Yesterday's Tractor Co. Tractor Parts for All Brands
Click Here or call 800-853-2651 
   Allis Chalmers Case Farmall IH Ford 8N,9N,2N Ford
   Ferguson John Deere Massey Ferguson Minn. Moline Oliver
 
Marketplace
Tractor Manuals
Tractor Parts
Classified Ads
Photo Ads

Community
Discussion Forums
Project Journals
Tractor Town
Your Stories
Show & Pull Guide
Events Calendar
Hauling Schedule

Galleries
Tractor Photos
Implement Photos
Vintage Photos
Help Identify
Parts & Pieces
Stuck & Troubled
Vintage Ads
Community Album
Photo Ad Archives

Research & Info
Articles
Tractor Registry
Tip of the Day
Safety Cartoons
Tractor Values
Serial Numbers
Tune-Up Guide
Paint Codes
List Prices
Production Nbrs
Tune-Up Specs
Torque Values
3-Point Specs
Glossary

Miscellaneous
Tractor Games
Just For Kids
Virtual Show
Museum Guide
Memorial Page
Feedback Form

Yesterday's Tractors Facebook Page

Related Sites
Tractor Shed
TractorLinks.com
Ford 8N/9N Club
Today's Tractors
Garden Tractors
Classic Trucks
Kountry Life
Enter your email address to receive our newsletter!

subscribe
unsubscribe
  
Tractor Talk Discussion Forum

Re: adding batteries together?

[Show Entire Topic]  

Author  [Modern View]
Texasmark1

01-14-2014 16:47:17
172.242.14.143



Report to Moderator

Problem with 6 volt batteries in series vs a 12v battery, or in the case of 2 12v batteries in parallel is the available current which is partially limited by the batteries internal resistance.

Internal resistance is realized by the difference between the terminal voltage of a battery at rest, vs a battery supplying current to a load. Older and more sulphated up the battery, the worse the internal resistance.

Example: Using round numbers, a fully charged battery reads 12v terminal to terminal. You push your start button and your battery is required to supply 100-150-200 amperes to the starter. Measuring the terminal voltage of the battery under that load and using ohms law tells you what the internal resistance of the battery is.

Ohms law is the association of voltage, current and resistance in an electrical circuit. For DC (direct current circuits, like battery circuits) current flow (which is what does the work) is the result of available (applied) voltage divided by circuit resistance; voltage is in volts and resistance is in ohms. An ohm is defined as a voltage drop of one volt across one ohm of resistance with a current of one ampere flowing.

So if you have 100 amperes required (small engine) to roll your starter and each of 2 6v or a single 12v battery have an internal resistance of 0.01 ohm, the voltage dropped across the battery for the 6 volt pair would be:

IxR =V drop. So for 0.01 ohm (which is nothing) at 100 amperes you would have 1 volt dropped across each battery for a total loss of 2v. Meaning the resultant available voltage to roll the starter would only be 10v. Butttttt 10v is needed AT the starter and you have wiring losses between the battery and the starter.

However, the 12v battery would only have one loss of 1v and would have 11 v available to spin the starter meaning it could accommodate 1v of drop in the wiring between the battery and the starter and still be able to supply the minimum voltage of 10v to the starter.

If you used 2 12v batteries in parallel (side by side, + to + and - to -), you would halve the resistance loss and would have 1.5 volts available for the wiring harness loss.

I had a 4230 JD tractor. Had a 6v on each side of the tractor wired in series.....like you are wanting to do. In short it was a dog to start.

I replaced the 6v batteries with 12v which were of the same physical size, wiring them in parallel (as described above) quartering the resistance rather than doubling it. I guarantee you that diesel would start before you could turn the key loose and at anything above 20 degrees you needed no starting aid.

Mark

[Reply]   [No Email]
Indiana Ken

01-14-2014 17:23:29
66.249.234.135



Report to Moderator
 Re: adding batteries together? in reply to Texasmark1, 01-14-2014 16:47:17  
Yes, when you add cells the internal resistance of a lead acid battery typically increases. However, the 12 volt battery (6 cells versus 3 cells for the 6 volt) starts out with a higher resistance. Some manufactures list the internal resistance along with the other battery data. I am looking at the spec sheet for Optima Batteries: a 12 volt battery with 800 CCA has an internal resistance of 0.0030 ohms which compares to their 6 volt battery with 800 CCA with an internal resistance of 0.0019 ohms.

Since the effect is rather small (0.0030 versus 0.0038) a pair of the 6 volt batterys could be an option if the price is right.

[Reply]  [No Email]
Texasmark1

01-15-2014 05:27:01
172.242.14.143



Report to Moderator
 Re: adding batteries together? in reply to Indiana Ken, 01-14-2014 17:23:29  
Well, I am more concerned with the midlife resistance when the battery starts sulphating up and the exterior wiring is getting corroded up sort of thing. Just using the logic of resistors in series vs in parallel and the miniscule circuit resistance that can be tolerated and get a good start.

I didn't check the resistance on the 6 volt batteries, nor the old circuit wiring when I replaced them, but I guarantee you the new setup made one whopping difference.

Mark

[Reply]  [No Email]
[Show Entire Topic]     [Options]  [Printer Friendly]  [Posting Help]  [Return to Forum]   [Add a Reply]

Hop to:
TRACTOR   PARTS TRACTOR   MANUALS
Same-Day Shipping! Most of our stocked parts ship the same day you order (M-F).  Expedited shipping available, just call!  Most prices for parts and manuals are below our competitors.  Compare our super low shipping rates!  We have the parts you need to repair your tractor.  We are a Company you can trust and have generous return policies!   Shop Online Today or call our friendly sales staff toll free (800) 853-2651. [ More Info ]

Home  |  Forums


Copyright © 1997-2014 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy

TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters