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Garden Tractor Battery

Old 09-24-2005, 04:28 PM
  #26  
JNorton
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Default RE: Garden Tractor Battery

Yah that is what was suggested on posts 9, 10 and 11 Sometimes I get sidetracked.
Old 09-24-2005, 04:31 PM
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Rodney
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Default RE: Garden Tractor Battery

JNorton, thanks for the good advice you are handing out. I appreciate the support. Rodney
Old 09-24-2005, 04:44 PM
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jlkonn
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Default RE: Garden Tractor Battery

I have found this discussion very informative!
I wish I was an electronics expert but I am afraid I have to follow Randall's advice.
I bought a battery maintainer and it's working great!
Thanks!
JLK
Old 09-24-2005, 06:35 PM
  #29  
LarryC
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Default RE: Garden Tractor Battery

Well, that was fun, but I still don't know the amp-hour capacity of my garden tractor battery.
I have been told to dump my battery in favor of a Gel-Cel by a HAM. I have at least three gel-cels; I wanted to know the AH capacity of the tractor battery. I first got my ham license when I was 13, a long time ago.

Chargers. The center-tap rectifier as drawn will tend to try to charge to the peak voltage of the rectified ac output, less diode loss, transformer loss etc. Approx (15x1.414) - .7 = 20.51 volts at no load, somewhat less loaded. The .7 is gesstimate of the diode voltage drop. A transformer at about 11 volts either side of center tap might be better. Unless you just enjoy building the stuff, it's safer to go by a good charger.

Larry
Old 09-24-2005, 06:40 PM
  #30  
AS-EE
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Default RE: Garden Tractor Battery

Plus 10% = 14.3 volts. Minus 10% = 11.7 volts and your charger just stopped working. Not quite the constant voltage in bold letters that you used to reply to Rodney. Sorry you've just lost all credibility from me. I gave up Hot Wheels a long time ago. Any engineer worth his salt worries about line voltage variations.


Pure ignorance is showing from you now. If the voltage dropped from the supply then the battery will not lose charge. Do you want to know why? BECAUSE THE DIODES BLOCK THE BATTERY VOLTAGE FROM DISCHARGING THROUGH THE CIRCUIT IF THE VOLTAGE DROP IS LESS THAN THE BATTERY. THE BATTERY WILL SIMPLY NOT CHARGE. ONCE IT GOES BACK UP TO 14.3 VOLTS THE BATTERY WILL CHARGE AGAIN.



My Sears charger is an automatic taper charger and contains more than just a transformer and two diodes. Even the most basic chargers you are alluding to contain a circuit breaker as well. You are starting to sound like a young man defending his turf at all cost. Don't you worry about someone copying something you've incompletely posted on the Internet and hurting themselves?

A very basic charger for lead acids has a ciruit breaker, current meter, multitap prmary with center tap secondary transformer, a switch to select different taps on the primary for current charge rates, and two diodes.

DO YOU SEE ANY F****** SPECIAL CIRCUITRY PROTECTING THE BATTERY OR COUNTERACTIG LINE VOLTAGE VARIANCE PROTECTION CIRCUITRY??? NO!!! THATS WHY THEY INCLUDE A CURRENT METER SO YOU CAN HAVE A ENOUGH DAMN COMMON SENSE TO REMOVE THE BATTERY ONCE THE CURRENT METER SAYS "CHARGED".


IF YOU WANT MORE PROOF ON THE SIMPLICITY OF LEAD ACID CHARGERS THEN:






Old 09-24-2005, 06:44 PM
  #31  
randall1959
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Default RE: Garden Tractor Battery

Do you have a specific purpose that you need an exact ma rating for? My thing is if it works, it works, especially for a lowly item like a starter motor. Go with the lightest battery that works. I recently made the mistake of going TOO light. I used to run my starter off a deep cycle lawnmower battery, but wanted to do everything from my flight box instead. The mower battery wouldn't fit so I got the biggest motorcycle battery I could fit in the case. It will start every one of my planes but two gassers that used to start right up. I carry along an Interstate Marine battery so I can always use that as I don't fly the two gassers enough to give me a hernia[X(]
If all you're starting are glow engines up to .91 you can get by with a pretty small battery.
Since the lawnmower battery is built for starting large items like that big old 19 horse B&S the rating is figured differently than the normal batteries that we do use. In that case they are tested for cranking ability at 32 degrees and then at zero degrees.
Old 09-24-2005, 06:51 PM
  #32  
AS-EE
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Default RE: Garden Tractor Battery

