Is my marine battery dying or dead?

[Fisherpete]

The past few trips, it seems to be dying really fast when using the trolling motor. Earlier last season, it would run all day and still have half a charge. I charged it a few days ago and used a battery tester, which read 12.75V after charging. Two days later after just sitting in the garage, I re-tested and it read 11.85V. Is she dying or is there some sort of maintenance to help revive it? I am going fishing for 9 days starting Saturday and don't want to do so with a wonky battery.

[forrest]

The past few trips, it seems to be dying really fast when using the trolling motor. Earlier last season, it would run all day and still have half a charge. I charged it a few days ago and used a battery tester, which read 12.75V after charging. Two days later after just sitting in the garage, I re-tested and it read 11.85V. Is she dying or is there some sort of maintenance to help revive it? I am going fishing for 9 days starting Saturday and don't want to do so with a wonky battery.

 

I think CTC still tests batteries for customers. They have a machine for it and will also check the fluid levels and mixture.

 

forrest

[Kerry]

My starting battery was like that.It wouldn't turn the motor over longer than 10 secs then it would die out after a night on the charger.Bought a new one.

Kerry

[Fisherman]

The past few trips, it seems to be dying really fast when using the trolling motor. Earlier last season, it would run all day and still have half a charge. I charged it a few days ago and used a battery tester, which read 12.75V after charging. Two days later after just sitting in the garage, I re-tested and it read 11.85V. Is she dying or is there some sort of maintenance to help revive it? I am going fishing for 9 days starting Saturday and don't want to do so with a wonky battery.

Unfortunately your battery is toast, after what you describe, the way to check resting voltage, full charge, let it sit for a day and it should go no lower than than 12.65 volts. Here is an easy chart to see the voltage percentage, although at 80F, it will be a bit less at lower temps. First column is percentage, second is specific gravity, third is voltage.

TABLE 1. State of charge as related to specific gravity and

open circuit voltage

 

Percentage of Charge Specific Gravity Corrected to

80o F Open-Circuit Voltage

12V

100 1.277 12.73

90 1.258 12.62

80 1.238 12.50

70 1.217 12.37

60 1.195 12.24

50 1.172 12.10

40 1.148 11.96

30 1.124 11.81

20 1.098 11.66

10 1.073 11.51

Edited June 6, 2008 by Fisherman

[Fisherpete]

Came back from CTC, had the battery tested and yep, she was toast. Picked up a Motomaster Nautilus for $100. OK, here's my next question about deep cycle batteries. Is it bad to discharge them till they are virtually dead? The battery ran strong all last summer, then one long day I used it until the trolling motor wouldn't go any more. I charged it a few hours later when I got home, but it never seemed the same after that.

[Gerritt]

Pete, How are you charging this battery? hard and fast? Low N slow? or a combination?

 

I was always told to charge a deep cycle on its lowest setting once the battery hits 60-70% (2a)

 

 

Take a good look at you're charger as well as it could very well be the reason you're battery is toast.

 

 

 

Deep Cycles are meant to be discharged and charged back up.. I believe unlike NmH type of batteries they do not develop crystals that will kill the battery.. you are safe to fully discharge it or partially discharge it as they have no memory.. They just die.

 

Have you used this charger on other batteries for long periods?... any ill affects?

 

G

Edited June 6, 2008 by Gerritt

[Fisherpete]

I charge it with a Minn Kota 110-P charger, which is "Fully automatic 3–stage charging (bulk, absorption,maintenance)" Should be good to go? I got the battery with my boat last year, so I don't really know how it was treated beforehand, or how old it was. It looked pretty new...?

[desship]

Same problem,replaced battery after CT tested at no charge

[Fisherman]

Pete, How are you charging this battery? hard and fast? Low N slow? or a combination?

 

Deep Cycles are meant to be discharged and charged back up.. I believe unlike NmH type of batteries they do not develop crystals that will kill the battery.. you are safe to fully discharge it or partially discharge it as they have no memory.. They just die.

