The cheap batteries

[john6206]

Hi All -

When we bought the “new to us” sailboat, it came with two new batteries.
Although new, they were the cheapest batteries you could buy at Costco.

The surveyor said they’d be fine for a year, check the water a couple times during the season, and count on replacing them in the Spring.

Last time they were charged was early October, they have been sitting in my garage since then, I just carried them down to the basement and hooked them up to a charger and they both clocked in at 98% charged. To me, this indicates that I have no need to replace them in the spring. Charge them a couple times over the winter and I should be good….

right?

thoughts?

 

[kappykaplan]

I think the only way to know for sure is to run a load test.

 

[dlochner]

A 20 hour load test will give you a definitive answer.

Cheap batteries from Costco may not be so bad. East Penn, a US battery manufacturer offers the same batteries under different labels, including West Marine, NAPA, and others. The batteries are the same as the ones they sell under their own brandname. Find out who made the batteries.

 

[LLoyd B]

I have bought Costco batteries both for my boat and for my car they did not fail before the expected dates. Costco keeps track of my date and proof of purchase by my membership number, don't know if the same guarantee would be in place if someone else made the purchase on their membership. Just out of curiosity how much longevity do you expect from a battery and have you checked Costco's guarantee?

 

[john6206]

Good feedback.
Answer is I don’t know anything about any of this except what the surveyor said (we have the receipts that verify they were purchased in May of ‘25). They performed as expected this season, and seem to be holding a full charge now.

What do I expect from a battery? I don’t know that either, I’ve never owned a boat near this big. On my Capri 18 I had a battery that lasted 10 years, and another that failed after 2. With the 32’ boat the batteries are being charged almost all the time with shore power or engine. Time spent under sail or at anchor drains it.

Capri had no shore power or alternator, took it home to charge it between adventures.

 

[Don S/V ILLusion]

what batteries do you have?
I’ve had a “cheap” Costco AGM in my car for 5 years which performs perfectly(so far). In general use on a boat, it’s common to expect 5-7 years lifetime for properly maintained and properly changed batteries.

 

[FastOlson]

Our "house bank" is a pair Trojan 6 volt golf cart batteries- traditional wet cell. The prior pair lasted 9 years and the current ones seem ok at about 5 years, IIRC.
Keep distilled water in them, i.e. check them regularly, and most any good quality battery should last 5 years.
Strictly..... IMHO.

 

[jssailem]

Well, first, Congrats on finishing your First new-to-you Big Boat season. May you enjoy many more.

Accepting your description as the Cheapest Batteries from Costco, it is nearly impossible to give you a life expectancy forecast.

Their performance will be based on how you charge and maintain them during the winter, and then again during the season. Your description suggests they are basic car batteries and not deep-cycle batteries. This difference will show up in their performance: suitable for motor starting but weaker in providing long-duration power to the boat's general electrical system. The thin plates in the cells of starter batteries are designed for short-duration power draw, then quick recharging.

If you keep them charged and maintained, you may get the full warranty time promised. On the other hand, you may find the lights dimming and the refrigerator warming prematurely for your liking.

Certainly, day sailing or the occasional overnight anchor out should not overtax the batteries.

When you got this reading,

they both clocked in at 98% charged

what type of tool was reporting this charged status?

 

[john6206]

@Don S/V ILLusion
These are Interstate 27DC marine/rv batteries.

I looked them up online and many people report having a good life span on them. I guess the part that weirded me out is that I haven't had to check the water in a battery since 1978 or so (when was the Diehard invented??). Also, the surveyors comments.

@jssailem when I hooked it up to the charger, it read as 98%.

 

[jssailem]

What type of charger?

The only way to know the state of charge is to run a load test.
Here is an explanation of "State of Charge" under-load-battery-voltage-vs-soc

You could also check the electrolyte's specific gravity to get an idea of its charge state.

A battery monitor is also a tool that will help you.

Installing A Battery Monitor - Marine How To

Battery Monitor Diagram This article features the older Victron BMV-602. The 602 has been replaced by the BMV-7oo series. Everything in this article is still relevant to the current series of BMV monitors. Purchasing recommended products from our affiliate partners.Helps keep content coming...

marinehowto.com

 

[dlochner]

@Don S/V ILLusion
These are Interstate 27DC marine/rv batteries.

I looked them up online and many people report having a good life span on them. I guess the part that weirded me out is that I haven't had to check the water in a battery since 1978 or so (when was the Diehard invented??). Also, the surveyors comments.

@jssailem when I hooked it up to the charger, it read as 98%.

The batteries look to be made by East Penn. The clue is the type of battery caps. You do have to check the water in these and use distilled water.