See what you made me do Jnorton. I had to show you pictures just to get your brain thinking correctly. Usually I never have to resort to extreme measures on this forum becuase people know who I am and know what I do for a living, but you sir have no reasoning nor logical thinking so I had to go this far just to make you understand!!!!!!!![:@][:@]
Old 09-24-2005, 06:52 PM
  #33  
JNorton
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Default RE: Garden Tractor Battery

Rodney,
The facts speak for themselves. I must say however I've never known you to hand out bad advise. It is usually well considered. I think AS-EE intentions are good. He just needs to think about his audience a little bit more and to present his ideas a little more thoroughly.

JLK,
Good choice.


Larry C,
I believe your thinking of a bridge rectifier giving 20 volts this is a center tapped half wave. I use both a gell cell and a garden tractor battery and as long as neither experiences deep cycles both will last a long time. I simply charge mine through a 12 volts auxilary jack in my car on the way to the field. The cars alternator does a good job keeping them topped off. Sorry I was not able to find out your batteries mAh capacities. I spent over an hour on the net before I gave up. Do a cycle test on it down to 12 volts and see what your capacity is. 11.9 is considered fully discharged and I wouldn't take it down that far. You've got the tractor battery my advise is to use it!

John
Old 09-24-2005, 06:56 PM
  #34  
LarryC
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Default RE: Garden Tractor Battery

Randall,

I usually use a gel-cel for my starter and that works fine.
The garden tractor battery is used for charging small Li-Pos, and a Hobbico multi-charger that I have modified for dc power. It works well for 4 and 5 cell packs, not so swift on 8 due to the voltage drop in the charger.

I was simply trying to get an get estimate as to the capacity of the battery at a 5 or 20 hour rate, to see what I can actually get from it without discharging it too deeply. Not seriously important, really. I may just base an estimate on similar size/ weight of deep cycle batteries and reduce that capacity a tad.

Larry
Old 09-24-2005, 07:39 PM
  #35  
AS-EE
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Default RE: Garden Tractor Battery

I believe your thinking of a bridge rectifier giving 20 volts this is a center tapped half wave.
Whoa now that's wrong. With center tap transformers when you use two diodes as configured in the above picture you have full wave rectification. Now if you only had a transformer that did not have a center tap then you would have to use a full-wave bridge (4 diodes).

Old 09-24-2005, 08:40 PM
  #36  
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Default RE: Garden Tractor Battery

Yup misspoke myself. I was thinking each phase of the transformer as a 1/2 wave rectifier and misspoke the whole thing is a full wave.
By the way just for giggles I learned about power supplies from an Army Air Core manual and a copy of the 1964 Radio Amateurs Handbook when I was in Jr High School study hall. Back then the only solid state rectifier was selenium - they stunk like rotten eggs if you overloaded them. 5U4's tubes were the hot ticket you could draw about 400 VDC at 350mA out of them.

Later,
John
Old 09-24-2005, 09:09 PM
  #37  
LarryC
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Default RE: Garden Tractor Battery

Smelly selenium rectifiers. Yup, you sure have that part right! Believe it or not, I still have to work on some equipment that has those!
Those old ARRL handbooks had a lot of information in them. I think I still have a '63 here somewhere. I did have 1955 and 1957, but they were destroyed in a fire that was started by......., you guessed it, a battery charger. My homebrew 813 transmitter went too.

I did find some information on a U1 sized deep cycle battery. It was rated at 23 amp-hours.
I found a U1 size rating for a Champion brand garden tractor battery that was rated for 40 minutes @ 25 amps. That works out to about 15 amp-hour at the high discharge rate of 25 amps. I would guess that at a load that would discharge it in 5 hours or longer it may be 17-18 ah. I think that is close enough for what I am doing. I want to avoid taking it down too low. But at the price of these things, they aren't bad. This battery was purchased in the spring of 04 and so far it's holding up well.

Larry
Old 09-24-2005, 09:48 PM
  #38  
JNorton
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Default RE: Garden Tractor Battery

LarryC,
Glad you figured out the approximate aH rating. This thread sure took some turns didn't it?

