Charging issue

JoeStang

So I've had a strange issue since middle of last season, and before I install my 2nd house battery & charger I want to figure it out.

I have the following switch with 1 starting and 1 house battery.



My normal routine since day 1 has been to ONLY use on & off, I've never had to combine the batteries for any reason. When the house battery was spent from a day on the radio I simply started the boat and charged it back up, never moving the switch. It always automatically charged both batteries in the 'On' position.

Well now it seems like it is NOT charging the house battery unless its in the 'combine' position. I confirmed this yesterday, as my VVM was showing 11.8V with the switch to 'On' and when I moved it to combine it jumped immediately to 12.9V. My house battery was basically dead from last weekend, but it should not have been. I had a 20 minute ride back that should have charged the house battery.

Is it as simple as replacing the switch? I just dont want to throw parts at it if it could possibly be something else.

Stodge

The last time I installed a battery charger (ProMariner 3 bank 30amp if memory serves)  the directions said to run the output from the charger directly to the batteries.  That's what I did.  Bank 1 to port starter, bank 2 to starboard starter, bank 3 to house.

In your case a 2 bank charger should do the trick.

JoeStang

Stodge, this is separate from a battery charger. I havent installed that yet, this is the charging from the alternator through the battery switch.

zaverin1

It’s deff the switch
ans FYI 
dead battery won’t charge in 30 minutes
thats when battery charger/tender kicks in

zaverin1

Flip side would be the house battery not taking a charge.
how old?

JoeStang

Both batteries are brand new, just got them a month or so ago. I'm gonna order a new switch, probably the best and easiest spot to start.

Handymans342

Those switches rarely fail

Cableguy Greg

I had a similar issue on my 280EC. The house battery wouldn't charge. I replaced the batteries to have the same problem. I found two issues, one was the breaker in the switch panel was bad. It kept tripping for no reason. The second issue was the wires on the back of the house breaker were loose. I replaced the breakers and tightened all connections and I haven't had a problem since. Chances are the breaker was good, and the loose connection was causing the problem. I can't picture the switch failing like Handy stated above.

zaverin1

Could be or corrosion behind the switch
lots it times your will see a burn spot on the back of the switch.

JoeStang

Cableguy Greg said:

I had a similar issue on my 280EC. The house battery wouldn't charge. I replaced the batteries to have the same problem. I found two issues, one was the breaker in the switch panel was bad. It kept tripping for no reason. The second issue was the wires on the back of the house breaker were loose. I replaced the breakers and tightened all connections and I haven't had a problem since. Chances are the breaker was good, and the loose connection was causing the problem. I can't picture the switch failing like Handy stated above.

The only difference is that my house is charging when I switch it to combine. I've checked it with a multimeter and the cables disconnected. Dead after a day of music, no charge when in the on position, charging when in combine. Makes sense it would be the switch, since if the breaker was bad it wouldn't charge at all. 

Willhound

Your alternator feed runs to the switch and then to batteries? Mine runs from alternator to isolator to batteries. Batteries all charge regardless of switch position. Switch doesn't come into it.

JoeStang

I didn't know that. I assume mine is wired the standard way. So I could have an isolator issue?

Handymans342

I did. Do you have an isolator?

Dude_Himself

Joe: I would start at the alternator and meter back to the house battery. You have an isolator on the firewall near the generator muffler - make sure it's still working (they don't fail often as they're dirt simple). Then follow that wire to the back of the battery switch. The battery switch doesn't disconnect the alternator output from the battery - it disconnects the load.

JoeStang

Ok well here's what is happening 100%. 

Switch set to ON = No charge to house battery, charging starting battery correctly. All systems powering correctly. 

Switch set to COMBINE = Charging both batteries equally and correctly. All systems powering correctly. 

Does that speak more to a switch or isolator issue?

