Battery Condition Check

J

JoLin

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31399
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368
I've always maintained that if you fully charge and disconnect your batts in the Fall they should still be charged in the Spring. No need to remove them from the boat or periodically top them up over the winter. If they lose charge by Spring, they're due for replacement.

Tough winter in the northeast this year. Temps on L.I. dropped for long periods into the teens and single digits, so I was anxious to see how mine stood up. They're a pair of Group 31 Lifeline AGM's that the PO installed - they'll be 4 years old in May. Normal full charge for AGM's is 12.8 - 12.9 volts.

Slapped the DVOM on them this morning - got a reading of 12.78 volts on one, 12.85 on the other.

At least there's one item I won't have to buy this year :-)
 
Well, you've confirmed they show a surface charge but unless you load test them not much else.
 
Not sure I follow you, but there's certainly plenty I don't know. Both batts worked fine all last season, cranked the engines over fast and provided house power for the weekends out.

They haven't been on a charger since late last October and stayed in the boat all winter. Can they go bad (i.e., not be able to withstand a load) over the winter and still show a full charge?
 
I may not be using the term exactly correctly but what I'm saying is just because you see what appears to be OK voltage with no load on the batteries, does not mean the batteries are in good condition. Once you put a load on the Hattie's the voltage could quickly drop away.

You need to slowly charge them up and load test them to get an accurate picture of there condition.
 
Okay, I get your point. What I failed to mention was that when I got the 12.78 reading on the first battery, I put my smart charger on it just to be sure. The charger displayed a voltage reading of 12.9, and when I fired it up it shut off after about 30 seconds because the battery is full.

I understand that a battery with issues (like an internal short) can show a full surface charge, but I believe one of 2 things will happen- either it'll run down rapidly when a load is introduced, or if left alone it'll lose its surface charge in a relatively short period of time.

Of course, I could be surprised when it's time to start the engines, but logic tells me that a battery that's maintained a full charge through 5 months of sub-freezing weather is gonna be okay.

I actually started this thread in response to the annual fall debate about leaving batteries in the boat vs taking them out, charging them monthly vs trickle charging them continuously vs not charging them at all, etc.

My .02
 
"Tough winter in the northeast this year. Temps on L.I. dropped for long periods into the teens and single digits, so I was anxious to see how mine stood up."

Low temperature storage is much easier on batteries left in the boat then high temperature storage.
I could not paste the link from the lifeline battery site showing just how much temperatures change the discharge rate but it is very significant greatly favoring colder temps. Here is a short cut and past form that site....

"Lifeline AGM Battery Storage and Self Discharge Specs
Lifeline AGM Batteries have the lowest self discharge rates in the industry. Depending on the temperature at which you store you equipment, you may or may not need a trickle charger all winter. Flooded batteries self discharge by over 10% in 24 hours, and 10% every 30 days. When you make the switch, you should take a look before you hook up that old trickle charger to your new batteries."

Hope this helps
 
Sounds like your batteries are ok. I do the same with mine. They won't discharge or freeze if they are still functional. They are however getting a bit old so watch them closely and replace at the first sign of trouble.
Jim
 
I found this Midtronics tester to be great for testing batteries, charging systems and starting systems. It will give you a digital reading of the actual CCA remaining in the battery even if the battery is discharged. It will also check alternators for output or diode ripple.

http://www.midtronics.com/shop/prod...x-p300-battery-tester-with-integrated-printer

Mine is an older unit with a separate printer, but the technology is the same.

Rich
 
A good analogy of Voltage, is electrical "pressure".
Very similar to a garden hose. Where the voltage is the water pressure and the water flow is current (measured in Amps)
You may have good pressure as soon as you open the valve, but when you relieve the pressure it drops significantly.
A load tester is a great tool for battery diagnostics. I have 8 group 31 wetcells and test them every spring.
 
We leave our boat in the water all Winter. So we can't disconnect batteries or the bilge pumps wont work. A couple years ago I came to the conclusion that I should just leave the smart charger on 24/7. I think that's the only way to go.
 
Why wouldn't you leave the smart changer on when in the water? I can't think of any circumstances where I would shut it off.
Jim
 
I don't pull mine becasue I want to keep them charged (although I do that). I remove them so they don't grow legs.
 
Up here in Central NJ; I used to pull those hernia boxes home every winter. It wasn't the weight as much as the position one had to be in to remove them; they were on size 36 batts. I eventually stopped bringing the home. Turned battery switches off & removed items that were wired directly to battery terminals. Would go down once a month; throw the charger on for an hour or so while I went to lunch. Did this for the last 10+ years I owned the boat. No problemo !
BOB J
 
I used to pull the batteries and give them to the yard to put on trickle charger over the winter. I think they charged around $40.00 per battery and I had 3. Seemed like almost every spring, one of the 3 batteries needed to be replaced. I decided to leave them on the boat and just turn off the battery switches. At a cost if $120.00 to trickle charge, I could save that money and buy a new battery if needed after the winter. Bottom line, since doing this I routinely get 5 plus years per battery.
I'm a fan of leave them on board!
 
My AGM for the stereo is totally isolated. Unhooked it last fall. Few weeks ago I hooked the digital charger up and it didn't run for 5 minutes before it showed full charge and shut itself down.
I think it's an 08 0r 09 battery.
Runs the stereo, both cRaZy amps and the 15" sub all day (last summer anyway). Only gets charged at the dock.
AGM Rules.
 
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