Operating w/o Battery Installed

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viscous

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Jun 6, 2020
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I posted a thread in the lawn mower section (see below), but I thought I'd ask more generally here: can a vehicle be harmed by operating it without a battery installed? Does this even hold true for a garden tractor?

Operate JD x540 w/o Battery

JD x540 battery no longer holds a charge. Can start unit by connecting 200-amp plug-in charger/starter. Battery gets hot during operation. (Why? Perhaps just engine heat?) Would it be fine to remove the battery, start unit using plug-in starter, and operate unit without battery installed? Any...
bobistheoilguy.com
 
Depends on the vehicle, but I can confirm my Grand Caravan won’t run at all without a battery… or with a battery that has a shorted cell or 2. Wouldn’t run under 2,000rpm, lights flickering, gauges absolutely freaking out and moving erratically, warning lights flickering on and off etc etc.
 
All I have ever heard regarding this, is "back in the day", you could test if your alternator was operating in your car, by disconnecting the positive battery terminal while the engine was running. If the car kept running, your alternator was putting out power. If your engine quit, it wasn't.

Fast forward to today's modern vehicles with all the "techno wizardry" they incorporate, and they tell you that is the absolute worst thing you can possibly do.

And if you do it, you will for sure and for certain damage something electrical / electronic in your vehicle. I have no idea how that transfers to lawn and garden equipment. If it was me, I wouldn't do it out of fear.
 
Voltage regulators were once electromechanical. They absorbed shocks by switching.
Today's "techno wizardry" can succumb to the shock of 100% charging instantaneously.
Same reason "running donor car" jump starts are verboten today.
 
Skippy722 said:
Depends on the vehicle, but I can confirm my Grand Caravan won’t run at all without a battery… or with a battery that has a shorted cell or 2. Wouldn’t run under 2,000rpm, lights flickering, gauges absolutely freaking out and moving erratically, warning lights flickering on and off etc etc.
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My 2000 Jeep Cherokee is like that. It wouldn't start one morning (11 or 12 years ago) and it seemed to crank fine but a bit slow. Someone told me to jump it off of a pack or another car. I initially thought they were nuts. Sure enough, hooked it up to my car and it started right up. As soon as I unhooked the jumper cables it shut right off. The battery had a bad cell.

And if I pull the battery cable with it running, it'll shut off. But other 2000 cherokees we've had floating around will run without the battery. It does have a new alternator too.
 
viscous said:
I posted a thread in the lawn mower section (see below), but I thought I'd ask more generally here: can a vehicle be harmed by operating it without a battery installed? Does this even hold true for a garden tractor?
Click to expand...
No. It won't hurt a thing to run the garden tractor without a battery. The ignition and charging systems are completely separate. The ignition system is a magneto and doesn't use the battery or electrical system. The alternator is very crude, low output, unregulated, and is really only used to keep the battery charged and in some cases to power lights, an electric clutch, and/or fuel solenoid.
Road-going cars and trucks are an entirely different matter. It is a very bad idea to run a vehicle with the battery disconnected or with a bad/dead battery. In many cases the vehicle won't even run as a significant percentage of today's vehicles have battery excited alternators.
 
What wag123 said. Older cars also needed the battery to stabilize the alternator. Disconnecting the battery could cause the alternator to rail at something higher than normal and start zapping things. My MG has a big warning label under the hood that specifically says to never disconnect the battery while the engine is running so you don't zap bulbs, ignition modules, the radio, etc.. I know someone who did this on a motorcycle and he ended up replacing several bulbs afterward.
 
Dave Sherman said:
My MG has a big warning label under the hood that specifically says to never disconnect the battery while the engine is running so you don't zap bulbs, ignition modules, the radio, etc.. I know someone who did this on a motorcycle and he ended up replacing several bulbs afterward.
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I had a 70's El Camino that I pulled the battery while running. The radio never worked again.
 
wag123 said:
No. It won't hurt a thing to run the garden tractor without a battery. The ignition and charging systems are completely separate. The ignition system is a magneto and doesn't use the battery or electrical system. The alternator is very crude, low output, unregulated, and is really only used to keep the battery charged and in some cases to power lights, an electric clutch, and/or fuel solenoid.
Road-going cars and trucks are an entirely different matter. It is a very bad idea to run a vehicle with the battery disconnected or with a bad/dead battery. In many cases the vehicle won't even run as a significant percentage of today's vehicles have battery excited alternators.
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Thank you for addressing the garden tractor, which is my primary concern. Responses here have varied, but perhaps most are addressing automobiles rather than garden tractors.

The battery gets rather warm/hot. Could this be because it's dead, or more likely just because it's located under the hood next to the radiator and engine?

I was concerned about the heating, which is why I was considering removing the battery. I do not plan to purchase a new battery at this time. Shall I operate with the dead battery in place, or remove it?
 
viscous said:
Thank you for addressing the garden tractor, which is my primary concern. Responses here have varied, but perhaps most are addressing automobiles rather than garden tractors.

The battery gets rather warm/hot. Could this be because it's dead, or more likely just because it's located under the hood next to the radiator and engine?

I was concerned about the heating, which is why I was considering removing the battery. I do not plan to purchase a new battery at this time. Shall I operate with the dead battery in place, or remove it?
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Leave the battery in place but disconnect the ground (negative) cable. The battery might have an internal short which could burn-out the alternator or rectifier.
 
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If the battery gets hot, it likely has an internal short. Be careful around it, a short can cause it to blow up (igniting the nitrogen present from charging), and spray acid all over you, your face, and your eyes!
 
The old mechanical regulators were quite quick in responding to changes in voltage. Electronic regulators, the earlier ones, did a decent job of it as well. But with more electronics, and significantly more powerful alternators, the sheer size and potential of these systems became more capable of spiking voltages. Ramp/up/down strategies and higher filtering of surges protects electronics, but also seems to numb the response time of alternators. I think they are still quick to reduce output, to avoid damage, but slow to ramp up. two things play against - 1 - slow ramp up won’t hold power as soon as a new load comes on, 2- since the regulator is now hidden within the ECU, probably behind its own voltage protection, the alt could be a little slow (comparatively) to reduce power when a load is removed.

im actually surprised we aren’t seeing a couple of “small” stiffening capacitors in the mains these days.
 
wag123 said:
Leave the battery in place but disconnect the ground (negative) cable. The battery might have an internal short which could burn-out the alternator or rectifier.
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I think I'll operate with the ground disconnected, for now, so as to mitigate the risk of an internally shorted battery. As some have stated, a new battery would be best. However, disconnecting the ground would serve as a band-aid solution.

The engine-start function on the charger provides 200 amps (many more than necessary). Any concerns using this powerful device on the small engine of the garden tractor? The tractor is a 12V system, as is the plug-in starter. I've started it this way a handful of times, and it seems to work fine.
 
bullwinkle said:
If the battery gets hot, it likely has an internal short. Be careful around it, a short can cause it to blow up (igniting the nitrogen present from charging), and spray acid all over you, your face, and your eyes!
Click to expand...

Generally only if the electrolyte is below the level of the plates will that happen. If it's full any sparks that might be caused by a shorted cell will be under electrolyte where they can't ignite hydrogen.
 
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