Have I shortened my batteries life?

[Cheechako]

Or try charging them and disconnecting everything. if they are 12.45 or more the next day you may be fine. Have you shortened the life? hard to say really.

[SV THIRD DAY]

Originally Posted by onestepcsy37

full charge is 12.73 volts, according to trojan. i've also seen 12.65 volts quoted by interstate.

Using voltage as a state of charge measurement can easily fool you.
My advice for anyone with wet acid batteries aboard is to use a Hydrometer to track your batteries. They are pretty cheap and easy to use.

[Mark Zarley]

I second the hydrometer, no amps per hr, math issues. That said if they still do the job use em, as long as you have healthy ones as emergency back-up. I lost a cell in my port start battery 3 yrs ago due to my grand kid flippin switches on the smart charger. I continue to use this battery today, for start only. Engine Lehman 120, battery 8-D Rolls. Love Em.

[scoobert]

Originally Posted by boatpoker

If the plates were showing, they can no longer be trusted. Bare plates are when they can go into three mile island syndrome.

its true! ask me how i know

[Thin Line]

Originally Posted by rw58ph

I check the battereis every month as once the plates are showing the battery is done.

So after fulling charging what was the voilt reading after letting it set for 30 minutes? 100% is 13.2 volts. 50% is 12.4 volts under 12.0 its dead. Do not discharge a battery below 50% or 12.4 volts as that will also shorten the life.

You are absolutely incorrect.. A 12 volt wet cell battery is considered "full" from around 12.8 to 12.6, as a matter of fact it's not until 12.06 when it is considered 50%, might as well say 12.0 and finally "dead" is actually 10.5v

The 13+volts you are stating above is a surface charge and isn't indicative of an actual voltage.

[SVTatia]

Originally Posted by Thin Line

You are absolutely incorrect.. A 12 volt wet cell battery is considered "full" from around 12.8 to 12.6, as a matter of fact it's not until 12.06 when it is considered 50%, might as well say 12.0 and finally "dead" is actually 10.5v

The 13+volts you are stating above is a surface charge and isn't indicative of an actual voltage.

But... he should be able to check the batteries individually, and in this case they are 6 volts. What would be the charge voltage for a 6 volts battery?
Also, maybe one of them is bad the other not so bad?

[scoobert]

Originally Posted by Thin Line

You are absolutely incorrect.. A 12 volt wet cell battery is considered "full" from around 12.8 to 12.6, as a matter of fact it's not until 12.06 when it is considered 50%, might as well say 12.0 and finally "dead" is actually 10.5v

The 13+volts you are stating above is a surface charge and isn't indicative of an actual voltage.

State of Charge

State of Charge
                 Sealed or Flooded Lead Acid
                 Gel battery
                 AGM battery
                       100%
                 12.70+
                 12.85+
                 12.80+
                       75%
                 12.40
                 12.65
                 12.60
                       50%
                 12.20
                 12.35
                 12.30
                       25%
                 12.00
                 12.00
                 12.00
                       0%
                 11.80
                 11.80
                 11.80

[Thin Line]

Yes he should each individually as one battery could cause the weak link. My post was to correct the person that listed very incorrect information on voltage. This is the chart I go by and I'm fairly certain in it's accuracy. The poster stated 12.4 as 50% which was more around 80%

State of Charge 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

[sailinglegend]

Originally Posted by Thin Line

You are absolutely incorrect.. A 12 volt wet cell battery is considered "full" from around 12.8 to 12.6, as a matter of fact it's not until 12.06 when it is considered 50%, might as well say 12.0 and finally "dead" is actually 10.5v..

These voltages are all OPEN CIRCUIT VOLTAGES, which means no charging or discharging for 5/6 hours. This difficult to do on a boat that is being used - so just disconnect one battery and see what that recovers to.

I've just done some 10 hour load tests at 8.3 amps per 200 AH battery to see how they all compared. After 10 hours the load voltage was 12.06 which recovered to 12.36 after 6 hours (12.3 volts after 30 minutes).

[westwinds]

Originally Posted by scoobert

its true! ask me how i know

Hope you were wearing eye protection. How did it happen?

[scoobert]

Originally Posted by westwinds

Hope you were wearing eye protection. How did it happen?

it was dead so i had a jump box on it, so i could use the hydros. i walked to the other side of the trailer, about 2min later i heard an explosion, sounded like a gunshot. i was in a bad neighborhood in NJ, so i hit the deck. i looked about, and saw no one, so i walked back to the other side, and thats what i found. the force was unbelievable. i found parts 3 lanes away. i always wince when messing with batteries now.

[westwinds]

Originally Posted by scoobert

it was dead so i had a jump box on it, so i could use the hydros. i walked to the other side of the trailer, about 2min later i heard an explosion, sounded like a gunshot. i was in a bad neighborhood in NJ, so i hit the deck. i looked about, and saw no one, so i walked back to the other side, and thats what i found. the force was unbelievable. i found parts 3 lanes away. i always wince when messing with batteries now.

I will be more careful myself, always unplug the battery charger before unhooking the + and - cables so no sparks. Could the hydros (what ever that is) caused a spark?

[cburger]

For giggles I let I shut down all power to the house bank today, seven hours later voltage read 13.2, thinking that is a good sign. Will be paying much more attention to the fluid levels in the future.

[westwinds]

Originally Posted by cburger

For giggles I let I shut down all power to the house bank today, seven hours later voltage read 13.2, thinking that is a good sign. Will be paying much more attention to the fluid levels in the future.

Something does not add up here. The maximum should be 12.7 volts for a fully charged battery. Either the battery is being charged from some unknown source, or your voltmeter is not accurate.

[sailinglegend]

Originally Posted by westwinds

Something does not add up here.....

I've had some of my AGM batteries disconnected after load tests and they are still at 13.2 volts. It's called surface charge, which puts a higher charge on the outside of the plates than on the inside. This is one of the reasons that charging takes so long when the battery is nearly full. The surface charge has to migrate to the inside to "fully" charge a battery.

EDIT: After 4 days they were still at 13.2 volts, and these are 10 years old.