:

- Shore power inlet receptacle
- Mains circuit breaker, usually 30amps
- Triplex wiring, should be inside conduit
- Branch circuit breaker, usually 15amps
- GFCI receptacle
- Galvanic isolator*
- Shore power cord (not cheap!)

About keeping the AC ground separate from the DC ground…that whole subject is not without a lot of controversy. There are safety issues associated with keeping them separate, as well as safety issues when they are common. There are recommendations for keeping them separate, and there are recommendations for having them common. There is no standard way to do it, and there is no ‘right’ way to do it. If you do install AC shore power on your boat, it is well worth read up on this controversy so you can decide which method best suits your needs.

*Note: new ABYC rules (you can ignore the ABYC rules, but I wouldn’t) has a visual indicator mandated for galvanic isolators. That means in addition to installing the passive isolator in your AC grounding, you also get to run a couple 12vdc conductors to it to enable the LEDs that are now common on the isolator.

[njfishing]

Thanks everyone - I will not be running anything but the charger and would rather not install an AC braker and panel if I don't have to.

Sue - I have 2 batteries one hybrid deep cycle 750 CCA and the other is a plain starting battery with 650 CCA. Not 100% sure on what you mean by power requirements at the dock. The reason I'm buying the charger is not to keep up with my power needs at the dock. My issue is that I have a fairly short run out to the fishing grounds. After anchoring up or drifting around for several hours using my Furuno CRT and my stero/cd player (which has a separate amp) I don't have long enough of a run to fully recharge the batteries. While tied up at the dock I run the stero/cd player but that's about it.

One thing I'm still concerned about and that is protection against galvanic corrosion. I've been told by many people down at the marina not to use a standard portable car battery charger with an extention cord and the 30 AMP to 110 adapter. They tell me it could/will introduce stray current and will damage mine and other boats in the area. Is there some sort of difference with the marine chargers or the way they are connected that make them more isolated then a portable charger ??

Thanks for all your patience here folks...... I just don't want to run the risk of corroding mine or other boats in the marina.

[Sue D.]

nj,

I'm thinking that the model 2633-OS may be perfect for your needs. It is a 2 bank charger with 10 amps to a start battery and 20 amps to an accessory battery, or in your case, to your combination battery bank. It will charge your batteries up plus provide power for any 12 volt accessories you wish to use at shore power. It also comes with a charing inlet for easier connections to AC power.

You have been told correctly about not using an automotive charger on your boat, as it can allow stray current as the AC and DC grounds in the charger are normally tird together. Plus they are not normally waterproof and you or someone else could get a nasty shock from it.

As for the galvanic isolator, unless you have both AC and DC grounds on a boat that are connected together, normally at the engine block, are at a marina or other public dock and are plugged into shore power, you do not need one. All three conditions are necessary for galvanic errosion to occur. if you are experiencing pitting or loss of zincs are not all of the above are true, you are experiencing electrolysis and a galvanic isolator will not help.

PLeae feel free to call me at Guest toll free at 1-888-483-7865 ext 135 MOnday through Friday between 8 AM and 4:30 PM EDT.

Have a great day!

Sue

[njfishing]

Many Thanks Sue - I will be contacting you when I'm ready to start the project.

Regards
Gerry

[kingair]

Sue,

Where can I get this kit to extend by DC cables on my Sportman Power center?

U-3632-P

Thank you