My oldest surviving Handbook is from 1973. I had copies from the 50's and 60's. I purchased a new copy in 98 and was immensely disappointed. The drawings and quality of the home brew projects have fallen off a cliff. Course it doesn't help when you can't get parts because they're not available and the finished project cost more to build than a commercial unit. Still some good came from it - I stopped building electronics projects and started building airplanes instead!
Of course I see parallels in the fact that it is now cheaper to buy ARFs for many models than it is to build kits. Ah well I still enjoy building.

John
Old 09-25-2005, 07:03 PM
  #39  
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Default RE: Garden Tractor Battery

Sooooo, can I use the Sears 1.5 Automatic Battery Charger and leave it connected for a few days (4 or 5 ) at a time, to my 12v 600ma sealed battery? Or not.
Old 09-25-2005, 08:03 PM
  #40  
JNorton
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Default RE: Garden Tractor Battery

Check the voltage of the battery after it is fully charged. A float charge should be about 13.2 to 13.5 volts. If your charger reads a higher voltage it may not be suitable, if it reads 13.8 to 14.2 it is still charging and is not suitable to used used as a maintenance device.

John
Old 09-28-2005, 06:36 AM
  #41  
B.L.E.
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Default RE: Garden Tractor Battery

The transformers used on battery chargers are specially designed to have a high magnetic flux leakage. This makes the output voltage sag with rising output current. You can short circuit the output of this type of transformer without tripping the circuit breakers in the house.

Arc welders and floresent light ballasts also use this type of transformer.

Some things are like gas turbines, what could be simpler? Try to build one though and you find out just how superficial that simplicity is.
Old 09-29-2005, 08:31 AM
  #42  
pbunn
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Default RE: Garden Tractor Battery

As stated - The battery charger transformers are current limited by their internal impedance. The high internal impedance is built in intentionally as stated above, where in a normal filament transformer, the internal impedance is made as low as possible by design. A lead acid batery has extremely low internl impedance - it looks like a short circuit to any voltage source higher than the battery terminal voltage. That being the case - something has to give and likely it will be a burned up transformer.

The published charger circuit by AS EE is an accident waiting to happen depending on what a novice builder might select as a transformer.

Most standard filament transformers are not even close to being current limiting and the transformer will overheat, melt out the potting and possibly catch fire.

The old selenium rectifier chargers use the internal resistance of the selenium rectifier as a current limiter. While the technology is dated - it worked very well in that application.

I have built maintenance type chargers that worked fairly well using a wall wart type supply.
For current limiting, I used a series resistor for current limiting and a resistor and LED in series shunting the limiting resistor as a charge indicator. It works, but a cheap charger from a discount store is probably a better choice.

BTW - Being and electrical engineer doesn't mean jack when it come to this type of stuff!
It all boils down to how you use what you learn in school.


I know -

Pat Bunn
BSEE
PE SC # 9801
licensed in over 15 states
Old 09-29-2005, 11:09 AM
  #43  
JNorton
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Default RE: Garden Tractor Battery

AS-EE
ORIGINAL: pbunn

BTW - Being and electrical engineer doesn't mean jack when it come to this type of stuff!
It all boils down to how you use what you learn in school.
See what you made me do Jnorton. I had to show you pictures just to get your brain thinking correctly. Usually I never have to resort to extreme measures on this forum becuase people know who I am and know what I do for a living, but you sir have no reasoning nor logical thinking so I had to go this far just to make you understand!!!!!!!!
Today is the first time I've these posts. We posted at about the same time. AS-EE Ive been employed as an Electrical Controls Engineer for the last 23 years. I refuse to come down to your level. I will say I was building battery chargers and power supplies in 1964 - were you even born then?

Pat,
Couldn't have stated it better myself. AS-EE just needs to get his hands dirty and build some stuff and gain some practical experience.
It would also help if he gained a little humility.
John
Old 09-29-2005, 11:27 PM
  #44  
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Default RE: Garden Tractor Battery

For current limiting, I used a series resistor for current limiting and a resistor and LED in series shunting the limiting resistor as a charge indicator. It works, but a cheap charger from a discount store is probably a better choice.

Thats how I set up my chargers (except the LED part) . The only problem is if I showed it with a resistor then people would get confused because they would not understand that some circuits are not in series or parallel nor the combination of the two. I would have to explain the superposition theorem which is above some people's heads and lets not even get into current sources.

