Electrical question; battery charger

[drb9]

Okay, when you finish reading this, your likely response will be, "hire a professional." But, I'm not going to, so if you have any help, I would appreciate it.

My battery charger is not charging either battery. Normally, there is a hum when it is on, but there is no hum.

I pulled the shore power panel, and found 120v across the "battery charger" circuit. So, that suggests that I have current from the dock to the panel.

I'm trying to narrow the suspects, but am not sure what components could be malfunctioning, and would like to consider others before concluding that I need a new battery charger.

Is it possible that my battery switch has failed? I understand that there is some kind of diode in the switch (because I was warned not to turn the dial when the alternator on the outboard was running). If something has failed in the battery switch, how could I test that? And, if the battery switch failed, would that prevent charging? [I have now learned that the diode is in the outboard alternator, not in the battery switch. It appears I would be well served replacing the battery switch with one with AFD, which seems to prevent burning out the alternator's diode.]

I'm not sure where the "galvanic current blocker" in the wiring system, or whether (1) it fails and (2) when it fails what the consequence is.

A lot of this wiring is original to the 1986 CD 26 (outboard engine), so I'm not sure what improvements there have been since then.

I would appreciate any suggestions. Thanks.

Darin

[Steve Laume]

A multi meter is your best ally in hunting down a problem like this. Just start through the system. Shore power, charger output, battery switch or along those lines.

Did you check for a fuse in the charger? If the charger is not humming as usual and it is receiving power then I don't think you have to look much farther, Steve.

[drb9]

Thanks, Steve. I have a multimeter, but as you can imagine, the wiring is tied in bundles and I don't have a great sense of what components follow the shore power panel.

The only reason I'm not ready to conclude it's the battery charger (based on the lack of hum) is that I'm not sure if there is some kind of "smart" sensor that won't turn on the charger unless there is a battery hooked up. So if, for example, the battery switch was broken, the charger would not detect a complete circuit and would not turn on.

Is it your sense that the current flow would be as follows:

Shore power (120v)-- Panel (120v) -- Battery Charger (120v in, 12v out) -- Battery Switch (12v) -- Battery (12v)

[Kickin Bears]

What type of battery charger?

There’s a ProMariner on board ours, and the flow is simply: shore power >> charger >> 2x AGM bank.

On ours, the battery selector switch is not part of the charger circuit. The selector switch directs flow from battery(ies) to boat electric system for starter, nav lights, cabin lights, etc., so is part of seperate circuit.

[drb9]

I went down into the cockpit locker and found that the charger is a Guest 2515, and is hardwired in. I see that new chargers either have a plug, or are hardwired.

Is it fair to say that the plug-in versions are not meant to be taken apart and hard-wired?

The Guest charger very well could be 34 years old--certainly it has lasted the 20 years that I have owned this boat. I'm actually wondering if it was mounted upside down, because the wires enter from the top, and the label, fuse, and "ready" light, are on the underside, where I couldn't see them. I suspect it was mounted upside down because the AC comes from the left side of the charger, and the DC/batteries are to the left of the charger--the opposite of how the charger appears to be set up for wiring.

[Kickin Bears]

I tried to find a manual for that model, and am surprised that I can’t find one.

I personally wouldn’t modify a unit, but rather purchase one that is intended for use with my system design.

Do you have an AC electrical system component (inverter / battery charger)? If not, basic chargers for a 2-3 battery bank DC system are cheap (from a boat buck stand point). Just put the corresponding connection on the battery terminal, and run an electric cord from shore to the charger, and voila! There are some basic combo inverter / chargers as well if you want AC capability

Recommend picking up a new charger and installing. Don’t mount it so you can test, and don’t trim wires either for test. Keep the box and materials in case you need to return it. Even if there’s a 10% restock fee you’re only talking being out $10-20

PS - if you’re dead set on the 2515 model, there are some available on ebay if you want to roll the dice and do a 1:1 swap

[S/V Ethan Grey]

I have an RM-8 and it wasn't charging as well. When I bought the boat, it was missing the external fuse and cap, so I assumed that was the problem. I replaced the cap and fuse, but it still didn't charge the batteries. I checked with a non-contact AC power detector that the charger was receiving AC power, which it was. I then removed it from the boat and took it home to troubleshoot. I opened the box (had to drill out a few rivets) and checked the thermal fuse with a multimeter, and it was okay. I then checked the poles of the external fuse (where the wires connect) with a known good fuse in place, and it wasn't connected. It seems that the external fuse holder had failed mechanically causing the circuit to be disconnected. I tell you this to let you know the process I went through. There isn't much to these old battery chargers. Basically a transformer a small circuit board an external fuse and an internal thermal fuse. In the end, a $5 fuse holder bought at the auto store fixed it and it now works like a champ. Definitely worth a couple hours of looking at. Hope that helps...

[drb9]

I have an RM-8 and it wasn't charging as well. When I bought the boat, it was missing the external fuse and cap, so I assumed that was the problem. I replaced the cap and fuse, but it still didn't charge the batteries. I checked with a non-contact AC power detector that the charger was receiving AC power, which it was. I then removed it from the boat and took it home to troubleshoot. I opened the box (had to drill out a few rivets) and checked the thermal fuse with a multimeter, and it was okay. I then checked the poles of the external fuse (where the wires connect) with a known good fuse in place, and it wasn't connected. It seems that the external fuse holder had failed mechanically causing the circuit to be disconnected. I tell you this to let you know the process I went through. There isn't much to these old battery chargers. Basically a transformer a small circuit board an external fuse and an internal thermal fuse. In the end, a $5 fuse holder bought at the auto store fixed it and it now works like a champ. Definitely worth a couple hours of looking at. Hope that helps...

Thanks! I may try that, but I'm also wondering if, after 30+ years, maybe a new, multi-stage charger would be a little more kind to my batteries.

[drb9]

I'm reviving this topic briefly. I finally wedged myself into the cockpit locker and retrieved the old Guest 15A charger. It was hardwired in, with the positives connected to separate posts on the battery switch, and the negatives connected to a common ground. I installed a GFCI outlet, because most of the chargers out there are waterproof, with a power cord installed.

I would like feedback on two things.

1. Rather than connecting through the battery switch, I was planning to simply connect a charger cable to each battery directly.

2. I'm looking at the Guest ChargePro 8A (4A for each bank), 2707A. My boat sits at the dock for most of its life, so I'm not sure I need the 10A (5A per), 2711A. I'm not sure why I would need the larger draw, given that, most of the time, I intend to go down to the boat, disconnect from shore power, and head out sailing. My load at the dock is basically a couple of small fans and some cabin lights.

Thoughts?