Voltage regulation?

See attached picture first.
"I think" that this was the original 1979 battery selector switches from my Grand Banks Classic. It has 3 switches that control 3 batteries. It also has the battery charger wires going to the 3 posts in the back of the switches.
Now the fun stuff ... my engine alternators and not sending any volts back to the batteries. (yes they both put out 13.5 Volts). I traced the positive wire from the alternators to the 2 round "things" highlighted in the picture.
What are they?? Diodes? Anyone see this before?
I suspect that these 2 "diodes" went bad along the way and won't allow the charge to go from the alternators into the battery (my guess). Are they serviceable?
Thank you for any advice !

I can't see much from the photo but it is likely that what you have is an early charge regulator. Our boat has one called a pathmaker where charging and batteries come together. The intent is to combine batteries for charging and decouple them for discharge. If all the batteries (or even just 2) connect here as well as the positive output from the alternators that's possible. Our pathfinder has adjustments for trigger voltages, I can't see what controls are on your 'box'. THis is a link to the more modern version from Blue Sea (not an ad, just info).
https://www.bluesea.com/support/articles/1366/Automatic_Charging_Relay_[ACR]_Explained

What is a bit confusing is that I'd expect a brand name be be plastered on it so you could look it up. If isn't working the best solution is to upgrade to a new unit. My marine electrician recommended the Blue Sea system to me. They're not that expensive and apparently work well. I plan to change over this winter from the pathmaker to blue sea.

One wonders about the alternator diodes if their harge path was actually cut off. 13.5 volts is anemic if we are talking about alternator voltage at start up, but if this was a steady state reading after the engines have been running awhile, maybe not. If none of the batteries read that same voltage at their terminals, where is it going? Hopefully, the real experts will chip in here in a minute. Not that slomo isn't one.... I had occasion to remove a faulty old Pathfinder unit from a single engine boat once and replaced it with a 613 model voltage regulator and a couple of Blueseas ACRs.

Thank you so much !

Don't sweat, help is on the way! Get your digital volt-ohm meter out and standby to follow the experts' directions.

Updates ...

The battery disconnect switches are Cole-Hersee No. 2484. There are 3 , 1 for each battery. The Round things in the middle are perplexing. All the wires are black coated, so tracing is going to be loads of fun ...
FYI - the red colored wires are from my battery charger.
See new attachments

They look like relays for parallel the batteries for emergency starting. Do you have a “parallel “ or “emergency start “ toggle at the helms?

I do believe the function is to bridge the 2 8 D batteries. You are correct! I pulled some of the panel out to see a metal bridge with connections for the 2 batteries. I was thinking (again) maybe the round things are Fuses? They must stick out for a reason...? (removal I'm hoping)

Remember how this started ... my alternators are not sending volts to the batteries, and I traced both hot alt. wires to the back of that thing (that connects that batteries together.) Still think it's the suspect ...

By connecting the alternator there it’s still connected to the battery. If not connected to the battery the alternator would have been severely damaged long ago.
Do this simple test. Shut down any chargers. Take a voltage reading with a DVM directly on the lead post of the start battery. Start the engine. In a few minutes take another voltage reading. If it’s higher than the pre-start reading then the alternator is working.

OK ! Will do .... stand by for updates.

That box looks different that the one that came with my 1972 GB42, but when I saw your post about the metal bridge, I had an AHA moment. Have you ever hit both starter buttons at once? Just for giggles, I tried it early in my long ownership of the boat, and NOTHING happened. Not exactly sure why, but one thing I did learn eventually is that that device is an automatic paralleling switch for the tow main engine start batteries, which is why you will not find a parallel switch at the lower helm like a lot of trawlers have. Pressing either engine start button parallels the batteries to start that one engine. Archie's advice is right on, and I would be HIGHLY surprised if you don't find that swapping the positive lead of your voltmeter between the positive posts of the two batteries and their respective alternator charging posts reveals the exact same voltage after a few minutes.

