House Batteries Not Charging

[Scott A]

Engine is a single 6BTA.  Looks like the alternator is not charging the house batteries.  Here is the scenario:  When I am running on the generator and the battery charger is running, there are no electronics issues.  If the generator is shut off and the engine is running, after a couple hours, the house batteries appear to start to go down and the first symptom is that I start to lose my troll function on my Glendinning controls, likely due to an amp issue.  I have replaced the alternator with the higher amp alternator (which was in my plans anyway) and it is still happening.  I have two battery banks.  One bank has starting batteries, which are on a separate battery switch.  My house batteries are two 6s in line and have one simple on/off switch.  I then have a separate emergency cross over switch if needed (never used it).  I’m thinking the battery switch may be bad on the house side and not allowing the alternator to charge the house batteries.  Also, is there possibly a fuse between the alternator and the battery switch somewhere that I need to track down.  One final thing.  Both house 6volts are brand new deep cycles.  I replaced them when the problem started, assuming it was old/bad batteries.  Any other Suggestions??

Topic

[Clark Leighs]

Glad you found it an it was simple.

[Scott A]

Update and easy fix.  As I originally suspected, it was a fuse, but not on the battery switch side (well, not exactly).  There were two in-line fuses between the Blue Sea Charging Relay and the different battery bank switches .  One on each side of the battery charging relay.  Stuck a volt meter on it and found one side was bad, the other was good.  It was a simple fuse replacement and everything works now without the generator being run.  Also discovered another fact as I was digging through it.  My AC is very low in the boat.  The AC drip pan is designed to go into a holding tank and then pump out.  The pump wire is wired directly to one side of the Charging Relay (on the other side of the fuse I replaced).  Consequently, the pump was not working and water was draining into the bilge.  Once the fuse was replaced, pump was energized again with the battery switch on and AC started pumping overboard again from the drip pan holding tank.

[Clark Leighs]

I wrote this in  flap so I hope you can decipher my meaning.     If you have trouble, ask

[Clark Leighs]

Late, I know.     I have only skimmed this    but I think somethnig basic has been missed.

WHen trolling what rpm do you operate at?

No voltage drop problem whwn the generator is running?

At idle or near it the alternator CANNOT supply all the current you are likely drawing.  Stereos, marine electronics..

Get ahold of  an output graph of your alternator or for that matter any alternator that has an ouput close to that of yours and take a look at the ratings or amperage output vs alternator rpm.    NOTE THIS IS ALTERNATOR RPM,    NOY ENGINE RPM.

ALL alternators require a MINIMUM rpm to produce maximum power or close it. If you are idling or operating close to that idle rpm the alternator   CANNO put out anywhere near its rated ouput.

Many alternators, most,  when operating slowly as is often the case when trolling  can only produce 10 to 20  % of the so called rated amperage.    NO, the alternator WILL NOT be even close to it’s rated output.

 

 

Before getting all haired up an changing things, blamint the alternator an so on get or borrow a clamp on DC ammeter, YES DC, AC ONLY IS USELESS and check the alternator  output at you trolling rpm.     THis can be done dockside.  I will guess you will find it can only produce a limited amperage.   THere are other alternators

that are built to produce much higher current at just off idle fo appications like EMTs,  Fire trucks, emergency vehicles.    

 

Check into it.

 

Clark

[Scott A]

I figure the crossover switch (as it is wired) should bypass ACR the way it is setup and send alternator current directly back to the house battery circuit.  That is probably the best way to test it for now.  If that shows current going to the house side, I think I’ve diagnosed the problem.  I’ll then replace the ACR and swap the alternator to the other side of the ACR to link it with the house batteries more directly.  I also assume once done, I can place a volt meter on the alternator side of the ACR and to the ACR ground wire and confirm the ground is good, right?  I guess I could also start by putting the volt meter on the alternator side of the ACR as it is now and then not only test the ground but also confirm the volts coming into the ACR to confirm alternator power is getting to the ACR.

[Gene Fuller]

I don’t agree that you should be using jumpers, even in the short term. In the short term you should be using the parallel switch to facilitate charging of the house bank.

That will certainly help determine if the overall charging system is working, but it adds an extra complication beyond the ACR by itself. The jumper is kludgy at best, but it completely targets the ACR and only the ACR.

There could be other wiring issues beside the ACR.

