Reviving flooded deep cycles

[wopachop]

Wanted to share this attempt at getting a little more use out of this battery. We accidentally drained it all the way down to 0.000v. Ive never seen my charger display that before. Even using Pb mode and calling it a 1 cell battery it still would not begin the charge process. 
The battery tender charger as well didnt want to begin the charge. We got jumper cables and jumped the battery for a few seconds and then the battery tender kicked in. Its the 5a version of battery tender brand.
I had 2 questions that the smart fellas here might be able to shed some light on. Im assuming the battery is dead, because one of the kids left the 12v LED lights on. I had an adjustable voltage regulator hooked up to (2) of the 8v batteries and the regulator knocks it down to 12v. 
What i found strange is the battery with the positive lead was low, while the battery with the negative lead was completely dead to 0.0v. 
1. Why did the negative battery die, instead of both batteries dying? The battery that died was 1 year old. While the battery that lived has got to be over 10 years old.
2. Second question is when i hook up my fancy charger to some of the batteries, the voltage will flash, then disappear. Its like it loses and regains connection. Sometimes if i catch it at the right time i can get the charge to start. But usually it tells me "connection error." What is going on inside to batteries to make the connection come and go like that? Pretending my alligator clips and nice and tight on clean metal. Only some of the batteries acted this way. My fancy charger didnt like those batteries. But the 5a battery tender has no problem recognizing them and charging away.

[MEXICOWANDERER]

Im still trying to wrap my head around 2 batteries in series, powering a light bulb for months, and only 1 battery died.

A battery in series can go 100% open circuit. One cell or all cells. It's acts like an off switch.

[wopachop]

Im still trying to wrap my head around 2 batteries in series, powering a light bulb for months, and only 1 battery died.

Now given i have not taken SG measurments. I picture the 2 batteries as 1 single larger battery. Since it was two 8v that are 4 cells each lets call it an 8s battery.

Its so weird how 4 of those cells were drained to zero. While the other 4 were depleted but not dead. While not identical in age and brand they are similar in capacity. I dont know if the voltage regulator and LED lights were still drawing small amounts of power when i discovered the dead battery. Its possible the battery that was drained low was on its way to being completely dead too. But the lights have been on for months. I would have expected 2 dead batteries. Maybe the voltage regular broke and stopped drawing power. Variables


....
Actually i was sitting here thinking. I think thats the answer....the voltage regulator. It has a little potentiometer that you turn to adjust output voltage. I bet as the battery voltage dropped, eventually the output voltage got down to zero. Thats why the 2nd battery was not drained to zero.

If it was a standard light bulb i would most likely have had 2 dead batteries? Its still interesting how the 1 year old battery is the battery that drained first. At some point i will have to weight the difference between the newer off brand battery and the old Trojan 8v.

[wopachop]

time2roll wrote:
The bottom of the second picture says 24.755 volts.

Good eyes!! I went with dual 12v power supplies. Looking back it was probably a waste of money. Also its rare but if one power supplies fails while in use it can damage the charger. But with a single power supply if it fails there is less chance of damage.

[CA_Traveler]

Batteries can have strange/unexpected results. Plus you have mismatched batteries physically and 9 years difference so failures should be expected not questioned.

Find a good battery shop and have them load tested especially since discharged batteries are not happy.

From an RV standpoint replace them. As an experiment see what you can learn.

[time2roll]

I am not sure what we are working with. The bottom of the second picture says 24.755 volts.

Yes some chargers need to see voltage within specification before they will start charging. They all have different specs.

[wopachop]

2oldman wrote:
Why do you have

time2roll wrote:
None of this matters

Not off to the best start.

[time2roll]

None of this matters until you install a 12v battery (or 2x 6v).

Or is this a 36v or 48v golf cart? Or something else?

[Lwiddis]

I’m a non-believer in RV battery revival. Hocus pocus, alakazame!

[wopachop]

Brings up a good 4th question.

4. Does the size of the cell effect its ability to be revived? My first thought is a 3s battery in normal RV size would have a better chance than a 6s.

[2oldman]

Why do you have 8v batteries?

[wopachop]

3rd question i forgot was about resistance. What can we learn from those numbers? I forgot to write it down darn it. I probed the battery with 0.0v and i think it said something ilke 2.47.

Then probed a good battery and i think it read 0 ohms. My bad not writing it down. Was a few days ago.