Battery Conundrum

[AlaskaProf]

Battery Conundrum:

I have two large symmetrical banks of golf cart batteries. (no generator). They run to two of the typical 4position rotary switches and are cross linked so either bank can be selected. The starboard switch has all the house load. At anchor, the port swith OFF protects the other bank for starting.

Normally, when we go to bed, the Magnum inverter will read 12.3 or so volts. as it did last night. By morning, fridge, computer, phone chargers may draw down to 11.9ish

This morning we were reading 9.8 on arising. Startling, but not fatal; there's another bank still reserved for critical functions. I turned on the Wallas cookstove and it showed a low voltage fault, seeming to eliminate gauge error. Fortunately my cabin heater will make coffee.

Now here's the puzzle: About an hour after we noted the issue, the voltage on the inverter steadily climbed to a normal 11.8v! Wallas stove confirmed this by starting normally.

WTF? over.

 

[KnotYet]

Assuming the voltage readings are accurate - check with a known good multimeter -
12.3 volts is an essentially dead battery. A charged battery will be more like 12.7 volts.
As it continues to be used the volts will decline.

If the load is reduced the voltage will slowly rise to the nominal dead reading again.

I hope this answers your question.

 

[Bacchus]

If this is the first occurrence and no trends of decline lately its worth checking & cleaning all connections.
Also check i dividual batty & cells w hydrometer.

 

[AlaskaProf]

If this is the first occurrence and no trends of decline lately its worth checking & cleaning all connections.
Also check i dividual batty & cells w hydrometer.

Sealed cells, clean terminals. Mystery just got mysteriouser. More soon.

 

[AlaskaProf]

Assuming the voltage readings are accurate - check with a known good multimeter -
12.3 volts is an essentially dead battery. A charged battery will be more like 12.7 volts.
As it continues to be used the volts will decline.

If the load is reduced the voltage will slowly rise to the nominal dead reading again.

I hope this answers your question.

I suspect you are close. New chapter evolving right now. More soon.

 

[AlaskaProf]

As Knotyet deduced, the batteries have aged out. I've owned the boat for four years and was told at purchase that they were "recent". No one to blame but myself, I have ignored the signs that Knotyet pointed out. Aditional one: my windlass has been less than enthusiastic, but because it was just rebuilt, i assumed it was a different motor

We spent last night in Blind Bay, Shaw Island, from where I originated this thread. At engine start, switched to the "protected" bank and found it to be dead also. OH S**T.

Made the $500 call to Boat US and he showed up in 45 minutes with one of those $75 "jumper packs". We are now at dockside in Anacortes, sucking up 110AC. We will marina-hop home for the next few nights.

Still a bit puzzled about both banks failing in unison, but...oh well.

 

[tpbrady]

I would start to trace battery cabling out and account for all connections to each bank. I suspect you might find the banks are paralleled in spite of the switch connection. If the banks are separate when not paralleled through the switch the voltages should be different with the house load running. If the voltages are the same then likely there is another parallel connection. When I bought my current boat I found three parallel connections including the switch. It caused a lot of strange discharge profiles because of different cable lengths.

Tom

 

[fractalphreak]

As Knotyet deduced, the batteries have aged out. I've owned the boat for four years and was told at purchase that they were "recent". No one to blame but myself, I have ignored the signs that Knotyet pointed out. Aditional one: my windlass has been less than enthusiastic, but because it was just rebuilt, i assumed it was a different motor

We spent last night in Blind Bay, Shaw Island, from where I originated this thread. At engine start, switched to the "protected" bank and found it to be dead also. OH S**T.

Made the $500 call to Boat US and he showed up in 45 minutes with one of those $75 "jumper packs". We are now at dockside in Anacortes, sucking up 110AC. We will marina-hop home for the next few nights.

Still a bit puzzled about both banks failing in unison, but...oh well.

Sorry to hear about your batteries dying! FYI We're about 25 minutes away from Anacortes with tools and a pickup, let me know if there's anything we can do to help! Actually headed out there in the AM to pick up a few things at that one store.

 

[AlaskaProf]

Sorry to hear about your batteries dying! FYI We're about 25 minutes away from Anacortes with tools and a pickup, let me know if there's anything we can do to help! Actually headed out there in the AM to pick up a few things at that one store.

