What size Battery?

I am planning on converting my B to 12V this spring. Who makes a 12V battery that will fit in the battery box? Part number would help, Thanks.....

I found that measuring your inside box size then refer to the following chart to find batteries, (by number), that will fit. I always buy the highest CCA, (cold cranking amps, (current)), that will fit.

Last post reminded me of something.  Worked with a fellow that used to work for exide making batteries for 10 years.  He always told me to buy the lowest CCA that would do the job.  He said that the lead plates in a low CCA battery were thick solid lead plates.  The lead plates are separated with a fiberglass type composite.  To get the higher cranking amps out of a battery of the same case size they have to have more surface area on these plates.  So instead of being solid lead plates they are perforated, very similar to expanded mesh steel.  These plates rub against the partitions and with their sharp edges wear through and short out, or even break away from the supporting grid in higher vibration/shock load applications such as a tractor.  He stated that High CCA batteries finally and catastrophically die.  The low CCA batteries eventually "die" because of the plates being sulfated, and are rebuilt buy putting them on a special charger and desulfating them and replacing the electrolyte solution in them. 

To add on to this, most tractors and older trucks have poor starting performance because of poorly maintained systems.  Corrosion on battery cables, the clamp on lead battery terminals, and poorly maintained grounds all contribute to poor starting ability especially in cold weather.  People attempt to make up for it with high CCA.

The cheap lead terminals are the worst offenders.  The style sold by auto parts stores that clamp onto the cable with 2 bolts and small steel plate.  Corrosion builds up, lead only is 7% conductive. 

The copper solder or crimp on style terminals  are much better.  While not Ideal, the hammer type crimper's are not very expensive and work well if you take your time.  Tin the cable, coat with a dielectric grease, crimp on terminal, and then use adhesive heat shrink tubing to secure.  I like soldering best, just don;t use acid core solder.  I like a little silver in the solder for decreased resistance.  Again use shrink tubing.  If you don't know how to solder correctly have someone teach you as a bad solder joint is not good.  
Check grounds regularly also. 

 We had an RC that was changed to 12 volt & the gear on the starter that hit the ring gear was always ground off, don't know it it was because of being 12 volt & much faster or if the other guy who used it alot just ground it off. Maybe someone else had the same problem or can shed some light just in case???...Harvey

AC - Just a word of caution.  Make sure that any battery you chose that you have room for a 1/8 plastic sheet or plywood to place between the batt terms and the cover.  Otherwise  in rough terrain the battery could short out.  I've seen it happen.  - AL

same as before group 26

I get that question asked frequently from customers looking to do a 12 conversion when they call and inquire about our 12V conversion wiring systems for these Tractors. The group 26 should do the job as mentioned. Its a tad smaller than the 6V group 1 battery that would normally go in the box. A group 25 will also fit. Its chassis size is almost the same as the group 1. A group 35 will also fit, being its the same dimensions as its cousin the 25, but the posts are reversed, so keep that in mind. All the listed groups I mentioned have a good CCA rating to do the job for stock engines. An optional Battery also to use would be a group 526. I used this one in my IB's Battery box being I have some extra accessories on the IB, and a little more reserve power couldn't hurt. The chassis on the 526 is even a tad smaller than the 26, so make sure that if you use this group Battery, you insulate around it also so it doesn't bang around. Al also made a good point. No matter what Battery group you decide to choose, make sure its insulated from the Battery box or it could look like the Fourth of July under the lid! When it comes to CCA's with these Tractors and their stock engines, CCA's really aren't an issue due to the stock engines low compression. The condition of the cranking system and its components are more important to use the CCA's you have efficiently. An issue comes along when these engines are modified for pulling because higher compression ratio's and much larger cubic inches are established. Obviously, when these engines have bigger lungs, you need more "umph" to turn em' over.  HTH
Steve@B&B

One thing you need to make sure of,is that you have the right size battery cables on that six volt battery. Most people these days go to the local auto parts store and purchase 4 gauge cables. They won't carry the amperage of a six volt battery. A six volt battery usually has twice the cranking amps of a similar twelve volt. You should have at least 2 gauge or larger cables to make that tractor crank well.

Brett