Handymans342

Didn't see an isolator in the pictures

Cableguy Greg

The alternator feeds the isolator. From there, the two lines, one for the house and one for the starting go to the breaker then to the switch. The charger is connected to the "output" side of the isolator. If you are getting a charge on shore power and not from the alternator, then I would start at the isolator. It is what feeds power to both batteries. Here is a diagram from my boat. Yours should be similar. The difference is the part with the Gen Power, STBD Shore Power, Port Shore power switch.

zaverin1

I don’t believe he ever had bank charger
installed 
so I doubt he has one of the oem isolators

JoeStang

No OEM charger, just installed an aftermarket unit, but that's got nothing to do with this. Trying to figure out why it's not charging the house battery with engine running in the ON position. 

zaverin1

If you have no isolator 
remove the switch and check wires with flow meter 

zaverin1

Lol
volt

Dude_Himself

Ok, let's see. First assumptions:

1. you're using the alternator to charge the batteries
2. you have a house and starting battery run through a BSS Dual Circuit Switch
3. It was working as intended previously and stopped.

The alternator provides 14.4-6 VDC to the battery(s), stabilized by a regulator. At higher RPM's and lower loads the regulator generates heat to keep the voltage near constant. This current is sent to the isolator, which allows the batteries to charge independently of their loads: if there's no current input on the isolator the batteries outputs are disconnected. One battery can't charge the other.

Isolators are great cause they're cheap, but suffer a voltage loss. There's alternatives: solid state combiners, and automatic charge relays (ACR's). Solid state combiners are small microcontrollers mated to heavy-duty transistors: it's great because you can add other behaviors with little modification to the software to protect the battery from being overdrawn (at 11.x volts disconnect the load from the battery). ACR's are similar, but instead of a microprocessor they use capacitors, relays, and a timer.

Without an isolator/combiner/ACR there's no way to have a two battery system charge off a single alternator without manually switching the loads. 

In your case, the reason why the Combine position works is because it's bridging the two batteries together. 



Normal operation is make/break for both battery 1 to load 1 and battery 2 to load 2. The Combine position bridges battery 1 to 2 directly, combining the batteries into one bank and sharing them to the loads. In this position the good battery will push a charge into the bad battery, and the alternator will keep both charging. I think the switch you have has a 350A rating, which is more than even a high-capacity alternator could put out.

So why aren't you charging? I dunno. I'd start with a voltmeter at the alternator. Check for the appropriate output, then follow the wire to the next stop:

Isolator/Combiner: meter out the inputs and outputs to verify operation.

Starting Battery: check that battery's load circuit for an ACR.

Battery Switch: check for loose connections.

My honest guess is that this happened following some work on/near the batteries, and that if you dig around you'll find a heavy-gauge wire disconnected from the battery, or possibly connected to the wrong battery (I've done this). Or a loose ground - cause that'll cause all sorts of odd behavior.

Dude_Himself

zaverin1 said:

I don’t believe he ever had bank charger
installed 
so I doubt he has one of the oem isolators

The oem isolator is specifically for the alternator. The bank charger has seperate banks - they connect directly to the batteries.

JasonA

Just had this same issue fixed, it was the isolator.

JoeStang

Sounds like I need to take some more pics and find out exactly what I have. Just to be clear, even if I dont have shore power or a charger from the factory, I still have an isolator?

Cableguy Greg

If you have two batteries and a switch from the factory, then you probably have an isolator.

JoeStang

Ok got it, will be at the boat tomorrow and investigate.

zaverin1

On some setups switch is the isolator 
depending on what he finds 

Willhound

Pretty easy. Just trace the feed wire from alternator and see where it goes first.

Dude_Himself

zaverin1 said:

On some setups switch is the isolator 
depending on what he finds 

You'll have to link a switch that has a built-in isolator/combiner/ACR. I've not seen one before. And the PO of his boat would have had to substantially re-wire the boat to support this architecture.

JoeStang

Ok, so did some more digging and found my isolator. Its mounted just forward of the battery switch box, which is the grey plastic covered area. 




 All wires are secure and everything appears to be fine. Just no charge to the house batteries when the switch is set to ON.