Repairing neglected flooded deep cycle batteries

[Daniel Who Wants to Know]

I was recently given an old early '90s model electric wheelchair that had
sat for several years in storage and during that time the pair of 60Ah 12v
batteries were allowed to completely discharge to zero terminal voltage.
There was acid in the bottom of one of the battery boxes that told me that
it had been previously overfilled and then charged in the past causing it to
overflow. I managed to bring them back to life by putting them on a 1.25
amp trickle charger for a half hour each which brought the terminal voltage
up high enough for the wheelchair's own 8 amp smart charger to recognize
them. That charger started out at 1 amp and slowly ramped up to the full 8
over a period of several hours. My only concern is that I had a "brain
fart" of sorts and forgot that the acid volume increases during charging and
managed to fill the cells to the full line before charging them causing me
to have to remove some from each cell during charging to keep them from
overflowing. Now I have 600ml sitting in a plastic cup waiting to be added
back in as needed as the battery naturally loses water. I don't have a
hydrometer or a digital multimeter at the moment and I need to know what to
do next. All 12 cells gas at the end of charging but they gas uneven
amounts which tells me that the specific gravity is uneven. I am thinking
of draining all of the acid into a large container then stirring to mix it
up and refilling the battery with that. Any advice other than buy a good
hydrometer would be appreciated along with ways to reduce the amount of
sulfation that I know has to be present.

BTW yes I know how to safely work with sulfuric acid without blinding or
burning myself and I have a box of baking soda nearby for spills.

 

[Nick Hull]

Any advice other than buy a good
hydrometer would be appreciated along with ways to reduce the amount of
sulfation that I know has to be present.

A usable hydrometer can be bought cheap, as well as a digital voltmeter.
With a little looking you can get b oth for less than $10. You cannot
seriously work in batteries without the right tools.

 

[Malc]

I was recently given an old early '90s model electric wheelchair that
had sat for several years in storage and during that time the pair of
60Ah 12v batteries were allowed to completely discharge to zero
terminal voltage.

I believe it's possible to buy some lead acid rejuvenator compound but TBH
I'm with every one else on this and your batteries are probably fucked. If
you do achieve some usable life out of them well done, but in the time I've
spent working with batteries in hospital equipment my experience leads me to
suspect that you won't get anything usable out of them.

--
Malc

"You cannot do better than go by Dover or Calais"
Chairman of the Royal Geographic Society when asked the best route to
Bolivia

 

[Nick Hull]

I think it is inherent in usenet that there will be posts along the
lines of "I want to do brain surgery, and I have a chain saw and a
crowbar. Where do I start?"

That's EZ; start on your own brain, Darwin will show you how

 

[Daniel Who Wants to Know]

I enjoyed the brain surgery with a chainsaw bit. I find myself finding a
need for good test equipment more and more often these days. I plan to buy
a Fluke 189 meter ASAP as I have very bad luck with the $15 cheapies from
Wal-Mart etc. as I have killed several so far. The batteries propelled the
wheelchair for a 1 hour round trip across town @ <60° fahrenheit with all 4
tires low and the battery meter on the joystick panel stayed above half.
Granted the only passenger was a basket of clothes with no seat so it was
carrying very little weight. Even if they only have 20% or so of original
capacity left that is still 24Ah with them in parallel which is more than
the standard 17Ah VRLA that is on my APC UPS and is more than enough to run
my car amplifier for a few hours so they will still see some usage. As far
as them being shot I planned to buy new batteries for it anyway. Any votes
for Rolls/Surrette as I have been on the website and they seem OK. I know
most of the battery talk in here is for stationary solar storage usage and
not sure what kind of battery would be good for motive/traction usage. I am
also looking at the Exide Select Orbital XCD for the vibration resistance.

My only other concern is that when I move the switch on the charger from
standard to gel during absorbtion charge @~4 amps the ammeter reading
increases to ~6 amps which makes me think that it is trying to push a higher
charge voltage but it is my understanding that gel batteries require a lower
voltage to keep from forming gas pockets that would force the gel mix out
from between the plates.

 

[daestrom]

Save your money until you're NOT killing the 15$ cheapies as often ;-).

Something you're doing with those cheapie meters is something you're
not supposed to be doing, and until you break that habit, I suggest you
resist blowing up a Fluke, because they die just like the cheapie ones
when you do something a bit absent mindedly.

I like the cheapies for doing the simple stuff, rough voltages in
series systems, polarities, PV (single panel) output amperages, and
working on a roof.And it's easy to have a few cheapies around, in
various tool boxes and pouches and not worry overmuch about them. Not
so much the case with a Fluke ;-).

Indeed. I've got some really nice Simpson meters, and some 'cheapies'. I
keep the 'cheapies' in the toolbox where they get some 'rough handling'.
But they still work because I know the difference between the ohm-V-A
readings. Haven't sent the Simpsons out for cal in quite a few years,
wonder if they still work?

daestrom

 

[daestrom]

Homer and Bart?

LOL,

No, BDM (before digital meters). Simpson and Weston were names you could
trust. Simpson 260 is still a 'work horse' tool for a lot of folks.

daestrom

 

[Daniel Who Wants to Know]

Just to clarify what happened to the meters: #1 was an analog that was
hooked to the battery of a running car monitoring the voltage and the needle
just dropped to zero and it never worked again, #2 DMM I probed the high
voltage side of a MOT resulting in a nice light show and the display reading
"1", and #3 the traces under the rotary selector switch wore through. I
guess I should have said I killed 1 and the other 2 died.