[Scott A]

Thanks JimmyK.  I’ve got a new relay switch arriving today.  Before I change out the switch, I’m going to get the engine going and engage the parallel switch and check the house breaker panel volt meter to ensure that the alternator is sending current and there is not an issue outside of the relay switch.  If no issues,  I am going to change out the relay and rewire the alternator to link straight with the house battery circuit at the relay switch.  I never turn the engine off while fishing.  I have a lot of electronics running, including electronic trolling valve actuators, side-scans, etc. that are of primary importance.  I feel like I need to ensure the shortest route to the house batteries.  Thanks for the input. 

[JimmyK]

I would agree that it sounds like the charging relay is not working.  I think you got some good tips on how to trouble shoot it.

I don’t agree that you should be using jumpers, even in the short term.  In the short term you should be using the parallel switch to facilitate charging of the house bank.  The charging relay does the same thing as the parallel switch, but does it automatically.  To replicate the behavior of the charging relay, turn the parallel switch ‘on’ after you start the engine and then ‘off’ after the engine is stopped.  Again, this is exactly what the charging relay does when it’s working.

Long term, either replace the charging relay or figure out what is wrong with it (fuse, ground, etc) and fix it.

[Gene Fuller]

The alternator will not care if the charger is connected, as long as the maximum voltages are more or less the same. (I assume this is a standard 12 volt system with a maximum voltage in the mid-14 volt range.) The alternator will just see what looks like a fully charged battery and will not try to produce any extra voltage or current.

[Scott A]

The lightening strike is an interesting comment.  The only thing that happened in the interim was I had a shore power plug go bad and start to burn up.  Luckily, I caught it immediately.  I am wondering if that may have damaged it.  I would have thought that AC system would have been more isolated than that.  

I am worried about damaging the alternator if the battery charger is on the same circuit and running at the same time as the alternator.  When the generator is turned on, the battery charger comes on automatically.  I can turn the charger off manually but since that is a human factor, we all know what can happen.

[Gene Fuller]

The Blue Sea charging relays will not combine if the ground connection is bad. A standard installation places a fuse in the ground lead to the ACR. (Unusual to fuse a ground, but in this case it is the right thing to do.)

Check for a bad ground.

You can temporarily “rewire” by using an ordinary jumper cable across the two ACR terminals. (Just one wire from the jumper cable pair, of course.) Most chargers will not be damaged by another source pushing the voltage higher. The “three-stage” behavior may get confused, but that is not permanent.

You can place an ordinary DC multimeter on the two main terminals for the ACR. If it is working (combining) the voltage difference should be less than about 0.02 volts.

I have used the Blue Sea ACRs for many years. The only failure was due to a direct lightning strike.

[Scott A]

Attached is what I believe is the wiring setup.  I traced the wires I could so a few of these are assumptions but make sense.  (there are some smaller starter wires, etc. not shown).  I think the Blue Sea charging relay is bad.  It is a 7610.  Tested this weekend.  House batteries are not charging at all when engine is running without generator and charger on.  House batteries are new.  Starter batteries are new as well.  I replaced both when this issue came up.  The relay seems to be the only common denominator.  One question I have is, could I move the alternator charging wire over to the house batteries so it is a direct connection, or is that a bad idea since the charger is on the same circuit?

[Bill Desmarais]

one more question?

When running on the engine (no generator or charger) is there an isolator between the alternator and both start and house battery banks to keep both banks charged ?

[Tony Athens]

IMO, if you do not know how your DC power distribution system  is wired,  and do not post a diagram of such, I do not see  a solution going about it this way.  No crystal balls here

[Rob Schepis]

A lot of important info is missing here.  From what you did post it sounds like the alternator setup to only be charging the crank bank.  Then there is a connecting device to connect the house bank to the crank bank such as a charging relay.  If this is the case that relay may have failed or has been switched into “always open” mode.  The alternator output is likely wired to the starter lug, no fuse.  All guesses as we have no real info on your setup and really need a DC diagram to offer anything but guesses.  And you should have voltmeters monitoring each bank so you know instantaneously what is happening at all times.

Installing Digital Volt Meters (DVM) on Your Boat

Typical DC Power Distribution Examples for Marine Engines

[Scott A]

This is a new problem that just started.  Never had the problem until just recently.  Nothing else has changed.  That’s why I’m thinking the switch is not allowing the alternator to send a current back to the batteries. 

[1969Roamer46]

Sounds like there’s no electrical connection between the alternator and your house bank. Have you tried putting jumper cables across the two banks? That would bypass all of the switches and let you know if it’s an alternator problem. My guess is, it’s not the alternator.

That “emergency cross over switch”…are you certain that’s only for emergency use? If a cable doesn’t connect your alternator to the house bank, it won’t get charged by the alternator.

[Author]

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