 

 

 

G

Wrong, wrong, wrong...Any respectable battery shop will tell you not to regularly go below 50% discharge, 80% at the very most. The further you discharge, the worse it gets. Batteries only have so many cycles in life from full to empty, the more you fully discharge them, the less cycles you have to use. Deep cycles will also sulfate(crystals) which prevent complete recharging and holding of a charge. Never charge your battery at more than C10(10 % of battery capacity) doing so overheats the plates. Get a 3 stage automatic float charger.

[forrest]

Wrong, wrong, wrong...Any respectable battery shop will tell you not to regularly go below 50% discharge, 80% at the very most. The further you discharge, the worse it gets. Batteries only have so many cycles in life from full to empty, the more you fully discharge them, the less cycles you have to use. Deep cycles will also sulfate(crystals) which prevent complete recharging and holding of a charge. Never charge your battery at more than C10(10 % of battery capacity) doing so overheats the plates. Get a 3 stage automatic float charger.

 

 

I have one of the CTC intelligent battery charges by schumacher: http://www.canadiantire.ca/browse/product_...fromSearch=true

 

12/8/2A charges that does deep cycle.....should I not be using it?

 

forrest

[Gerritt]

Wrong, wrong, wrong...Any respectable battery shop will tell you not to regularly go below 50% discharge, 80% at the very most. The further you discharge, the worse it gets. Batteries only have so many cycles in life from full to empty, the more you fully discharge them, the less cycles you have to use. Deep cycles will also sulfate(crystals) which prevent complete recharging and holding of a charge. Never charge your battery at more than C10(10 % of battery capacity) doing so overheats the plates. Get a 3 stage automatic float charger.

 

 

Thats good to know! Looks like I am going to have a conversation with my mechanic buddy... Thanks for the ammunition!

 

 

Does the same hold true for Gelcells etc?

 

G

[Roy]

Read THIS ...it should disspell a few deep cycle myths.

[Fisherman]

For forrest, I can't access the link from work, but generally Schumacher chargers are okay,

For Gerritt, Gell and AGM's also have different specs for charging, don't quote me, but if I remember right, GELL cells must be charged at a slightly lower voltage, otherwise they fry very quickly with irreparable damage.

And for Roy, good link and info.

[Tybo]

Voltages of a battery means very little.

 

It's all about amperage.

 

To check a battery you have to put it under load.

 

to check the the trolling motor battery. Turn your trolling motor to high.

the voltage of the battery should drop no lower the 12.4 volts on a fully charge battery.

To check cranking battery turn on all eclectic components, hit your kill switch.

then give the engine a quick turn while testing. the battery should not under 12.4 volts.

 

If you don't like this way of testing. Get your self a load tester.

[Fisherman]

Voltages of a battery means very little.

 

It's all about amperage.

 

To check a battery you have to put it under load.

 

to check the the trolling motor battery. Turn your trolling motor to high.

the voltage of the battery should drop no lower the 12.4 volts on a fully charge battery.

To check cranking battery turn on all eclectic components, hit your kill switch.

then give the engine a quick turn while testing. the battery should not under 12.4 volts.

 

If you don't like this way of testing. Get your self a load tester.

Don't want to sound offishbut, if you say voltage means nothing, then why are you quoting voltage while conducting a load test? Testing battery fluid to check specific gravity at a certain temp also works and, at the same instant, those voltages pretty much fall in line with the specific gravity of the battery.

[Tybo]

Most multi meters only can handle a amperage draw of 10 amps.

The starter draw 60 amps and a trolling motor is 30 to 40 amps on full.

 

If you tried to check the amperage straight across your battery, You would

draw the full amperage that the battery is holding at the time.Blowing the

fuse and or burning up the resistor in your meter.

So using voltage as a guide. A good battery will not drop under 12.4 volts when drawing

the amperage that you need.

This is why you never draw the amperage from you deep cycle below 2/3.

It will cause the battery to heat up and cause sulfating.

 

Voltage just sits in the wire until the amperage is commanded to push the voltage,

creating a current.

 

Gravity testers are nice.But are only accurate if you wash them out with distilled water after each use.

Some residue will be left behind, giving you a false reading with the next use.