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MacGyver

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Joined: 12/05/2009
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Posted: 07:42pm 22 Jun 2010

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Does anyone know how long it takes a new 12-volt automobile battery (not traction type) to sulphate if it's discharged 100% repeatedly?

The reason I ask is, I just figured out that's what likely happened to one I was using in my shop. I'd use it until it wouldn't run things, then charge it back up to full, then use it all up again and so on. Lasted about a month and a half! Good thing it was only $15, eh?

Think that's what happened or should I be looking elsewhere?

. . . . . Mac

Nothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas

wind-pirate

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Joined: 01/02/2007
Location: Canada
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Posted: 10:54pm 22 Jun 2010

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Mac

Auto batteries are not ment to be dicarged. they are ment to use enough power to start the auto and them be charged up again. Leaving them discarged is the worst thing you can do to any wet battery.

most batteries in motor homes trailer ect are only ment to discharge to about 50% any more your asking for trouble... With a capital T.

Ron

THE Pirate.
stealing wind & solar energy is fun

MacGyver

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Posted: 12:07am 23 Jun 2010

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[Quote=wind-pirate]most batteries in motor homes trailer ect are only ment to discharge to about 50% any more your asking for trouble... With a capital T.

Yup, kinda figured that.

Now,I leave the little battery that runs my lathe on a charger all the time (24/7). It's a motorcycle charger, which doesn't put out enough charge to do much at all with the size battery it's hooked to, so I just let it camp out there day and night. It's plugged into the same outlet as my shop lights, so when I'm workin', it's workin'!

Seems I can't win for losing lately. My personal trainer is a 21-year-old kid without a car, so I gave him one of my Volvos as a gift. The day he came over to pick it up, what do you think happened? The battery failed! See what I mean?

Maybe he'd like the white Mercedes too, eh?

. . . . . MacEdited by MacGyver 2010-06-24

Nothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas

VK4AYQ
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Joined: 02/12/2009
Location: Australia
Posts: 2539

Posted: 02:58am 23 Jun 2010

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Hi Mack

You need a desulphator on the battery if you haven't killed it completely already and as Ron said never go below 50% capacity on a automotive battery, I have had auto batteries used to run Ham radio gear last for 7 years by putting on a 200 ma float charger on permanently and if possible a desulphator but they can cost more than a battery if you buy cheeep batteries, but they do last for years and you can use them to revive old batteries if they arn't faulty mechanically.
www.infinitumstore.com are the ones I use and would recommend.
One of those small solar panels sold in auto stores are good to. They just keep a trickle going in but don't rely on them to actually charge it for work as they only float charge.
Any new battery can start to sulphate from the day it has acid added even deep cycle batteries suffer if taken beyond 80% discharge.

All the best

Bob

Foolin Around

MacGyver

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Posted: 04:25pm 23 Jun 2010

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[Quote=Mac]It's a motorcycle charger, which doesn't put out enough charge to do much at all with the size battery it's hooked to, so I just let it camp out there day and night.

I've been playing around with copper coils a lot lately as Oz tries to pound some understanding into my thick head and the thought occurred to me, perhaps leaving the charger hooked to the battery that runs my little lathe is not a good idea.

With that in mind, I hooked my multi-meter to things and found out even though the house current is off, the secondary coil of the charger still completes a circuit to my battery, so if I leave it hooked up but not "on", the charger actually does me a disservice and drains the battery. Duh!

So, you see Oz, there's hope; the boy can be taught! If anyone is secretly thinking "short bus"

you're likely not far from the truth! Sometimes I amaze even myself!

. . . . . Mac

Edited by MacGyver 2010-06-25

Nothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas

Downwind

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Joined: 09/09/2009
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Posted: 05:15pm 23 Jun 2010

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Without knowing what the charger is and how its constructed its a little hard to comment on your light bulb moment.

Before i turn your light bulb off, perhaps you can tell me where the power from the battery is going in circuit to do the disservice.

Answer.............................

Lets assume its a standard transformer style charger, that would mean it puts out low voltage AC from the secondary windings.
Now we all know with windmills we dont use AC to charge the battery and need to add a rectifier to convert the AC to DC.

As a rectifier is made up of diodes that prevent the current from flowing backwards through them, i would expect the current from the battery would be blocked from going anywhere by the diodes in the rectifier.

So yes it would complete a circuit connected to the battery, but no it should not consume any power from the battery.

As i said i dont know the charger and it might well have more inside than the average charge, being a transformer + rectifier and could be consuming power from the battery.

A good practice is ..when in doubt disconnect it.

Pete.

Sometimes it just works

isaiah

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Joined: 25/12/2009
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Posted: 08:57am 26 Jun 2010

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Mac
the charger could have a leaky rectifier
what you really want for battery's is golf cart battery's as they are meant to charge and discharge.(probably get some used ones at the golf course if they havent fallen off into the ocean yet)auto battery's are meant to just start the motor.. i think bub has plans here to build a desulphator.
the older cars that used the generator and mechanical regulator did not have this problem.'

URL=http://www.motherearthnews.com/Renewable-Energy/1973-11- 01/The-Plowboy-Interview.aspx>The Plowboy Interview[/URL>

MacGyver

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Posted: 03:02pm 26 Jun 2010

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Crew

Keeping in mind the fact "I don't understand all I know" about this and (most) other things, what I do know is when I touch the battery charger leads to the posts of the battery, with the charger in the "off" position, there's a teensy-weensy little spark. That's what clued me into what may be happening.

Realizing this, I have of late been leaving the little charger hooked onto the battery, plugged into the wall and "on" 24/7. It's my hope this will act as a floating charge and not hurt anything.

Then again, if the battery explodes in the middle of the night, I'll let you know!

. . . . . Mac

Nothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas

davef
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Joined: 14/05/2006
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Posted: 07:41am 27 Jun 2010

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It just might be a capacitor charging up. Stick a multimeter in series and measure what the actual steady-state current that is be sucked outa' your battery then you can make an informed decision.

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