Battery Question

[Bradenvlp]

Hi - I have a standard set up on some older Grand Banks with 2 8ds that serve both as starters for their respective engine with a combiner on the ignition switch as well as two house banks on a 1-2-both switch. Addl group 31 for the gen.

Have a promariner 60 amp charger and balmar alts and regulators. Victron batt monitors. Batts really never been below about 65% and usually at 100.

Batts are lead acid and are 7 years old so likely at end of life. However, been out all summer with no issue at all seemed to be holding just fine.

Tonight got to anchor and 1 battery suddenly won’t hold a load at all - flush toilet and lights go out, voltage drops to 9.75 etc.

My question is do LA batts go bad suddenly like this? Or do I have something else to track down?

Thanks -

 

[rsn48]

If you lead acid batteries have lasted 7 years, you are definitely doing something right. The old saying for FLA batteries is - they don't die, they are murdered.

I won't comment on your question as I know there are others here much more capable than I. But to me it sounds like your battery has gone to battery heaven.

 

[BruceK]

Check connections and simple things like that, but at 7 years something might have let go internally. If it`s not happening with the other battery that`s indicative. If they are flooded with caps, try a hydrometer test, easy to do and cheap to buy, or a battery tester. Remove the caps, shine a torch into the cells, you might see something that looks wrong in one or more cells,I`ve even fished out plastic separators in sick batts.

 

[tiltrider1]

Don’t just check connections. Take off the leads and make them shinny again. A classic problem is one of bad connections. Most don’t think about this but a bad connection can keep the amps from getting in as well as getting out.

Cells due short them selves, my experience is that the rest of the battery will cover this fact up for awhile at the expense of rapidly shorting the remaining cell’s lives.

 

[WayneDana2]

At 9.75 volts you have one shorted cell somewhere. With all the cables disconnected hooking a 12v load to each battery and measuring voltage drops with a voltmeter will find your bad battery pretty quick. Take the bad one out of service as it will be generating a lot of hydrogen gas as it boils during charging.

As others have said, you got your money's worth. Time for a new bank.

 

[High Wire]

A rapid failure is usually a bad connection, a dead cell, or ran low on water. Before you change out 300+ pounds of batteries, do an assessment of the banks condition.
Connections clean and tight?
Proper electrolytes levels?
Specific Gravity good on all cells?
When was the last time you equalized the batteries?
Battery case tops clean?

 

[FF]

A quick look will show if a batt case has bulged, IF so that's the one that probably needs to be removed from the set.

 

[Pete Meisinger]

What difference does it make? Dead is dead.

While it may look like a sudden death, those batteries were slowly dying every year for the past seven years.

Some of the new battery chargers,additives and voodoo may get you another year but do you want to go boating knowing your batteries are on borrowed time?

pete

 

[Bradenvlp]

Thanks everyone. I will check and clean all connections this AM (I did that at the battery but will check the other end of the runs etc). Batteries are watered, clean, no bulge etc.

The Victron meter where I can see the voltage drop when load is applied measures off a shunt first in line off the negative leg and that connection is clean and solid. I think that eliminates some of the downstream things...?

I’m just 1-2-both so no banks to sort through. I know which battery it is (1) an can isolate it with the switch.

I haven't equalized in a long time as the charger has an automated conditioning / desulfication mode it runs every 21days. If anyone thinks that really could be this issue let me know but a bit nervous to boil these if there may be an internal issue...

Again, I’m not surprised I need new batts at all, only at how quickly this failed - really in just a few days.

 

[Bradenvlp]

What difference does it make? Dead is dead.

While it may look like a sudden death, those batteries were slowly dying every year for the past seven years.

Some of the new battery chargers,additives and voodoo may get you another year but do you want to go boating knowing your batteries are on borrowed time?

pete

Planned to replace this winter so doesn’t really. But am out on the water for a few days currently. Also didn’t want to stick all new batts in and have the same problem.

 

[Olebird]

The answer is Yes, they can and often do fail suddenly - usually a shorted cell. Find it with voltmeter or hydrometer. Take that battery out of service as it can cause damage elsewhere in the bank. The bank (without the bad battery) should operate normally - but at less AH capacity. Shorts occur as cells degrade and byproduct material accumulates in the bottom of the battery until it's high enough to reach the bottom edge of the plates and short two or more together. LA batteries in a bank " wear" or degrade at the same rate, it's usually a sign that others in the bank will soon be in the same shape.


The life of a LA battery is very predicable - that's why a 60 month warranty battery dies in month 63 - by design!!

 

[Bradenvlp]

Hah. Thanks all for your feedback. All connections are solid and clean. Bum battery is isolated. All new Batteries will be ordered on Tuesday. I had a quote in March for full river
AGM. If anyone can let me know if they have any strong feelings against that would be great.

I would “prefer” to go with 6v but as these work as both start and house in my configuration I think I’ll stick with the current set up. It’s plenty of AH for us.

 

[Bacchus]

Check w mfg but at least East Penn confirmed that for their AGM line all sizes work as deep cycle and/ or start. Unlike FLA apparently AGM plate design are not tailored for different applications.

 

[Olebird]

The "right" battery is a function of the application, ie frequent shallow discharge vs frequent deep discharge, rapid recharge, long periods of no discharge etc. This web site - https://batteryuniversity.com/ - will give you all the info you need to choose. Sticking with builders design is a safe route.



Personally I buy the best I can afford for starting the engine(s) - house bank is a different story. Right now I'm playing with a Lithium-Ion house bank - from a wrecked Chevy Volt.-lotta juice for the weight!

 

[AusCan]

Hah. Thanks all for your feedback. All connections are solid and clean. Bum battery is isolated. All new Batteries will be ordered on Tuesday. I had a quote in March for full river
AGM. If anyone can let me know if they have any strong feelings against that would be great.

I would “prefer” to go with 6v but as these work as both start and house in my configuration I think I’ll stick with the current set up. It’s plenty of AH for us.

Full River are one of the best AGM batteries out there.
With most AGM's, weight=quality. Full River make a good solid deep cycle battery. There are plenty of cheaper AGM's that claim to have high Ah rating but are much lighter. Don't believe it.