BatteryDear Ole Mechanic;

I know you wrote about batteries awhile back, but I think that was about lawn-mower batteries and I have some tractor-battery questions.  My Dad told me to use rain water or distilled water if the battery got low on liquid, because well-water has too many minerals in it.  Was he right?  Are tractor batteries built better than car batteries so that they can withstand the constant vibration and jolting?  What is the best thing to use on battery terminals to prevent that green corrosion buildup?  When replacing a battery, should I buy an exact replacement or is there an advantage in stuffing in the biggest d**n battery that I can afford?  Is it smart to use one of the float-chargers or chare-maintainers to keep a battery fully charged all the time and ready for use?  If one is used, will it make the battery last significantly longer? 

I know this is a bunch of questions but they are all about my tractor battery.    Thanks

Keepin’ the Tractor Ready
 

Dear Tractor Ready;

Whew, you really do want Battery 101, don’t you?  Well, why not.  The article on lawn-mower batteries was published quite awhile ago, ago, so his article will have some of the same information as that article.

Yes, Dear-Ol- Dad was right.  There are minerals dissolved in well water, and some of those minerals will react with the sulfuric acid that is in the liquid electrolyte solution in the battery.  When that reaction occurs, there is less acid for the plates in the battery to work with to make electricity.  Distilled, rainwater or de-mineralized (purified) water is the best thing to use.  However, well water is better than letting the electrolyte level get below the top of the plates.  Some of the bottled “spring” water that is sold in stores is actual spring water and it can have minerals in it just like well water.

Tractor batteries are normally built with a heavier construction than car batteries.  Since there is not a worry about the gas-mileage weight penalty, the cases are heaver and a stronger plate construction is used.  Because there is less demand for tractor batteries than for car batteries, they are going to cost more.  It is the economy of mass production that keeps car battery prices lower.  If you are pounding through the fields tilling, cultivating, shredding and doing heavy work, then a tractor battery would probably be best and cheaper in the long run.  If you are working in smoother areas and doing lighter work, such as in an orchard, then a car battery might perform just fine. Even though the battery might need more frequent replacement, it might be cheaper in the long run.  If your tractor is a restored antique or what I call a pet tractor and is used only in parades and such, then a car battery will work fine as long as it can be hidden so as not to detract from the restoration.

Terminal corrosion is a problem that has been around as long as batteries.  There are almost as many theories as to how to prevent corrosion as there are tractor operators.  Important factors are clean battery-posts and clean-terminal clamps properly tightened.  A less than tight connection will corrode quickly.  After the posts and clamps are clean and tight, some folks apply a liberal coat of gun grease.  That helps keep moisture out and slows corrosion.  The treated green and red felt washers that go around the post before the terminal is clamped on will also help control the moisture and slow corrosion.  Putting pennies on the top of the battery near the terminals is another theory.  The copper should corrode before the post and clamp and sacrifice itself before the terminal corrodes--at least that is the theory.  Some folks will mask off the battery and spray paint the post and terminal after they are tightened.  The paint should reduce moisture out and corrosion down.  There are spray corrosion cleaners and preventers that are available in auto and tractor supply stores.  They temporarily neutralize the acid content of the moisture and loosen corrosion, so it is easier to clean off.  The real problem is that electricity is flowing across a less than perfect metal to metal connection, with a slightly-acidic moisture around on the top of the battery.  This will cause corrosion.  In short, cleaning the terminals should be regular maintenance, followed by the treatment of your choice to help slow the corrosion.  Keeping the top of the battery clean and dry will also help, but because of the charging and discharging action of the electrolyte, there will normally always be some acidic moisture on top of the battery.

Now for the exact replacement or "the biggest d**n battery I can afford” question.  Even tractor manufacturers are cost-sensitive, and a bigger battery will cost more and that cost must be included in the selling price.  They are going to install the smallest battery that will give satisfactory performance under “normal” service conditions. You will probably get better service life out of a bigger battery.  I say probably, because if you can not get it mounted securely, then the extra bouncing and banging around will shorten the life of the battery considerably and any possible longer-life advantage will quickly be lost.  Also, make sure that there is adequate ventilation around the battery.  When being charged, a battery gives off hydrogen and oxygen.  If those gasses build up because of inadequate ventilation they can be explosive.  Usually this is not a problem in a tractor as they tend to be open, but it is something that you should keep in mind.  You definitely need to remember this if the battery is in a case.  Also make sure that the bigger battery does not get the terminals too close to other components.  A shorted-out battery tends to end the life of the battery quickly and sometimes explosively.

A float-charger or charge-maintainer seems like a good idea and it is a lot better than running a battery down and then trying to save it by charging it back up.  There are draw backs to them, as many people hook them up and then think that they can just forget it for many months.  At least that is what I did when I first got one.  When I later went to use the battery, it was only about one-half full of electrolyte.  The constant--although small--charging current had converted the electrolyte water (H2O) into hydrogen (H) and oxygen (O).  Even though I added distilled water, it had been below the top of the plates too long and I had to replace the battery.  If you are going to use a charge-maintainer, don’t forget to check the electrolyte level at least monthly.  What I do now is hook the float charger up for one or two days each month and this has helped lengthen the life of batteries that I don’t use very often.  Once in a while I still forget and leave the charger on for a week or more.  When that happens, I make darn sure that I check the electrolyte level.

I think that I have covered all of your questions, but there is one thing that I have not mentioned--the charging system.  Make sure that it is working properly.  If you have questions about the charging system, be sure to tell me if it is a six volt or a twelve volt system and if it has a generator or an alternator.  If it is a six volt system or has a generator, then I will also need to know the make of the tractor or vehicle.  That information is essential and needed if you don't want me to give you information that will fry the regulator.

Herr Professor Nuzanbolts