[KYHAM] Battery Lesson Learned...help needed

[Tyler Allison]

First the story...it's long.

I've been running a 12VDC battery system for about a year. It powers my
ham radio equipment, my weather station and my home network (cable modem,
hubs, wireless routers, etc).  It ran off (2) two 12V Everstart Deep Cycle
Marine Trolling motors I purchased at Walmart.  I was very careful, I
thought, about reading as much as I could about proper wiring, wire size,
etc.  I hooked them up with black and red 6 gauge wire. Thicker that it
needs be..I think. Everything was hooked up to an Everstart 2/10/20 amp AC
charger that has auto-shutoff (green light) when everything is fully
charged. I put the batteries in the garage since I'd read some conflicting
stories about the risk of non-sealed batteries in the living area of the
house.

Okay now the 'lesson learned'

About 5 to 6 months ago(?) I noticed that I was never seeing the green
light (auto-shutoff) when I would check on the batteries. I use to. I can
see the charger everytime I pull in the garage. I figured it was just
because I was pulling more amps than the charger could provide when I had
it on the low 2amp trickle setting. So I pulled the manual out to double
check and it seemed to read that I would be safe to put the charger on the
10amp settings since my batteries were large enough to handle the higher
current (75AH each). So I flicked the switch to 10amp and thought nothing
of it. I noticed that the green light still wouldn't come on but I thought
maybe that had to do with the constant flow of current and it would
'never' show full. I took some readings while the batteries where under
load with my amp/volt meter and everything looked normal.

Anyway....more of the story.

In preparation of hooking up these batteries to a solar panel I wanted to
cleanup my wiring. I installed circuit breakers, an on/off box, the works
in my basement. I tested all the wiring, unplugged the batteries from up
in the garage and installed them in the basement. I hadn't seen any
problems in the garage so I figured after a year it was safe. (Lesson
Learned)

This morning my wife wakes me up with "can you smell that? I think we have
a gas leak". Oh great! Just what I need on a monday morning.  I
immediately told her it didnt smell like gas to me. It smelled like rotten
eggs, not what I remember natural gas smelling like.

We go hunting around the house and the smell is definitely stronger in the
basement. She heads off to call Cinergy because she swears it's a gas
leak. I think it's probably a sewer backup or something. The smell doesn't
seem stronger in any one portion of the basement. Which seems odd to my
mind.

As a professional troubleshooter/investigator at work my mind starts
recapping what has changed that day.  DING DING DING! I moved the
batteries into the basement. But they arnt suppose to vent...I know they
CAN but they arnt suppose to.  A quick check of the batteries.  WARNING
SULPHURIC ACID label on them. Sulfur has a rotten egg smell. *sigh*

I use my main on/off switch (hey it works!) and turn off all power in and
out of the batteries. I touch the batteries, ooh my goodness are they hot.
I had felt the batteries when they were in the garage mind you, they were
hot but the garage was 90+ degrees at the time...I didnt think anything of
it.

I get out my amp/volt meter and test each battery. One shows 13.03 V the
other shows 9V. What the heck?!?!  13.03V is correct but 9V?!?

I move the batteries up to the garage again and try and charge each
battery individually.  The good battery takes a full charge and the
battery charger shuts off and shows green.  The 9V battery charges for
30minutes while waiting for the Cinergy guy to show up.  It never makes it
passed 12.6 before I turn off the charger. By the time I test the battery
with my volt/amp meter the volts have dropped to 11V and are quickly on
the way down. I let the battery sit for another 10 minutes and the voltage
has dropped down to around 9V again.

Okay..so I have a dead battery.

But I don't know why I have a dead battery.

I drew a picture of the physical wiring of my system.
http://www.allisonhouse.com/battery.jpg

Could the way I had the system configured been the cause of the damage?

Any thoughts on what happened?

ps: Cinergy guy showed up. I didnt tell him about the batteries until he
did his check. He swears no gas leak. He asks if I have any punctured
'things' in the basement. I mention I was charging car batteries. He says
"that's what that smells like".  *sigh*

-Tyler
KI4BUM