Battery Charging Question

[will-max dairy]

Thanks for the replies everyone.

Tractors are over 40 years old. All but one are 12V. Some are single batteries, a couple have two batteries in parallel.

With two batteries in parallel, there may be a couple of reasons to disconnect before charging; but mostly for diagnostic purposes. If you can't get good performance out of the two in parallel, even after charging. Disconnecting and charging one battery at a time may reveal, by their behavior on the charger, which battery is stronger or weaker.

 

[Texasmark]

I have/had reds, blues, and greens and never have even thought about removing the power connectors when attaching/using a charger.

 

[Fixingfarmer]

Most things new enough to be hurt by a battery charger or at least have an engineer scared of the battery charger have a 3 amp (or similar size not usually a big one) fuse that will pop to protect the ecm (usually engine ecm) and then you can charge the battery till it’s perfect when you try to start all it will do is crank crank crank and not light. You can even put batteries in at this point and machine will still not start but you can crank till these new batteries are drained. Ask me how I know.

Charge on the lowest amp setting you can and hook them up to the terminals before plugging the battery charger in and you will be fine.

Now to operate a welder on the tractor on the other hand you need to unhook the battery. There was a local welder I knew that would hook this fancy box to the battery before welding. I never did much research into what it was but if it was me I’d unhook the batteries it’s 5 grand if you are wrong and your little box isn’t hooked up right. At least I can’t afford that.

 

[DWF]

There is a guy on Heavy Equipment Forums that had his big truck, like a big dump truck welde on and now they can't get it started. Guy that welded it says he disconnected the batteries, but who knows?
DWF

 

[wore out]

There is a guy on Heavy Equipment Forums that had his big truck, like a big dump truck welde on and now they can't get it started. Guy that welded it says he disconnected the batteries, but who knows?
DWF

IMHO, with the battery cables disconnected, welding on a truck or tractor can induce a high voltage in the electrical system, even worse than if the battery was still connected to sort of "clamp" the voltage.

I disconnect the battery(s) and clamp the (+) and (-) cable terminals together with a ViceGrip to prevent that, instructions from one of the mfg's "back in the day" suggested that. I wish I had a copy at hand that I could post.

 

[farmersamm]

There's always some controversy when it comes to welding on a vehicle.

The upfitters manual for my older Ford tells you to disconnect the PCM, not the battery.

This makes some sense. No matter where your battery cables are, there will be voltage on the truck when you're welding. Striking an arc energizes the truck frame. The work lead provides a return to the welder, but you really never know where else the voltage will go on that frame. But it's there.

But what everybody, including myself, fails to really explain is................. Rig welders generally have a vise on the welding bed....which they use to hold stuff that's welded on. That stray voltage is still wandering all over the truck frame. I've never seen a guy scurry up under the hood to disconnect anything before welding.

I'm thinking that most PCM's are diode protected. This would prevent the stray voltage from completing any kind of circuit through that PCM. At least I think it would?

 

[Texasmark]

On the necessity to disconnect or not thing:

If the battery can put out 300 amperes with 10 volts across the terminals....easily for a battery fully charged in good condition, the internal impedance (resistance) has to be mighty low....do the math...R= V/I.....10/300 is fractional Ohms so it would take some powerful amperes for an arc current, generated elsewhere on the vehicle to develop any appreciable change in the battery condition, especially when welding amperage runs usually around 200A or less....much less for the welding I have to do.... and is done in a tight loop around where the welding is being accomplished....normally the welder return is at the welding site....is for me. I have a load tester and 10/300 is my pass/fail point for my batteries in service in cars, PUs, boats, and tractors.

 

[ss55]

When charging a battery in a tractor with a regular charger or trickle charger, I have always unhooked the battery cables and put the charging clamps on the battery posts.

I was suggested to me, with these old tractors with no computers, etc., that disconnecting the battery was not necessary.

How do you hook up a battery in your old tractor?

Just curious.

Thanks!

When a battery is weak or there is a parasitic loss somewhere, I install a quick disconnect on the battery ground terminal. That prevents the battery from discharging while parked and also makes it easy to disconnect the ground when charging.

If the maximum charger amps is smaller than what the generator or alternator can make I rarely disconnect the battery when charging. If the charger is bigger, yes I disconnect the battery.

 

[Janicholson]

Two items not mentioned are voltage and frequency. Some welders (all types can be considered) have open circuit voltage of 40+ volts and that is certainly enough to force its way past all but an air gap protection. High frequency start, or continuous, can also generate stray induced voltages in wiring (even at the rear bumper!) One takes one's chances. Jim

 

[JMOR]

My trickle charger/maintainer is hard wired to battery with 120 plug hanging by grill. Just drive in and plug in