Obvisously just using a center tap transformer with rectifiers was not easy enough and I did not take into account the internal impendence as you have mentioned.

Just a question are you reffering to the impendace as in at an angle with the reactive inductance of the transformer with a defined frequency of 60 Hertz or do you mean the transformer's coil resistance because in class we only use impendace when angles are involved and not if just measuring the DC resistance using a ohmmeter.

For my charger I use a shut off system of my design using a zener diode on the battery side connected to the transistor's BASE and the transisor's COLLECTOR connected to a relay with the relay's normally closed contact connected to the current limiting resistor. The downside of course is the transistor having to hold the relay open when the battery is at full charge which is a waste of energy.

Just like to add that I am still in College. The transformer part about their internal impendaces being different from one another, I did not know about. In my last semester class we only talked about how transformers had the same power output as the power input (ideally of course, not the real world) and that different turn ratios determined the voltages.
Old 09-30-2005, 04:53 AM
  #45  
JNorton
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Default RE: Garden Tractor Battery

For my charger I use a shut off system of my design using a zener diode on the battery side connected to the transistor's BASE and the transisor's COLLECTOR connected to a relay with the relay's normally closed contact connected to the current limiting resistor. The downside of course is the transistor having to hold the relay open when the battery is at full charge which is a waste of energy.
All this and what you posted isn't even what you use.

You don't have to explain superposition theorem or Kirkoffs law or anything else. What you should do is have a circuit you would use with a parts list detailing components and a pictorial wiring diagram wouldn't be out of place either. Better yet is a circuit you have tested and know works. The point is people will build things you post and if what you post is not well thought out you could hurt people.

Wait until you get further along in your career and you build and design the prototype and everything passes but the production version has a 30% failure rate. Your boss is breathing down your neck and accounting is screaming and you've no idea why. Believe me you'll learn about line variations, spikes, harmonics, dropouts, temperature dependencies, frequency limits, phantom grounding, unwanted coupling, ground planes - you get the idea. Engineering in the real world will teach you humility, there is never any perfect solution. There are always multitudes of solutions some better than others and always some accountant in the background wanting to make it cheaper.

John
Old 09-30-2005, 01:12 PM
  #46  
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Default RE: Garden Tractor Battery

JNorton:

I bit my tongue but I just couldn't allow that arrogance to go unchecked.

I graduated in 1973 and have seen that type of attitude for years. I'd love to see what the techs say about him behind his back.

Old 09-30-2005, 03:16 PM
  #47  
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Default RE: Garden Tractor Battery

Pat,
The arrogance just comes from being young and proud that he's mastered his studies so far. Wait till he runs 1500 feet of instrumentation cables and finds out he has ground loops. This vocation has ways of making you quite certain you should have gone into another profession. Some arrogance is needed or your defeated before you start but the people I've looked up to and enjoyed working with were almost always very depreaciative of their skill set. It was their co-workers who said just how good they were.
John
Old 09-30-2005, 03:48 PM
  #48  
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Default RE: Garden Tractor Battery

I have to say that this battery maintainer I bought is the greatest thing since sliced bread. I have no problems keeping my field box battery safely charged plus I put it on the wife's '84 CJ7 that's been sitting since April. In less than 24 hours it brought that battery up and dropped to maintain. Don't have to keep watching the amp meter on our big old charger from 20 years ago. So far it's been great!
Thanks!
JLK
Old 10-02-2005, 12:00 AM
  #49  
JPMacG
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Default RE: Garden Tractor Battery

Well, does anyone know what the capacity of a normal tractor battery (not the deep cycle kind) might be? I mean the capacity that will not damage the battery? Or did I miss this information somewhere in the previous posts?

I too have a tractor battery in my field box. I've been using the same $20 battery for 5 years - no problem. Just charge it every month or so with a 1A wall wart from my son's old electric riding jeep toy. I'm thinking of using the same battery for field charging, so it would be useful to know the practical capaciy.
Old 10-02-2005, 07:48 AM
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JNorton
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Default RE: Garden Tractor Battery

JPMacG ,

LarryC found this out by looking at the size of the battery. I couldn't find anything!

I did find some information on a U1 sized deep cycle battery. It was rated at 23 amp-hours.
I found a U1 size rating for a Champion brand garden tractor battery that was rated for 40 minutes @ 25 amps.
John

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