Thanks. Most generous, but the immediate problem was solved by the $500 jump start. As long as we can plug in to AC each night, ops are basically normal. We'll be here at Anacortes for Monday night, LaConner Tue., Bell Harbor Wed, and Tacoma on Thursday. Driving home to Ashland Friday, we'll leave battery replacement for next boat visit in a couple weeks.

p.s. come by Tue and we'll have a properly distanced adult beverage.
Bill

 

[FF]

"Still a bit puzzled about both banks failing in unison, but...oh well."

Any one batt that dies in a string of batts will drag the entire set down.

The 1-2-Both switch was used to solve this problem , until they figured out the largest string of batts last longer.

 

[fractalphreak]

p.s. come by Tue and we'll have a properly distanced adult beverage.
Bill

I'm back to work Tues, but might try to find you in Anacortes later today if you're around. Should be out there after lunch running an errand.

 

[DDW]

Lead acid batteries routinely run down to 11.9V are either dead, or you are killing them.

As you replace the batteries, consider a small bank (one or two G24 for example) dedicated to engine start, and the rest paralleled for house use. The 1-2 battery switch went out of style with bell bottom trousers and mod shirts.

 

[AlaskaProf]

I'm back to work Tues, but might try to find you in Anacortes later today if you're around. Should be out there after lunch running an errand.

Inboard end of C dock. Charlie 2; green hull trawler.

 

[FlyWright]

Are your voltage readings being taken when loads are on the bank? What happens when the loads are removed for an hour? Do you have a SOC meter?

I'd take a very close look at all the large cable connections and focus on the grounds. If the batts were paralleled when the 2nd bank went TU, maybe a bad cell(s) on the first bank is/are taking the entire paralleled bank down. Have you checked the specific gravity of the cells? (I'm assuming Lead Acid).

If you need replacement GC lead acids in a hurry, check out Costco for about $90-$100 each.

 

[Art]

Battery Conundrum:

I have two large symmetrical banks of golf cart batteries. (no generator). They run to two of the typical 4position rotary switches and are cross linked so either bank can be selected. The starboard switch has all the house load. At anchor, the port swith OFF protects the other bank for starting.

Normally, when we go to bed, the Magnum inverter will read 12.3 or so volts. as it did last night. By morning, fridge, computer, phone chargers may draw down to 11.9ish

This morning we were reading 9.8 on arising. Startling, but not fatal; there's another bank still reserved for critical functions. I turned on the Wallas cookstove and it showed a low voltage fault, seeming to eliminate gauge error. Fortunately my cabin heater will make coffee.

Now here's the puzzle: About an hour after we noted the issue, the voltage on the inverter steadily climbed to a normal 11.8v! Wallas stove confirmed this by starting normally.

WTF? over.

"no generator"?? - Small portable would run a portable batt charger when needed. Also good for utilizing power tools while out and about!

 

[Slowmo]

I've noticed that when batteries go they tend to fail quickly. Like you we were told our start batteries were 'recent' AGM by the PO. They worked fine, but the engines start instantly so not easy to tell. We were also in Blind Bay earlier this summer and I noticed it cranked a bit slower than I expected but wasn't too concerned (we have a gen). Two days later I realized they were failing. The 'recent' AGMs were neither. I'd guess they were 10 years old, flooded, and some off brand I'd never heard of. We ended up going over to Friday Harbor and buying new Interstates from Jensen Marine. But then Jensens forgot to reconnect the alternator wire, which the young electrician from North Harbor Diesel in Anacortes found in about 3 minutes. Lessons: Don't believe a PO and going to Anacortes v.s Friday Harbor is worth the time.

 

[AlaskaProf]

"no generator"?? - Small portable would run a portable batt charger when needed. Also good for utilizing power tools while out and about!

I had begun thinking like that while anchored in Nodamnplace, Alaska in 2018, but the lesson I came away with yesterday, in addition to: "When your inverter/charger starts sending you messages, pay attention," is, one of those $ 100 jumper cells would be an excellent investment.

 

[AlaskaProf]

Other Warning Ignored:

Over the years I've owned this boat, when shore power is connected, it has gone directly to "float charge" mode. This summer, it has gone to "bulk charge" first.

In the immortal words of Homer Simpson, "DOH!"

 

[AlaskaProf]

Are your voltage readings being taken when loads are on the bank? What happens when the loads are removed for an hour? Do you have a SOC meter?

I'd take a very close look at all the large cable connections and focus on the grounds. If the batts were paralleled when the 2nd bank went TU, maybe a bad cell(s) on the first bank is/are taking the entire paralleled bank down. Have you checked the specific gravity of the cells? (I'm assuming Lead Acid).

If you need replacement GC lead acids in a hurry, check out Costco for about $90-$100 each.

