Battery question

[Loose Cannon]

I have two Deka multi-purpose batteries that have been used for two seasons. During the offseason I keep them in the garage and charge with a tender about once a month. One battery charges to 14.0 and the other tops out at 13.5. Should I be concerned? Would like to get one more season out of them.

 

[Wylie_Tunes]

Yes, your charger is over charging them or you are measuring right after removing the charger and what you are reading is called the surface charger. Let the battery sit for 24 hours and remeasure.

 

[northern]

Found this long ago. It may help you. After % number is total volts per battery next is volts per cell. You have 6 cells in a 12 volt battery.
State of Charge 12 Volt battery Volts per Cell
100% 12.7 2.12
90% 12.5 2.08
80% 12.42 2.07
70% 12.32 2.05
60% 12.20 2.03
50% 12.06 2.01
40% 11.9 1.98
30% 11.75 1.96
20% 11.58 1.93
10% 11.31 1.89
0 10.5 1.75

 

[thegotoguyr]

Check them before you charge them. I wouldn't put a charger on a battery with over 12.2 volts unless I was planning on using it within 24 hours.
12.5 - 12.7 I consider fully charged.

 

[Loose Cannon]

Very useful responses, thank you. I checked the charge level again after waiting >24 hours and they are at 12.4 and 12.5. Sounds like I may be OK.

 

[JimT]

Check them before you charge them. I wouldn't put a charger on a battery with over 12.2 volts unless I was planning on using it within 24 hours.
12.5 - 12.7 I consider fully charged.

He is using a battery tender.

 

[paulswagelock]

Very useful responses, thank you. I checked the charge level again after waiting >24 hours and they are at 12.4 and 12.5. Sounds like I may be OK.

They are ok, but starting to show degradation.

 

[Loose Cannon]

Opinion? Can these be trusted for another season (May - Oct) or replace?

They are ok, but starting to show degradation.

 

[paulswagelock]

Hard to say. The voltage is half the story. A load test tells the other half.

 

[Lazy Daze]

IF they were fully charged, then I agree that they are getting close to borderline (and also that a load test is the best way to determine overall health). But Deka's are one of the better lead acid batteries out there and they usually last a good 5 years. Especially if you've got your onboard charger hooked up through the season and a quality tender in the off season.

What kind of tender are you using?

 

[Mike Blake]

So your testing them how? By voltage? How about a draw test after fully charging them? That will give you the truth if they are an good.

 

[Wylie_Tunes]

Very useful responses, thank you. I checked the charge level again after waiting >24 hours and they are at 12.4 and 12.5. Sounds like I may be OK.

For a battery with a couple seasons of use, those levels are not out of the question. However, I would check the fluid level.

 

[Loose Cannon]

Answers: I am using the West Marine portable 15 Amp Smart Charger on the lowest tender/charge setting (2.0); I do not leave on the tender - just top off once/month. There is a voltage button that I press for readings. I filled the cells to proper levels with distilled water when I removed them for winter storage. I will do some research on doing a load test.. I remember doing this on a car battery years ago using a multi-meter (min/max function) but battery was in the car so it could be started to produce the load.

 

[Lazy Daze]

OK, that's good that you're using distilled water. IF that tender is indeed a "smart charger" (for reference, something like this http://www.batteryminders.com/12-volt-maintenance-charger-desfulator-with-warranty can, and should, be left on ALL the time, just like your onboard charger... note that this one also desulphates) then you can leave it on longer. A battery get's fully charged in a similar fashion to how you totally fill a glass of water. You start out with lot's of water, but as you get towards the top you need to slow the water flow down, eventually ending at a trickle. If the WM charger doesn't regulate the output well enough, you either get a not-quite-fully charged battery, or a cooked battery.

I have about 6 of those Battery Minders for various batteries. As much as possible, they're hooked up and on 24/7.

If there's a way to do a load test with a standard multi-meter, I'm not aware of it. You need lot's of amps and that would blow up your DVM. Local auto parts stores can do laod testing. But you need the battery FULLY charger, first.

 

[dvx216]

Most people these day do not do this but a hydrometer will tell you the overall health of a lead acid battery cell by cell.If you do have a low cell then you can run an equalizer charge to even things out.A proper charging system and a healthy battery should not be using water.