What happened? House batts went dead

[Per]

Hope to enlist a few of the marine electrical experts on this board..

recently on the hook, for just one day and one night.

went ashore for some dinner and fun times with friends.

come back to a dark boat with no power..

the starting batts were fine, i could crank the engines, but anything related to house banks were dead.

in the AM I ran the genset for 30 mins and got some power back on the house batts.

then cranked the engines and headed home, apprx 1 hr into the cruise home the house system got depleted again and was NOT taking a charge from the engine Alternators (i could see the alternators were putting out but perhaps only to the engine batts?)

got home safe and hooked up shorepower, everything came back fine but i do not understand why the alternators were not charging the house batteries....

mind you the house bank was dead, completly system shutdown.

what i have:

4 x AGM batts (2 for starting and 2 for house)

blue sea switch

*

help?

 

[Codger2]

Per wrote:
.....the starting batts were fine, I could crank the engines, but anything related to house banks were dead.

_________________________________________________________________

I had a similar happening a few years ago. House batts were dead but starting batt (not connected with house batts) was fine!

Solution: I don't have a generator on the boat & I left my inverter on when I left the boat & the batt charger (110v) was still on! The inverter continued to invert and run the batt charger until the house went dark.

I have learned to turn the breaker to the charger off* when I'm running (I need 110v for the refrig, coffee pot, TV, etc.) or at anchor and can last 3 full days on the inverter alone.

 

[JD]

SeaHorse II wrote:Per wrote:
.....the starting batts were fine, I could crank the engines, but anything related to house banks were dead.

_________________________________________________________________

I had a similar happening a few years ago. House batts were dead but starting batt (not connected with house batts) was fine!

Solution: I don't have a generator on the boat & I left my inverter on when I left the boat & the batt charger (110v) was still on! The inverter continued to invert and run the batt charger until the house went dark.

I have learned to turn the breaker to the charger off* when I'm running (I need 110v for the refrig, coffee pot, TV, etc.) or at anchor and can last 3 full days on the inverter alone.

Seahorse may be right.* If not could be a short in one of the house batteries which would affect both.*


-- Edited by JD on Tuesday 12th of July 2011 03:50:20 PM

 

[Moonstruck]

SeaHorse II wrote:Per wrote:
.....the starting batts were fine, I could crank the engines, but anything related to house banks were dead.

_________________________________________________________________

I had a similar happening a few years ago. House batts were dead but starting batt (not connected with house batts) was fine!

Solution: I don't have a generator on the boat & I left my inverter on when I left the boat & the batt charger (110v) was still on! The inverter continued to invert and run the batt charger until the house went dark.

I have learned to turn the breaker to the charger off* when I'm running (I need 110v for the refrig, coffee pot, TV, etc.) or at anchor and can last 3 full days on the inverter alone.

*Per, Walt, and JD,

So as not to high jack this thread I am going to start another about setting up inverters.

 

[FlyWright]

Bad ground on the house bank? How are your alternators connected? Do you have a 1-all-2 off switch? Old or weak, dying batts from insufficient charging?

Battery voltage speaks volumes about battery state. Do you have a way to measure the house battery bank voltage?

We need more info.

 

[Steve]

One of the battery monitoring systems as made by Link or others can give a lot of information about the system.
Steve W.

 

[Per]

FlyWright wrote:
Bad ground on the house bank? How are your alternators connected? Do you have a 1-all-2 off switch? Old or weak, dying batts from insufficient charging?

Battery voltage speaks volumes about battery state. Do you have a way to measure the house battery bank voltage?

We need more info.

*yes i have a 1all2 switch and a bluesea installed switch.

the switch is in the 1+2 position, i never turn it off.

i dont think i could run the charger off the inverter since it is one and same unit (xantrex).

the batts are in good shape (i am pretty sure), i will double check the voltage (i do have a batt v-meter built in), once i take it off the charger/shore power how long should i wait to meter the voltage?

what i really dont understand is why when i was running home, the house batts did not get recharged by the amps from the engine alternators. could it be somehow the bluesea switch did not open up to let the charge come in? perhaps if the voltage is lower than a set voltage like 11 volt, it will not open?

 

[FlyWright]

I'm not sure how the Blue Sea ACR works, but my combiner only closes after the charging battery reaches 13.2V for several seconds. Here are some specs I found on a Blue Sea website. (http://bluesea.com/category/2/productline/overview/387) Not sure if it's the same as your model.

Combine (30 sec.) 13.6V @ 12V DC
Combine (90 sec.) 13.0 V @ 12V DC
Open (10 sec.) 12.35V @ 12V DC
Open (30 sec.) 12.75V @ 12V
Open High 16.0V @ 12V DC

I'm not sure how your alternators and switching is wired, so it's hard to diagnose.

On my former setup, the alternators charged the batteries through the start cables and the Perko switch. If the Perko was on 1, only the house batt got charged. If the Perko was on 2, only the start batt for charged. I'd start in the 2 position, then switch to all to charge both banks while underway. Then when I got to my destination, I had to remember to select 1 to avoid draining the start bank while on the hook.