Oh, and my guess on those two cylindrical things sticking out of the front of the battery disconnect panel is that they enclose the ends of the solenoid pistons and that rather than make the box bigger to accommodate their size, GB just cut holes in the panel to let them protrude.

rgano said:

That box looks different that the one that came with my 1972 GB42, but when I saw your post about the metal bridge, I had an AHA moment. Have you ever hit both starter buttons at once? Just for giggles, I tried it early in my long ownership of the boat, and NOTHING happened. Not exactly sure why, but one thing I did learn eventually is that that device is an automatic paralleling switch for the tow main engine start batteries, which is why you will not find a parallel switch at the lower helm like a lot of trawlers have. Pressing either engine start button parallels the batteries to start that one engine. Archie's advice is right on, and I would be HIGHLY surprised if you don't find that swapping the positive lead of your voltmeter between the positive posts of the two batteries and their respective alternator charging posts reveals the exact same voltage after a few minutes.

Click to expand...

This is how it works on my 1980 42. This is a parallel between the start batteries that activates when you push ignition. Per my thread from this weekend, I got to test it out it with 1 shorted battery.

Bradenvlp said:

This is how it works on my 1980 42. This is a parallel between the start batteries that activates when you push ignition. Per my thread from this weekend, I got to test it out it with 1 shorted battery.

Click to expand...

All good stuff. I will run some tests and report back !

@ragno And what do the solenoid pistons do? How do I know if they are working?

Test results

The two round things do have a cross over bridge that connects the 2 8D's. Confirmed.
And yes both engines will start simultaneously. Confirmed
Tests: (With Battery Charger off.)
Battery Check, nothing running: Port 12.79 Stb 12.79
Alternators test from the back of the positive post to ground on each Alternator: Port 12.99 STB 12.81

Both engines running Battery test: Port 12.62 Stb 12.62
Since they both dropped in voltage after start up, and never increased while running, tells me the Volts are not being sent back to the batteries.
Now what ?


Maybe this whole cross over "thing" and round knobs is a red herring ?
FYI - turned the charger back on: Port 13.98 Stb 13.96

rneedham said:

The two round things do have a cross over bridge that connects the 2 8D's. Confirmed.
And yes both engines will start simultaneously. Confirmed
Tests: (With Battery Charger off.)
Battery Check, nothing running: Port 12.79 Stb 12.79
Alternators test from the back of the positive post to ground on each Alternator: Port 12.99 STB 12.81

Both engines running Battery test: Port 12.62 Stb 12.62
Since they both dropped in voltage after start up, and never increased while running, tells me the Volts are not being sent back to the batteries.
Now what ?

Maybe this whole cross over "thing" and round knobs is a red herring ?
FYI - turned the charger back on: Port 13.98 Stb 13.96

Click to expand...

It could be that your alternators are fried. Have one checked and repaired if needed.
If the combiner box interrupted the connection from the alternators to the batteries
even for a split second that would blow the diodes. Same with the main switches.
Fortunately that is repairable. This could be a good time to rebuild the alternators.

If you're reading essentially the same voltage at the battery and alternator when everything is off it says the alternator is connected to a battery. However your current readings show no charge from the alternator when running on either side. What is confusing is your first post seemed to suggest that the alternators were charging at least a little (13.5V). First thing is I assume you increased RPM enough to get the alternator charging? You should see voltage increase as the RPM comes up. Don't just test it at dead slow idle., I've seen a low voltage at low RPM with perfectly good alternators (just running too slow). If it doesn't increase some with some RPM that's a strong indicator of a non-functional alternator. I know with mine I need to get at least over 1000RPM to get much of anything out of the alternator. I'm assuming in this that you're using internally regulated alternators of course.

By any chance did you switch the battery switches to off with the engines running? Or, even just switched them. Even if you didn't mean to, a faulty switch may momentarily go 'open' when changed. If so it causes the alternator to 'over-volt' and often kills the alternator, or at least the internal regulator.

If you're unsure you could take the alternator off and take it into most car parts stores and ask the to test it. If they are dead though you want to understand why. The probability of two alternators just dying at the same time isn't very high.

rneedham said:

@ragno And what do the solenoid pistons do? How do I know if they are working?