Thanks for the advice. Current batts are AGM, and I'd like to stay with those if only because we live far from the boat and can't check levels as frequently as we should.

No rush to replace, as we are marina-hopping home and the batteries support low-demand systems just fine until the next plug-in.

 

[rgano]

Sealed golf carts which you cannot access the electrolyte for hydrometer testing??

With no genny, you live and die by those batteries; so if you are going to continue with non-AGM GCs, don't you think you'd like to have hydrometer access to keep on top of the batts?

As an aside, is there any part of your engine(s) which require voltage to keep running, say, like a fuel solenoid which has to be held open by voltage? Something to think about as you cruise along on a dead bunch of batteries. I am not sure I would leave the next marina without at least one good battery aboard. How about your VHF if you should go dead in the water or your bilge pumps while sitting DIW. Things to think about before getting UW.

 

[AlaskaProf]

[[dead batteries]]

Thanks for your concern. The batteries charge fine at dockside, and the alternators keep them up at full operational voltage. Issues only arise when we anchor out and they discharge overnight.

 

[FlyWright]

They work great...until they don't.

 

[AlaskaProf]

They work great...until they don't.

As I certainly have discovered this week, but we'll be home in two days where we can deal with this properly.

 

[Art]

[[dead batteries]]

Thanks for your concern. The batteries charge fine at dockside, and the alternators keep them up at full operational voltage. Issues only arise when we anchor out and they discharge overnight.

AP - With all due respect... Please read your post above twice outloud to yourself. Then think deeply about what you depicted actually means.

 

[AlaskaProf]

AP - With all due respect... Please read your post above twice outloud to yourself. Then think deeply about what you depicted actually means.

Okay. Youre too subtle for me. I recognize that the batteries will not maintain a charge, but as long as I am energizing them via shore power or alternator, they will sustain the 12 volt dc systems and the inverter. Certainly what we experienced during the three-hour run yesterday and the 36 hours at dockside.

I must say that Rich pulled me up short when he mentioned the fuel cut-off solenoids, as i hadnt considered this only part of a running diesel engine which requires electricity, but once we got them started, they ran just fine.

Charger and inverter now read 13.7 volts. I am not foo!ish enough to believe the batteries have "healed" themselves, but observation and experience seem to say that throughput will allow normal operation for the 100 miles to home where I can address the problem.

Help me understand the flaw in this analysis.

 

[fractalphreak]

Prof,

What you might consider, since you are having some laytime at marinas during the day, is shut off shorepower for a few hours or so while using some of your electrical load, and see just how bad the batteries are now that they've had some charge. You can monitor your charge state and see just what happens since you're awake and can watch your monitors, such as they are. If they are able to run the boat, start the engines (plus the fact not affect your run back in to Anacortes from Blind Bay) should give you some added assurance that there is not such an issue the boat can't run even for a short period without a degree of safety....

I recall coming out of Roche Harbor after thinking I'd switched fuel tanks and not done it correctly, effectively starving my engines of fuel, and having to bleed one out in open water...needing some start battery power. It happens. Not to you! (But it would to me)

While the batteries have proven they aren't up for overnight, you really don't know what they are up for at this point, correct? A dockside test might help you know their current (ack!) state (and help all your followers here feel a little better

You still don't know if the problem is from how your inverter(S) are using the batteries -vs- how the switches are wired, or if the batteries have truely died died....

 

[AlaskaProf]

Fractal:

Good idea. We'll try it. Chager shows "float charge", suggesting the batteries still have life, just insufficient duration. Just a two-hour run to LaConner today.

 

[rgano]

I am guessing you will be OK; so now you can sit at the helm and worry about all of out what-ifs.

 

[AlaskaProf]

I am guessing you will be OK; so now you can sit at the helm and worry about all of out what-ifs.

It is ever thus.

 

[Wxx3]

Are your voltage readings being taken when loads are on the bank? What happens when the loads are removed for an hour? Do you have a SOC meter?

I'd take a very close look at all the large cable connections and focus on the grounds. If the batts were paralleled when the 2nd bank went TU, maybe a bad cell(s) on the first bank is/are taking the entire paralleled bank down. Have you checked the specific gravity of the cells? (I'm assuming Lead Acid).

If you need replacement GC lead acids in a hurry, check out Costco for about $90-$100 each.

Exactly. Voltage values are suspect without knowing the load at any give voltage reading.
My guess is that there was a significant load with the reading 9.8v, thus when that load was removed, the voltage climbed back to its normal status of 11.8v.