What do you consider a dead battery?

[Jeff T]

What is considered a "dead" battery?

My deep cycle is roughly 1-1.5 years old. It is the same deep cycle battery that came with my 07 22ve from Tige. Since I took delivery May of last year, the battery only received a full charge a few times (outside of the small amounts of charge received from alt). I bought a new, fairly high end battery charger that reads the battery's % charge. This weekend, I pulled the deep cycle out and brought it home as I was really curious to see the remaining level of the battery. Long story short, it was really, really low @ 30%. I charged it back up (it is a multi-stage charger) to 100%, took it off the charger, and let it sit overnight (elevated off the concrete floor). When I put the charger back on the battery, it had already dropped down to 70%, with literally nothing hooked to it. I'm going to test again tomorrow to see what charge is lost overnight tonight.

Should a battery lose charge with nothing pulling power from it?

[dogbert]

Not that much

[lee]

I have some Deka batteries that have been sitting on a rack for eight months and they still show 12 volts or a little more.

[chpthril]

Need to go by the voltage level, not a % displayed by a charger.


State of Charge...... Specific Gravity ......Voltage
.................................................. .......12V/6V
100% ........................1.265 ................12.7/ 6.3
*75% ........................1.225 ................12.4/ 6.2
50% ..........................1.190 ................12.2/ 6.1
25% ..........................1.155 ................12.0/ 6.0
Discharged .................1.120 ................11.9/ 6.0

[Fast1911]

The battery will usually read 12 volts but that doesn't necessarily mean it's good. You need to read voltage across the terminals when your starting the engine. This puts a load on the battery. It shouldn't go lower than around 10.5 or 10. If it does it is time to replace the battery. If this happens with a new battery then you might have a starter issue or something else. We usually replace ours every 2-3 years. You can usually tell a slow decline on the sound of the engine startup as the battery gets weaker with age. Another tip, check your alternator for around 14 volts output for charging.

[Jeff T]

Just thought i would give you an update. I had the battery load tested yesterday, after charging to full.

They ran three diff tests:
1-Battery dropped to 70%, but still read that it was good
2-Battery dropped to 65%, but read was good
3-Battery dropped to 47%, battery not good.

They told me that it appeared as though I had a cracked plate and the battery was toast.

[Jason B]

If it's still doing its job why replace it? Use it until it goes out completely (assuming you have dual batteries). If it's your only battery, I'd add a 2nd and use that one until it croaks....then replace it.

[Jeff T]

It is under warranty now. If i know it is bad, i'm having it replaced while i can.

[lee]

It is under warranty now. If i know it is bad, i'm having it replaced while i can.

Hum, that sounds easy enough to do.

[chpthril]

Just thought i would give you an update. I had the battery load tested yesterday, after charging to full.

They ran three diff tests:
1-Battery dropped to 70%, but still read that it was good
2-Battery dropped to 65%, but read was good
3-Battery dropped to 47%, battery not good.

They told me that it appeared as though I had a cracked plate and the battery was toast.

What was the before and after voltage on the first test? It's sounding like a bad battery IMPO