Click to expand...

Get somebody to touch the starter buttons one at a time while you are looking at the metal bridge. I think it should slam into place connecting both batteries in parallel. Mine did. I THINK those cylinders just enclose the ends of the solenoid rods.

Thank you all for your suggestions.
@Slowmo - I ran up the RPM's and the volts did come up, but I was checking the alternators in the post you mentioned When I checked the batteries they went down a little after start up, never up.
Wicked frustrating
Sadly, I took the alternators off last fall, one tested good, one bad (regulators), but had them replaced anyway. Maybe both blown ? idk
"Something aint right"

The mistaken switching off of a battery at the box in the ER while the engines were running could have been something you don't even remember, or want to remember. It won't help the blow alternators, if that is the case, but would a continuity test from battery terminal to alternator power stud be in order, or are we all pretty sure that path is good?

'The mistaken switching off of a battery at the box in the ER while the engines were running could have been something you don't even remember, or want to remember."

This common error need not be a disaster if the better rotary switches are used.

There should be 2 small terminals on the back of the switch that are field disconnect terminals.They are built to "break , before break", the field is cut before the batt goes to OFF .

Costs only two thin wires and a buck or two extra when purchasing the switch.

The labor to install the better switches is why there seldom found on stock boats.

Did you say that the alternator voltage is responding as RPM goes up but you don't see this at any of the batteries? Your alternator wire goes to the switch, not directly to a battery, is that right? That suggests a lack of good connection between the alternator and battery. If all the other connections are good then I'd be suspicious of the selector switch and/or its connections. I'm also assuming there are no splices or other connections either between the alternator and switch or switch and battery.

I'm not sure how your boat is wired but are you able to temporarily wire alternator output cable directly to a battery rather than through a switch to test it? If it charges then it seems to me the problem must be in that switch...unless I'm missing something.

One last thought. If you have 12V at the alternator it is connected to something. I don't recall if you determined if the switch was only a switch but also a charge manager. In any case it sounds as if something is working like a diode, allowing current to flow from the battery to the engine (and alt) but not the reverse.

Thank you all !
I will be running a few more tests this weekend, Will update accordingly.

I have an almost identical box on my 1983 Model 42 GB Classic with twin Lehmans. But I do NOT have the round cylinders sticking out; just have the same three switches. I have three 4D batteries; engine 1, engine 2 and generator. My switches only turn off the battery itself to the engine/gen starter solenoids. My boat has no parallel battery function.

Updates ...and resolution !

First, thank you to all who viewed and responded to my post.
I'm going with the responses to "the mystery box" provided above. What I do know is that the 3 switches work, they each turn off a battery, and the 2 8D's are connected between the 2 round knobs sticking out.
Turns out to be a red herring. In fact there are wires going there, that I thought would be coming from the Alternators, that I just can't trace! uggg.

I spent the weekend tracing wires and reading Volt meters. My GB has all black wires (numbered at the ends) so it's a scavenger hunt (at best).

Fact - I followed the Positive post wires from the back of the 2 alternators to the lower helm AMP gauges ... then traced the other side of the AMP gauge wires to 2 sides of the battery selector switch (Port and Stb) (this is key) installed at the control panel (added by another owner along the way)
I was stuck at that point and called from Marina help.
Answer:
When this battery selector switch is in the "ALL" position, the 2 alternators "compete" and my STB ALt would lose and the Port Alt took over and could not keep up trying to charge the 2 - 8D batteries, hence the Volt gauges at upper station read low, or not putting out at all (STB side).
So the whole thing was as simple as turning the Battery selector switch to Port or Stb underway. How this got mixed up after so many years of ownership is maddening.
So a consultation with a marina expert and 50 bucks told me what I seemed to already know ...
BTW - I can't tell you what the label under the selector switch read ... too embarrassing at this point

"BTW - I can't tell you what the label under the selector switch read ... too embarrassing at this point "

Come on! After all this effort, we DESERVE to know.

Found this for a 32 GB