Lead acid battery life

My house bank is 6 years old next month. It is 8-6 volt Crown CR235 rated at 940 amphrs. We cruise about 3000 miles a year and anchor about 40 times a year. Recently the Sterling regulators shutdown due to high battery temp at 122F. Crown tells me this is normal and the batteries are approaching end of life. I see no decline in performance during normal 220 amphr discharges. Has anyone pushed lead acid wet cells beyond 6 years? I need to decide if I want to proactively replace or run to failure.

I have had them last 8 years but they were always on solar.
Therefore, always charged correctly.

Life span ios a function of discharge cycles as a function mostly of total amp hours out and secondarily depth of individual discharges as a percentage of capacity, not years.

Chronological age isn't as telling as number of cycles, and how deep those cycles are. If your batteries have regularly been discharged to a reasonable DOD (<50%) with regular charging to 100% SOC, they'll last longer than an identical bank that's been cycled deeper than 50% DOD and not recharged to 100%. How long they'll last is difficult to predict. You can do a capacity test and check specific gravity to determine the capacity of the bank, there are instructions on performing capacity tests, that may give you some insight into what sort of life is left in the bank, but I wouldn't arbitrarily replace them based on age alone. I'd check individual battery temps, if there's one that's hot, I'd be inclined to replace. That choice also might be influenced by cruising plans. If you're cruising in areas where it's not a problem to replace the bank, running them to failure may not be terribly risky. Golf cart batteries are pretty commonly available.

fryedaze said:

My house bank is 6 years old next month. It is 8-6 volt Crown CR235 rated at 940 amphrs. We cruise about 3000 miles a year and anchor about 40 times a year. Recently the Sterling regulators shutdown due to high battery temp at 122F. Crown tells me this is normal and the batteries are approaching end of life. I see no decline in performance during normal 220 amphr discharges. Has anyone pushed lead acid wet cells beyond 6 years? I need to decide if I want to proactively replace or run to failure.

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Hi Dave,
What is your charging rate (alternator amps)?
Before I did anything, I would verify the temperature by repeating the event and then checking the temperature with another thermometer. I wouldn't call the Sterling temperature probes mil spec. Would also want to measure room temperature. If the engine room is at 115 degrees or greater, it may not be a battery issue. If you have a battery charger / inverter with a temperature sensor, you could try running the batteries down to 70% and then with a cool engine room recharge them with the battery charger and measure battery temperatures during the process.

As a side note my Sterling regulator died again (intermittent functioning), this time out of warranty. Now using a Balmar regulator. So far so good.

Ted

Are aging batts a bit like fading paint, happens so gradually you hardly notice it until...
Are they unsealed and able to be tested with a hydrometer? Easy, and it will tell you how they are. If you`ve been kind to them they may easily exceed 6 years. I`m sure you`ll get some clearer signs without a catastrophe occurring.

I went 7 years on 6 - 6 volt wet cell golf cart batteries once.

During the summer cruise, one battery started dying at a time. I had to shuffle the batteries around as each one died. By the time we got home, we were down to two batteries or 220 amp hours!

As someone mentioned, battery life is based on a number of factors. For my usage, 6 years seems to be the ideal time to replace the house batteries. I buy my Interstate wet cell golf cart batteries from Costco. It's the most battery bang for the buck.

About 20 years ago, house batteries were replaced at 5 year intervals. Since then, more advanced alternator smart regulators and battery chargers were installed and they seemed to have increased battery life and decreased water usage.

"I buy my Interstate wet cell golf cart batteries from Costco. It's the most battery bang for the buck."

Interstates are good , good warranty service ,and lots of dealers which is a concern cruising.Car dealers will have to order the deep cycles , but usually next day delivery.

Uses to be Sears was "everywhere" but......

fryedaze said:

My house bank is 6 years old next month. It is 8-6 volt Crown CR235 rated at 940 amphrs. We cruise about 3000 miles a year and anchor about 40 times a year. Recently the Sterling regulators shutdown due to high battery temp at 122F. Crown tells me this is normal and the batteries are approaching end of life. I see no decline in performance during normal 220 amphr discharges. Has anyone pushed lead acid wet cells beyond 6 years? I need to decide if I want to proactively replace or run to failure.

Click to expand...

Do you routinely, or have you ever, run an equalization routine on those? (Does Crown support that process?)

