Battery Question

[c23380]

One quick way to tell what you have is hooking you meter to your battery clamps and turn on your lights. Usually a bad battery will begin to drop voltage and fal below 12.5 volts within a minute or so.A good battery will remain 12.5 to 13 volt for 5 to 10 minutes befor dropping. The specific gravity is a sure way to test, as soundguy suggest, but if you do not have a tester The meter trick will lead you in the right direction, Mike

 

[Soundguy]

Drphil.

if the tractor still has a generator, and does NOT have an alternator, then yeah.. you can swap the battery to negative ground, and then repolarize the genny by jumpering bat to field for a second.

soundguy

 

[ampsucker]

the battery absolutely does not care which pole is ground. you can design the system either way. in a DC system, the ground is just using the metal in the frame as the conductor for simplifying the wiring.

why change it?

if you do want to change it, in addition to changing the the connections on the charging system, don't you have to change the polarity of your starter motor so it doesn't crank the engine backwards? DC motors are directional aren't they? and also your meters if you have any on the tractor? ammeter and volt meter would try to show negative if not rewired.

i would just leave it the way it is.

amp

 

[Soundguy]

Amp...

Permanent field dc motors spin backwards when you reverse polarity..

fortunately that ford starter we are talking about has a non permanent field 'coil' ! polarity swaps on it just the same as the armature.. thus the same rotational direction is achieved positive or negative ground.


Also, when OEM,.. no amp gauge or voltage gauge oem on that machine.. just a charge indicator lamp... lamp on = discharge, lamp off=charge.. was designed to work on the lucas regulator.. but is EASILLY made to work on a gm 3-wire alternator so that the lamp functions the same way.

the machine was designed and rolled out of the factory as negative ground.. best to run it THAT way. less problems with jumps and chargers from non observant individuals down the road.

soundguy

 

[ampsucker]

thanks for the education! i always like learning something new....

;-)

amp

 

[ArTrvlr]

When you buy a new battery make sure you get an AGM (absorbed glass mat) battery.

Spend a few bucks more than you would for a trickle charger and get a "battery tender" or other brand of maintainer. The newer ones are 3 stage with a brain. A cheap trickle charger will toast the battery over a long period unless it is voltage and current regulated. I once tried placing a trickle charger on a timer but that was even worse. It had leakage when off.

I'm amazed that we have lead acid batteries at work (phone company) that are 30 years old. They are always float charged and don't get too hot or too cold.

I've got a '71 Ford 4000 tractor. It won't start. I figured the battery was bad (It's 6 years old)

But when I checked the battery with a meter it showed good with 12.6 volts.

Maybe I'm just stupid, but....can a battery be fully charged but not have the amps to start the engine?

I agree that the AGM (Optima, Odyssey, etc.) batteries are worth the extra cost. Just the lack of acid leakage and resulting corrosion is worth a lot to me.

I have had good luck so far with the Harbor Freight battery maintainers. I believe they are more than a trickle charger, at least they claim to stop charging when the battery is fully charged, and they claim to charge again when voltage drops. I say "claim" because HF makes some questionable claims. But, as with any HF tool, the only way to know is to try it. I have three old cars that I drive very infrequently, always leaving a HF charger on each one while it is parked. Knock on wood, but in about three years, (all with batteries two to three years old when I started using the HF chargers) I have never had a dead battery, And never had one overcharged, at least not to the point of loosing water. This is what I use: Harbor Freight Tools - Quality Tools at the Lowest Prices
It may not have as sophisticated electronics as a Battery Tenda brand, but it sure costs a lot less. I got some of mine on sale for a couple of bucks.

One other thing those phone company batteries don't have to contend with that auto/truck/Ag batteries do, is vibration.

DrPhil, did you get the tractor started???? Was it the battery or something else? Inquiring minds want to know!