How do you know when your battery is dead?

[Davekfl]

How do you know when a wet cell battery has bit the dust? My depthfinder wouldnt work today other than GPS and my trolling motor was running real slow at all speeds. I finally saw a quick message on my depthfinder that said low voltage before going blank. I have an onboard charger and it does not give me any indication of a battery problem. matter of fact it shows fully charged batteries on both banks. the depth finder and trolling motor are on the same deep cycle battery. Thanks in advance for any advice.
Davekfl

[Putershark]

Batteries can show good voltage, but not enough amps... Their are a couple of ways to tell though without having a load tester handy.

1. Feel the sides of the battery and see if you feel a bulge, usually a good indication of a shorted cell.
2. Hydrometer test is pretty simple and a low cost tool as well as being pretty accurate. Test each cell (if the water level is correct) and measure the specific gravity for each. If found low on water which is very common here in the Florida heat which usually kills unloved (un-watered) batteries in 3 years or less... Just put in some distilled water and put on a low charge overnight then re-test.
3. Use the engine as a load tester... If it cannot start the engine several times in row without getting the click of death, time for a water level check and overnight charge. If still acts the same, time for a new one...
4. Take it out and run it by any auto parts store. They pretty much all have load testers to check them.

Dave your issue though could also be a simple loose ground or connections that are loose behind the battery switch if you have one... Loose connections on the back of the A-B switch has burned me more than once! Well, at least till I got smart put some lock washers on them

[Davekfl]

Thanks Dave

[cagrove]

Originally Posted by Putershark

Dave your issue though could also be a simple loose ground or connections that are loose behind the battery switch if you have one... Loose connections on the back of the A-B switch has burned me more than once! Well, at least till I got smart put some lock washers on them

I had the same thing...voltmeter showed a full charge but fishfinder wouldn't power up and engine wouldn't start...cranked once and then nothing. Found a loose negative terminal connection, wing nut had backed off about 1/4 turn. Tightened it up and everything worked fine. Now it's part of my pre-launch routine to check the wing nuts. I hope this helps.

[Troll]

When a battery gets more than 3 years old, it is probably time to replace it. Boat batteries just can't take the abouse a boat setup gives. Go to your local big box store and look at the warranties on the batteries for cars. Many will give you a free replacement for 36 months and a prorate for up to 72 months.

Now look at the marine starting batteries. Most have a 12 month warranty with some giving an additional 12 months with a pro rate. As far as Deep Cycle batteries, 12 months is about it. Also, I have been told by many battery stores that there is no accurate way to test a deep cycle battery.

I use the calendar to change my batteries and if I have any problems before the 3 years, I just bite the bullet and buy a new one. BEING STRANDED IN THE WATER IS NOT FUN AND CAN BE VERY EXPENSIVE.

Troll

[Putershark]

Or better yet, just spend a little more money and bypass the 3 year (or less) replacement process and get AGM units http://www.odysseysoutheast.com/odys...-batteries.php

[OspreyVic]

I agree with Putershark, just like a different manufacturer. Try http://www.lifelinebatteries.com/marine.php for AGM batteries. Also, never put your batteries away without a full charge. It will help extend their life.

[Davekfl]

Well I took the deep cycle battery to Advance Auto Parts and they load tested it and said it was DOA which I figured. While there I looked at Optima AGM battery ( blue top) but at $188 plus I held off. I may have a problem with my onboard charger as far as mixing and matching AGM and lead acid. The charger has a setting for lead acid or AGM or gel. It is one setting for the unit which is a two bank unit. I sent an email to the ProMariner folks asking if I would have a problem with setting if I use Optima on one bank and lead acid ( starting) on the other bank. Still waiting for answer. Yes I can also replace my starting battery with AGM but $380 plus tax for two batteries is too much!
That would get my per fish pound average cost down to about $100. Maybe I should sell the boat and eat lobster at every meal and still be ahead in the game. And I dont even kill any fish!
No decision yet.
Davekfl

[Genelie]

Well, I guess I just must be lucky. I use two deep cycle batteries, obvious one is for starting and running most of my electronics. The 2nd is primarely just a spare, sort of to speak. I have the batteries since I bought the boat in 2002. Still working great. Perhaps because I do not let the batteries drain fully. Heck who knows, I am no way an expert. So I will leave it at luck.

[ILLOGICAL GGC]

I Am Still Using 2 Agm Batteries I Bought On '01 And Believe The Extra Money Up Front Will Save You Over The Long Haul Of Replacing Cheaper Batteries And Lost Trips On The Water From Power Failures
Berto