Guest Chargers

Park · Posted: Sun Jul 20, 2025 12:55 am Post subject: Guest Chargers

Boat is a 2011 C Dory with a 20 amp Guest Charger. I'm assuming it's original to the boat. Anyone know anything about them? Doesn't seem to be charging my starter or house batteries. Plan on tearing into it tomorrow. May not be the charger but something else. If replacing, what would you recommend as a replacement. Thanks[/img]

thataway · Posted: Sun Jul 20, 2025 11:04 am Post subject:

I have had the factory guest charger fail. I went with Mastervolt or Victron. A fan cooled battery charger is best when the charger is protected from the weather. NOCO Genius also makes good marine chargers, and my last 25 had one of those.

Promariner Pronautic and Blue Seas are excellent, but perhaps overkill...Both have been used in C Dorys.

ssobol · Posted: Sun Jul 20, 2025 11:31 am Post subject:

My original guest charger gave up after about 8 years. Replaced it with a ProNautica one.

C-Wolfe · Posted: Sun Jul 20, 2025 1:15 pm Post subject:

I would start with the fuses, you might have one at both end of the wire lead, near battery and near charger.

Tom Hruby · Posted: Sun Jul 20, 2025 4:40 pm Post subject:

If you decide you need a new charger, avoid any with an internal fan (a good indicator is a grill on the housing that lets air into the interior). I started by using these because they were less expensive, but they all failed within a year. After a lot of research and reading the fine print when I could find it, it turns out these units are only rated to a 80-85% humidity. Here in the Pacific Northwest we often have higher humidity, especially in the winter. The humidity permeates even into the cabin and I found that these chargers will fail even when put into the cabin.

jkidd · Posted: Mon Jul 21, 2025 9:30 am Post subject:

I've been using Victron I don't mount them any more because I use them for other things besides them. I like the Bluetooth in them cause I can monitor them from my phone and don't have to climb into the boat. It uses the same app as the battery monitor. I just put an Anderson plug on the batteries.

thataway · Posted: Mon Jul 21, 2025 10:23 am Post subject:

colbysmith · Posted: Mon Jul 21, 2025 10:49 am Post subject:

FWIW, I put a Mastervolt charger in my 25 right after purchasing the boat. It only lasted 3 seasons, and then started working intermittently. I finally gave up on it, and purchased a new one, same model, last year. Tom may have a point... I did pull it apart before trashing it, and didn't see any corrosion or anything, so not sure why it stopped. It may have been the fan, as I don't think I heard that running anymore, the few times it did turn on. I also had put the same model Mastervolt in my earlier 22, and it lasted well over 6 or 7 years... Colby

Schuster · Posted: Mon Jul 21, 2025 11:06 am Post subject:

Just curious, are the Guest chargers not considered good replacement chargers when the originally installed chargers go bad? I still have the original guest charger in my boat and its a 2007 model. I may be having a problem with mine as both green lights are on as well a a red light that never seems to go off. Thinking of replacing it but not sure what the best option may be.

thataway · Posted: Mon Jul 21, 2025 1:08 pm Post subject:

Hunkydory · Posted: Mon Jul 21, 2025 7:27 pm Post subject:

I agree with Bob saying there are better chargers than Guest & also agree they will cost more. For me the original Guest charger lasted 15 years & its replacement another Quest, now going on 10 years. With my more simple system that is good enough for me. Your choice on what’s good enough for you.

Jay

colbysmith · Posted: Tue Jul 22, 2025 2:08 pm Post subject:

Tom Hruby · Posted: Tue Jul 22, 2025 2:46 pm Post subject:

Bob, It seems that the two of us have had a radically different experience with chargers. Here is my situation:
I keep, and have kept, my boats on a trailer. In the winter we can get several days with temperatures around freezing and the boat hull and equipment equilibrate to these temperatures. However, a wet, and warm, front can move in within 4-5 hours that raises the temperature by 25 degrees and the humidity to 100%. These are currently called atmospheric rivers, but we used to call them the Pineapple Express. As a result, the entire boat and everything in the cabin becomes covered in condensation since its temperature has not warmed up to the ambient. I had lost 5 chargers with internal fans before I found the problem. It was the condensation inside the unit.

As a result, I also now spray a conformal coating on all my electronics. Luckily the RV park where I store my boat now has "shore" power, so I can run a dehumidifier as well.

Schuster · Posted: Wed Jul 23, 2025 2:34 pm Post subject:

Thanks Colby for the reply. I read the same manual and replaced both the house batteries this spring and last year replaced the starting battery. So I'll rule out the batteries and look at the charger. I've quit using it for now as the engine has been quite good at charging. I'll have to do some checks with my multimeter to see what charge rates are being put into the batteries when the charger is on. One thing I will say is that I discovered a wire that was separated at a crimp coupling that I cleaned up and reconnected and the red light problem started after that point. So I've got some investigation to do to solve this problem before making any big moves.

Schuster · Posted: Wed Jul 23, 2025 2:39 pm Post subject:

Jay, thanks for your incite. I tend to agree with your logic on replacement. Mine has been good for many years and definitely has done the job. I tend to agree at this point not to change things up too much and stick with what has worked for years.