Testing and maybe Reviving dead/low Deep Cycle Marine Battery?

[jimmwaller]

Hello,

My trailer has been having issues, which means I haven't used my boat in like a year.... just tried to give it a start to make sure everything is still all good and I think (both) batteries are dead or low.

Light, blower, trim, etc all work, but when I try to crank the motor, the solenoid just makes one big click. So maybe it's not 100% dead.

Just to confirm, this is a dead battery, correct? If so, I have a few other questions:

1) what reading should I be getting on a multimeter to know if the battery is good or bad?

2) is it worth reviving? I have a battery shop near me and the guy swears he can revive old batteries.... not sure if it's worth it.

My batteries are 400CCA at 0f; and 500 Marine CCA at 32F.

Is there anything I should try, or just suck it up and get new batteries?

Thanks!

 

[Grub54891]

Did you even consider putting a battery charger on them overnight??

 

[jimmwaller]

Yes I will do that, but wanted to cover all my bases beforehand.

i figure, before I charge them, I should check them with a multimeter and do all those kinds of checks before I charge them.

I kind of feel like, worst case scenario would be to charge them and have them LOOK solid, but then to have them die out in the water. Especially if there is something I could have checked beforehand, like their voltage or something

just want to make sure I’m being safe!

thanks though... good suggestion. Kind of thing I could see my self just... not thinking of, ha

 

[MTboatguy]

Put the charger on them first before anything else, batteries bleed power when they sit for a long time, I have ot charge my deep cycles every spring after they sit for the winter, they don't go dead and they have never froze, but they always need about 12 hours at 10 amps to bring them back to full potential.

 

[jimmwaller]

Interesting... and before they’re charged, can they start an engine? And it’s fine to recharge a dead deep cycle battery and it doesn’t make it more likely to strand you somewhere?
im just worried about... Ive seen like motorcycle/car batteries that die and you can recharge them, but they’re not “healthy”. And they’ll just keep dying after 1-2 starts and won’t hold a charge, etc.

not a worry with deep cycke marine batteries?

thanks!

 

[MTboatguy]

All batteries can be a chance after they have been run down below acceptable limits, but it costs nothing to throw them on the charger and let them sit for 24 hours, find out for sure before you chuck and get new ones, go to Harbor Freight and pick up a load tester for less than $30 bucks and that way after you charge them, you will know for a fact if they have gone bad.

Put the charger on them for 24 hours and then let them sit for a day and then check them, you are not getting a false reading, I always let mine sit and then check.

Reading with a multimeter is not always reliable because you are not putting a load on them. You need to know what they are going to do under a load. During the winter around here, my load tester is my best friend, when you are trying to plow a couple miles of road and you die, you need to be able to rule out the battery.

 

[oldrem]

I would recommend pulling the caps and check fluid levels before charging - charging cells with low fluids can make things worse. If the levels are low, top them off with distilled water. THEN charge and test.

 

[KJM]

as far as i know deep cycle batteries are supposed to be able to be able to be run down low and recharged without any lose of capacity. i think thats what " deep cycle" means. recharge the battery or boost it from a car and let it charge up, it should be fine