I changed this setup recently so that each alternator now charges its own bank via direct cabling. A combiner is present to allow one alternator to charge both banks, if needed. The loads are completely split and there is no need to mess with the Perko switches unless i need to tie the banks together due to a low start bank.

I have had problems in the past of one alternator not coming online unless I revved the engine above idle RPMs. Then the alternator charges and the tach comes to life. Maybe you had something similar happen? Maybe a slipping or broken alternator belt? Do you have ammeters? A constant scan of the voltmeter will also help in identifying a problem. You should see 14V+/- when the alternator is charging properly.

The way it was explained to me, the voltage difference between the alternator and the battery (i.e. 14V minus 12V) is kind of like the size of a pipe filling a reservoir. The larger the pipe, the easier it is to pump water into the reservoir. The amperage is like the flow of water going through the pipe. If you have a small difference between the charge voltage and the battery, there won't be many amps flowing into your battery. If your alternator voltage is dropping (i.e. bad voltage regulator), you won't be able to charge the battery very efficiently. The ammeter will allow you to monitor the flow of amps into the battery. A volt meter will give you a look at the size of your pipe. ;-)

I just installed a Xantrex LinkPro battery monitor to help me watch these parameters and the batteries' state of charge. It will help me to keep the batteries healthier and more fully charged so I do not deplete them unknowingly. I'm hoping it also helps me see potential problems before they reach crisis level.

After receiving a charge, the batteries will show high voltage, but this can be just a surface charge. If you place a light load on the batteries (5 amps?) for about an hour, you'll get a better look at the true battery voltage. Checking the specific gravity of each cell can also help ID a bad battery. Usually one cell gives out before the others. If they are all weak, you might have more of a charging problem than a battery capacity problem.

Check all battery connections and grounds.

 

[Per]

Flywright, I appreciate your input and will have to do some trouble shooting to figure it out.

 

[Per]

ok , all 4 batteries are showing 13.25 V (after being fully charged and then taken off the charger for 30 mins with load) so i think the batteries are all intact and in decent shape.

i checked alternators and they work fine, putting out little over 14V at 1200 RPM.

there must be some reason the bluesea switch didnt open to let the current into the house batts and only the engine batts were charged...

 

[dwhatty]

If your Blue Seas ACR is like mine (the one on the right below), it has a rotary switch on top. Don't want to offend, but is it in the correct position and with the push button on top of the rotary knob in the correct position?

*

 

[Per]

yeah, thats not the unit i have.
this is the one i have:
http://bluesea.com/category/2/productline/overview/387

i crawled around in my ER last night trying to solve this mystery.
the ACR is connected to the two house batts on one end, and the engine batts on the other side.
lets just pretend the juice is getting sucked out of the house batts, at some point the ACR isolates the engine batts from the house circuit to protect everything to get depleted (lockout happens at 10.8V)
this is fine, thats how its supposed to work.
so i crank up the two CATS with no problem..
now the engines are running, alternators are cranking some amps into the engine batts.. but why not also into the house bank?
the unit should "combine" when it senses a charge of 13V or higher for a period of 2 minutes. (i have tested my alts and work fine).

now my batts are fully charged and the ACR is combined.
perhaps the only way to find the error is to deplete the batts to 10.8V again..

 

[FlyWright]

The ACR should combine the batts during charging, then disconnect when the charging stops to keep the house loads from draining the start batt. With proper charging and healthy batteries, your batts should never become depleted.

Is your house bank holding a charge after some loads have been applied for a longer period of time? I don't think checking battery voltage 30 minutes after charging with a light load is accurate. Any voltage over 12.6V is surface charge.* If your batts got down to 10.8V, they were down to about 5% charge.* Anything below 50% (approx 12.1V) can cause battery damage.* I wouldn't intentionally run a bank that low.

Here's a good guide on testing your batteries:

http://www.marxrv.com/12volt/12volt.htm#testing

*

Here's a good Voltage-State of Charge Table

 

[Per]

i cant say if the house batts was at 10.8 or under, just according to the blue sea folks thats when the ACR lockout the two batts.. sounds to me like perhaps they should have set that threshold slightly higher.
i did not enter the ER to verify one way or another when i had the problem (to see if the combined LED was lit or not..)

 

[Per]

well, i have learned a lot about my electric system..

finally i called bluesea system and now i understand..
when the banks are being depleted, volt is going under 12.75 (both banks combined), the acr will isolate.
if between 10.8 and 12.75 Volt a charging source is detected for 30 secs or 120 secs (depending the voltage), the acr will combine again to accomodate charging of both banks.
if the V on either bank goes to 10.8, then it will shutout to avoid a bad cell depletion even if a charging current is detected (on the other bank).
the only two options are:
jump the two banks (my acr doesnt have the override switch).
supply a charging current to the 10.8 V bank to bring it over at which point the acr will combine again.

i have alternators only charging the engine banks.

the house banks are charged by shore power, generator and solar panels.

i guess the good news is that everything works the way it is supposed to do.

btw
i am upgrading my starboard alternator to a 105 amp hd version..