Tested with a hydrometer?

-Chris

My 4 Interstate 6 volt GCs are in their 8 season. They are getting weak, but still usable.
I've never done any equalization cycle, they have been low on water on several occasions, but I don't let them get below 12.3 v on the meter.

caltexflanc said:

Life span ios a function of discharge cycles as a function mostly of total amp hours out and secondarily depth of individual discharges as a percentage of capacity, not years.

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Using the 500 cycle life standard I should have lots of life left, but I think age will outweigh cycles. My guess is you could get those 500 cycles if you did it in 5 or 6 years. After the years builds up, age degradation eats away at the available cycles. I estimate that we have about 40 discharge/charge cycles a year. The discharge is 220 amphrs or about 25% of the 940 amphr bank.
As a side note, when I was a pup I was a Nuke Electrician on a submarine. A big part of that job was battery maintenance.

If the batteries are truly at 122deg with an ambient temp engine room, then they are ready to be replaced. Also a lot of the charging current is going to make that heat, so it is wasted.


David

O C Diver said:

Hi Dave,
What is your charging rate (alternator amps)?
Before I did anything, I would verify the temperature by repeating the event and then checking the temperature with another thermometer. I wouldn't call the Sterling temperature probes mil spec. Would also want to measure room temperature. If the engine room is at 115 degrees or greater, it may not be a battery issue. If you have a battery charger / inverter with a temperature sensor, you could try running the batteries down to 70% and then with a cool engine room recharge them with the battery charger and measure battery temperatures during the process.

As a side note my Sterling regulator died again (intermittent functioning), this time out of warranty. Now using a Balmar regulator. So far so good.

Ted

Click to expand...

The alts start out charging at 160-180 amps when the banks are down 200+ amp-hrs. I have two Sterling regs on two 120 amp alts. The Sterling temp sensors are on different batteries a few feet from each other. Both regulators reach 122F shutdown at about the same time. This has happened about 6 times on the way north and once while cruising to Norfolk. I also have a temp probe that reads out on my solar controller. It is on another battery and it agrees with the Sterling shutdown. My engine room is hot. It was getting to 110F.

BruceK said:

Are aging batts a bit like fading paint, happens so gradually you hardly notice it until...
Are they unsealed and able to be tested with a hydrometer? Easy, and it will tell you how they are. If you`ve been kind to them they may easily exceed 6 years. I`m sure you`ll get some clearer signs without a catastrophe occurring.

Click to expand...

I have taken hydrometer readings and they are all 1.275 or greater. I agree the hydometer is the best way determine if a cell is bad.

ranger42c said:

Do you routinely, or have you ever, run an equalization routine on those? (Does Crown support that process?)

Tested with a hydrometer?

-Chris

Click to expand...

I only equalize 2 or 3 times a year. I should be doing it monthly. Yes, I do take hydrometer reading 1.275 or greater.

My boat came with 6 6v 435ah batteries that were new in 2009. I am WAY past what could be considered a normal life span. I've had the boat 2 years+ and believe that the boat spent most of its life safely plugged in at the dock. So the charging cycles must be pretty low in number. However, I am looking at replacing them in the near future. I am also adding solar soon, so I might wait until after that has been installed to deal with the batteries. They have been working fine, but recently seem to be more depleted after a night at anchor. Anyway, I am pretty happy with 10 years on my house bank. Just equalized them for the first time. YMMV.

Cheers, Bill

I have 8 seasons of frequent anchoring out on my set of L16HC batteries.

I admit my boat is a power hog and will go through 50% of the 820 amp hour capacity overnight.

This last week I was down to 43% capacity one morning, and my voltage was down to 11.7 volts.

Voltage is what I look at in terms of replacement. When this same set of batteries were new the voltage was about 0.2 volts higher at the same discharge level.

I’ll probably preemptively replace the house bank over winter, but I am doing that to avoid future problems, not because I am experiencing any problems.

There is no advantage in running to failure. With Crown telling you they are nearing the end of life maybe just replace them.

If we boated near a Costco or Walmart, I’d run them until issues appear. Maybe your turn around time could come into play. For us it could take weeks.

My T105s are good for 6 to 8 years with a few months or years likely left. Kinda like an oil or fuel filter change, normal preemptive maintenance for us to avoid that “gotcha” moment.

