Lead/Acid Battery Storage Data

[Cate&Rob]

I have six 12V Group 27 Deep Cycle Wet Cell Lead/Acid batteries (on my boat) that I store completely disconnected for 5 months each winter. Due to COVID 19 concerns, it looks like the boats will not be launched this spring, so I brought the six batteries home for some careful analysis (can you tell that I am bored) These batteries are of various ages.

First, I applied a 600W load (battery tester) to each battery for 10 seconds to equally stabilize them. Then I measured battery voltage at the terminals with two different digital volt meters.
Remember that the following data is after 5 months of "cold storage" with no loads and no charging of any kind.

I was surprised at the two 2018 batteries. 12.56V (95% state of charge)
There are three matching 2016 batteries . Two years older and each individually at 12.39V (75% state of charge)
One 2012 battery was at 12.21V (60% state of charge) I knew that this one was weak and left it in a tub in case it froze and split (it didn’t)

Proves that battery age is an important storage consideration, particularly for these relatively inexpensive Costco/Walmart batteries.

Just FYI . . .
Rob

[bertschb]

Thanks for sharing this information Rob. I'm impressed that 8 year old battery is doing so well.

[Second Chance]

Rob,

Are the six lead/acid batteries for ballast or do you use them in the electrical system?

(Another) Rob

[Cate&Rob]

Thanks for sharing this information Rob. I'm impressed that 8 year old battery is doing so well.

The 8 year old battery is not really doing that well . . . it drops way down during the load test . . . time to replace that one!

Rob

[Cate&Rob]

Rob,

Are the six lead/acid batteries for ballast or do you use them in the electrical system?

(Another) Rob

Ballast or Electrical . . . "Yes" to both!

[Canyonlight]

Thanks for sharing this information Rob. I'm impressed that 8 year old battery is doing so well.

Brian - it is interesting but in the three boats we owned over the years, we experienced the same thing. Our last boat (a performance Baja) the 2 batteries lasted 12 years before we replaced them. This seemed to be the same with many of our other performance boating friends.

I think it may be attributable to only using the boats on and off over 3 - 4 summer months here in the upper plains region and rarely running one of the batteries down to even 60% of capacity. It seems with the batteries being located (for most of our performance boats anyway) in the wide open and large engine compartment near the rear of the boat and as low as could be, they stay pretty cool as well. We all know that heat is an enemy to battery life.

Our boats all had the dual battery cutoff switch to kill both or one of the batteries as well as tap into both at the same time. I think you added one of these to your Solitude(s.)

Dan

[bertschb]

Our boats all had the dual battery cutoff switch to kill both or one of the batteries as well as tap into both at the same time. I think you added one of these to your Solitude(s.

I did add a true dual battery cutoff switch to my last Solitude (Cate&Rob 's recommendation) and plan to do the same today to my new Solitude. I always removed the batteries from my boats and snowmobiles during the offseason and put them on trickle chargers. Never had a problem doing this but after seeing how well Rob's batteries held up by just leaving them alone (with a cutoff switch), I probably could have done the same.

[Cate&Rob]

Canyonlight
Hi Dan,
It sounds like a bit of a cliche . . . but, they don't build batteries like they used to 😄. 20 years ago, we would buy a Trojan battery (for $200 back then) and it would last for 10 years or more. Then that battery became $400. It would still last 10 years, but I found that I could now buy a $100 battery (with the same capacity) that would last 5 years. The math says . . . just buy new cheap batteries every 5 years.

bertschb
Hi Brian,
I have always been afraid of leaving anything powered up on the boat during winter storage, so that meant hauling the batteries home if I wanted to trickle charge them. This is about 500 lbs of batteries! Many years ago, I thought I would try the "cold storage" theory. That first year, I would check those batteries (left disconnected in the boat) about every two weeks! After that, I trusted that they would be fine if they passed the load test before leaving them for the winter. I never had one lose charge, freeze and break . . . but, I know of others who have. Ironically, expensive Trojans that were not properly disconnected. A bilge full of battery acid is a conundrum.

Rob

[Guest]

I disconnect my marine batteries and leave them in the boat which its stored in a building in Ohio. Not had a problem doing this where I typically have been getting about 10 years out of my batteries. I replace them at the same time (2x) and use marine starting batteries, They do not take a beating like a deep cycle battery, so I've been happy with the durability for cheap auto zone marine batteries.

Hope we can do some boating this year as well as camping. I'm getting cabin fever. Not literally.

Jim