What type of charger are you using? Old style chargers are deadly to batteries.

Don't put too much faith in surveyors. They are often biased and ill informed. Good ones are worth their money, others not so much. A recent thread was started here because a surveyor told the new boat owner his prop was not suitable for traveling the ICW and he needed to install a new 3 blade prop. That's hogwash. Dozens of boats with feathering props travel the ICW each year. I've done it twice with the very prop he was told to remove.

 

[john6206]

@dlochner

hmmm ... I threw out the Schumacher battery charger in my garage that was probably circa 1990. I think I bought the "new" Schumacher battery charger about 10 years ago. It won't overcharge the battery, and you select different types of batteries (auto -vs - marine - vs atv /// AGM vs Standard vs gel). There are other safety features as well.

I was not too impressed with the surveyor. We worked with a great surveyor in Detroit, he was willing to travel to northern Wisconsin, but it would have cost us.

 

[Captain Larry-DH]

Nothing wrong with Costco batteries. Anything they put their Kirkland brand on tends to be significantly better than average in their class and often top notch (In my judgement “grade B“ often better).

 

[dlochner]

I was not too impressed with the surveyor.

I rest my case.

What you want is a 3 stage charger, sometimes called a smart charger. For home based charging Victron makes an affordable one, the Blue Smart 17a (Amazon link). It is a 3 stage programable charger that will work with FLA, AGM, and LFP batteries. I have one I use to maintain my LFP batteries at home.

You mentioned your batteries are home. If they are fully charged and watered disconnect them and leave them in the boat. The self-discharge rate drops significantly the colder it gets. I only brought my LFP batteries home because they weigh under 30 lbs. Who wants to lug 65+lbs batteries around?

 

[john6206]

@dlochner
The advice I was given originally was to leave them in the boat, but then go up once a month or so in the winter season to charge them.

When they parked my boat, they parked it as far away from power as possible. I think there is no way I could charge them on the boat - that's why they are in the basement.

I thought I could leave them in the garage, but every fall I pull all the batteries from the cordless tools and park them in the basement (along with wood glue and a bunch of other stuff). I thought boat batteries might benefit from the same treatment?

 

[john6206]

Thanks everyone fro the input.

What I'm hearing is that there is no need to fear the Costco batteries, and I need to figure out how to load test them, probably invest in a new charger.

 

[dlochner]

Thanks everyone fro the input.

What I'm hearing is that there is no need to fear the Costco batteries, and I need to figure out how to load test them, probably invest in a new charger.

That would be a good plan and you can leave the batteries in the garage, unless you want to skip a day at the Gym.

 

[Don S/V ILLusion]

@Don S/V ILLusion
These are Interstate 27DC marine/rv batteries.

I looked them up online and many people report having a good life span on them. I guess the part that weirded me out is that I haven't had to check the water in a battery since 1978 or so (when was the Diehard invented??). Also, the surveyors comments.

there are all kinds of surveyors. Yours sounds like an example of one buyers should avoid.

 

[dLj]

Are these flooded lead.acid batteries? Are they deep cycle?

It's almost irrelevant who made them. But as others have said, these are likely built by a very reputable producer.

If you can get a charger that can also perform equalization cycles you can get many years of use from these as in more like 15 years. Although that's hard to do on boats, it is achievable. But understand how to care for them correctly is a learning curve. Also getting a charger that will perform a correct equalization cycle is difficult. I use a laboratory controlled voltage / current power supply.

But even without, you should easily get 6 to 8 years even without ...

dj

 

[BarryL]

Hello,

IMO how you treat batteries has more of an affect on battery life than the particular battery manufacturer.

I bought my boat in sprint of 2021. I quickly learned that the house battery bank of 4 AGM batteries was bad. I wasn’t sure what I wanted long term, so I bought 4 of the cheapest marine batteries I could find. These were Walmart group 29DC, 100ah FLA batteries And cost about $120 each. A month later the 2 batteries in the bow that power the windlass and bow thruster were dead as well. I replace those with 2 group 24 batteries. This spring (4 years later) I thought the Walmart batteries would need replacement. I bought a low,cost battery tester and all batteries tested as good.

My boat is on a mooring, so I do t have access to shore power. I used a 100watt solar panel when the boat is on the mooring. The solar makes sure the batteries are always fully charged, and I believe that keeps the batteries in good condition. The only time the batteries get run down is during a distance race. I have a balmar monitor, when the battery is discharged to 50% i run the engine to recharge them. The distance races take 36-48 hours. After the race the batter get completely recharged.

In another year or two I will go to lithium batteries but that’s another story.

good luck,
Barry