I use Dyno batteries, 8Dc & 8Dd for starting and deep cycle. With care, a proper charger, keeping the water level correct, clean connections, I easily go 10 years on 8Dds and longer on 8Dcs. When I bought the current boat, it had 21 year old Dyno starting batteries, still working, but not holding a charge more than a week.

Dyno is a top rated US battery made in Seattle. A standard in many commercial boats in the PNW.

T-105's are used in most golf carts they are little work horses



been using them forever.


Also used in many solar applications

Lepke said:

I use Dyno batteries, 8Dc & 8Dd for starting and deep cycle. With care, a proper charger, keeping the water level correct, clean connections, I easily go 10 years on 8Dds and longer on 8Dcs. When I bought the current boat, it had 21 year old Dyno starting batteries, still working, but not holding a charge more than a week.

Dyno is a top rated US battery made in Seattle. A standard in many commercial boats in the PNW.

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I easily get 10 years out of my DYNO L16’s. If you have access to Dyno’s it’s worth the extra money.

I have no name Chinese AGMs that are about 12 years old and currently well maintained except that they have never been equalized. My 24v 500AH house bank, after 225AH has been used overnight, reads about 24.6V without resting in the morning indicating well over 50% remaining. Yes, I have checked the voltage meter against another quality unit and they read the same.
I am the second owner and estimate the boat has spent 200-250 nights on the hook. So, go figure.

GC batteries are good for 1200 to 1500 cycles according to the Club Car and EZ Go and GEM who I used to work with.
That's experience.

Why push your luck. If in doubt, replace the batteries.
I thought my 12vt fridge was going belly up.... turns out, was a low voltage of the batteries even though they were floating with solar.

When mine started giving the symptoms of age that you are seeing, I replaced. Start went 12 yrs, house GCs 11.

OldDan1943 said:

Why push your luck. If in doubt, replace the batteries.

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I don`t get the doubt. The hydrometer reading is better than full, the OP reports no lack of performance. Apart from temp all is normal. The sea won`t open up and swallow the boat when battery performance begin to diminish, there will be indications and there will be time to replace. Unless of course the OP is planning a remote area cruise,then I`d replace.

OldDan1943 said:

Why push your luck. If in doubt, replace the batteries.

I thought my 12vt fridge was going belly up.... turns out, was a low voltage of the batteries even though they were floating with solar.

Click to expand...

Being a former sailor, I’m cheap. If my batteries are 6 years old and I can get another year of use out of them before replacing, then I have just reduced the cost of my battery bank by about 14%. On a large battery bank, that is not insignificant.

Here is a link to some real world testing data on a bank of L16 batteries.

https://pssurvival.com/PS/Batteries/Lead_Acid/Lead-Acid_Battery_State_Of_Charge_Vs_Voltage_1993.pdf

Here is a photo of one of the charts showing the voltage of the bank under discharge at various discharge rates and States Of Charge.

This is far and away the best explanation I have seen written regarding real world voltages to expect from your deep cycle battery bank under load.

Very interesting!

I got 8 years on my dynos before an overcharge and water loss killed them. Had they not been abused, might have gone further. Replaced with agm’s at significant cost and a failing charger cycled them to zero twice in years 2 and 3, but so far so good, but I expect I won’t get the life I hoped. Moral of the story is that batteries only go the distance if taken care of, but often things break and it doesn’t work out. I’ll likely go back to dynos next time and hire someone younger to haul them in and out. I target 10 years, but don’t always get there.

ksanders said:

Here is a link to some real world testing data on a bank of L16 batteries.

https://pssurvival.com/PS/Batteries/Lead_Acid/Lead-Acid_Battery_State_Of_Charge_Vs_Voltage_1993.pdf

Here is a photo of one of the charts showing the voltage of the bank under discharge at various discharge rates and States Of Charge.

This is far and away the best explanation I have seen written regarding real world voltages to expect from your deep cycle battery bank under load.

Very interesting!

Click to expand...

This corroborates measurements I did on my inverter bank of L16s. However voltages themselves at any given point of time are not a good indicator of state of charge, you can have a big temporary draw down (like a microwave or a starter) that when over, the bank is still near full SOC. Before we upgraded to an automatic generator starter that used SOC rather than volts, we often got "false starts" in the morning from running the microwave and /or the coffeemaker if we didn't turn the AGS off first.