New batteries but low voltage

[a64pilot]

Autozone test is a load test, you can buy on e of those for $25 or so at a cheap tools place. I used to have one years ago and it is pretty good for a battery used for starting there all you want is lots of amps for a few seconds.
But to test a deep cycle battery for capacity, they are useless.

[thomm225]

Originally Posted by Bleemus

Why would you even bring it to AutoZone. If it had no load and showed 10.8 a few hours after being charged it would seem to be done.

I was there buying a new deep cycle battery!

So I was like hey, can you test this core to see what your tester says......

[thomm225]

Originally Posted by a64pilot

Autozone test is a load test, you can buy on e of those for $25 or so at a cheap tools place. I used to have one years ago and it is pretty good for a battery used for starting there all you want is lots of amps for a few seconds.
But to test a deep cycle battery for capacity, they are useless.

I don't need a tester. I used my DVM and did several tests under load and unloaded before buying. (also recently charged and uncharged) My batteries had been showing some signs of failure for a month or so. (my fan wouldn't run all night like it had in the past, but the batteries would do ok the next day with solar assist)

I definitely wouldn't change out all batteries because they read 12.2 volts in the am

I thought it (a tester of some sort) might help the OP since at one point he realized he may not have needed new batteries......which would have been better than not test at all

[Bleemus]

These work fine for start batteries but are useless for deep cycle.

[thomm225]

Originally Posted by Bleemus

These work fine for start batteries but are useless for deep cycle.

Maybe so if you had to depend just on a tester, but you could troubleshoot a battery problem with it.

Looks like it has a nice display there where you could get a good comparison on your batteries

The first indication I had was my inverter alarm going off at 0200 in the am. My fan had worn the batteries down which had never happened before.

Shutting down the inverter gave me enough power for lights, autopilot in the early am, GPS, VHF, and depth until the solar could help. I would usually just run autopilot until I started seeing the battery power coming back up on the old Altus Battery Power Monitor the PO mounted on the boat

The point is if you are really out in the boonies you may have to remove a bad battery from your string to get the best results until you can get a replacement if you aren't already carrying a spare

I was able to wait a few weeks not being a full time cruiser. I never did charge the batteries though with anything except the 100 watt solar panel until the bad battery finally failed totally

[a64pilot]

Originally Posted by thomm225

I definitely wouldn't change out all batteries because they read 12.2 volts in the am

A bank that is several years old you really do need to change them all out, it seems if you put one new battery in an old bank that in a couple of months it's "aged" just like the rest of the bank.
If your going somewhere batteries are not readily available, or are stupid expensive, or are starting out cruising full time, doing so with a new bank may well be a very good idea, one less thing to worry about.

[Terra Nova]

a6--good post.

[thomm225]

Originally Posted by a64pilot

A bank that is several years old you really do need to change them all out, it seems if you put one new battery in an old bank that in a couple of months it's "aged" just like the rest of the bank.
If your going somewhere batteries are not readily available, or are stupid expensive, or are starting out cruising full time, doing so with a new bank may well be a very good idea, one less thing to worry about.

It's all up to the boat owner. And if he believes voyaging (motoring) the ICW along the East Coast of the US is comparable to Conrad's Heart Of Darkness I can see why he'd replace them all!

My opinion was that since the OP appears to be motoring the ICW along the East Coast of the USA and not really going to a remote area a battery bank reading 12.2 volts in the am especially if under some load all night simply isn't a problem.

It is interesting though this bad battery, new battery thing and I plan to monitor it. Also my 2 batteries are in parallel. One starter battery (from when the boat had an old diesel) and one deep cycle battery.

This am they read 12.74 (with an uncalibrated DVM) after being unloaded and off the charger all night. And my old Altus Battery Power Monitor had them over the fully charged scale which is good data to have for later

[sailorboy1]

If you are a cruiser with 6 year batteries that have costed out to $83/yr, and you believe the batteries are down to half capacity, and you have the chance to replace them, and instead you feel it is better to try to get another year out of them so that the batteries use only costs you $71/yr, you probably are an .................... idiot.

This is of course my opinion and I have no burning need to talk idiots out their courses of action.

[Terra Nova]

........

[thomm225]

Originally Posted by sailorboy1

I'm just pissed that I may have replaced batteries for no reason.

You gotta love CF.

The OP goes from the realization he wasted his money to knowing he did the right thing because a few posters agree with his actions later in the thread.

That awesome.......but quite sad at the same time.

[kmacdonald]

You can lead a horse to water but you can't make him drink.

[sailorboy1]

Use partial posts to take whatever you want out of context. I did the right thing and like I wrote if you would have chosen not to replace 6 year old 6v wet cell batteries given the same conditions you're an idiot!

[thomm225]

Originally Posted by sailorboy1

Use partial posts to take whatever you want out of context. I did the right thing and like I wrote if you would have chosen not to replace 6 year old 6v wet cell batteries given the same conditions you're an idiot!

on with the show.......

[leftbrainstuff]

Originally Posted by sailorboy1

I had been getting up in the morning with battery voltage of 12.2 with 60-90AH out. So since the batteries were 6 years old and I had abused them I replaced them yesterday with 4 new Trojan T105s that I charged till they accepted 9A at 14.4V. To test them I turned off shore power and went to bed. This morning they were reading 12.25V at -6.3A and -67 AH. This seems way too low based on the AH and is the same as the old batteries.

Its not unusual to see 12.2V on house batts under load. Its resting voltage that is important.

If you remove all load, ie isolate the batts, you should see the voltage quickly recover to 12.4+ V. Ideally 12.6V.

We have 10 year old T105s that are still going strong. They are thirsty at this age.

Have you checked electrolyte levels. While you're at it check specific gravity which is a more consistent measure of charge.

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